const slugify = require("@sindresorhus/slugify");
const markdownIt = require("markdown-it");
const fs = require('fs');
const matter = require('gray-matter')
module.exports = function(eleventyConfig) {

    let markdownLib = markdownIt({
            breaks: true,
            html: true
        })
        .use(require("markdown-it-footnote"))
        .use(function(md) {
            //https://github.com/DCsunset/markdown-it-mermaid-plugin
            const origFenceRule = md.renderer.rules.fence || function(tokens, idx, options, env, self) {
                return self.renderToken(tokens, idx, options, env, self);
            };
            md.renderer.rules.fence = (tokens, idx, options, env, slf) => {
                const token = tokens[idx];
                if (token.info === 'mermaid') {
                    const code = token.content.trim();
                    return `<pre class="mermaid">${code}</pre>`;
                }
                if (token.info === 'transclusion') {
                    const code = token.content.trim();
                    return `<div class="transclusion">${md.render(code)}</div>`;
                }
                if (token.info.startsWith("ad-")) {
                    const code = token.content.trim();
                    return `<pre class="language-${token.info}">${md.render(code)}</pre>`;
                }

                // Other languages
                return origFenceRule(tokens, idx, options, env, slf);
            };



            const defaultImageRule = md.renderer.rules.image || function(tokens, idx, options, env, self) {
                return self.renderToken(tokens, idx, options, env, self);
            };
            md.renderer.rules.image = (tokens, idx, options, env, self) => {
                const imageName = tokens[idx].content;
                const [fileName, width] = imageName.split("|");
                if (width) {
                    const widthIndex = tokens[idx].attrIndex('width');
                    const widthAttr = `${width}px`;
                    if (widthIndex < 0) {
                        tokens[idx].attrPush(['width', widthAttr]);
                    } else {
                        tokens[idx].attrs[widthIndex][1] = widthAttr;
                    }
                }

                return defaultImageRule(tokens, idx, options, env, self);
            };


            const defaultLinkRule = md.renderer.rules.link_open || function(tokens, idx, options, env, self) {
                return self.renderToken(tokens, idx, options, env, self);
            };
            md.renderer.rules.link_open = function(tokens, idx, options, env, self) {
                const aIndex = tokens[idx].attrIndex('target');
                const classIndex = tokens[idx].attrIndex('class');

                if (aIndex < 0) {
                    tokens[idx].attrPush(['target', '_blank']);
                } else {
                    tokens[idx].attrs[aIndex][1] = '_blank';
                }

                if (classIndex < 0) {
                    tokens[idx].attrPush(['class', 'external-link']);
                } else {
                    tokens[idx].attrs[classIndex][1] = 'external-link';
                }

                return defaultLinkRule(tokens, idx, options, env, self);
            };
        });

    eleventyConfig.setLibrary("md", markdownLib);

    eleventyConfig.addTransform('link', function(str) {
        return str && str.replace(/\[\[(.*?)\]\]/g, function(match, p1) {
            const [fileName, linkTitle] = p1.split("|");

            let permalink = `/notes/${slugify(fileName)}`;
            const title = linkTitle ? linkTitle : fileName;

            try {
                const file = fs.readFileSync(`./src/site/notes/${fileName}.md`, 'utf8');
                const frontMatter = matter(file);
                if (frontMatter.data.permalink) {
                    permalink = frontMatter.data.permalink;
                }
            } catch {
                //Ignore if file doesn't exist
            }

            return `<a class="internal-link" href="${permalink}">${title}</a>`;
        });
    })

    eleventyConfig.addTransform('highlight', function(str) {
        //replace ==random text== with <mark>random text</mark>
        return str && str.replace(/\=\=(.*?)\=\=/g, function(match, p1) {
            return `<mark>${p1}</mark>`;
        });
    });

    return {
        dir: {
            input: "src/site",
            output: "dist",
            data: `_data`
        },
        templateFormats: ["njk", "md", "11ty.js", "css"],
        htmlTemplateEngine: "njk",
        markdownTemplateEngine: "njk",
        passthroughFileCopy: true,
    };

};