#!/bin/env -S deno run -A

import * as path from "https://deno.land/std@0.138.0/path/mod.ts"

main()
async function main() {
    const img_url = await find_daily_xkcd()
    const tmp_dir = module_dir(import.meta) + "/tmp"
    const dl_path = `${tmp_dir}/downloaded.png`
    const bg_path = `${tmp_dir}/gen_${Date.now()}.png`
    const curr_path = `${tmp_dir}/latest.png`
    log("parameters", { img_url, tmp_dir, dl_path, bg_path, curr_path })
    await run("mkdir", "-p", tmp_dir)
    await download_file(img_url, dl_path)
    await generate_wallpaper(dl_path, bg_path)
    await set_wallpaper(bg_path)
    await run("cp", bg_path, curr_path)
    log("done")
}

async function find_daily_xkcd() {
    const res = await fetch("https://xkcd.com/info.0.json")
    const { img } = await res.json()
    return img
}

async function download_file(url: string, dl_path: string) {
    await run("wget", url, "-O", dl_path)
}

async function generate_wallpaper(src: string, dest: string) {
    const [w, h] = await get_max_res()
    await run(
        "magick",
        src,
        ...["-gravity", "Center"],
        ...["-extent", `${w}x${h}`],
        ...["-background", "#ffffff"],
        ...["-negate"],
        ...["-level", "-50"],
        ...["-brightness-contrast", "14x1"],
        dest,
    )
}

async function set_wallpaper(bg_path: string) {
    const abs_path = path.resolve(bg_path)
    await run(
        "gsettings",
        "set",
        "org.cinnamon.desktop.background",
        "picture-uri",
        `file://${abs_path}`,
    )
}

async function get_max_res() {
    const output = await run("xrandr")
    const stdout = (new TextDecoder()).decode(output.stdout)
    const resolutions = [] as [number, number][]
    for (const line of stdout.split("\n")) {
        const [_, rest] = line.split(" connected ")
        if (rest === undefined) continue
        const stripped = rest.replace("primary", "")
        const [res] = stripped.split("+")
        const [w, h] = res.split("x").map((n) => parseInt(n))
        resolutions.push([w, h])
    }
    const maxes = [0, 0] as [number, number]
    for (const res of resolutions) {
        maxes[0] = Math.max(res[0], maxes[0])
        maxes[1] = Math.max(res[1], maxes[1])
    }
    return maxes
}

function log(...args: unknown[]) {
    console.log("[download.ts]", ...args)
}

async function run(name: string, ...args: string[]) {
    return await new Deno.Command(name, { args, stdout: "piped", stderr: "inherit" }).output()
}

function module_dir({ url }: ImportMeta): string {
    return path.resolve(path.dirname(path.fromFileUrl(url)))
}