const { deflateSync } = require('zlib')

const krokiLangs = [
    'actdiag',
    'blockdiag',
    'bpmn',
    'bytefield',
    'c4plantuml',
    'ditaa',
    'dot',
    'erd',
    'excalidraw',
    'graphviz',
    'mermaid',
    'nomnoml',
    'nwdiag',
    'packetdiag',
    'pikchr',
    'plantuml',
    'rackdiag',
    'seqdiag',
    'svgbob',
    'umlet',
    'vega',
    'vegalite',
    'wavedrom',
]

const entrypoint = 'https://kroki.io/'

const marpKrokiPlugin = (md) => {
    const { fence } = md.renderer.rules

    md.renderer.rules.fence = (tokens, idx, options, env, self) => {
        const info = md.utils.unescapeAll(tokens[idx].info).trim()

        if (info) {
            const [lang] = info.split(/(\s+)/g)

            if (krokiLangs.includes(lang)) {
                const data = deflateSync(tokens[idx].content).toString('base64url')

                // <marp-auto-scaling> is working only with Marp Core v3
                return `<p><marp-auto-scaling data-downscale-only><img src="${entrypoint}${lang}/svg/${data}"/></marp-auto-scaling></p>`
            }
        }

        return fence.call(self, tokens, idx, options, env, self)
    }
}

module.exports = marpKrokiPlugin