/* -*- Mode: java; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

package org.mozilla.javascript;

import org.mozilla.javascript.dtoa.DecimalFormatter;

/**
 * This class implements the Number native object.
 *
 * <p>See ECMA 15.7.
 *
 * @author Norris Boyd
 */
final class NativeNumber extends IdScriptableObject {
    private static final long serialVersionUID = 3504516769741512101L;

    /** @see https://www.ecma-international.org/ecma-262/6.0/#sec-number.max_safe_integer */
    public static final double MAX_SAFE_INTEGER = 9007199254740991.0; // Math.pow(2, 53) - 1

    private static final Object NUMBER_TAG = "Number";

    private static final int MAX_PRECISION = 100;
    private static final double MIN_SAFE_INTEGER = -MAX_SAFE_INTEGER;
    private static final double EPSILON = 2.220446049250313e-16; // Math.pow(2, -52)

    static void init(Scriptable scope, boolean sealed) {
        NativeNumber obj = new NativeNumber(0.0);
        obj.exportAsJSClass(MAX_PROTOTYPE_ID, scope, sealed);
    }

    NativeNumber(double number) {
        doubleValue = number;
    }

    @Override
    public String getClassName() {
        return "Number";
    }

    @Override
    protected void fillConstructorProperties(IdFunctionObject ctor) {
        final int attr =
                ScriptableObject.DONTENUM | ScriptableObject.PERMANENT | ScriptableObject.READONLY;

        ctor.defineProperty("NaN", ScriptRuntime.NaNobj, attr);
        ctor.defineProperty(
                "POSITIVE_INFINITY", ScriptRuntime.wrapNumber(Double.POSITIVE_INFINITY), attr);
        ctor.defineProperty(
                "NEGATIVE_INFINITY", ScriptRuntime.wrapNumber(Double.NEGATIVE_INFINITY), attr);
        ctor.defineProperty("MAX_VALUE", ScriptRuntime.wrapNumber(Double.MAX_VALUE), attr);
        ctor.defineProperty("MIN_VALUE", ScriptRuntime.wrapNumber(Double.MIN_VALUE), attr);
        ctor.defineProperty("MAX_SAFE_INTEGER", ScriptRuntime.wrapNumber(MAX_SAFE_INTEGER), attr);
        ctor.defineProperty("MIN_SAFE_INTEGER", ScriptRuntime.wrapNumber(MIN_SAFE_INTEGER), attr);
        ctor.defineProperty("EPSILON", ScriptRuntime.wrapNumber(EPSILON), attr);

        addIdFunctionProperty(ctor, NUMBER_TAG, ConstructorId_isFinite, "isFinite", 1);
        addIdFunctionProperty(ctor, NUMBER_TAG, ConstructorId_isNaN, "isNaN", 1);
        addIdFunctionProperty(ctor, NUMBER_TAG, ConstructorId_isInteger, "isInteger", 1);
        addIdFunctionProperty(ctor, NUMBER_TAG, ConstructorId_isSafeInteger, "isSafeInteger", 1);
        Object parseFloat = ScriptRuntime.getTopLevelProp(ctor, "parseFloat");
        if (parseFloat instanceof IdFunctionObject) {
            ((IdFunctionObject) parseFloat).addAsProperty(ctor);
        }
        Object parseInt = ScriptRuntime.getTopLevelProp(ctor, "parseInt");
        if (parseInt instanceof IdFunctionObject) {
            ((IdFunctionObject) parseInt).addAsProperty(ctor);
        }

        super.fillConstructorProperties(ctor);
    }

    @Override
    protected void initPrototypeId(int id) {
        String s;
        int arity;
        switch (id) {
            case Id_constructor:
                arity = 1;
                s = "constructor";
                break;
            case Id_toString:
                arity = 1;
                s = "toString";
                break;
            case Id_toLocaleString:
                arity = 1;
                s = "toLocaleString";
                break;
            case Id_toSource:
                arity = 0;
                s = "toSource";
                break;
            case Id_valueOf:
                arity = 0;
                s = "valueOf";
                break;
            case Id_toFixed:
                arity = 1;
                s = "toFixed";
                break;
            case Id_toExponential:
                arity = 1;
                s = "toExponential";
                break;
            case Id_toPrecision:
                arity = 1;
                s = "toPrecision";
                break;
            default:
                throw new IllegalArgumentException(String.valueOf(id));
        }
        initPrototypeMethod(NUMBER_TAG, id, s, arity);
    }

    @Override
    public Object execIdCall(
            IdFunctionObject f, Context cx, Scriptable scope, Scriptable thisObj, Object[] args) {
        if (!f.hasTag(NUMBER_TAG)) {
            return super.execIdCall(f, cx, scope, thisObj, args);
        }
        int id = f.methodId();
        if (id == Id_constructor) {
            double val = (args.length >= 1) ? ScriptRuntime.toNumeric(args[0]).doubleValue() : 0.0;
            if (thisObj == null) {
                // new Number(val) creates a new Number object.
                return new NativeNumber(val);
            }
            // Number(val) converts val to a number value.
            return ScriptRuntime.wrapNumber(val);

        } else if (id < Id_constructor) {
            return execConstructorCall(id, args);
        }

        // The rest of Number.prototype methods require thisObj to be Number
        double value = ensureType(thisObj, NativeNumber.class, f).doubleValue;

        switch (id) {
            case Id_toString:
            case Id_toLocaleString:
                {
                    // toLocaleString is just an alias for toString for now
                    int base =
                            (args.length == 0 || Undefined.isUndefined(args[0]))
                                    ? 10
                                    : ScriptRuntime.toInt32(args[0]);
                    return ScriptRuntime.numberToString(value, base);
                }

            case Id_toSource:
                return "(new Number(" + ScriptRuntime.toString(value) + "))";

            case Id_valueOf:
                return ScriptRuntime.wrapNumber(value);

            case Id_toFixed:
                return js_toFixed(cx, value, args);

            case Id_toExponential:
                return js_toExponential(value, args);

            case Id_toPrecision:
                return js_toPrecision(value, args);

            default:
                throw new IllegalArgumentException(String.valueOf(id));
        }
    }

    private static Object execConstructorCall(int id, Object[] args) {
        switch (id) {
            case ConstructorId_isFinite:
                if ((args.length == 0) || Undefined.isUndefined(args[0])) {
                    return Boolean.FALSE;
                }
                if (args[0] instanceof Number) {
                    // Match ES6 polyfill, which only works for "number" types
                    return isFinite(args[0]);
                }
                return Boolean.FALSE;

            case ConstructorId_isNaN:
                if ((args.length == 0) || Undefined.isUndefined(args[0])) {
                    return Boolean.FALSE;
                }
                if (args[0] instanceof Number) {
                    return isNaN((Number) args[0]);
                }
                return Boolean.FALSE;

            case ConstructorId_isInteger:
                if ((args.length == 0) || Undefined.isUndefined(args[0])) {
                    return Boolean.FALSE;
                }
                if (args[0] instanceof Number) {
                    return Boolean.valueOf(isInteger((Number) args[0]));
                }
                return Boolean.FALSE;

            case ConstructorId_isSafeInteger:
                if ((args.length == 0) || (Undefined.instance == args[0])) {
                    return Boolean.FALSE;
                }
                if (args[0] instanceof Number) {
                    return Boolean.valueOf(isSafeInteger((Number) args[0]));
                }
                return Boolean.FALSE;

            default:
                throw new IllegalArgumentException(String.valueOf(id));
        }
    }

    private static Object js_toFixed(Context cx, double value, Object[] args) {
        int fractionDigits;
        if (args.length > 0 && !Undefined.isUndefined(args[0])) {
            double p = ScriptRuntime.toInteger(args[0]);
            int precisionMin = cx.version < Context.VERSION_ES6 ? -20 : 0;
            /* We allow a larger range of precision than
            ECMA requires; this is permitted by ECMA. */
            checkPrecision(p, precisionMin, args[0]);
            fractionDigits = ScriptRuntime.toInt32(p);
        } else {
            fractionDigits = 0;
        }

        if (!Double.isFinite(value)) {
            return ScriptRuntime.toString(value);
        }
        return DecimalFormatter.toFixed(value, fractionDigits);
    }

    private static Object js_toExponential(double value, Object[] args) {
        double p;
        boolean wasUndefined;
        if (args.length > 0 && !Undefined.isUndefined(args[0])) {
            wasUndefined = false;
            p = ScriptRuntime.toInteger(args[0]);
        } else {
            wasUndefined = true;
            p = 0.0;
        }

        if (!Double.isFinite(value)) {
            return ScriptRuntime.toString(value);
        }
        checkPrecision(p, 0.0, args.length > 0 ? args[0] : Undefined.instance);

        // Trigger the special handling for undefined, which requires that
        // we hold off on this bit until the checks above,.
        int fractionDigits = wasUndefined ? -1 : ScriptRuntime.toInt32(p);

        return DecimalFormatter.toExponential(value, fractionDigits);
    }

    private static Object js_toPrecision(double value, Object[] args) {
        // Undefined precision, fall back to ToString()
        if (args.length == 0 || Undefined.isUndefined(args[0])) {
            return ScriptRuntime.toString(value);
        }

        double p = ScriptRuntime.toInteger(args[0]);
        if (!Double.isFinite(value)) {
            return ScriptRuntime.toString(value);
        }
        checkPrecision(p, 1.0, args[0]);
        int precision = ScriptRuntime.toInt32(p);

        return DecimalFormatter.toPrecision(value, precision);
    }

    private static void checkPrecision(double p, double min, Object arg) {
        if (p < min || p > MAX_PRECISION) {
            String msg =
                    ScriptRuntime.getMessageById("msg.bad.precision", ScriptRuntime.toString(arg));
            throw ScriptRuntime.rangeError(msg);
        }
    }

    @Override
    public String toString() {
        return ScriptRuntime.numberToString(doubleValue, 10);
    }

    static Object isFinite(Object val) {
        double d = ScriptRuntime.toNumber(val);
        Double nd = Double.valueOf(d);
        return ScriptRuntime.wrapBoolean(!nd.isInfinite() && !nd.isNaN());
    }

    private static Boolean isNaN(Number val) {
        if (val instanceof Double) {
            return Boolean.valueOf(((Double) val).isNaN());
        }

        double d = val.doubleValue();
        return Boolean.valueOf(Double.isNaN(d));
    }

    private static boolean isInteger(Number val) {
        if (val instanceof Double) {
            return isDoubleInteger((Double) val);
        }
        return isDoubleInteger(val.doubleValue());
    }

    private static boolean isDoubleInteger(Double d) {
        return !d.isInfinite() && !d.isNaN() && (Math.floor(d.doubleValue()) == d.doubleValue());
    }

    private static boolean isDoubleInteger(double d) {
        return Double.isFinite(d) && (Math.floor(d) == d);
    }

    private static boolean isSafeInteger(Number val) {
        if (val instanceof Double) {
            return isDoubleSafeInteger((Double) val);
        }
        return isDoubleSafeInteger(val.doubleValue());
    }

    private static boolean isDoubleSafeInteger(Double d) {
        return isDoubleInteger(d)
                && (d.doubleValue() <= MAX_SAFE_INTEGER)
                && (d.doubleValue() >= MIN_SAFE_INTEGER);
    }

    private static boolean isDoubleSafeInteger(double d) {
        return isDoubleInteger(d) && (d <= MAX_SAFE_INTEGER) && (d >= MIN_SAFE_INTEGER);
    }

    @Override
    protected int findPrototypeId(String s) {
        int id;
        switch (s) {
            case "constructor":
                id = Id_constructor;
                break;
            case "toString":
                id = Id_toString;
                break;
            case "toLocaleString":
                id = Id_toLocaleString;
                break;
            case "toSource":
                id = Id_toSource;
                break;
            case "valueOf":
                id = Id_valueOf;
                break;
            case "toFixed":
                id = Id_toFixed;
                break;
            case "toExponential":
                id = Id_toExponential;
                break;
            case "toPrecision":
                id = Id_toPrecision;
                break;
            default:
                id = 0;
                break;
        }
        return id;
    }

    private static final int ConstructorId_isFinite = -1,
            ConstructorId_isNaN = -2,
            ConstructorId_isInteger = -3,
            ConstructorId_isSafeInteger = -4,
            Id_constructor = 1,
            Id_toString = 2,
            Id_toLocaleString = 3,
            Id_toSource = 4,
            Id_valueOf = 5,
            Id_toFixed = 6,
            Id_toExponential = 7,
            Id_toPrecision = 8,
            MAX_PROTOTYPE_ID = 8;

    private double doubleValue;
}
