// Enclose abbreviations in <abbr> tags
//
import MarkdownIt, {StateBlock, StateCore, Token} from 'markdown-it';

/**
 * 环境接口，包含缩写定义
 */
interface AbbrEnv {
    abbreviations?: { [key: string]: string };
}

/**
 * markdown-it-abbr 插件
 * 用于支持缩写语法
 */
export default function abbr_plugin(md: MarkdownIt): void {
    const escapeRE = md.utils.escapeRE;
    const arrayReplaceAt = md.utils.arrayReplaceAt;

    // ASCII characters in Cc, Sc, Sm, Sk categories we should terminate on;
    // you can check character classes here:
    // http://www.unicode.org/Public/UNIDATA/UnicodeData.txt
    const OTHER_CHARS = ' \r\n$+<=>^`|~';

    const UNICODE_PUNCT_RE = md.utils.lib.ucmicro.P.source;
    const UNICODE_SPACE_RE = md.utils.lib.ucmicro.Z.source;

    function abbr_def(state: StateBlock, startLine: number, endLine: number, silent: boolean): boolean {
        let labelEnd: number;
        let pos = state.bMarks[startLine] + state.tShift[startLine];
        const max = state.eMarks[startLine];

        if (pos + 2 >= max) { return false; }

        if (state.src.charCodeAt(pos++) !== 0x2A/* * */) { return false; }
        if (state.src.charCodeAt(pos++) !== 0x5B/* [ */) { return false; }

        const labelStart = pos;

        for (; pos < max; pos++) {
            const ch = state.src.charCodeAt(pos);
            if (ch === 0x5B /* [ */) {
                return false;
            } else if (ch === 0x5D /* ] */) {
                labelEnd = pos;
                break;
            } else if (ch === 0x5C /* \ */) {
                pos++;
            }
        }

        if (labelEnd! < 0 || state.src.charCodeAt(labelEnd! + 1) !== 0x3A/* : */) {
            return false;
        }

        if (silent) { return true; }

        const label = state.src.slice(labelStart, labelEnd!).replace(/\\(.)/g, '$1');
        const title = state.src.slice(labelEnd! + 2, max).trim();
        if (label.length === 0) { return false; }
        if (title.length === 0) { return false; }
        
        const env = state.env as AbbrEnv;
        if (!env.abbreviations) { env.abbreviations = {}; }
        // prepend ':' to avoid conflict with Object.prototype members
        if (typeof env.abbreviations[':' + label] === 'undefined') {
            env.abbreviations[':' + label] = title;
        }

        state.line = startLine + 1;
        return true;
    }

    function abbr_replace(state: StateCore): void {
        const blockTokens = state.tokens;

        const env = state.env as AbbrEnv;
        if (!env.abbreviations) { return; }

        const regSimple = new RegExp('(?:' +
            Object.keys(env.abbreviations).map(function (x: string) {
                return x.substr(1);
            }).sort(function (a: string, b: string) {
                return b.length - a.length;
            }).map(escapeRE).join('|') +
            ')');

        const regText = '(^|' + UNICODE_PUNCT_RE + '|' + UNICODE_SPACE_RE +
            '|[' + OTHER_CHARS.split('').map(escapeRE).join('') + '])' +
            '(' + Object.keys(env.abbreviations).map(function (x: string) {
                return x.substr(1);
            }).sort(function (a: string, b: string) {
                return b.length - a.length;
            }).map(escapeRE).join('|') + ')' +
            '($|' + UNICODE_PUNCT_RE + '|' + UNICODE_SPACE_RE +
            '|[' + OTHER_CHARS.split('').map(escapeRE).join('') + '])'

        const reg = new RegExp(regText, 'g');

        for (let j = 0, l = blockTokens.length; j < l; j++) {
            if (blockTokens[j].type !== 'inline') { continue; }
            let tokens = blockTokens[j].children!;

            // We scan from the end, to keep position when new tags added.
            for (let i = tokens.length - 1; i >= 0; i--) {
                const currentToken = tokens[i];
                if (currentToken.type !== 'text') { continue; }

                let pos = 0;
                const text = currentToken.content;
                reg.lastIndex = 0;
                const nodes: Token[] = [];

                // fast regexp run to determine whether there are any abbreviated words
                // in the current token
                if (!regSimple.test(text)) { continue; }

                let m: RegExpExecArray | null;

                while ((m = reg.exec(text))) {
                    if (m.index > 0 || m[1].length > 0) {
                        const token = new state.Token('text', '', 0);
                        token.content = text.slice(pos, m.index + m[1].length);
                        nodes.push(token);
                    }

                    const token_o = new state.Token('abbr_open', 'abbr', 1);
                    token_o.attrs = [['title', env.abbreviations[':' + m[2]]]];
                    nodes.push(token_o);

                    const token_t = new state.Token('text', '', 0);
                    token_t.content = m[2];
                    nodes.push(token_t);

                    const token_c = new state.Token('abbr_close', 'abbr', -1);
                    nodes.push(token_c);

                    reg.lastIndex -= m[3].length;
                    pos = reg.lastIndex;
                }

                if (!nodes.length) { continue; }

                if (pos < text.length) {
                    const token = new state.Token('text', '', 0);
                    token.content = text.slice(pos);
                    nodes.push(token);
                }

                // replace current node
                blockTokens[j].children = tokens = arrayReplaceAt(tokens, i, nodes);
            }
        }
    }

    md.block.ruler.before('reference', 'abbr_def', abbr_def, { alt: ['paragraph', 'reference'] });

    md.core.ruler.after('linkify', 'abbr_replace', abbr_replace);
}