const {readdirSync, lstatSync, readFileSync, writeFileSync} = require("fs")

const path = require("path")

let images = []

function scanDir(dir) {

for (let file of readdirSync(dir)) {

let full = path.resolve(dir, file), type

if (lstatSync(full).isDirectory())

return scanDir(full)

if (/\.svg$/.test(file))

type = "image/svg+xml"

else if (/\.png$/.test(file))

type = "image/png"

else if (/\.jpg$/.test(file))

type = "image/jpeg"

else

throw new Error("Unknown image type: " + full)

let local = full.slice(full.indexOf("/img/") + 1)

images.push(` <item id="image.${file}" href="${local}" media-type="${type}"/>`)

}

}

scanDir("epub/img")

let out = readFileSync("epub/content.opf.src", "utf8").replace("{{images}}", images.join("\n"))

writeFileSync("epub/content.opf", out)