// The Font object

import Path from './path';
import { DefaultEncoding } from './encoding';
import glyphset from './glyphset';
import Position from './position';
import Substitution from './substitution';
import { checkArgument } from './util';
import HintingTrueType from './hintingtt';
import Bidi from './bidi';

/**
 * @typedef FontOptions
 * @type Object
 * @property {Boolean} empty - whether to create a new empty font
 * @property {string} familyName
 * @property {string} styleName
 * @property {string=} fullName
 * @property {string=} postScriptName
 * @property {string=} designer
 * @property {string=} designerURL
 * @property {string=} manufacturer
 * @property {string=} manufacturerURL
 * @property {string=} license
 * @property {string=} licenseURL
 * @property {string=} version
 * @property {string=} description
 * @property {string=} copyright
 * @property {string=} trademark
 * @property {Number} unitsPerEm
 * @property {Number} ascender
 * @property {Number} descender
 * @property {Number} createdTimestamp
 * @property {string=} weightClass
 * @property {string=} widthClass
 * @property {string=} fsSelection
 */

/**
 * A Font represents a loaded OpenType font file.
 * It contains a set of glyphs and methods to draw text on a drawing context,
 * or to get a path representing the text.
 * @exports opentype.Font
 * @class
 * @param {FontOptions}
 * @constructor
 */
function Font(options) {
    options = options || {};
    options.tables = options.tables || {};

    if (!options.empty) {
        // Check that we've provided the minimum set of names.
        checkArgument(
            options.familyName,
            'When creating a new Font object, familyName is required.'
        );
        checkArgument(
            options.styleName,
            'When creating a new Font object, styleName is required.'
        );
        checkArgument(
            options.unitsPerEm,
            'When creating a new Font object, unitsPerEm is required.'
        );
        checkArgument(
            options.ascender,
            'When creating a new Font object, ascender is required.'
        );
        checkArgument(
            options.descender <= 0,
            'When creating a new Font object, negative descender value is required.'
        );

        this.unitsPerEm = options.unitsPerEm || 1000;
        this.ascender = options.ascender;
        this.descender = options.descender;
        this.createdTimestamp = options.createdTimestamp;
        this.tables = Object.assign(options.tables, {
            os2: Object.assign(
                {
                    usWeightClass:
                        options.weightClass || this.usWeightClasses.MEDIUM,
                    usWidthClass:
                        options.widthClass || this.usWidthClasses.MEDIUM,
                    fsSelection:
                        options.fsSelection || this.fsSelectionValues.REGULAR,
                },
                options.tables.os2
            ),
        });
    }

    this.supported = true; // Deprecated: parseBuffer will throw an error if font is not supported.
    this.glyphs = new glyphset.GlyphSet(this, options.glyphs || []);
    this.encoding = new DefaultEncoding(this);
    this.position = new Position(this);
    this.substitution = new Substitution(this);
    this.tables = this.tables || {};

    // needed for low memory mode only.
    this._push = null;
    this._hmtxTableData = {};

    Object.defineProperty(this, 'hinting', {
        get: function () {
            if (this._hinting) return this._hinting;
            if (this.outlinesFormat === 'truetype') {
                return (this._hinting = new HintingTrueType(this));
            }
        },
    });
}

/**
 * Check if the font has a glyph for the given character.
 * @param  {string}
 * @return {Boolean}
 */
Font.prototype.hasChar = function (c) {
    return this.encoding.charToGlyphIndex(c) !== null;
};

/**
 * Convert the given character to a single glyph index.
 * Note that this function assumes that there is a one-to-one mapping between
 * the given character and a glyph; for complex scripts this might not be the case.
 * @param  {string}
 * @return {Number}
 */
Font.prototype.charToGlyphIndex = function (s) {
    return this.encoding.charToGlyphIndex(s);
};

/**
 * Convert the given character to a single Glyph object.
 * Note that this function assumes that there is a one-to-one mapping between
 * the given character and a glyph; for complex scripts this might not be the case.
 * @param  {string}
 * @return {opentype.Glyph}
 */
Font.prototype.charToGlyph = function (c) {
    const glyphIndex = this.charToGlyphIndex(c);
    let glyph = this.glyphs.get(glyphIndex);
    if (!glyph) {
        // .notdef
        glyph = this.glyphs.get(0);
    }

    return glyph;
};

/**
 * Update features
 * @param {any} options features options
 */
Font.prototype.updateFeatures = function (options) {
    // TODO: update all features options not only 'latn'.
    return this.defaultRenderOptions.features.map((feature) => {
        if (feature.script === 'latn') {
            return {
                script: 'latn',
                tags: feature.tags.filter((tag) => options[tag]),
            };
        } else {
            return feature;
        }
    });
};

/**
 * Convert the given text to a list of Glyph objects.
 * Note that there is no strict one-to-one mapping between characters and
 * glyphs, so the list of returned glyphs can be larger or smaller than the
 * length of the given string.
 * @param  {string}
 * @param  {GlyphRenderOptions} [options]
 * @return {opentype.Glyph[]}
 */
Font.prototype.stringToGlyphs = function (s, options) {
    const bidi = new Bidi();

    // Create and register 'glyphIndex' state modifier
    const charToGlyphIndexMod = (token) => this.charToGlyphIndex(token.char);
    bidi.registerModifier('glyphIndex', null, charToGlyphIndexMod);

    // roll-back to default features
    let features = options
        ? this.updateFeatures(options.features)
        : this.defaultRenderOptions.features;

    bidi.applyFeatures(this, features);

    const indexes = bidi.getTextGlyphs(s);

    let length = indexes.length;

    // convert glyph indexes to glyph objects
    const glyphs = new Array(length);
    const notdef = this.glyphs.get(0);
    for (let i = 0; i < length; i += 1) {
        glyphs[i] = this.glyphs.get(indexes[i]) || notdef;
    }
    return glyphs;
};

/**
 * Retrieve the value of the kerning pair between the left glyph (or its index)
 * and the right glyph (or its index). If no kerning pair is found, return 0.
 * The kerning value gets added to the advance width when calculating the spacing
 * between glyphs.
 * For GPOS kerning, this method uses the default script and language, which covers
 * most use cases. To have greater control, use font.position.getKerningValue .
 * @param  {opentype.Glyph} leftGlyph
 * @param  {opentype.Glyph} rightGlyph
 * @return {Number}
 */
Font.prototype.getKerningValue = function (leftGlyph, rightGlyph) {
    leftGlyph = leftGlyph.index || leftGlyph;
    rightGlyph = rightGlyph.index || rightGlyph;
    const gposKerning = this.position.defaultKerningTables;
    if (gposKerning) {
        return this.position.getKerningValue(
            gposKerning,
            leftGlyph,
            rightGlyph
        );
    }
    // "kern" table
    return this.kerningPairs[leftGlyph + ',' + rightGlyph] || 0;
};

/**
 * @typedef GlyphRenderOptions
 * @type Object
 * @property {string} [script] - script used to determine which features to apply. By default, 'DFLT' or 'latn' is used.
 *                               See https://www.microsoft.com/typography/otspec/scripttags.htm
 * @property {string} [language='dflt'] - language system used to determine which features to apply.
 *                                        See https://www.microsoft.com/typography/developers/opentype/languagetags.aspx
 * @property {boolean} [kerning=true] - whether to include kerning values
 * @property {object} [features] - OpenType Layout feature tags. Used to enable or disable the features of the given script/language system.
 *                                 See https://www.microsoft.com/typography/otspec/featuretags.htm
 */
Font.prototype.defaultRenderOptions = {
    kerning: true,
    features: [
        /**
         * these 4 features are required to render Arabic text properly
         * and shouldn't be turned off when rendering arabic text.
         */
        { script: 'arab', tags: ['init', 'medi', 'fina', 'rlig'] },
        { script: 'latn', tags: ['liga', 'rlig'] },
    ],
};

/**
 * Helper function that invokes the given callback for each glyph in the given text.
 * The callback gets `(glyph, x, y, fontSize, options)`.* @param  {string} text
 * @param {string} text - The text to apply.
 * @param  {number} [x=0] - Horizontal position of the beginning of the text.
 * @param  {number} [y=0] - Vertical position of the *baseline* of the text.
 * @param  {number} [fontSize=72] - Font size in pixels. We scale the glyph units by `1 / unitsPerEm * fontSize`.
 * @param  {GlyphRenderOptions=} options
 * @param  {Function} callback
 */
Font.prototype.forEachGlyph = function (
    text,
    x,
    y,
    fontSize,
    options,
    callback
) {
    x = x !== undefined ? x : 0;
    y = y !== undefined ? y : 0;
    fontSize = fontSize !== undefined ? fontSize : 72;
    options = Object.assign({}, this.defaultRenderOptions, options);
    const fontScale = (1 / this.unitsPerEm) * fontSize;
    const glyphs = this.stringToGlyphs(text, options);
    let kerningLookups;
    if (options.kerning) {
        const script = options.script || this.position.getDefaultScriptName();
        kerningLookups = this.position.getKerningTables(
            script,
            options.language
        );
    }
    for (let i = 0; i < glyphs.length; i += 1) {
        const glyph = glyphs[i];
        callback.call(this, glyph, x, y, fontSize, options);
        if (glyph.advanceWidth) {
            x += glyph.advanceWidth * fontScale;
        }

        if (options.kerning && i < glyphs.length - 1) {
            // We should apply position adjustment lookups in a more generic way.
            // Here we only use the xAdvance value.
            const kerningValue = kerningLookups
                ? this.position.getKerningValue(
                      kerningLookups,
                      glyph.index,
                      glyphs[i + 1].index
                  )
                : this.getKerningValue(glyph, glyphs[i + 1]);
            x += kerningValue * fontScale;
        }

        if (options.letterSpacing) {
            x += options.letterSpacing * fontSize;
        } else if (options.tracking) {
            x += (options.tracking / 1000) * fontSize;
        }
    }
    return x;
};

/**
 * Create a Path object that represents the given text.
 * @param  {string} text - The text to create.
 * @param  {number} [x=0] - Horizontal position of the beginning of the text.
 * @param  {number} [y=0] - Vertical position of the *baseline* of the text.
 * @param  {number} [fontSize=72] - Font size in pixels. We scale the glyph units by `1 / unitsPerEm * fontSize`.
 * @param  {GlyphRenderOptions=} options
 * @return {opentype.Path}
 */
Font.prototype.getPath = function (text, x, y, fontSize, options) {
    const fullPath = new Path();
    this.forEachGlyph(
        text,
        x,
        y,
        fontSize,
        options,
        function (glyph, gX, gY, gFontSize) {
            const glyphPath = glyph.getPath(gX, gY, gFontSize, options, this);
            fullPath.extend(glyphPath);
        }
    );
    return fullPath;
};

/**
 * Create an array of Path objects that represent the glyphs of a given text.
 * @param  {string} text - The text to create.
 * @param  {number} [x=0] - Horizontal position of the beginning of the text.
 * @param  {number} [y=0] - Vertical position of the *baseline* of the text.
 * @param  {number} [fontSize=72] - Font size in pixels. We scale the glyph units by `1 / unitsPerEm * fontSize`.
 * @param  {GlyphRenderOptions=} options
 * @return {opentype.Path[]}
 */
Font.prototype.getPaths = function (text, x, y, fontSize, options) {
    const glyphPaths = [];
    this.forEachGlyph(
        text,
        x,
        y,
        fontSize,
        options,
        function (glyph, gX, gY, gFontSize) {
            const glyphPath = glyph.getPath(gX, gY, gFontSize, options, this);
            glyphPaths.push(glyphPath);
        }
    );

    return glyphPaths;
};

/**
 * Returns the advance width of a text.
 *
 * This is something different than Path.getBoundingBox() as for example a
 * suffixed whitespace increases the advanceWidth but not the bounding box
 * or an overhanging letter like a calligraphic 'f' might have a quite larger
 * bounding box than its advance width.
 *
 * This corresponds to canvas2dContext.measureText(text).width
 *
 * @param  {string} text - The text to create.
 * @param  {number} [fontSize=72] - Font size in pixels. We scale the glyph units by `1 / unitsPerEm * fontSize`.
 * @param  {GlyphRenderOptions=} options
 * @return advance width
 */
Font.prototype.getAdvanceWidth = function (text, fontSize, options) {
    return this.forEachGlyph(text, 0, 0, fontSize, options, function () {});
};

/**
 * @private
 */
Font.prototype.fsSelectionValues = {
    ITALIC: 0x001, //1
    UNDERSCORE: 0x002, //2
    NEGATIVE: 0x004, //4
    OUTLINED: 0x008, //8
    STRIKEOUT: 0x010, //16
    BOLD: 0x020, //32
    REGULAR: 0x040, //64
    USER_TYPO_METRICS: 0x080, //128
    WWS: 0x100, //256
    OBLIQUE: 0x200, //512
};

/**
 * @private
 */
Font.prototype.usWidthClasses = {
    ULTRA_CONDENSED: 1,
    EXTRA_CONDENSED: 2,
    CONDENSED: 3,
    SEMI_CONDENSED: 4,
    MEDIUM: 5,
    SEMI_EXPANDED: 6,
    EXPANDED: 7,
    EXTRA_EXPANDED: 8,
    ULTRA_EXPANDED: 9,
};

/**
 * @private
 */
Font.prototype.usWeightClasses = {
    THIN: 100,
    EXTRA_LIGHT: 200,
    LIGHT: 300,
    NORMAL: 400,
    MEDIUM: 500,
    SEMI_BOLD: 600,
    BOLD: 700,
    EXTRA_BOLD: 800,
    BLACK: 900,
};

export default Font;