"use strict";

export const MarkDown = (function(){

    const MarkDown = function(anp){};

    MarkDown.Item = function(pattern, replace, block = false){
        this.pattern = pattern;
        this.replace = replace;
        this.block = block;
        this.match = null;
        this.length = 0;
        this.more = true;
        this.index = -1;
    };

    MarkDown.Header = () => new MarkDown.Item(/^(#{1,6})\s*(.+)$/m, (match, hashes, content) => `<h${hashes.length}>${MarkDown.to_html(content, false)}</h${hashes.length}>`, true);

    MarkDown.Block = () => new MarkDown.Item(/^```([a-z]*)\r?\n([\s\S]*?)\r?\n```/, (match, lang, content) => `<fieldset><legend>${lang}</legend><pre><code class="${lang}">${content}</code></pre></fieldset>`, true);

    MarkDown.BlockQuote = () => new MarkDown.Item(/^>\s?(.+)$/m, (match, content) => `<blockquote>${MarkDown.to_html(content, false)}</blockquote>`, true);

    MarkDown.Paragraph = () => new MarkDown.Item(/^((?:[^\r\n]+(?:\r\n|[\r\n])?)+)/m, (match, content) => `<p>${MarkDown.to_html(content, false)}</p>\n\n`, true);

    MarkDown.Link = () => new MarkDown.Item(/\[([^\]]+)\]\(([^)]+)\)|([a-z]{2,12}:\/{2}[^ "']+)/, (match, text, url, link) => `<a href="${url || link}" target="_blank" title="${text || link}">${text || link}</a>`);

    MarkDown.Bold = () => new MarkDown.Item(/\*{2}((?:(?!(?:\*{2})).)+)\*{2}/, (match, content) => `<b>${MarkDown.to_html(content, false)}</b>`);

    MarkDown.Italic = () => new MarkDown.Item(/\*((?:(?!(?:\*)).|\*{2})+)\*(?!\*)/, (match, content) => `<i>${MarkDown.to_html(content, false)}</i>`);

    MarkDown.to_html = (string, blocks = true) => {

        let html = ``;
        const matches = [
            MarkDown.Header(), 
            MarkDown.Block(), 
            MarkDown.BlockQuote(), 
            MarkDown.Paragraph(), 
            MarkDown.Link(),
            MarkDown.Bold(), 
            MarkDown.Italic()
        ];

        do{

            let index = 1 << 28, 
                i = null;

            [...matches].forEach((item, j) => {
                if(!item.more)
                    return;

                if(item.block && !blocks){
                    item.more = false;
                    return;
                };

                if(item.index < 0){

                    const submatches = string.match(item.pattern);

                    if(!submatches){
                        item.more = false;
                        return;
                    };

                    item.match = submatches;
                    item.length = submatches[0].length;
                    item.index = submatches.index;

                };

                if(index > item.index){
                    index = item.index;
                    i = j;
                };

            });

            if(i === null)
                break;

            const item = matches[i], 
                  total = index + item.length;

            html += string.substring(0, index) + item.replace(...item.match);
            string = string.substring(total);

            matches.forEach(item => {
                item.index -= total;
            });

        }while(matches.length)

        html += string;

        return html;
    }

    return MarkDown;
})();