"""This module implements input and output processing from Gaussian."""

from __future__ import annotations

import re
import warnings
from typing import TYPE_CHECKING

import numpy as np
import scipy.constants as cst
from monty.io import zopen
from scipy.stats import norm

from pymatgen.core import Composition, Element, Molecule
from pymatgen.core.operations import SymmOp
from pymatgen.core.units import Ha_to_eV
from pymatgen.electronic_structure.core import Spin
from pymatgen.util.coord import get_angle
from pymatgen.util.plotting import pretty_plot

if TYPE_CHECKING:
    from pathlib import Path
    from typing import Self

    from pymatgen.util.typing import PathLike

__author__ = "Shyue Ping Ong, Germain Salvato-Vallverdu, Xin Chen"
__copyright__ = "Copyright 2013, The Materials Virtual Lab"
__version__ = "0.1"
__maintainer__ = "Shyue Ping Ong"
__email__ = "ongsp@ucsd.edu"
__date__ = "8/1/15"


float_patt = re.compile(r"\s*([+-]?\d+\.\d+)")


def read_route_line(route):
    """
    read route line in gaussian input/output and return functional basis_set
    and a dictionary of other route parameters.

    Args:
        route (str) : the route line

    Returns:
        functional (str) : the method (HF, PBE ...)
        basis_set (str) : the basis set
        route (dict) : dictionary of parameters
    """
    scrf_patt = re.compile(r"^([sS][cC][rR][fF])\s*=\s*(.+)")
    multi_params_patt = re.compile(r"^([A-z]+[0-9]*)[\s=]+\((.*)\)$")
    functional = basis_set = None
    route_params = {}
    dieze_tag = None
    if route:
        if "/" in route:
            tok = route.split("/")
            functional = tok[0].split()[-1]
            basis_set = tok[1].split()[0]
            for tok in [functional, basis_set, "/"]:
                route = route.replace(tok, "")

        for tok in route.split():
            if match := scrf_patt.match(tok):
                route_params[match[1]] = match[2]
            elif tok.upper() in ["#", "#N", "#P", "#T"]:
                # does not store # in route to avoid error in input
                dieze_tag = "#N" if tok == "#" else tok
                continue
            elif match := re.match(multi_params_patt, tok.strip("#")):
                pars = {}
                for par in match[2].split(","):
                    p = par.split("=")
                    pars[p[0]] = None if len(p) == 1 else p[1]
                route_params[match[1]] = pars
            else:
                d = tok.strip("#").split("=")
                route_params[d[0]] = None if len(d) == 1 else d[1]

    return functional, basis_set, route_params, dieze_tag


class GaussianInput:
    """A Gaussian input file."""

    # Commonly used regex patterns
    _zmat_patt = re.compile(r"^(\w+)([\s,]+(\w+)[\s,]+(\w+)){0,3}[\-\.\s,\w]*$")
    _xyz_patt = re.compile(r"^(\w+)[\s,]+([\d\.eE\-]+)[\s,]+([\d\.eE\-]+)[\s,]+([\d\.eE\-]+)[\-\.\s,\w.]*$")

    def __init__(
        self,
        mol,
        charge=None,
        spin_multiplicity=None,
        title=None,
        functional="HF",
        basis_set="6-31G(d)",
        route_parameters=None,
        input_parameters=None,
        link0_parameters=None,
        dieze_tag="#P",
        gen_basis=None,
    ):
        """
        Args:
            mol: Input molecule. It can either be a Molecule object,
                a string giving the geometry in a format supported by Gaussian,
                or ``None``. If the molecule is ``None``, you will need to use
                read it in from a checkpoint. Consider adding ``CHK`` to the
                ``link0_parameters``.
            charge: Charge of the molecule. If None, charge on molecule is used.
                Defaults to None. This allows the input file to be set a
                charge independently from the molecule itself.
                If ``mol`` is not a Molecule object, then you must specify a charge.
            spin_multiplicity: Spin multiplicity of molecule. Defaults to None,
                which means that the spin multiplicity is set to 1 if the
                molecule has no unpaired electrons and to 2 if there are
                unpaired electrons. If ``mol`` is not a Molecule object, then you
                 must specify the multiplicity
            title: Title for run. Defaults to formula of molecule if None.
            functional: Functional for run.
            basis_set: Basis set for run.
            route_parameters: Additional route parameters as a dict. For example,
                {'SP':"", "SCF":"Tight"}
            input_parameters: Additional input parameters for run as a dict. Used
                for example, in PCM calculations. e.g. {"EPS":12}
            link0_parameters: Link0 parameters as a dict. e.g. {"%mem": "1000MW"}
            dieze_tag: # preceding the route line. E.g. "#p"
            gen_basis: allows a user-specified basis set to be used in a Gaussian
                calculation. If this is not None, the attribute ``basis_set`` will
                be set to "Gen".
        """
        self._mol = mol

        # Determine multiplicity and charge settings
        if isinstance(mol, Molecule):
            self.charge = charge if charge is not None else mol.charge
            n_electrons = mol.charge + mol.nelectrons - self.charge
            if spin_multiplicity is not None:
                self.spin_multiplicity = spin_multiplicity
                if (n_electrons + spin_multiplicity) % 2 != 1:
                    raise ValueError(
                        f"Charge of {self.charge} and spin multiplicity of {spin_multiplicity} is"
                        " not possible for this molecule"
                    )
            else:
                self.spin_multiplicity = 1 if n_electrons % 2 == 0 else 2

            # Get a title from the molecule name
            self.title = title or self._mol.formula
        else:
            self.charge = charge
            self.spin_multiplicity = spin_multiplicity

            # Set a title
            self.title = title or "Restart"

        # Store the remaining settings
        self.functional = functional
        self.basis_set = basis_set
        self.link0_parameters = link0_parameters or {}
        self.route_parameters = route_parameters or {}
        self.input_parameters = input_parameters or {}
        self.dieze_tag = dieze_tag if dieze_tag[0] == "#" else f"#{dieze_tag}"
        self.gen_basis = gen_basis
        if gen_basis is not None:
            self.basis_set = "Gen"

    @property
    def molecule(self):
        """Molecule associated with this GaussianInput."""
        return self._mol

    @staticmethod
    def _parse_coords(coord_lines):
        """Helper method to parse coordinates."""
        paras = {}
        var_pattern = re.compile(r"^([A-Za-z]+\S*)[\s=,]+([\d\-\.]+)$")
        for line in coord_lines:
            if match := var_pattern.match(line.strip()):
                paras[match[1].strip("=")] = float(match[2])

        species = []
        coords = []
        # Stores whether a Zmatrix format is detected. Once a zmatrix format
        # is detected, it is assumed for the remaining of the parsing.
        zmode = False
        for line in coord_lines:
            line = line.strip()
            if not line:
                break
            if (not zmode) and GaussianInput._xyz_patt.match(line):
                match = GaussianInput._xyz_patt.match(line)
                species.append(match[1])
                tokens = re.split(r"[,\s]+", line.strip())
                if len(tokens) > 4:
                    coords.append([float(i) for i in tokens[2:5]])
                else:
                    coords.append([float(i) for i in tokens[1:4]])
            elif GaussianInput._zmat_patt.match(line):
                zmode = True
                tokens = re.split(r"[,\s]+", line.strip())
                species.append(tokens[0])
                tokens.pop(0)
                if len(tokens) == 0:
                    coords.append(np.array([0, 0, 0]))
                else:
                    nn = []
                    parameters = []
                    while len(tokens) > 1:
                        ind = tokens.pop(0)
                        data = tokens.pop(0)
                        try:
                            nn.append(int(ind))
                        except ValueError:
                            nn.append(species.index(ind) + 1)
                        try:
                            val = float(data)
                            parameters.append(val)
                        except ValueError:
                            if data.startswith("-"):
                                parameters.append(-paras[data[1:]])
                            else:
                                parameters.append(paras[data])
                    if len(nn) == 1:
                        coords.append(np.array([0, 0, parameters[0]]))
                    elif len(nn) == 2:
                        coords1 = coords[nn[0] - 1]
                        coords2 = coords[nn[1] - 1]
                        bl = parameters[0]
                        angle = parameters[1]
                        axis = [0, 1, 0]
                        op = SymmOp.from_origin_axis_angle(coords1, axis, angle)
                        coord = op.operate(coords2)
                        vec = coord - coords1
                        coord = vec * bl / np.linalg.norm(vec) + coords1
                        coords.append(coord)
                    elif len(nn) == 3:
                        coords1 = coords[nn[0] - 1]
                        coords2 = coords[nn[1] - 1]
                        coords3 = coords[nn[2] - 1]
                        bl = parameters[0]
                        angle = parameters[1]
                        dih = parameters[2]
                        v1 = coords3 - coords2
                        v2 = coords1 - coords2
                        axis = np.cross(v1, v2)
                        op = SymmOp.from_origin_axis_angle(coords1, axis, angle)
                        coord = op.operate(coords2)
                        v1 = coord - coords1
                        v2 = coords1 - coords2
                        v3 = np.cross(v1, v2)
                        adj = get_angle(v3, axis)
                        axis = coords1 - coords2
                        op = SymmOp.from_origin_axis_angle(coords1, axis, dih - adj)
                        coord = op.operate(coord)
                        vec = coord - coords1
                        coord = vec * bl / np.linalg.norm(vec) + coords1
                        coords.append(coord)

        def _parse_species(sp_str):
            """
            The species specification can take many forms. e.g.
            simple integers representing atomic numbers ("8"),
            actual species string ("C") or a labelled species ("C1").
            Sometimes, the species string is also not properly capitalized,
            e.g, ("c1"). This method should take care of these known formats.
            """
            try:
                return int(sp_str)
            except ValueError:
                sp = re.sub(r"\d", "", sp_str)
                return sp.capitalize()

        species = [_parse_species(sp) for sp in species]

        return Molecule(species, coords)

    @classmethod
    def from_str(cls, contents: str) -> Self:
        """
        Creates GaussianInput from a string.

        Args:
            contents: String representing an Gaussian input file.

        Returns:
            GaussianInput object
        """
        lines = [line.strip() for line in contents.split("\n")]

        link0_patt = re.compile(r"^(%.+)\s*=\s*(.+)")
        link0_dict = {}
        for line in lines:
            if link0_patt.match(line):
                match = link0_patt.match(line)
                if match is None:
                    raise ValueError("no match found")
                link0_dict[match[1].strip("=")] = match[2]

        route_patt = re.compile(r"^#[sSpPnN]*.*")
        route = ""
        route_index = None
        for idx, line in enumerate(lines):
            if route_patt.match(line):
                route += f" {line}"
                route_index = idx
            # This condition allows for route cards spanning multiple lines
            elif (line == "" or line.isspace()) and route_index is not None:
                break
            if route_index is not None:
                route += f" {line}"
                route_index = idx
        functional, basis_set, route_paras, dieze_tag = read_route_line(route)
        ind = 2
        title = []
        if route_index is None:
            raise ValueError("route_index cannot be None")
        while lines[route_index + ind].strip():
            title.append(lines[route_index + ind].strip())
            ind += 1
        title_str = " ".join(title)
        ind += 1
        tokens = re.split(r"[,\s]+", lines[route_index + ind])
        charge = int(float(tokens[0]))
        spin_mult = int(tokens[1])
        coord_lines = []
        spaces = 0
        input_paras = {}
        ind += 1
        if cls._xyz_patt.match(lines[route_index + ind]):
            spaces += 1
        for i in range(route_index + ind, len(lines)):
            if lines[i].strip() == "":
                spaces += 1
            if spaces >= 2:
                d = lines[i].split("=")
                if len(d) == 2:
                    input_paras[d[0]] = d[1]
            else:
                coord_lines.append(lines[i].strip())
        mol = cls._parse_coords(coord_lines)
        mol.set_charge_and_spin(charge, spin_mult)

        return cls(
            mol,
            charge=charge,
            spin_multiplicity=spin_mult,
            title=title_str,
            functional=functional,
            basis_set=basis_set,
            route_parameters=route_paras,
            input_parameters=input_paras,
            link0_parameters=link0_dict,
            dieze_tag=dieze_tag,
        )

    @classmethod
    def from_file(cls, filename: str | Path) -> Self:
        """
        Creates GaussianInput from a file.

        Args:
            filename: Gaussian input filename

        Returns:
            GaussianInput object
        """
        with zopen(filename, mode="rt", encoding="utf-8") as file:
            return cls.from_str(file.read())  # type:ignore[arg-type]

    def get_zmatrix(self):
        """Get a z-matrix representation of the molecule."""
        return self._mol.get_zmatrix()

    def get_cart_coords(self) -> str:
        """Return the Cartesian coordinates of the molecule."""
        outs = [f"{site.species_string} {' '.join(f'{x:0.6f}' for x in site.coords)}" for site in self._mol]
        return "\n".join(outs)

    def __str__(self):
        return self.to_str()

    def to_str(self, cart_coords=False):
        """Return GaussianInput string.

        Args:
            cart_coords (bool): If True, return Cartesian coordinates instead of z-matrix.
                Defaults to False.
        """

        def para_dict_to_str(para, joiner=" "):
            para_str = []
            # sorted is only done to make unit tests work reliably
            for par, val in sorted(para.items()):
                if val is None or val == "":
                    para_str.append(par)
                elif isinstance(val, dict):
                    val_str = para_dict_to_str(val, joiner=",")
                    para_str.append(f"{par}=({val_str})")
                else:
                    para_str.append(f"{par}={val}")
            return joiner.join(para_str)

        output = []
        if self.link0_parameters:
            output.append(para_dict_to_str(self.link0_parameters, "\n"))

        # Handle functional or basis set to None, empty string or whitespace
        func_str = "" if self.functional is None else self.functional.strip()
        bset_str = "" if self.basis_set is None else self.basis_set.strip()

        if func_str != "" and bset_str != "":
            func_bset_str = f" {func_str}/{bset_str}"
        else:
            # don't use the slash if either or both are set as empty
            func_bset_str = f" {func_str}{bset_str}".rstrip()

        output += (
            f"{self.dieze_tag}{func_bset_str} {para_dict_to_str(self.route_parameters)}",
            "",
            self.title,
            "",
        )

        charge_str = "" if self.charge is None else f"{self.charge:.0f}"
        multip_str = "" if self.spin_multiplicity is None else f" {self.spin_multiplicity:.0f}"
        output.append(f"{charge_str}{multip_str}")

        if isinstance(self._mol, Molecule):
            if cart_coords is True:
                output.append(self.get_cart_coords())
            else:
                output.append(self.get_zmatrix())
        elif self._mol is not None:
            output.append(str(self._mol))
        output.append("")
        if self.gen_basis is not None:
            output.append(f"{self.gen_basis}\n")
        output.extend((para_dict_to_str(self.input_parameters, "\n"), "\n"))
        return "\n".join(output)

    def write_file(self, filename, cart_coords=False):
        """Write the input string into a file.

        Option: see `__str__` method
        """
        with zopen(filename, mode="wt", encoding="utf-8") as file:
            file.write(self.to_str(cart_coords))

    def as_dict(self):
        """MSONable dict."""
        return {
            "@module": type(self).__module__,
            "@class": type(self).__name__,
            "molecule": self.molecule.as_dict(),
            "functional": self.functional,
            "basis_set": self.basis_set,
            "route_parameters": self.route_parameters,
            "title": self.title,
            "charge": self.charge,
            "spin_multiplicity": self.spin_multiplicity,
            "input_parameters": self.input_parameters,
            "link0_parameters": self.link0_parameters,
            "dieze_tag": self.dieze_tag,
        }

    @classmethod
    def from_dict(cls, dct: dict) -> Self:
        """
        Args:
            dct: dict.

        Returns:
            GaussianInput
        """
        return cls(
            mol=Molecule.from_dict(dct["molecule"]),
            functional=dct["functional"],
            basis_set=dct["basis_set"],
            route_parameters=dct["route_parameters"],
            title=dct["title"],
            charge=dct["charge"],
            spin_multiplicity=dct["spin_multiplicity"],
            input_parameters=dct["input_parameters"],
            link0_parameters=dct["link0_parameters"],
        )


class GaussianOutput:
    """
    Parser for Gaussian output files.

    Note: Still in early beta.

    Attributes:
        structures (list[Structure]): All structures from the calculation in the standard orientation. If the
            symmetry is not considered, the standard orientation is not printed out
            and the input orientation is used instead. Check the `standard_orientation`
            attribute.
        structures_input_orientation (list): All structures from the calculation in the input
            orientation or the Z-matrix orientation (if an opt=z-matrix was requested).
        opt_structures (list): All optimized structures from the calculation in the standard
            orientation, if the attribute 'standard_orientation' is True, otherwise in the input
            or the Z-matrix orientation.
        energies (list): All energies from the calculation.
        eigenvalues (list): List of eigenvalues for the last geometry.
        MO_coefficients (list): Matrix of MO coefficients for the last geometry.
        cart_forces (list): All Cartesian forces from the calculation.
        frequencies (list): A list for each freq calculation and for each mode of a dict with
            {
                "frequency": freq in cm-1,
                "symmetry": symmetry tag
                "r_mass": Reduce mass,
                "f_constant": force constant,
                "IR_intensity": IR Intensity,
                "mode": normal mode
             }
            The normal mode is a 1D vector of dx, dy dz of each atom.
        hessian (ndarray): Matrix of second derivatives of the energy with respect to cartesian
            coordinates in the input orientation frame. Need #P in the route section in order to
            be in the output.
        properly_terminated (bool): True if run has properly terminated.
        is_pcm (bool): True if run is a PCM run.
        is_spin (bool): True if it is an unrestricted run.
        stationary_type (str): If it is a relaxation run, indicates whether it is a minimum
            (Minimum) or a saddle point ("Saddle").
        corrections (dict): Thermochemical corrections if this run is a Freq run as a dict. Keys
            are "Zero-point", "Thermal", "Enthalpy" and "Gibbs Free Energy".
        functional (str): Functional used in the run.
        basis_set (str): Basis set used in the run.
        route (dict): Additional route parameters as a dict. For example,
            {'SP':"", "SCF":"Tight"}.
        dieze_tag (str): # preceding the route line, e.g. "#P".
        link0 (dict): Link0 parameters as a dict. e.g. {"%mem": "1000MW"}.
        charge (int): Charge for structure.
        spin_multiplicity (int): Spin multiplicity for structure.
        num_basis_func (int): Number of basis functions in the run.
        electrons (tuple): Number of alpha and beta electrons as (N alpha, N beta).
        pcm (dict): PCM parameters and output if available.
        errors (list): Error if not properly terminated (list to be completed in error_defs).
        Mulliken_charges (list): Mulliken atomic charges.
        eigenvectors (dict): Matrix of shape (num_basis_func, num_basis_func). Each column is an
            eigenvectors and contains AO coefficients of an MO.
            eigenvectors[Spin] = mat(num_basis_func, num_basis_func).
        molecular_orbital (dict): MO development coefficients on AO in a more convenient array dict
            for each atom and basis set label.
            mo[Spin][OM j][atom i] = {AO_k: coeff, AO_k: coeff ... }.
        atom_basis_labels (list): Labels of AO for each atoms. These labels are those used in the
            output of molecular orbital coefficients (POP=Full) and in the molecular_orbital array
            dict. atom_basis_labels[iatom] = [AO_k, AO_k, ...].
        resumes (list): List of gaussian data resume given at the end of the output file before
            the quotation. The resumes are given as string.
        title (str): Title of the gaussian run.
        standard_orientation (bool): If True, the geometries stored in the structures are in the
            standard orientation. Else, the geometries are in the input orientation.
        bond_orders (dict): Dict of bond order values read in the output file such as:
            {(0, 1): 0.8709, (1, 6): 1.234, ...}.
            The keys are the atom indexes and the values are the Wiberg bond indexes that are
            printed using `pop=NBOREAD` and `$nbo bndidx $end`.

    Methods:
        to_input()
            Return a GaussianInput object using the last geometry and the same
            calculation parameters.

        read_scan()
            Read a potential energy surface from a gaussian scan calculation.

        get_scan_plot()
            Get a matplotlib plot of the potential energy surface

        save_scan_plot()
            Save a matplotlib plot of the potential energy surface to a file
    """

    def __init__(self, filename: PathLike) -> None:
        """
        Args:
            filename: Filename of Gaussian output file.
        """
        self.filename = str(filename)
        self._parse(self.filename)

    @property
    def final_energy(self):
        """Final energy in Gaussian output."""
        return self.energies[-1]

    @property
    def final_structure(self):
        """Final structure in Gaussian output."""
        return self.structures[-1]

    def _parse(self, filename):
        start_patt = re.compile(r" \(Enter \S+l101\.exe\)")
        route_patt = re.compile(r" #[pPnNtT]*.*")
        link0_patt = re.compile(r"^\s(%.+)\s*=\s*(.+)")
        charge_mul_patt = re.compile(r"Charge\s+=\s*([-\d]+)\s+Multiplicity\s+=\s*(\d+)")
        num_basis_func_patt = re.compile(r"([0-9]+)\s+basis functions")
        num_elec_patt = re.compile(r"(\d+)\s+alpha electrons\s+(\d+)\s+beta electrons")
        pcm_patt = re.compile(r"Polarizable Continuum Model")
        stat_type_patt = re.compile(r"imaginary frequencies")
        scf_patt = re.compile(r"E\(.*\)\s*=\s*([-\.\d]+)\s+")
        mp2_patt = re.compile(r"EUMP2\s*=\s*(.*)")
        oniom_patt = re.compile(r"ONIOM:\s+extrapolated energy\s*=\s*(.*)")
        termination_patt = re.compile(r"(Normal|Error) termination")
        error_patt = re.compile(r"(! Non-Optimized Parameters !|Convergence failure)")
        mulliken_patt = re.compile(r"^\s*(Mulliken charges|Mulliken atomic charges)")
        mulliken_charge_patt = re.compile(r"^\s+(\d+)\s+([A-Z][a-z]?)\s*(\S*)")
        end_mulliken_patt = re.compile(r"(Sum of Mulliken )(.*)(charges)\s*=\s*(\D)")
        std_orientation_patt = re.compile(r"Standard orientation")
        input_orientation_patt = re.compile(r"Input orientation|Z-Matrix orientation")
        orbital_patt = re.compile(r"(Alpha|Beta)\s*\S+\s*eigenvalues --(.*)")
        thermo_patt = re.compile(r"(Zero-point|Thermal) correction(.*)=\s+([\d\.-]+)")
        forces_on_patt = re.compile(r"Center\s+Atomic\s+Forces\s+\(Hartrees/Bohr\)")
        forces_off_patt = re.compile(r"Cartesian\s+Forces:\s+Max.*RMS.*")
        forces_patt = re.compile(r"\s+(\d+)\s+(\d+)\s+([0-9\.-]+)\s+([0-9\.-]+)\s+([0-9\.-]+)")

        freq_on_patt = re.compile(r"Harmonic\sfrequencies\s+\(cm\*\*-1\),\sIR\sintensities.*Raman.*")

        normal_mode_patt = re.compile(r"\s+(\d+)\s+(\d+)\s+([0-9\.-]{4,5})\s+([0-9\.-]{4,5}).*")

        mo_coeff_patt = re.compile(r"Molecular Orbital Coefficients:")
        mo_coeff_name_patt = re.compile(r"\d+\s((\d+|\s+)\s+([a-zA-Z]{1,2}|\s+))\s+(\d+\S+)")

        hessian_patt = re.compile(r"Force constants in Cartesian coordinates:")
        resume_patt = re.compile(r"^\s1\\1\\GINC-\S*")
        resume_end_patt = re.compile(r"^\s.*\\\\@")

        bond_order_patt = re.compile(r"Wiberg bond index matrix in the NAO basis:")

        self.properly_terminated = self.is_pcm = self.is_spin = False
        self.pcm = self.hessian = self.title = None
        self.stationary_type = "Minimum"
        self.corrections = {}
        self.energies = []
        self.errors = []
        self.Mulliken_charges = {}
        self.link0 = {}
        self.cart_forces = []
        self.frequencies = []
        self.eigenvalues = []
        self.resumes = []
        self.bond_orders = {}

        read_mulliken = read_eigen = num_basis_found = terminated = parse_forces = False
        read_mo = parse_hessian = standard_orientation = parse_bond_order = parse_freq = False
        read_coord = parse_stage = 0
        eigen_txt = []
        forces = []
        frequencies = []
        route_line = ""
        input_structures = []
        std_structures = []
        geom_orientation = None
        opt_structures = []
        route_lower = {}

        with zopen(filename, mode="rt", encoding="utf-8") as file:
            for line in file:
                if parse_stage == 0:
                    if start_patt.search(line):
                        parse_stage = 1
                    elif link0_patt.match(line):
                        match = link0_patt.match(line)
                        self.link0[match[1]] = match[2]
                    elif route_patt.search(line) or route_line != "":
                        if set(line.strip()) == {"-"}:
                            params = read_route_line(route_line)
                            self.functional = params[0]
                            self.basis_set = params[1]
                            self.route_parameters = params[2]
                            route_lower = {k.lower(): v for k, v in self.route_parameters.items()}
                            self.dieze_tag = params[3]
                            parse_stage = 1
                        else:
                            line = line.replace(" ", "", 1).rstrip("\n")
                            route_line += line
                elif parse_stage == 1:
                    if set(line.strip()) == {"-"} and self.title is None:
                        self.title = ""
                    elif self.title == "":
                        self.title = line.strip()
                    elif charge_mul_patt.search(line):
                        match = charge_mul_patt.search(line)
                        self.charge = int(match[1])
                        self.spin_multiplicity = int(match[2])
                        parse_stage = 2
                elif parse_stage == 2:
                    if self.is_pcm:
                        self._check_pcm(line)

                    if "freq" in route_lower and thermo_patt.search(line):
                        match = thermo_patt.search(line)
                        if match[1] == "Zero-point":
                            self.corrections["Zero-point"] = float(match[3])
                        else:
                            key = match[2].replace(" to ", "")
                            self.corrections[key] = float(match[3])

                    if read_coord:
                        [file.readline() for i in range(3)]
                        line = file.readline()
                        sp = []
                        coords = []
                        while set(line.strip()) != {"-"}:
                            tokens = line.split()
                            sp.append(Element.from_Z(int(tokens[1])))
                            coords.append([float(x) for x in tokens[3:6]])
                            line = file.readline()

                        read_coord = False
                        if geom_orientation == "input":
                            input_structures.append(Molecule(sp, coords))
                        elif geom_orientation == "standard":
                            std_structures.append(Molecule(sp, coords))

                    if parse_forces:
                        if match := forces_patt.search(line):
                            forces.extend([float(_v) for _v in match.groups()[2:5]])
                        elif forces_off_patt.search(line):
                            self.cart_forces.append(forces)
                            forces = []
                            parse_forces = False

                    # read molecular orbital eigenvalues
                    if read_eigen:
                        if match := orbital_patt.search(line):
                            eigen_txt.append(line)
                        else:
                            read_eigen = False
                            self.eigenvalues = {Spin.up: []}
                            for eigen_line in eigen_txt:
                                if "Alpha" in eigen_line:
                                    self.eigenvalues[Spin.up] += [float(e) for e in float_patt.findall(eigen_line)]
                                elif "Beta" in eigen_line:
                                    if Spin.down not in self.eigenvalues:
                                        self.eigenvalues[Spin.down] = []
                                    self.eigenvalues[Spin.down] += [float(e) for e in float_patt.findall(eigen_line)]
                            eigen_txt = []

                    # read molecular orbital coefficients
                    if (not num_basis_found) and num_basis_func_patt.search(line):
                        match = num_basis_func_patt.search(line)
                        self.num_basis_func = int(match[1])
                        num_basis_found = True
                    elif read_mo:
                        # build a matrix with all coefficients
                        all_spin = [Spin.up]
                        if self.is_spin:
                            all_spin.append(Spin.down)

                        mat_mo = {}
                        for spin in all_spin:
                            mat_mo[spin] = np.zeros((self.num_basis_func, self.num_basis_func))
                            nMO = 0
                            end_mo = False
                            atom_idx = None
                            coeffs = []
                            while nMO < self.num_basis_func and not end_mo:
                                file.readline()
                                file.readline()
                                self.atom_basis_labels = []
                                for idx in range(self.num_basis_func):
                                    line = file.readline()

                                    # identify atom and OA labels
                                    match = mo_coeff_name_patt.search(line)
                                    if match[1].strip() != "":
                                        atom_idx = int(match[2]) - 1
                                        # atname = match[3]
                                        self.atom_basis_labels.append([match[4]])
                                    else:
                                        self.atom_basis_labels[atom_idx].append(match[4])

                                    # MO coefficients
                                    coeffs = [float(c) for c in float_patt.findall(line)]
                                    for j, c in enumerate(coeffs):
                                        mat_mo[spin][idx, nMO + j] = c

                                nMO += len(coeffs)
                                line = file.readline()
                                # manage pop=regular case (not all MO)
                                if nMO < self.num_basis_func and (
                                    "Density Matrix:" in line or mo_coeff_patt.search(line)
                                ):
                                    end_mo = True
                                    warnings.warn(
                                        "POP=regular case, matrix coefficients not complete",
                                        stacklevel=2,
                                    )
                            file.readline()

                        self.eigenvectors = mat_mo
                        read_mo = False

                        # build a more convenient array dict with MO
                        # coefficient of each atom in each MO.
                        # mo[Spin][OM j][atom i] =
                        # {AO_k: coeff, AO_k: coeff ... }
                        mo = {}
                        for spin in all_spin:
                            mo[spin] = [
                                [{} for iat in range(len(self.atom_basis_labels))] for j in range(self.num_basis_func)
                            ]
                            for j in range(self.num_basis_func):
                                idx = 0
                                for atom_idx, labels in enumerate(self.atom_basis_labels):
                                    for label in labels:
                                        mo[spin][j][atom_idx][label] = self.eigenvectors[spin][idx, j]
                                        idx += 1

                        self.molecular_orbital = mo

                    elif parse_freq:
                        while line.strip() != "":  # blank line
                            ifreqs = [int(val) - 1 for val in line.split()]
                            frequencies.extend(
                                {
                                    "frequency": None,
                                    "r_mass": None,
                                    "f_constant": None,
                                    "IR_intensity": None,
                                    "symmetry": None,
                                    "mode": [],
                                }
                                for _ in ifreqs
                            )
                            # read freq, intensity, masses, symmetry ...
                            while "Atom  AN" not in line:
                                if "Frequencies --" in line:
                                    freqs = map(float, float_patt.findall(line))
                                    for ifreq, freq in zip(ifreqs, freqs, strict=True):
                                        frequencies[ifreq]["frequency"] = freq
                                elif "Red. masses --" in line:
                                    r_masses = map(float, float_patt.findall(line))
                                    for ifreq, r_mass in zip(ifreqs, r_masses, strict=True):
                                        frequencies[ifreq]["r_mass"] = r_mass
                                elif "Frc consts  --" in line:
                                    f_consts = map(float, float_patt.findall(line))
                                    for ifreq, f_const in zip(ifreqs, f_consts, strict=True):
                                        frequencies[ifreq]["f_constant"] = f_const
                                elif "IR Inten    --" in line:
                                    IR_intens = map(float, float_patt.findall(line))
                                    for ifreq, intens in zip(ifreqs, IR_intens, strict=True):
                                        frequencies[ifreq]["IR_intensity"] = intens
                                else:
                                    syms = line.split()[:3]
                                    for ifreq, sym in zip(ifreqs, syms, strict=True):
                                        frequencies[ifreq]["symmetry"] = sym
                                line = file.readline()

                            # read normal modes
                            line = file.readline()
                            while normal_mode_patt.search(line):
                                values = list(map(float, float_patt.findall(line)))
                                for idx, ifreq in zip(range(0, len(values), 3), ifreqs, strict=True):
                                    frequencies[ifreq]["mode"].extend(values[idx : idx + 3])
                                line = file.readline()

                        parse_freq = False
                        self.frequencies.append(frequencies)
                        frequencies = []

                    elif parse_hessian:
                        if not (input_structures or std_structures):
                            raise ValueError("Both input_structures and std_structures are empty.")
                        parse_hessian = False
                        self._parse_hessian(file, (input_structures or std_structures)[0])

                    elif parse_bond_order:
                        # parse Wiberg bond order
                        line = file.readline()
                        line = file.readline()
                        n_atoms = len(input_structures[0])
                        matrix = []
                        for _ in range(n_atoms):
                            line = file.readline()
                            matrix.append([float(v) for v in line.split()[2:]])

                        self.bond_orders = {}
                        for atom_idx in range(n_atoms):
                            for atom_jdx in range(atom_idx + 1, n_atoms):
                                self.bond_orders[atom_idx, atom_jdx] = matrix[atom_idx][atom_jdx]
                        parse_bond_order = False

                    elif termination_patt.search(line):
                        match = termination_patt.search(line)
                        if match[1] == "Normal":
                            self.properly_terminated = True
                            terminated = True
                    elif error_patt.search(line):
                        error_defs = {
                            "! Non-Optimized Parameters !": "Optimization error",
                            "Convergence failure": "SCF convergence error",
                        }
                        match = error_patt.search(line)
                        self.errors.append(error_defs[match[1]])
                    elif num_elec_patt.search(line):
                        match = num_elec_patt.search(line)
                        self.electrons = (int(match[1]), int(match[2]))
                    elif (not self.is_pcm) and pcm_patt.search(line):
                        self.is_pcm = True
                        self.pcm = {}
                    elif "freq" in route_lower and "opt" in route_lower and stat_type_patt.search(line):
                        self.stationary_type = "Saddle"
                    elif mp2_patt.search(line):
                        match = mp2_patt.search(line)
                        self.energies.append(float(match[1].replace("D", "E")))
                    elif oniom_patt.search(line):
                        match = oniom_patt.matcher(line)
                        self.energies.append(float(match[1]))
                    elif scf_patt.search(line):
                        match = scf_patt.search(line)
                        self.energies.append(float(match[1]))
                    elif std_orientation_patt.search(line):
                        standard_orientation = True
                        geom_orientation = "standard"
                        read_coord = True
                    elif input_orientation_patt.search(line):
                        geom_orientation = "input"
                        read_coord = True
                    elif "Optimization completed." in line:
                        line = file.readline()
                        if " -- Stationary point found." not in line:
                            warnings.warn(
                                f"\n{self.filename}: Optimization complete but this is not a stationary point",
                                stacklevel=2,
                            )
                        if standard_orientation:
                            opt_structures.append(std_structures[-1])
                        else:
                            opt_structures.append(input_structures[-1])
                    elif not read_eigen and orbital_patt.search(line):
                        eigen_txt.append(line)
                        read_eigen = True
                    elif mulliken_patt.search(line):
                        read_mulliken = True
                    elif not parse_forces and forces_on_patt.search(line):
                        parse_forces = True
                    elif freq_on_patt.search(line):
                        parse_freq = True
                        _ = [file.readline() for _ in range(3)]
                    elif mo_coeff_patt.search(line):
                        if "Alpha" in line:
                            self.is_spin = True
                        read_mo = True
                    elif hessian_patt.search(line):
                        parse_hessian = True
                    elif resume_patt.search(line):
                        resume = []
                        while not resume_end_patt.search(line):
                            resume.append(line)
                            line = file.readline()
                            # security if \\@ not in one line !
                            if line == "\n":
                                break
                        resume.append(line)
                        resume = "".join(r.strip() for r in resume)
                        self.resumes.append(resume)
                    elif bond_order_patt.search(line):
                        parse_bond_order = True

                    if read_mulliken:
                        mulliken_txt = []
                        if not end_mulliken_patt.search(line):
                            mulliken_txt.append(line)
                        else:
                            match = end_mulliken_patt.search(line)
                            mulliken_charges = {}
                            for line in mulliken_txt:
                                if mulliken_charge_patt.search(line):
                                    match = mulliken_charge_patt.search(line)
                                    dic = {int(match[1]): [match[2], float(match[3])]}
                                    mulliken_charges.update(dic)
                            read_mulliken = False
                            self.Mulliken_charges = mulliken_charges

        # store the structures. If symmetry is considered, the standard orientation
        # is used. Else the input orientation is used.
        self.structures_input_orientation = input_structures
        if standard_orientation:
            self.structures = std_structures
        else:
            self.structures = input_structures

        # store optimized structure in input orientation
        self.opt_structures = opt_structures

        if not terminated:
            warnings.warn(
                f"\n{self.filename}: Termination error or bad Gaussian output file !",
                stacklevel=2,
            )

    def _parse_hessian(self, file, structure):
        """Parse the hessian matrix in the output file.

        Args:
            file: file object
            structure: structure in the output file
        """
        # read Hessian matrix under "Force constants in Cartesian coordinates"
        # Hessian matrix is in the input orientation framework
        # WARNING : need #P in the route line

        ndf = 3 * len(structure)
        self.hessian = np.zeros((ndf, ndf))
        j_indices = range(5)
        ndf_idx = 0
        vals = None
        while ndf_idx < ndf:
            for i in range(ndf_idx, ndf):
                line = file.readline()
                vals = re.findall(r"\s*([+-]?\d+\.\d+[eEdD]?[+-]\d+)", line)
                vals = [float(val.replace("D", "E")) for val in vals]
                for val_idx, val in enumerate(vals):
                    j = j_indices[val_idx]
                    self.hessian[i, j] = val
                    self.hessian[j, i] = val
            ndf_idx += len(vals)
            line = file.readline()
            j_indices = [j + 5 for j in j_indices]

    def _check_pcm(self, line):
        energy_patt = re.compile(r"(Dispersion|Cavitation|Repulsion) energy\s+\S+\s+=\s+(\S*)")
        total_patt = re.compile(r"with all non electrostatic terms\s+\S+\s+=\s+(\S*)")
        parameter_patt = re.compile(r"(Eps|Numeral density|RSolv|Eps\(inf[inity]*\))\s+=\s*(\S*)")

        if energy_patt.search(line):
            match = energy_patt.search(line)
            self.pcm[f"{match[1]} energy"] = float(match[2])
        elif total_patt.search(line):
            match = total_patt.search(line)
            self.pcm["Total energy"] = float(match[1])
        elif parameter_patt.search(line):
            match = parameter_patt.search(line)
            self.pcm[match[1]] = float(match[2])

    def as_dict(self):
        """JSON-serializable dict representation."""
        structure = self.final_structure
        dct = {
            "has_gaussian_completed": self.properly_terminated,
            "nsites": len(structure),
        }
        comp = structure.composition
        dct["unit_cell_formula"] = comp.as_dict()
        dct["reduced_cell_formula"] = Composition(comp.reduced_formula).as_dict()
        dct["pretty_formula"] = comp.reduced_formula
        dct["is_pcm"] = self.is_pcm
        dct["errors"] = self.errors
        dct["Mulliken_charges"] = self.Mulliken_charges

        unique_symbols = sorted(dct["unit_cell_formula"])
        dct["elements"] = unique_symbols
        dct["nelements"] = len(unique_symbols)
        dct["charge"] = self.charge
        dct["spin_multiplicity"] = self.spin_multiplicity

        vin = {
            "route": self.route_parameters,
            "functional": self.functional,
            "basis_set": self.basis_set,
            "nbasisfunctions": self.num_basis_func,
            "pcm_parameters": self.pcm,
        }

        dct["input"] = vin

        n_sites = len(self.final_structure)

        vout = {
            "energies": self.energies,
            "final_energy": self.final_energy,
            "final_energy_per_atom": self.final_energy / n_sites,
            "molecule": structure.as_dict(),
            "stationary_type": self.stationary_type,
            "corrections": self.corrections,
        }

        dct["output"] = vout
        dct["@module"] = type(self).__module__
        dct["@class"] = type(self).__name__

        return dct

    def read_scan(self):
        """
        Read a potential energy surface from a gaussian scan calculation.

        Returns:
            dict[str, list]: {"energies": [...], "coords": {"d1": [...], "A2", [...], ... }}
            "energies" are the energies of all points of the potential energy
            surface. "coords" are the internal coordinates used to compute the
            potential energy surface and the internal coordinates optimized,
            labelled by their name as defined in the calculation.
        """
        scan_patt = re.compile(r"^\sSummary of the potential surface scan:")
        optscan_patt = re.compile(r"^\sSummary of Optimized Potential Surface Scan")
        coord_patt = re.compile(r"^\s*(\w+)((\s*[+-]?\d+\.\d+)+)")

        # data dict return
        data = {"energies": [], "coords": {}}

        # read in file
        with zopen(self.filename, mode="rt", encoding="utf-8") as file:
            line = file.readline()

            while line != "":
                if optscan_patt.match(line):
                    file.readline()
                    line = file.readline()
                    endScan = False
                    while not endScan:
                        data["energies"] += list(map(float, float_patt.findall(line)))
                        line = file.readline()
                        while coord_patt.match(line):
                            icname = line.split()[0].strip()
                            if icname in data["coords"]:
                                data["coords"][icname] += list(map(float, float_patt.findall(line)))
                            else:
                                data["coords"][icname] = list(map(float, float_patt.findall(line)))
                            line = file.readline()
                        if not re.search(r"^\s+((\s*\d+)+)", line):
                            endScan = True
                        else:
                            line = file.readline()

                elif scan_patt.match(line):
                    line = file.readline()
                    data["coords"] = {icname: [] for icname in line.split()[1:-1]}
                    file.readline()
                    line = file.readline()
                    while not re.search(r"^\s-+", line):
                        values = list(map(float, line.split()))
                        data["energies"].append(values[-1])
                        for i, icname in enumerate(data["coords"], start=1):
                            data["coords"][icname].append(values[i])
                        line = file.readline()
                else:
                    line = file.readline()

        return data

    def get_scan_plot(self, coords=None):
        """Get a matplotlib plot of the potential energy surface.

        Args:
            coords: internal coordinate name to use as abscissa.
        """
        ax = pretty_plot(12, 8)

        dct = self.read_scan()

        if coords and coords in dct["coords"]:
            x = dct["coords"][coords]
            ax.set_xlabel(coords)
        else:
            x = range(len(dct["energies"]))
            ax.set_xlabel("points")

        ax.set_ylabel("Energy (eV)")

        e_min = min(dct["energies"])
        y = [(e - e_min) * Ha_to_eV for e in dct["energies"]]

        ax.plot(x, y, "ro--")
        return ax

    def save_scan_plot(self, filename="scan.pdf", img_format="pdf", coords=None):
        """Save matplotlib plot of the potential energy surface to a file.

        Args:
            filename: Filename to write to.
            img_format: Image format to use. Defaults to EPS.
            coords: internal coordinate name to use as abcissa.
        """
        plt = self.get_scan_plot(coords)
        plt.savefig(filename, format=img_format)

    def read_excitation_energies(self):
        """
        Read a excitation energies after a TD-DFT calculation.

        Returns:
            A list: A list of tuple for each transition such as
                    [(energie (eV), lambda (nm), oscillatory strength), ... ]
        """
        transitions = []

        # read in file
        with zopen(self.filename, mode="rt", encoding="utf-8") as file:
            line = file.readline()
            td = False
            while line != "":
                if re.search(r"^\sExcitation energies and oscillator strengths:", line):
                    td = True

                if td and re.search(r"^\sExcited State\s*\d", line):
                    val = [float(v) for v in float_patt.findall(line)]
                    transitions.append(tuple(val[:3]))
                line = file.readline()
        return transitions

    def get_spectre_plot(self, sigma=0.05, step=0.01):
        """Get a matplotlib plot of the UV-visible xas. Transitions are plotted
        as vertical lines and as a sum of normal functions with sigma with. The
        broadening is applied in energy and the xas is plotted as a function
        of the wavelength.

        Args:
            sigma: Full width at half maximum in eV for normal functions.
            step: bin interval in eV

        Returns:
            A dict: {"energies": values, "lambda": values, "xas": values}
                    where values are lists of abscissa (energies, lambda) and
                    the sum of gaussian functions (xas).
            A matplotlib plot.
        """
        ax = pretty_plot(12, 8)

        transitions = self.read_excitation_energies()

        minval = min(val[0] for val in transitions) - 5.0 * sigma
        maxval = max(val[0] for val in transitions) + 5.0 * sigma
        npts = int((maxval - minval) / step) + 1

        eneval = np.linspace(minval, maxval, npts)  # in eV
        lambdaval = [cst.h * cst.c / (val * cst.e) * 1.0e9 for val in eneval]  # in nm

        # sum of gaussian functions
        spectre = np.zeros(npts)
        for trans in transitions:
            spectre += trans[2] * norm(eneval, trans[0], sigma)
        spectre /= spectre.max()
        ax.plot(lambdaval, spectre, "r-", label="spectre")

        data = {"energies": eneval, "lambda": lambdaval, "xas": spectre}

        # plot transitions as vlines
        ax.vlines(
            [val[1] for val in transitions],
            0.0,
            [val[2] for val in transitions],
            color="blue",
            label="transitions",
            linewidth=2,
        )

        ax.set_xlabel("$\\lambda$ (nm)")
        ax.set_ylabel("Arbitrary unit")
        ax.legend()

        return data, ax

    def save_spectre_plot(self, filename="spectre.pdf", img_format="pdf", sigma=0.05, step=0.01):
        """Save matplotlib plot of the spectre to a file.

        Args:
            filename: Filename to write to.
            img_format: Image format to use. Defaults to EPS.
            sigma: Full width at half maximum in eV for normal functions.
            step: bin interval in eV
        """
        _d, plt = self.get_spectre_plot(sigma, step)
        plt.savefig(filename, format=img_format)

    def to_input(
        self,
        mol=None,
        charge=None,
        spin_multiplicity=None,
        title=None,
        functional=None,
        basis_set=None,
        route_parameters=None,
        input_parameters=None,
        link0_parameters=None,
        dieze_tag=None,
        cart_coords=False,
    ):
        """
        Create a new input object using by default the last geometry read in
        the output file and with the same calculation parameters. Arguments
        are the same as GaussianInput class.

        Returns:
            GaussianInput: the gaussian input object
        """
        if not mol:
            mol = self.final_structure

        if charge is None:
            charge = self.charge

        if spin_multiplicity is None:
            spin_multiplicity = self.spin_multiplicity

        if not title:
            title = self.title

        if not functional:
            functional = self.functional

        if not basis_set:
            basis_set = self.basis_set

        if not route_parameters:
            route_parameters = self.route_parameters

        if not link0_parameters:
            link0_parameters = self.link0

        if not dieze_tag:
            dieze_tag = self.dieze_tag

        return GaussianInput(
            mol=mol,
            charge=charge,
            spin_multiplicity=spin_multiplicity,
            title=title,
            functional=functional,
            basis_set=basis_set,
            route_parameters=route_parameters,
            input_parameters=input_parameters,
            link0_parameters=link0_parameters,
            dieze_tag=dieze_tag,
        )
