const eventRegx = /^(click)(\s)*=|(param)(\s)*=/;
const imageAttrReg = /(\s)*src(\s)*=|(\s)*height(\s)*=|(\s)*width(\s)*=|(\s)*align(\s)*=|(\s)*offset(\s)*=|(\s)*click(\s)*=|(\s)*param(\s)*=/;

export interface IHtmlTextParserResultObj {
    text?: string;
    style?: IHtmlTextParserStack;
}

export interface IHtmlTextParserStack {
    color?: string;
    size?: number;
    event?: { [k: string]: string };
    isNewLine?: boolean;
    isImage?: boolean;
    src?: string;
    imageWidth?: number;
    imageHeight?: number;
    imageOffset?: string;
    imageAlign?: string;
    underline?: boolean;
    strikethrough?: boolean;
    offset?: number;
    italic?: boolean;
    bold?: boolean;
    colorGradient?: { lb: string; rb: string; lt: string; rt: string; };
    face?: { color: string; dilate: number; softness: number; };
    outline?: { color: string, thickness: number };
    underlay?: { color: string; x: number; y: number; dilate: number; softness: number; };
    glow?: { color: string; offset: number; inner: number; outer: number; power: number; };
}

/**
 * A utils class for parsing HTML texts. The parsed results will be an object array.
 */
export class HtmlTextParser {
    private _specialSymbolArray: Array<[RegExp, string]> = [];
    private _stack: IHtmlTextParserStack[] = [];
    private _resultObjectArray: IHtmlTextParserResultObj[] = [];

    constructor() {
        this._specialSymbolArray.push([/&lt;/g, '<']);
        this._specialSymbolArray.push([/&gt;/g, '>']);
        this._specialSymbolArray.push([/&amp;/g, '&']);
        this._specialSymbolArray.push([/&quot;/g, '"']);
        this._specialSymbolArray.push([/&apos;/g, '\'']);
        this._specialSymbolArray.push([/&nbsp;/g, ' ']);
    }

    public parse(htmlString: string) {
        this._resultObjectArray.length = 0;
        this._stack.length = 0;

        let startIndex = 0;
        const length = htmlString.length;
        while (startIndex < length) {
            let tagEndIndex = htmlString.indexOf('>', startIndex);
            let tagBeginIndex = -1;
            if (tagEndIndex >= 0) {
                tagBeginIndex = htmlString.lastIndexOf('<', tagEndIndex);
                const noTagBegin = tagBeginIndex < (startIndex - 1);

                if (noTagBegin) {
                    tagBeginIndex = htmlString.indexOf('<', tagEndIndex + 1);
                    tagEndIndex = htmlString.indexOf('>', tagBeginIndex + 1);
                }
            }
            if (tagBeginIndex < 0) {
                this._stack.pop();
                this._processResult(htmlString.substring(startIndex));
                startIndex = length;
            } else {
                let newStr = htmlString.substring(startIndex, tagBeginIndex);
                const tagStr = htmlString.substring(tagBeginIndex + 1, tagEndIndex);
                if (tagStr === '') newStr = htmlString.substring(startIndex, tagEndIndex + 1);
                this._processResult(newStr);
                if (tagEndIndex === -1) {
                    // cc.error('The HTML tag is invalid!');
                    tagEndIndex = tagBeginIndex;
                } else if (htmlString.charAt(tagBeginIndex + 1) === '/') {
                    this._stack.pop();
                } else {
                    this._addToStack(tagStr);
                }
                startIndex = tagEndIndex + 1;
            }
        }

        return this._resultObjectArray;
    }

    private _attributeToObject(attribute: string) {
        attribute = attribute.trim();

        const obj: IHtmlTextParserStack = {};
        let header = /^(color|size)(\s)*=/.exec(attribute);
        let tagName = '';
        let nextSpace = 0;
        let eventHanlderString = '';
        if (header) {
            tagName = header[0];
            attribute = attribute.substring(tagName.length).trim();
            if (attribute === '') {
                return obj;
            }

            // parse color
            nextSpace = attribute.indexOf(' ');
            switch (tagName[0]) {
                case 'c':
                    if (nextSpace > -1) {
                        obj.color = attribute.substring(0, nextSpace).trim();
                    } else {
                        obj.color = attribute;
                    }
                    break;
                case 's':
                    obj.size = parseInt(attribute);
                    break;
                default:
                    break;
            }

            // tag has event arguments
            if (nextSpace > -1) {
                eventHanlderString = attribute.substring(nextSpace + 1).trim();
                obj.event = this._processEventHandler(eventHanlderString);
            }
            return obj;
        }

        header = /^(br(\s)*\/)/.exec(attribute);
        if (header && header[0].length > 0) {
            tagName = header[0].trim();
            if (tagName.startsWith('br') && tagName[tagName.length - 1] === '/') {
                obj.isNewLine = true;
                this._resultObjectArray.push({ text: '', style: { isNewLine: true } as IHtmlTextParserStack });
                return obj;
            }
        }

        header = /^(img(\s)*src(\s)*=[^>]+\/)/.exec(attribute);
        let remainingArgument = '';
        let rightQuot = -1;
        if (header && header[0].length > 0) {
            tagName = header[0].trim();
            if (tagName.startsWith('img') && tagName[tagName.length - 1] === '/') {
                header = imageAttrReg.exec(attribute);
                let tagValue: string;
                let isValidImageTag = false;
                while (header) {
                    // skip the invalid tags at first
                    attribute = attribute.substring(attribute.indexOf(header[0]));
                    tagName = attribute.substr(0, header[0].length);
                    const originTagNameLength = tagName.length;
                    tagName = tagName.replace(/[^a-zA-Z]/g, '').trim();
                    tagName = tagName.toLowerCase();

                    // remove space and = character
                    remainingArgument = attribute.substring(originTagNameLength).trim();
                    if (tagName === 'src') {
                        rightQuot = this.getRightQuotationIndex(remainingArgument);
                    } else {
                        rightQuot = -1;
                    }
                    nextSpace = remainingArgument.indexOf(' ', rightQuot + 1 >= remainingArgument.length ? -1 : rightQuot + 1);
                    tagValue = (nextSpace > -1) ? remainingArgument.substr(0, nextSpace) : remainingArgument;
                    attribute = remainingArgument.substring(nextSpace).trim();

                    if (tagValue.endsWith('/')) {
                        tagValue = tagValue.slice(0, -1);
                    }
                    if (tagName === 'src') {
                        switch (tagValue.charCodeAt(0)) {
                            case 34: // "
                            case 39: // '
                                isValidImageTag = true;
                                tagValue = tagValue.slice(1, -1);
                                break;
                            default:
                                break;
                        }
                        obj.isImage = true;
                        obj.src = tagValue;
                    } else if (tagName === 'height') {
                        obj.imageHeight = parseInt(tagValue);
                    } else if (tagName === 'width') {
                        obj.imageWidth = parseInt(tagValue);
                    } else if (tagName === 'align') {
                        switch (tagValue.charCodeAt(0)) {
                            case 34: // "
                            case 39: // '
                                tagValue = tagValue.slice(1, -1);
                                break;
                            default:
                                break;
                        }
                        obj.imageAlign = tagValue.toLowerCase();
                    } else if (tagName === 'offset') {
                        obj.imageOffset = tagValue;
                    } else if (tagName === 'click') {
                        obj.event = this._processEventHandler(`${tagName}=${tagValue}`);
                    }

                    if (obj.event && tagName === 'param') {
                        obj.event[tagName] = tagValue.replace(/^"|"$/g, '');
                    }

                    header = imageAttrReg.exec(attribute);
                }

                if (isValidImageTag && obj.isImage) {
                    this._resultObjectArray.push({ text: '', style: obj });
                }

                return {};
            }
        }

        header = /^(cg(\s)*[^>]*)/.exec(attribute);
        if (header) {
            attribute = header[0].substring("cg".length).trim();
            let defaultColorGradientObject = { lb: "#ffffff", rb: "#ffffff", lt: "#ffffff", rt: "#ffffff" };
            if (attribute) {
                let colorGradientAttrReg = /(\s)*lb(\s)*=|(\s)*rb(\s)*=|(\s)*lt(\s)*=|(\s)*rt(\s)*=/;
                header = colorGradientAttrReg.exec(attribute);
                let tagValue: string;
                let remainingArgument;
                while (header) {
                    //skip the invalid tags at first
                    attribute = attribute.substring(attribute.indexOf(header[0]));
                    tagName = attribute.substr(0, header[0].length);
                    //remove space and = character
                    remainingArgument = attribute.substring(tagName.length).trim();
                    nextSpace = remainingArgument.indexOf(' ');
                    if (nextSpace > -1) {
                        tagValue = remainingArgument.substr(0, nextSpace);
                    } else {
                        tagValue = remainingArgument;
                    }
                    tagName = tagName.replace(/[^a-zA-Z]/g, "").trim();
                    tagName = tagName.toLocaleLowerCase();

                    attribute = remainingArgument.substring(nextSpace).trim();
                    if (tagName === "lb") {
                        defaultColorGradientObject.lb = tagValue;
                    } else if (tagName === "rb") {
                        defaultColorGradientObject.rb = tagValue;
                    } else if (tagName === "lt") {
                        defaultColorGradientObject.lt = tagValue;
                    } else if (tagName === "rt") {
                        defaultColorGradientObject.rt = tagValue;
                    }

                    header = colorGradientAttrReg.exec(attribute);
                }
            }
            obj.colorGradient = defaultColorGradientObject;
        }

        header = /^(face(\s)*[^>]*)/.exec(attribute);
        if (header) {
            attribute = header[0].substring("face".length).trim();
            let defaultFaceObject = { color: "#ffffff", dilate: 0.5, softness: 0.01 };
            if (attribute) {
                let faceAttrReg = /(\s)*color(\s)*=|(\s)*dilate(\s)*=|(\s)*softness(\s)*=|(\s)*click(\s)*=|(\s)*param(\s)*=/;
                header = faceAttrReg.exec(attribute);
                let tagValue: string;
                let remainingArgument;
                while (header) {
                    //skip the invalid tags at first
                    attribute = attribute.substring(attribute.indexOf(header[0]));
                    tagName = attribute.substr(0, header[0].length);
                    //remove space and = character
                    remainingArgument = attribute.substring(tagName.length).trim();
                    nextSpace = remainingArgument.indexOf(' ');
                    if (nextSpace > -1) {
                        tagValue = remainingArgument.substr(0, nextSpace);
                    } else {
                        tagValue = remainingArgument;
                    }
                    tagName = tagName.replace(/[^a-zA-Z]/g, "").trim();
                    tagName = tagName.toLocaleLowerCase();

                    attribute = remainingArgument.substring(nextSpace).trim();
                    if (tagName === "click") {
                        obj.event = this._processEventHandler(`${tagName}=${tagValue}`);
                    } else if (tagName === "color") {
                        defaultFaceObject.color = tagValue;
                    } else if (tagName === "dilate") {
                        defaultFaceObject.dilate = Number(tagValue);
                    } else if (tagName === "softness") {
                        defaultFaceObject.softness = Number(tagValue);
                    }

                    if (obj.event && tagName === 'param') {
                        obj.event.param = tagValue.replace(/^\"|\"$/g, '');
                    }

                    header = faceAttrReg.exec(attribute);
                }
            }
            obj.face = defaultFaceObject;
        }

        header = /^(outline(\s)*[^>]*)/.exec(attribute);
        if (header) {
            attribute = header[0].substring('outline'.length).trim();
            const defaultOutlineObject = { color: '#ffffff', thickness: 0.1 };
            if (attribute) {
                const outlineAttrReg = /(\s)*color(\s)*=|(\s)*thickness(\s)*=|(\s)*click(\s)*=|(\s)*param(\s)*=/;
                header = outlineAttrReg.exec(attribute);
                let tagValue: string;
                while (header) {
                    // skip the invalid tags at first
                    attribute = attribute.substring(attribute.indexOf(header[0]));
                    tagName = attribute.substr(0, header[0].length);
                    // remove space and = character
                    remainingArgument = attribute.substring(tagName.length).trim();
                    nextSpace = remainingArgument.indexOf(' ');
                    if (nextSpace > -1) {
                        tagValue = remainingArgument.substr(0, nextSpace);
                    } else {
                        tagValue = remainingArgument;
                    }
                    tagName = tagName.replace(/[^a-zA-Z]/g, '').trim();
                    tagName = tagName.toLowerCase();

                    attribute = remainingArgument.substring(nextSpace).trim();
                    if (tagName === 'click') {
                        obj.event = this._processEventHandler(`${tagName}=${tagValue}`);
                    } else if (tagName === 'color') {
                        defaultOutlineObject.color = tagValue;
                    } else if (tagName === 'thickness') {
                        defaultOutlineObject.thickness = Number(tagValue);
                    }

                    if (obj.event && tagName === 'param') {
                        obj.event[tagName] = tagValue.replace(/^"|"$/g, '');
                    }

                    header = outlineAttrReg.exec(attribute);
                }
            }
            obj.outline = defaultOutlineObject;
        }

        header = /^(underlay(\s)*[^>]*)/.exec(attribute);
        if (header) {
            attribute = header[0].substring("underlay".length).trim();
            let defaultUnderlayObject = { color: "#ffffff", x: 0, y: 0, dilate: 0.5, softness: 0.1 };
            if (attribute) {
                let underlayAttrReg = /(\s)*color(\s)*=|(\s)*x(\s)*=|(\s)*y(\s)*=|(\s)*dilate(\s)*=|(\s)*softness(\s)*=|(\s)*click(\s)*=|(\s)*param(\s)*=/;
                header = underlayAttrReg.exec(attribute);
                let tagValue: string;
                let remainingArgument;
                while (header) {
                    //skip the invalid tags at first
                    attribute = attribute.substring(attribute.indexOf(header[0]));
                    tagName = attribute.substr(0, header[0].length);
                    //remove space and = character
                    remainingArgument = attribute.substring(tagName.length).trim();
                    nextSpace = remainingArgument.indexOf(' ');
                    if (nextSpace > -1) {
                        tagValue = remainingArgument.substr(0, nextSpace);
                    } else {
                        tagValue = remainingArgument;
                    }
                    tagName = tagName.replace(/[^a-zA-Z]/g, "").trim();
                    tagName = tagName.toLocaleLowerCase();

                    attribute = remainingArgument.substring(nextSpace).trim();
                    if (tagName === "click") {
                        obj.event = this._processEventHandler(`${tagName}=${tagValue}`);
                    } else if (tagName === "color") {
                        defaultUnderlayObject.color = tagValue;
                    } else if (tagName === "dilate") {
                        defaultUnderlayObject.dilate = Number(tagValue);
                    } else if (tagName === "softness") {
                        defaultUnderlayObject.softness = Number(tagValue);
                    } else if (tagName === "x") {
                        defaultUnderlayObject.x = Number(tagValue);
                    } else if (tagName === "y") {
                        defaultUnderlayObject.y = Number(tagValue);
                    }

                    if (obj.event && tagName === 'param') {
                        obj.event.param = tagValue.replace(/^\"|\"$/g, '');
                    }

                    header = underlayAttrReg.exec(attribute);
                }
            }
            obj.underlay = defaultUnderlayObject;
        }

        header = /^(glow(\s)*[^>]*)/.exec(attribute);
        if (header) {
            attribute = header[0].substring("glow".length).trim();
            let defaultGlowObject = { color: "#000000", offset: 0.5, inner: 0.01, outer: 0.01, power: 1 };
            if (attribute) {
                let glowAttrReg = /(\s)*color(\s)*=|(\s)*offset(\s)*=|(\s)*inner(\s)*=|(\s)*outer(\s)*=|(\s)*power(\s)*=|(\s)*click(\s)*=|(\s)*param(\s)*=/;
                header = glowAttrReg.exec(attribute);
                let tagValue: string;
                let remainingArgument;
                while (header) {
                    //skip the invalid tags at first
                    attribute = attribute.substring(attribute.indexOf(header[0]));
                    tagName = attribute.substr(0, header[0].length);
                    //remove space and = character
                    remainingArgument = attribute.substring(tagName.length).trim();
                    nextSpace = remainingArgument.indexOf(' ');
                    if (nextSpace > -1) {
                        tagValue = remainingArgument.substr(0, nextSpace);
                    } else {
                        tagValue = remainingArgument;
                    }
                    tagName = tagName.replace(/[^a-zA-Z]/g, "").trim();
                    tagName = tagName.toLocaleLowerCase();

                    attribute = remainingArgument.substring(nextSpace).trim();
                    if (tagName === "click") {
                        obj.event = this._processEventHandler(`${tagName}=${tagValue}`);
                    } else if (tagName === "color") {
                        defaultGlowObject.color = tagValue;
                    } else if (tagName === "offset") {
                        defaultGlowObject.offset = Number(tagValue);
                    } else if (tagName === "inner") {
                        defaultGlowObject.inner = Number(tagValue);
                    } else if (tagName === "outer") {
                        defaultGlowObject.outer = Number(tagValue);
                    } else if (tagName === "power") {
                        defaultGlowObject.power = Number(tagValue);
                    }

                    if (obj.event && tagName === 'param') {
                        obj.event.param = tagValue.replace(/^\"|\"$/g, '');
                    }

                    header = glowAttrReg.exec(attribute);
                }
            }
            obj.glow = defaultGlowObject;
        }

        header = /^(on|u|s|b|i)(\s)*/.exec(attribute);
        if (header && header[0].length > 0) {
            tagName = header[0];
            attribute = attribute.substring(tagName.length).trim();
            switch (tagName[0]) {
                case 'u':
                    obj.underline = true;
                    obj.offset = attribute[0] === "=" ? Number(attribute.slice(1)) : 0;
                    break;
                case 's':
                    obj.strikethrough = true;
                    obj.offset = attribute[0] === "=" ? Number(attribute.slice(1)) : 0;
                    break;
                case 'i':
                    obj.italic = true;
                    break;
                case 'b':
                    obj.bold = true;
                    break;
                default:
                    break;
            }
            if (attribute === '') {
                return obj;
            }

            obj.event = this._processEventHandler(attribute);
        }

        return obj;
    }

    // find the right part of the first pair of following quotations.
    private getRightQuotationIndex(remainingArgument: string) {
        let leftQuot = -1;
        let rightQuot = -1;
        // Skip a pair of quotations for avoiding spaces in image name are detected.
        const leftSingleQuot = remainingArgument.indexOf('\'');
        const leftDoubleQuot = remainingArgument.indexOf('"');

        const useSingleQuot = leftSingleQuot > -1 && (leftSingleQuot < leftDoubleQuot || leftDoubleQuot === -1);
        const useDoubleQuot = leftDoubleQuot > -1 && (leftDoubleQuot < leftSingleQuot || leftSingleQuot === -1);
        if (useSingleQuot) {
            leftQuot = leftSingleQuot;
            rightQuot = remainingArgument.indexOf('\'', leftQuot + 1 >= remainingArgument.length ? -1 : leftQuot + 1);
        } else if (useDoubleQuot) {
            leftQuot = leftDoubleQuot;
            rightQuot = remainingArgument.indexOf('"', leftQuot + 1 >= remainingArgument.length ? -1 : leftQuot + 1);
        }

        return rightQuot;
    }

    private _processEventHandler(eventString: string) {
        const obj = {};
        let index = 0;
        let isValidTag = false;
        let eventNames = eventRegx.exec(eventString);
        while (eventNames) {
            let eventName = eventNames[0];
            let eventValue = '';
            isValidTag = false;
            eventString = eventString.substring(eventName.length).trim();
            if (eventString.charAt(0) === '"') {
                index = eventString.indexOf('"', 1);
                if (index > -1) {
                    eventValue = eventString.substring(1, index).trim();
                    isValidTag = true;
                }
                index++;
            } else if (eventString.charAt(0) === '\'') {
                index = eventString.indexOf('\'', 1);
                if (index > -1) {
                    eventValue = eventString.substring(1, index).trim();
                    isValidTag = true;
                }
                index++;
            } else {
                // skip the invalid attribute value
                const match = /(\S)+/.exec(eventString);
                if (match) {
                    eventValue = match[0];
                } else {
                    eventValue = '';
                }
                index = eventValue.length;
            }

            if (isValidTag) {
                eventName = eventName.substring(0, eventName.length - 1).trim();
                obj[eventName] = eventValue;
            }

            eventString = eventString.substring(index).trim();
            eventNames = eventRegx.exec(eventString);
        }

        return obj;
    }

    private _addToStack(attribute: string) {
        const obj = this._attributeToObject(attribute);

        if (this._stack.length === 0) {
            this._stack.push(obj);
        } else {
            if (obj.isNewLine || obj.isImage) {
                return;
            }
            // for nested tags
            const previousTagObj = this._stack[this._stack.length - 1];
            for (const key in previousTagObj) {
                if (!(obj[key])) {
                    obj[key] = previousTagObj[key];
                }
            }
            this._stack.push(obj);
        }
    }

    private _processResult(value: string) {
        if (value.length === 0) {
            return;
        }

        value = this._escapeSpecialSymbol(value);
        if (this._stack.length > 0) {
            this._resultObjectArray.push({ text: value, style: this._stack[this._stack.length - 1] });
        } else {
            this._resultObjectArray.push({ text: value } as IHtmlTextParserResultObj);
        }
    }

    private _escapeSpecialSymbol(str: string) {
        for (const symbolArr of this._specialSymbolArray) {
            const key = symbolArr[0];
            const value = symbolArr[1];

            str = str.replace(key, value);
        }

        return str;
    }
}