#![doc = include_str!("../README.md")]

use std::{
    collections::HashMap,
    env,
    ffi::{OsStr, OsString},
    fs,
    io::{BufRead, BufReader},
    mem,
    ops::Range,
    path::{Path, PathBuf},
    process::Command,
    sync::Mutex,
    time::SystemTime,
};

use anyhow::{anyhow, Context, Error, Result};
use fs4::FileExt;
use indoc::indoc;
use libloading::{Library, Symbol};
use once_cell::unsync::OnceCell;
use regex::{Regex, RegexBuilder};
use serde::{Deserialize, Deserializer, Serialize};
use tree_sitter::{Language, QueryError, QueryErrorKind};
use tree_sitter_highlight::HighlightConfiguration;
use tree_sitter_tags::{Error as TagsError, TagsConfiguration};

pub const EMSCRIPTEN_TAG: &str = concat!("docker.io/emscripten/emsdk:", env!("EMSCRIPTEN_VERSION"));

#[derive(Default, Deserialize, Serialize)]
pub struct Config {
    #[serde(default)]
    #[serde(
        rename = "parser-directories",
        deserialize_with = "deserialize_parser_directories"
    )]
    pub parser_directories: Vec<PathBuf>,
}

// Replace `~` or `$HOME` with home path string.
// (While paths like "~/.tree-sitter/config.json" can be deserialized,
// they're not valid path for I/O modules.)
fn deserialize_parser_directories<'de, D>(deserializer: D) -> Result<Vec<PathBuf>, D::Error>
where
    D: Deserializer<'de>,
{
    let paths = Vec::<PathBuf>::deserialize(deserializer)?;
    let Some(home) = dirs::home_dir() else {
        return Ok(paths);
    };
    let standardized = paths
        .into_iter()
        .map(|path| standardize_path(path, &home))
        .collect();
    Ok(standardized)
}

fn standardize_path(path: PathBuf, home: &Path) -> PathBuf {
    if let Ok(p) = path.strip_prefix("~") {
        return home.join(p);
    }
    if let Ok(p) = path.strip_prefix("$HOME") {
        return home.join(p);
    }
    path
}

impl Config {
    #[must_use]
    pub fn initial() -> Self {
        let home_dir = dirs::home_dir().expect("Cannot determine home directory");
        Self {
            parser_directories: vec![
                home_dir.join("github"),
                home_dir.join("src"),
                home_dir.join("source"),
                home_dir.join("projects"),
                home_dir.join("dev"),
                home_dir.join("git"),
            ],
        }
    }
}

const BUILD_TARGET: &str = env!("BUILD_TARGET");
const BUILD_HOST: &str = env!("BUILD_HOST");

pub struct LanguageConfiguration<'a> {
    pub scope: Option<String>,
    pub content_regex: Option<Regex>,
    pub first_line_regex: Option<Regex>,
    pub injection_regex: Option<Regex>,
    pub file_types: Vec<String>,
    pub root_path: PathBuf,
    pub highlights_filenames: Option<Vec<String>>,
    pub injections_filenames: Option<Vec<String>>,
    pub locals_filenames: Option<Vec<String>>,
    pub tags_filenames: Option<Vec<String>>,
    pub language_name: String,
    language_id: usize,
    highlight_config: OnceCell<Option<HighlightConfiguration>>,
    tags_config: OnceCell<Option<TagsConfiguration>>,
    highlight_names: &'a Mutex<Vec<String>>,
    use_all_highlight_names: bool,
}

pub struct Loader {
    pub parser_lib_path: PathBuf,
    languages_by_id: Vec<(PathBuf, OnceCell<Language>, Option<Vec<PathBuf>>)>,
    language_configurations: Vec<LanguageConfiguration<'static>>,
    language_configuration_ids_by_file_type: HashMap<String, Vec<usize>>,
    language_configuration_in_current_path: Option<usize>,
    language_configuration_ids_by_first_line_regex: HashMap<String, Vec<usize>>,
    highlight_names: Box<Mutex<Vec<String>>>,
    use_all_highlight_names: bool,
    debug_build: bool,

    #[cfg(feature = "wasm")]
    wasm_store: Mutex<Option<tree_sitter::WasmStore>>,
}

pub struct CompileConfig<'a> {
    pub src_path: &'a Path,
    pub header_paths: Vec<&'a Path>,
    pub parser_path: PathBuf,
    pub scanner_path: Option<PathBuf>,
    pub external_files: Option<&'a [PathBuf]>,
    pub output_path: Option<PathBuf>,
    pub flags: &'a [&'a str],
    pub name: String,
}

impl<'a> CompileConfig<'a> {
    #[must_use]
    pub fn new(
        src_path: &'a Path,
        externals: Option<&'a [PathBuf]>,
        output_path: Option<PathBuf>,
    ) -> Self {
        Self {
            src_path,
            header_paths: vec![src_path],
            parser_path: src_path.join("parser.c"),
            scanner_path: None,
            external_files: externals,
            output_path,
            flags: &[],
            name: String::new(),
        }
    }
}

unsafe impl Send for Loader {}
unsafe impl Sync for Loader {}

impl Loader {
    pub fn new() -> Result<Self> {
        let parser_lib_path = match env::var("TREE_SITTER_LIBDIR") {
            Ok(path) => PathBuf::from(path),
            _ => dirs::cache_dir()
                .ok_or_else(|| anyhow!("Cannot determine cache directory"))?
                .join("tree-sitter")
                .join("lib"),
        };
        Ok(Self::with_parser_lib_path(parser_lib_path))
    }

    #[must_use]
    pub fn with_parser_lib_path(parser_lib_path: PathBuf) -> Self {
        Self {
            parser_lib_path,
            languages_by_id: Vec::new(),
            language_configurations: Vec::new(),
            language_configuration_ids_by_file_type: HashMap::new(),
            language_configuration_in_current_path: None,
            language_configuration_ids_by_first_line_regex: HashMap::new(),
            highlight_names: Box::new(Mutex::new(Vec::new())),
            use_all_highlight_names: true,
            debug_build: false,

            #[cfg(feature = "wasm")]
            wasm_store: Mutex::default(),
        }
    }

    pub fn configure_highlights(&mut self, names: &[String]) {
        self.use_all_highlight_names = false;
        let mut highlights = self.highlight_names.lock().unwrap();
        highlights.clear();
        highlights.extend(names.iter().cloned());
    }

    #[must_use]
    pub fn highlight_names(&self) -> Vec<String> {
        self.highlight_names.lock().unwrap().clone()
    }

    pub fn find_all_languages(&mut self, config: &Config) -> Result<()> {
        if config.parser_directories.is_empty() {
            eprintln!("Warning: You have not configured any parser directories!");
            eprintln!("Please run `tree-sitter init-config` and edit the resulting");
            eprintln!("configuration file to indicate where we should look for");
            eprintln!("language grammars.\n");
        }
        for parser_container_dir in &config.parser_directories {
            if let Ok(entries) = fs::read_dir(parser_container_dir) {
                for entry in entries {
                    let entry = entry?;
                    if let Some(parser_dir_name) = entry.file_name().to_str() {
                        if parser_dir_name.starts_with("tree-sitter-") {
                            self.find_language_configurations_at_path(
                                &parser_container_dir.join(parser_dir_name),
                                false,
                            )
                            .ok();
                        }
                    }
                }
            }
        }
        Ok(())
    }

    pub fn languages_at_path(&mut self, path: &Path) -> Result<Vec<(Language, String)>> {
        if let Ok(configurations) = self.find_language_configurations_at_path(path, true) {
            let mut language_ids = configurations
                .iter()
                .map(|c| (c.language_id, c.language_name.clone()))
                .collect::<Vec<_>>();
            language_ids.sort_unstable();
            language_ids.dedup();
            language_ids
                .into_iter()
                .map(|(id, name)| Ok((self.language_for_id(id)?, name)))
                .collect::<Result<Vec<_>>>()
        } else {
            Ok(Vec::new())
        }
    }

    #[must_use]
    pub fn get_all_language_configurations(&self) -> Vec<(&LanguageConfiguration, &Path)> {
        self.language_configurations
            .iter()
            .map(|c| (c, self.languages_by_id[c.language_id].0.as_ref()))
            .collect()
    }

    pub fn language_configuration_for_scope(
        &self,
        scope: &str,
    ) -> Result<Option<(Language, &LanguageConfiguration)>> {
        for configuration in &self.language_configurations {
            if configuration.scope.as_ref().map_or(false, |s| s == scope) {
                let language = self.language_for_id(configuration.language_id)?;
                return Ok(Some((language, configuration)));
            }
        }
        Ok(None)
    }

    pub fn language_configuration_for_first_line_regex(
        &self,
        path: &Path,
    ) -> Result<Option<(Language, &LanguageConfiguration)>> {
        self.language_configuration_ids_by_first_line_regex
            .iter()
            .try_fold(None, |_, (regex, ids)| {
                if let Some(regex) = Self::regex(Some(regex)) {
                    let file = fs::File::open(path)?;
                    let reader = BufReader::new(file);
                    let first_line = reader.lines().next().transpose()?;
                    if let Some(first_line) = first_line {
                        if regex.is_match(&first_line) && !ids.is_empty() {
                            let configuration = &self.language_configurations[ids[0]];
                            let language = self.language_for_id(configuration.language_id)?;
                            return Ok(Some((language, configuration)));
                        }
                    }
                }

                Ok(None)
            })
    }

    pub fn language_configuration_for_file_name(
        &self,
        path: &Path,
    ) -> Result<Option<(Language, &LanguageConfiguration)>> {
        // Find all the language configurations that match this file name
        // or a suffix of the file name.
        let configuration_ids = path
            .file_name()
            .and_then(|n| n.to_str())
            .and_then(|file_name| self.language_configuration_ids_by_file_type.get(file_name))
            .or_else(|| {
                path.extension()
                    .and_then(|extension| extension.to_str())
                    .and_then(|extension| {
                        self.language_configuration_ids_by_file_type.get(extension)
                    })
            });

        if let Some(configuration_ids) = configuration_ids {
            if !configuration_ids.is_empty() {
                let configuration = if configuration_ids.len() == 1 {
                    &self.language_configurations[configuration_ids[0]]
                }
                // If multiple language configurations match, then determine which
                // one to use by applying the configurations' content regexes.
                else {
                    let file_contents =
                        fs::read(path).with_context(|| format!("Failed to read path {path:?}"))?;
                    let file_contents = String::from_utf8_lossy(&file_contents);
                    let mut best_score = -2isize;
                    let mut best_configuration_id = None;
                    for configuration_id in configuration_ids {
                        let config = &self.language_configurations[*configuration_id];

                        // If the language configuration has a content regex, assign
                        // a score based on the length of the first match.
                        let score;
                        if let Some(content_regex) = &config.content_regex {
                            if let Some(mat) = content_regex.find(&file_contents) {
                                score = (mat.end() - mat.start()) as isize;
                            }
                            // If the content regex does not match, then *penalize* this
                            // language configuration, so that language configurations
                            // without content regexes are preferred over those with
                            // non-matching content regexes.
                            else {
                                score = -1;
                            }
                        } else {
                            score = 0;
                        }
                        if score > best_score {
                            best_configuration_id = Some(*configuration_id);
                            best_score = score;
                        }
                    }

                    &self.language_configurations[best_configuration_id.unwrap()]
                };

                let language = self.language_for_id(configuration.language_id)?;
                return Ok(Some((language, configuration)));
            }
        }

        Ok(None)
    }

    pub fn language_configuration_for_injection_string(
        &self,
        string: &str,
    ) -> Result<Option<(Language, &LanguageConfiguration)>> {
        let mut best_match_length = 0;
        let mut best_match_position = None;
        for (i, configuration) in self.language_configurations.iter().enumerate() {
            if let Some(injection_regex) = &configuration.injection_regex {
                if let Some(mat) = injection_regex.find(string) {
                    let length = mat.end() - mat.start();
                    if length > best_match_length {
                        best_match_position = Some(i);
                        best_match_length = length;
                    }
                }
            }
        }

        if let Some(i) = best_match_position {
            let configuration = &self.language_configurations[i];
            let language = self.language_for_id(configuration.language_id)?;
            Ok(Some((language, configuration)))
        } else {
            Ok(None)
        }
    }

    fn language_for_id(&self, id: usize) -> Result<Language> {
        let (path, language, externals) = &self.languages_by_id[id];
        language
            .get_or_try_init(|| {
                let src_path = path.join("src");
                self.load_language_at_path(CompileConfig::new(
                    &src_path,
                    externals.as_deref(),
                    None,
                ))
            })
            .cloned()
    }

    pub fn compile_parser_at_path(
        &self,
        grammar_path: &Path,
        output_path: PathBuf,
        flags: &[&str],
    ) -> Result<()> {
        let src_path = grammar_path.join("src");
        let mut config = CompileConfig::new(&src_path, None, Some(output_path));
        config.flags = flags;
        self.load_language_at_path(config).map(|_| ())
    }

    pub fn load_language_at_path(&self, mut config: CompileConfig) -> Result<Language> {
        let grammar_path = config.src_path.join("grammar.json");

        #[derive(Deserialize)]
        struct GrammarJSON {
            name: String,
        }
        let mut grammar_file =
            fs::File::open(grammar_path).with_context(|| "Failed to read grammar.json")?;
        let grammar_json: GrammarJSON = serde_json::from_reader(BufReader::new(&mut grammar_file))
            .with_context(|| "Failed to parse grammar.json")?;

        config.name = grammar_json.name;

        self.load_language_at_path_with_name(config)
    }

    pub fn load_language_at_path_with_name(&self, mut config: CompileConfig) -> Result<Language> {
        let mut lib_name = config.name.to_string();
        let language_fn_name = format!(
            "tree_sitter_{}",
            replace_dashes_with_underscores(&config.name)
        );
        if self.debug_build {
            lib_name.push_str(".debug._");
        }

        if config.output_path.is_none() {
            fs::create_dir_all(&self.parser_lib_path)?;
        }

        let mut recompile = config.output_path.is_some(); // if specified, always recompile

        let output_path = config.output_path.unwrap_or_else(|| {
            let mut path = self.parser_lib_path.join(lib_name);
            path.set_extension(env::consts::DLL_EXTENSION);
            #[cfg(feature = "wasm")]
            if self.wasm_store.lock().unwrap().is_some() {
                path.set_extension("wasm");
            }
            path
        });
        config.output_path = Some(output_path.clone());

        let parser_path = config.src_path.join("parser.c");
        config.scanner_path = self.get_scanner_path(config.src_path);

        let mut paths_to_check = vec![parser_path];

        if let Some(scanner_path) = config.scanner_path.as_ref() {
            paths_to_check.push(scanner_path.clone());
        }

        paths_to_check.extend(
            config
                .external_files
                .unwrap_or_default()
                .iter()
                .map(|p| config.src_path.join(p)),
        );

        if !recompile {
            recompile = needs_recompile(&output_path, &paths_to_check)
                .with_context(|| "Failed to compare source and binary timestamps")?;
        }

        #[cfg(feature = "wasm")]
        if let Some(wasm_store) = self.wasm_store.lock().unwrap().as_mut() {
            if recompile {
                self.compile_parser_to_wasm(
                    &config.name,
                    None,
                    config.src_path,
                    config
                        .scanner_path
                        .as_ref()
                        .and_then(|p| p.strip_prefix(config.src_path).ok()),
                    &output_path,
                    false,
                )?;
            }

            let wasm_bytes = fs::read(&output_path)?;
            return Ok(wasm_store.load_language(&config.name, &wasm_bytes)?);
        }

        let lock_path = if env::var("CROSS_RUNNER").is_ok() {
            tempfile::tempdir()
                .unwrap()
                .path()
                .join("tree-sitter")
                .join("lock")
                .join(format!("{}.lock", config.name))
        } else {
            dirs::cache_dir()
                .ok_or_else(|| anyhow!("Cannot determine cache directory"))?
                .join("tree-sitter")
                .join("lock")
                .join(format!("{}.lock", config.name))
        };

        if let Ok(lock_file) = fs::OpenOptions::new().write(true).open(&lock_path) {
            recompile = false;
            if lock_file.try_lock_exclusive().is_err() {
                // if we can't acquire the lock, another process is compiling the parser, wait for
                // it and don't recompile
                lock_file.lock_exclusive()?;
                recompile = false;
            } else {
                // if we can acquire the lock, check if the lock file is older than 30 seconds, a
                // run that was interrupted and left the lock file behind should not block
                // subsequent runs
                let time = lock_file.metadata()?.modified()?.elapsed()?.as_secs();
                if time > 30 {
                    fs::remove_file(&lock_path)?;
                    recompile = true;
                }
            }
        }

        if recompile {
            fs::create_dir_all(lock_path.parent().unwrap()).with_context(|| {
                format!(
                    "Failed to create directory {:?}",
                    lock_path.parent().unwrap()
                )
            })?;
            let lock_file = fs::OpenOptions::new()
                .create(true)
                .truncate(true)
                .write(true)
                .open(&lock_path)?;
            lock_file.lock_exclusive()?;

            self.compile_parser_to_dylib(&config, &lock_file, &lock_path)?;

            if config.scanner_path.is_some() {
                self.check_external_scanner(&config.name, &output_path)?;
            }
        }

        let library = unsafe { Library::new(&output_path) }
            .with_context(|| format!("Error opening dynamic library {output_path:?}"))?;
        let language = unsafe {
            let language_fn = library
                .get::<Symbol<unsafe extern "C" fn() -> Language>>(language_fn_name.as_bytes())
                .with_context(|| format!("Failed to load symbol {language_fn_name}"))?;
            language_fn()
        };
        mem::forget(library);
        Ok(language)
    }

    fn compile_parser_to_dylib(
        &self,
        config: &CompileConfig,
        lock_file: &fs::File,
        lock_path: &Path,
    ) -> Result<(), Error> {
        let mut cc_config = cc::Build::new();
        cc_config
            .cargo_metadata(false)
            .cargo_warnings(false)
            .target(BUILD_TARGET)
            .host(BUILD_HOST)
            .file(&config.parser_path)
            .includes(&config.header_paths);

        if let Some(scanner_path) = config.scanner_path.as_ref() {
            if scanner_path.extension() != Some("c".as_ref()) {
                cc_config.cpp(true);
                eprintln!("Warning: Using a C++ scanner is now deprecated. Please migrate your scanner code to C, as C++ support will be removed in the near future.");
            } else {
                cc_config.std("c11");
            }
            cc_config.file(scanner_path);
        }

        if self.debug_build {
            cc_config.opt_level(0).extra_warnings(true);
        } else {
            cc_config.opt_level(2).extra_warnings(false);
        }

        for flag in config.flags {
            cc_config.define(flag, None);
        }

        let compiler = cc_config.get_compiler();
        let mut command = Command::new(compiler.path());
        command.args(compiler.args());
        for (key, value) in compiler.env() {
            command.env(key, value);
        }

        let output_path = config.output_path.as_ref().unwrap();

        if compiler.is_like_msvc() {
            let out = format!("-out:{}", output_path.to_str().unwrap());
            command.arg(if self.debug_build { "-LDd" } else { "-LD" });
            command.arg("-utf-8");
            command.args(cc_config.get_files());
            command.arg("-link").arg(out);
        } else {
            command.args(["-Werror=implicit-function-declaration", "-g"]);
            if cfg!(any(target_os = "macos", target_os = "ios")) {
                command.arg("-dynamiclib");
                // TODO: remove when supported
                command.arg("-UTREE_SITTER_REUSE_ALLOCATOR");
            } else {
                command.arg("-shared");
            }
            command.args(cc_config.get_files());
            command.arg("-o").arg(output_path);
        }

        let output = command.output().with_context(|| {
            format!("Failed to execute the C compiler with the following command:\n{command:?}")
        })?;

        lock_file.unlock()?;
        fs::remove_file(lock_path)?;

        if output.status.success() {
            Ok(())
        } else {
            Err(anyhow!(
                "Parser compilation failed.\nStdout: {}\nStderr: {}",
                String::from_utf8_lossy(&output.stdout),
                String::from_utf8_lossy(&output.stderr)
            ))
        }
    }

    #[cfg(unix)]
    fn check_external_scanner(&self, name: &str, library_path: &Path) -> Result<()> {
        let prefix = if cfg!(any(target_os = "macos", target_os = "ios")) {
            "_"
        } else {
            ""
        };
        let mut must_have = vec![
            format!("{prefix}tree_sitter_{name}_external_scanner_create"),
            format!("{prefix}tree_sitter_{name}_external_scanner_destroy"),
            format!("{prefix}tree_sitter_{name}_external_scanner_serialize"),
            format!("{prefix}tree_sitter_{name}_external_scanner_deserialize"),
            format!("{prefix}tree_sitter_{name}_external_scanner_scan"),
        ];

        let command = Command::new("nm")
            .arg("-W")
            .arg("-U")
            .arg(library_path)
            .output();
        if let Ok(output) = command {
            if output.status.success() {
                let mut found_non_static = false;
                for line in String::from_utf8_lossy(&output.stdout).lines() {
                    if line.contains(" T ") {
                        if let Some(function_name) =
                            line.split_whitespace().collect::<Vec<_>>().get(2)
                        {
                            if !line.contains("tree_sitter_") {
                                if !found_non_static {
                                    found_non_static = true;
                                    eprintln!("Warning: Found non-static non-tree-sitter functions in the external scannner");
                                }
                                eprintln!("  `{function_name}`");
                            } else {
                                must_have.retain(|f| f != function_name);
                            }
                        }
                    }
                }
                if found_non_static {
                    eprintln!("Consider making these functions static, they can cause conflicts when another tree-sitter project uses the same function name");
                }

                if !must_have.is_empty() {
                    let missing = must_have
                        .iter()
                        .map(|f| format!("  `{f}`"))
                        .collect::<Vec<_>>()
                        .join("\n");

                    return Err(anyhow!(format!(
                        indoc! {"
                            Missing required functions in the external scanner, parsing won't work without these!

                            {}

                            You can read more about this at https://tree-sitter.github.io/tree-sitter/creating-parsers#external-scanners
                        "},
                        missing,
                    )));
                }
            }
        }

        Ok(())
    }

    #[cfg(windows)]
    fn check_external_scanner(&self, _name: &str, _library_path: &Path) -> Result<()> {
        // TODO: there's no nm command on windows, whoever wants to implement this can and should :)

        // let mut must_have = vec![
        //     format!("tree_sitter_{name}_external_scanner_create"),
        //     format!("tree_sitter_{name}_external_scanner_destroy"),
        //     format!("tree_sitter_{name}_external_scanner_serialize"),
        //     format!("tree_sitter_{name}_external_scanner_deserialize"),
        //     format!("tree_sitter_{name}_external_scanner_scan"),
        // ];

        Ok(())
    }

    pub fn compile_parser_to_wasm(
        &self,
        language_name: &str,
        root_path: Option<&Path>,
        src_path: &Path,
        scanner_filename: Option<&Path>,
        output_path: &Path,
        force_docker: bool,
    ) -> Result<(), Error> {
        #[derive(PartialEq, Eq)]
        enum EmccSource {
            Native,
            Docker,
            Podman,
        }

        let root_path = root_path.unwrap_or(src_path);
        let emcc_name = if cfg!(windows) { "emcc.bat" } else { "emcc" };

        // Order of preference: emscripten > docker > podman > error
        let source = if !force_docker && Command::new(emcc_name).output().is_ok() {
            EmccSource::Native
        } else if Command::new("docker")
            .arg("info")
            .output()
            .map_or(false, |out| out.status.success())
        {
            EmccSource::Docker
        } else if Command::new("podman")
            .arg("--version")
            .output()
            .map_or(false, |out| out.status.success())
        {
            EmccSource::Podman
        } else {
            return Err(anyhow!(
                "You must have either emcc, docker, or podman on your PATH to run this command"
            ));
        };

        let mut command = match source {
            EmccSource::Native => {
                let mut command = Command::new(emcc_name);
                command.current_dir(src_path);
                command
            }

            EmccSource::Docker | EmccSource::Podman => {
                let mut command = match source {
                    EmccSource::Docker => Command::new("docker"),
                    EmccSource::Podman => Command::new("podman"),
                    _ => unreachable!(),
                };
                command.args(["run", "--rm"]);

                // The working directory is the directory containing the parser itself
                let workdir = if root_path == src_path {
                    PathBuf::from("/src")
                } else {
                    let mut path = PathBuf::from("/src");
                    path.push(src_path.strip_prefix(root_path).unwrap());
                    path
                };
                command.args(["--workdir", &workdir.to_string_lossy()]);

                // Mount the root directory as a volume, which is the repo root
                let mut volume_string = OsString::from(&root_path);
                volume_string.push(":/src:Z");
                command.args([OsStr::new("--volume"), &volume_string]);

                // In case `docker` is an alias to `podman`, ensure that podman
                // mounts the current directory as writable by the container
                // user which has the same uid as the host user. Setting the
                // podman-specific variable is more reliable than attempting to
                // detect whether `docker` is an alias for `podman`.
                // see https://docs.podman.io/en/latest/markdown/podman-run.1.html#userns-mode
                command.env("PODMAN_USERNS", "keep-id");

                // Get the current user id so that files created in the docker container will have
                // the same owner.
                #[cfg(unix)]
                {
                    #[link(name = "c")]
                    extern "C" {
                        fn getuid() -> u32;
                    }
                    // don't need to set user for podman since PODMAN_USERNS=keep-id is already set
                    if source == EmccSource::Docker {
                        let user_id = unsafe { getuid() };
                        command.args(["--user", &user_id.to_string()]);
                    }
                };

                // Run `emcc` in a container using the `emscripten-slim` image
                command.args([EMSCRIPTEN_TAG, "emcc"]);
                command
            }
        };

        let output_name = "output.wasm";

        command.args([
            "-o",
            output_name,
            "-Os",
            "-s",
            "WASM=1",
            "-s",
            "SIDE_MODULE=2",
            "-s",
            "TOTAL_MEMORY=33554432",
            "-s",
            "NODEJS_CATCH_EXIT=0",
            "-s",
            &format!("EXPORTED_FUNCTIONS=[\"_tree_sitter_{language_name}\"]"),
            "-fno-exceptions",
            "-fvisibility=hidden",
            "-I",
            ".",
        ]);

        if let Some(scanner_filename) = scanner_filename {
            if scanner_filename
                .extension()
                .and_then(|ext| ext.to_str())
                .map_or(false, |ext| ["cc", "cpp"].contains(&ext))
            {
                eprintln!("Warning: Using a C++ scanner is now deprecated. Please migrate your scanner code to C, as C++ support will be removed in the near future.");
                command.arg("-xc++");
            }
            command.arg(scanner_filename);
        }

        command.arg("parser.c");
        let status = command
            .spawn()
            .with_context(|| "Failed to run emcc command")?
            .wait()?;
        if !status.success() {
            return Err(anyhow!("emcc command failed"));
        }

        fs::rename(src_path.join(output_name), output_path)
            .context("failed to rename wasm output file")?;

        Ok(())
    }

    #[must_use]
    pub fn highlight_config_for_injection_string<'a>(
        &'a self,
        string: &str,
    ) -> Option<&'a HighlightConfiguration> {
        match self.language_configuration_for_injection_string(string) {
            Err(e) => {
                eprintln!("Failed to load language for injection string '{string}': {e}",);
                None
            }
            Ok(None) => None,
            Ok(Some((language, configuration))) => {
                match configuration.highlight_config(language, None) {
                    Err(e) => {
                        eprintln!(
                            "Failed to load property sheet for injection string '{string}': {e}",
                        );
                        None
                    }
                    Ok(None) => None,
                    Ok(Some(config)) => Some(config),
                }
            }
        }
    }

    pub fn find_language_configurations_at_path(
        &mut self,
        parser_path: &Path,
        set_current_path_config: bool,
    ) -> Result<&[LanguageConfiguration]> {
        #[derive(Deserialize, Clone, Default)]
        #[serde(untagged)]
        enum PathsJSON {
            #[default]
            Empty,
            Single(String),
            Multiple(Vec<String>),
        }

        impl PathsJSON {
            fn into_vec(self) -> Option<Vec<String>> {
                match self {
                    Self::Empty => None,
                    Self::Single(s) => Some(vec![s]),
                    Self::Multiple(s) => Some(s),
                }
            }
        }

        #[derive(Deserialize)]
        struct LanguageConfigurationJSON {
            #[serde(default)]
            path: PathBuf,
            scope: Option<String>,
            #[serde(rename = "file-types")]
            file_types: Option<Vec<String>>,
            #[serde(rename = "content-regex")]
            content_regex: Option<String>,
            #[serde(rename = "first-line-regex")]
            first_line_regex: Option<String>,
            #[serde(rename = "injection-regex")]
            injection_regex: Option<String>,
            #[serde(default)]
            highlights: PathsJSON,
            #[serde(default)]
            injections: PathsJSON,
            #[serde(default)]
            locals: PathsJSON,
            #[serde(default)]
            tags: PathsJSON,
            #[serde(default, rename = "external-files")]
            external_files: PathsJSON,
        }

        #[derive(Deserialize)]
        struct PackageJSON {
            #[serde(default)]
            #[serde(rename = "tree-sitter")]
            tree_sitter: Vec<LanguageConfigurationJSON>,
        }

        #[derive(Deserialize)]
        struct GrammarJSON {
            name: String,
        }

        let initial_language_configuration_count = self.language_configurations.len();

        if let Ok(package_json_contents) = fs::read_to_string(parser_path.join("package.json")) {
            let package_json = serde_json::from_str::<PackageJSON>(&package_json_contents);
            if let Ok(package_json) = package_json {
                let language_count = self.languages_by_id.len();
                for config_json in package_json.tree_sitter {
                    // Determine the path to the parser directory. This can be specified in
                    // the package.json, but defaults to the directory containing the package.json.
                    let language_path = parser_path.join(config_json.path);

                    let grammar_path = language_path.join("src").join("grammar.json");
                    let mut grammar_file = fs::File::open(grammar_path)
                        .with_context(|| "Failed to read grammar.json")?;
                    let grammar_json: GrammarJSON =
                        serde_json::from_reader(BufReader::new(&mut grammar_file))
                            .with_context(|| "Failed to parse grammar.json")?;

                    // Determine if a previous language configuration in this package.json file
                    // already uses the same language.
                    let mut language_id = None;
                    for (id, (path, _, _)) in
                        self.languages_by_id.iter().enumerate().skip(language_count)
                    {
                        if language_path == *path {
                            language_id = Some(id);
                        }
                    }

                    // If not, add a new language path to the list.
                    let language_id = if let Some(language_id) = language_id {
                        language_id
                    } else {
                        self.languages_by_id.push((
                            language_path,
                            OnceCell::new(),
                            config_json.external_files.clone().into_vec().map(|files| {
                                files.into_iter()
                                    .map(|path| {
                                       let path = parser_path.join(path);
                                        // prevent p being above/outside of parser_path
                                        if path.starts_with(parser_path) {
                                            Ok(path)
                                        } else {
                                            Err(anyhow!("External file path {path:?} is outside of parser directory {parser_path:?}"))
                                        }
                                    })
                                    .collect::<Result<Vec<_>>>()
                            }).transpose()?,
                        ));
                        self.languages_by_id.len() - 1
                    };

                    let configuration = LanguageConfiguration {
                        root_path: parser_path.to_path_buf(),
                        language_name: grammar_json.name.clone(),
                        scope: config_json.scope,
                        language_id,
                        file_types: config_json.file_types.unwrap_or_default(),
                        content_regex: Self::regex(config_json.content_regex.as_deref()),
                        first_line_regex: Self::regex(config_json.first_line_regex.as_deref()),
                        injection_regex: Self::regex(config_json.injection_regex.as_deref()),
                        injections_filenames: config_json.injections.into_vec(),
                        locals_filenames: config_json.locals.into_vec(),
                        tags_filenames: config_json.tags.into_vec(),
                        highlights_filenames: config_json.highlights.into_vec(),
                        highlight_config: OnceCell::new(),
                        tags_config: OnceCell::new(),
                        highlight_names: &self.highlight_names,
                        use_all_highlight_names: self.use_all_highlight_names,
                    };

                    for file_type in &configuration.file_types {
                        self.language_configuration_ids_by_file_type
                            .entry(file_type.to_string())
                            .or_default()
                            .push(self.language_configurations.len());
                    }
                    if let Some(first_line_regex) = &configuration.first_line_regex {
                        self.language_configuration_ids_by_first_line_regex
                            .entry(first_line_regex.to_string())
                            .or_default()
                            .push(self.language_configurations.len());
                    }

                    self.language_configurations.push(unsafe {
                        mem::transmute::<LanguageConfiguration<'_>, LanguageConfiguration<'static>>(
                            configuration,
                        )
                    });

                    if set_current_path_config
                        && self.language_configuration_in_current_path.is_none()
                    {
                        self.language_configuration_in_current_path =
                            Some(self.language_configurations.len() - 1);
                    }
                }
            }
        }

        if self.language_configurations.len() == initial_language_configuration_count
            && parser_path.join("src").join("grammar.json").exists()
        {
            let grammar_path = parser_path.join("src").join("grammar.json");
            let mut grammar_file =
                fs::File::open(grammar_path).with_context(|| "Failed to read grammar.json")?;
            let grammar_json: GrammarJSON =
                serde_json::from_reader(BufReader::new(&mut grammar_file))
                    .with_context(|| "Failed to parse grammar.json")?;
            let configuration = LanguageConfiguration {
                root_path: parser_path.to_owned(),
                language_name: grammar_json.name,
                language_id: self.languages_by_id.len(),
                file_types: Vec::new(),
                scope: None,
                content_regex: None,
                first_line_regex: None,
                injection_regex: None,
                injections_filenames: None,
                locals_filenames: None,
                highlights_filenames: None,
                tags_filenames: None,
                highlight_config: OnceCell::new(),
                tags_config: OnceCell::new(),
                highlight_names: &self.highlight_names,
                use_all_highlight_names: self.use_all_highlight_names,
            };
            self.language_configurations.push(unsafe {
                mem::transmute::<LanguageConfiguration<'_>, LanguageConfiguration<'static>>(
                    configuration,
                )
            });
            self.languages_by_id
                .push((parser_path.to_owned(), OnceCell::new(), None));
        }

        Ok(&self.language_configurations[initial_language_configuration_count..])
    }

    fn regex(pattern: Option<&str>) -> Option<Regex> {
        pattern.and_then(|r| RegexBuilder::new(r).multi_line(true).build().ok())
    }

    pub fn select_language(
        &mut self,
        path: &Path,
        current_dir: &Path,
        scope: Option<&str>,
    ) -> Result<Language> {
        if let Some(scope) = scope {
            if let Some(config) = self
                .language_configuration_for_scope(scope)
                .with_context(|| format!("Failed to load language for scope '{scope}'"))?
            {
                Ok(config.0)
            } else {
                Err(anyhow!("Unknown scope '{scope}'"))
            }
        } else if let Some((lang, _)) = self
            .language_configuration_for_file_name(path)
            .with_context(|| {
                format!(
                    "Failed to load language for file name {}",
                    &path.file_name().unwrap().to_string_lossy()
                )
            })?
        {
            Ok(lang)
        } else if let Some(id) = self.language_configuration_in_current_path {
            Ok(self.language_for_id(self.language_configurations[id].language_id)?)
        } else if let Some(lang) = self
            .languages_at_path(current_dir)
            .with_context(|| "Failed to load language in current directory")?
            .first()
            .cloned()
        {
            Ok(lang.0)
        } else if let Some(lang) = self.language_configuration_for_first_line_regex(path)? {
            Ok(lang.0)
        } else {
            Err(anyhow!("No language found"))
        }
    }

    pub fn use_debug_build(&mut self, flag: bool) {
        self.debug_build = flag;
    }

    #[cfg(feature = "wasm")]
    pub fn use_wasm(&mut self, engine: tree_sitter::wasmtime::Engine) {
        *self.wasm_store.lock().unwrap() = Some(tree_sitter::WasmStore::new(engine).unwrap());
    }

    #[must_use]
    pub fn get_scanner_path(&self, src_path: &Path) -> Option<PathBuf> {
        let mut path = src_path.join("scanner.c");
        for extension in ["c", "cc", "cpp"] {
            path.set_extension(extension);
            if path.exists() {
                return Some(path);
            }
        }
        None
    }
}

impl<'a> LanguageConfiguration<'a> {
    pub fn highlight_config(
        &self,
        language: Language,
        paths: Option<&[String]>,
    ) -> Result<Option<&HighlightConfiguration>> {
        let (highlights_filenames, injections_filenames, locals_filenames) = match paths {
            Some(paths) => (
                Some(
                    paths
                        .iter()
                        .filter(|p| p.ends_with("highlights.scm"))
                        .cloned()
                        .collect::<Vec<_>>(),
                ),
                Some(
                    paths
                        .iter()
                        .filter(|p| p.ends_with("tags.scm"))
                        .cloned()
                        .collect::<Vec<_>>(),
                ),
                Some(
                    paths
                        .iter()
                        .filter(|p| p.ends_with("locals.scm"))
                        .cloned()
                        .collect::<Vec<_>>(),
                ),
            ),
            None => (None, None, None),
        };
        self.highlight_config
            .get_or_try_init(|| {
                let (highlights_query, highlight_ranges) = self.read_queries(
                    if highlights_filenames.is_some() {
                        highlights_filenames.as_deref()
                    } else {
                        self.highlights_filenames.as_deref()
                    },
                    "highlights.scm",
                )?;
                let (injections_query, injection_ranges) = self.read_queries(
                    if injections_filenames.is_some() {
                        injections_filenames.as_deref()
                    } else {
                        self.injections_filenames.as_deref()
                    },
                    "injections.scm",
                )?;
                let (locals_query, locals_ranges) = self.read_queries(
                    if locals_filenames.is_some() {
                        locals_filenames.as_deref()
                    } else {
                        self.locals_filenames.as_deref()
                    },
                    "locals.scm",
                )?;

                if highlights_query.is_empty() {
                    Ok(None)
                } else {
                    let mut result = HighlightConfiguration::new(
                        language,
                        &self.language_name,
                        &highlights_query,
                        &injections_query,
                        &locals_query,
                    )
                    .map_err(|error| match error.kind {
                        QueryErrorKind::Language => Error::from(error),
                        _ => {
                            if error.offset < injections_query.len() {
                                Self::include_path_in_query_error(
                                    error,
                                    &injection_ranges,
                                    &injections_query,
                                    0,
                                )
                            } else if error.offset < injections_query.len() + locals_query.len() {
                                Self::include_path_in_query_error(
                                    error,
                                    &locals_ranges,
                                    &locals_query,
                                    injections_query.len(),
                                )
                            } else {
                                Self::include_path_in_query_error(
                                    error,
                                    &highlight_ranges,
                                    &highlights_query,
                                    injections_query.len() + locals_query.len(),
                                )
                            }
                        }
                    })?;
                    let mut all_highlight_names = self.highlight_names.lock().unwrap();
                    if self.use_all_highlight_names {
                        for capture_name in result.query.capture_names() {
                            if !all_highlight_names.iter().any(|x| x == capture_name) {
                                all_highlight_names.push((*capture_name).to_string());
                            }
                        }
                    }
                    result.configure(all_highlight_names.as_slice());
                    drop(all_highlight_names);
                    Ok(Some(result))
                }
            })
            .map(Option::as_ref)
    }

    pub fn tags_config(&self, language: Language) -> Result<Option<&TagsConfiguration>> {
        self.tags_config
            .get_or_try_init(|| {
                let (tags_query, tags_ranges) =
                    self.read_queries(self.tags_filenames.as_deref(), "tags.scm")?;
                let (locals_query, locals_ranges) =
                    self.read_queries(self.locals_filenames.as_deref(), "locals.scm")?;
                if tags_query.is_empty() {
                    Ok(None)
                } else {
                    TagsConfiguration::new(language, &tags_query, &locals_query)
                        .map(Some)
                        .map_err(|error| {
                            if let TagsError::Query(error) = error {
                                if error.offset < locals_query.len() {
                                    Self::include_path_in_query_error(
                                        error,
                                        &locals_ranges,
                                        &locals_query,
                                        0,
                                    )
                                } else {
                                    Self::include_path_in_query_error(
                                        error,
                                        &tags_ranges,
                                        &tags_query,
                                        locals_query.len(),
                                    )
                                }
                            } else {
                                error.into()
                            }
                        })
                }
            })
            .map(Option::as_ref)
    }

    fn include_path_in_query_error(
        mut error: QueryError,
        ranges: &[(String, Range<usize>)],
        source: &str,
        start_offset: usize,
    ) -> Error {
        let offset_within_section = error.offset - start_offset;
        let (path, range) = ranges
            .iter()
            .find(|(_, range)| range.contains(&offset_within_section))
            .unwrap_or_else(|| ranges.last().unwrap());
        error.offset = offset_within_section - range.start;
        error.row = source[range.start..offset_within_section]
            .matches(|c| c == '\n')
            .count();
        Error::from(error).context(format!("Error in query file {path:?}"))
    }

    #[allow(clippy::type_complexity)]
    fn read_queries(
        &self,
        paths: Option<&[String]>,
        default_path: &str,
    ) -> Result<(String, Vec<(String, Range<usize>)>)> {
        let mut query = String::new();
        let mut path_ranges = Vec::new();
        if let Some(paths) = paths {
            for path in paths {
                let abs_path = self.root_path.join(path);
                let prev_query_len = query.len();
                query += &fs::read_to_string(&abs_path)
                    .with_context(|| format!("Failed to read query file {path:?}"))?;
                path_ranges.push((path.clone(), prev_query_len..query.len()));
            }
        } else {
            // highlights.scm is needed to test highlights, and tags.scm to test tags
            if default_path == "highlights.scm" || default_path == "tags.scm" {
                eprintln!(
                    indoc! {"
                        Warning: you should add a `{}` entry pointing to the highlights path in `tree-sitter` language list in the grammar's package.json
                        See more here: https://tree-sitter.github.io/tree-sitter/syntax-highlighting#query-paths
                    "},
                    default_path.replace(".scm", "")
                );
            }
            let queries_path = self.root_path.join("queries");
            let path = queries_path.join(default_path);
            if path.exists() {
                query = fs::read_to_string(&path)
                    .with_context(|| format!("Failed to read query file {path:?}"))?;
                path_ranges.push((default_path.to_string(), 0..query.len()));
            }
        }

        Ok((query, path_ranges))
    }
}

fn needs_recompile(lib_path: &Path, paths_to_check: &[PathBuf]) -> Result<bool> {
    if !lib_path.exists() {
        return Ok(true);
    }
    let lib_mtime =
        mtime(lib_path).with_context(|| format!("Failed to read mtime of {lib_path:?}"))?;
    for path in paths_to_check {
        if mtime(path)? > lib_mtime {
            return Ok(true);
        }
    }
    Ok(false)
}

fn mtime(path: &Path) -> Result<SystemTime> {
    Ok(fs::metadata(path)?.modified()?)
}

fn replace_dashes_with_underscores(name: &str) -> String {
    let mut result = String::with_capacity(name.len());
    for c in name.chars() {
        if c == '-' {
            result.push('_');
        } else {
            result.push(c);
        }
    }
    result
}
