const MASTODON_INSTANCE_URL = Deno.env.get("MASTODON_INSTANCE_URL"); // e.g. https://botsin.space
const MASTODON_ACCESS_TOKEN = Deno.env.get("MASTODON_ACCESS_TOKEN"); // you can get this at $INSTANCE_URL/settings/applications

if (MASTODON_INSTANCE_URL == null || MASTODON_INSTANCE_URL === '' || MASTODON_ACCESS_TOKEN == null || MASTODON_ACCESS_TOKEN === '') {
  console.error('Please set MASTODON_INSTANE_URL and MASTODON_ACCESS_TOKEN!')
  Deno.exit(1)
}

// some helpers to work with the mastodon api

const handleResponse = async (res: Response) => {
  if (res.ok) return { response: res, data: await res.json() }
  throw new Error(await res.text())
}

const api = (path: string, params: { body?: FormData | string, method?: string }) => fetch(`${MASTODON_INSTANCE_URL.replace(/\/+$/, '')}/${path.replace(/^\/+/, '')}`, {
  method: "POST",
  headers: {
    Authorization: `Bearer ${MASTODON_ACCESS_TOKEN}`,
  },
  ...params,
}).then(handleResponse)

// first we need to find out which files we can post, and which ones we already
// have posted

console.log("Picking file to post…");
const alreadyPostedFiles = new Set();
for await (const dirEntry of Deno.readDir("./posts/.posted")) {
  if (dirEntry.isSymlink) {
    alreadyPostedFiles.add(dirEntry.name);
  }
}

const availableFiles = [];
for await (const dirEntry of Deno.readDir("./posts/")) {
  if (dirEntry.name === ".gitignore") continue;

  if (dirEntry.isFile && !alreadyPostedFiles.has(dirEntry.name)) {
    availableFiles.push(dirEntry.name);
  }
}

console.log(`Found ${availableFiles.length} files which are not yet posted`);

if (availableFiles.length === 0) {
  console.log("Nothing left to post at the moment. Bye!");
  Deno.exit();
}

const fileToPost =
  availableFiles[Math.floor(Math.random() * availableFiles.length)];
const bytes = await Deno.readFile(`./posts/${fileToPost}`);

console.log(`Will post file ${fileToPost}`)

// we need two requests
// 1. upload media
// 2. create status with media id

// see https://docs.joinmastodon.org/methods/media/#v2
const mediaData = new FormData();
mediaData.append("file", new Blob([bytes]));

console.log("Sending post request to", `${MASTODON_INSTANCE_URL}/api/v2/media`);
const { data: mediaRequest } = await api('/api/v2/media', { body: mediaData }) as unknown as { data: { id: string } };
console.log("mediaRequest", mediaRequest);

// now we have to wait until the media file is processed
const sleep = (milliseconds: number) => new Promise((resolve, reject) => {
  setTimeout(resolve, milliseconds)
})

const startTime = Date.now()
while (true) {
  if ((Date.now() - startTime) / 1000 >= 60) {
    console.error('Timeout waiting for media to be processed.')
    Deno.exit(1)
  }

  const { response } = await api(`/api/v1/media/${mediaRequest.id}`, {
    method: 'GET'
  })
  if (response.status === 200) {
    console.log('Media finished processing!')
    break
  } else {
    console.log('Media still processing…')
    await sleep(5000)
  }
}

// see https://docs.joinmastodon.org/methods/statuses/#create
const statusData = new FormData();
statusData.append("media_ids[]", mediaRequest.id);

console.log(
  "Sending post request to",
  `${MASTODON_INSTANCE_URL}/api/v1/statuses`,
);
const { data: statusRequest } = await api('/api/v1/statuses', { body: statusData });
console.log("statusRequest", statusRequest);

console.log("Linking posted file so we can skip it in the future…");
// FIXME: This requires unrestricted `--allow-read` and `--allow-write` at the;
// deno should provide a finer-grained permission prompt here
await Deno.symlink(`./posts/${fileToPost}`, `./posts/.posted/${fileToPost}`);
console.log("Done!");