// Download every album's photos to a directory, with each photo's metadata
// beside it, using only quak's public API. The README's "Examples" section
// describes the files it writes.
//
//     yarn build
//     QUAK_EMAIL=… QUAK_PASSWORD=… node dist/examples/download-albums.js [dir]

import { realpathSync } from "node:fs";
import { mkdir, readFile, writeFile } from "node:fs/promises";
import { join, relative } from "node:path";
import { stdin, stdout } from "node:process";
import { createInterface } from "node:readline/promises";
import { pathToFileURL } from "node:url";

import { Client, Library } from "../src/index.js";

// Write `text` to `path` unless the file already holds exactly that, so a
// second run rewrites nothing.
async function writeIfChanged(path: string, text: string): Promise<void> {
    const current = await readFile(path, "utf-8").catch(() => undefined);
    if (current !== text) await writeFile(path, text);
}

const pretty = (value: unknown): string =>
    JSON.stringify(value, null, 2) + "\n";

// For every album in `lib`, download each photo to its save path, write the
// photo's metadata to `{savePath}.json`, and write the album's photos to
// `{dir}/albums/{collectionID}.json`. Returns how many photos it downloaded
// and how many were already at their save paths.
export async function downloadAlbums(
    lib: Library,
    dir: string,
): Promise<{ downloaded: number; alreadyLocal: number }> {
    let downloaded = 0;
    let alreadyLocal = 0;
    // A photo in several albums is handled once.
    const done = new Set<number>();
    for (const album of lib.albums.list()) {
        const savePaths: string[] = [];
        for (const photo of album.photos.list()) {
            if (!done.has(photo.fileID)) {
                done.add(photo.fileID);
                if (photo.isLocal) alreadyLocal++;
                else downloaded++;
                await photo.download();
                // The cache paths say where quak's cache keeps copies, not
                // anything about the photo.
                const record = { ...photo.record() };
                delete record.thumbnailPath;
                delete record.originalPath;
                const exif = await photo.exif();
                // savePath is read after download(): a live photo's names its
                // image only once the image is stored.
                await writeIfChanged(
                    `${photo.savePath}.json`,
                    pretty({ ...record, exif }),
                );
            }
            savePaths.push(relative(dir, photo.savePath));
        }
        await mkdir(join(dir, "albums"), { recursive: true });
        await writeIfChanged(
            join(dir, "albums", `${album.collectionID}.json`),
            pretty({
                collectionID: album.collectionID,
                name: album.name,
                savePaths,
            }),
        );
    }
    return { downloaded, alreadyLocal };
}

// Ask for a login code on the terminal. Client.login calls this only when the
// account requires a code.
async function ask(question: string): Promise<string> {
    const terminal = createInterface({ input: stdin, output: stdout });
    try {
        return await terminal.question(question);
    } finally {
        terminal.close();
    }
}

async function main(): Promise<void> {
    const email = process.env.QUAK_EMAIL;
    const password = process.env.QUAK_PASSWORD;
    if (!email || !password) {
        console.error(
            "Set QUAK_EMAIL and QUAK_PASSWORD to the account's email and password.",
        );
        process.exit(1);
    }
    const dir = process.argv[2] ?? "photos";

    const client = await Client.login({
        email,
        password,
        totp: () => ask("Two-factor code: "),
        emailOTP: () => ask("Code sent to your email: "),
    });
    const lib = await Library.open({
        client,
        downloadDirectory: dir,
        // As in `quak backup`: fetch only the originals this script saves,
        // not every thumbnail and the recent originals into the cache too.
        precacheThumbnails: false,
        precacheOriginals: false,
    });
    try {
        const { downloaded, alreadyLocal } = await downloadAlbums(lib, dir);
        console.log(
            `${downloaded} photos downloaded, ${alreadyLocal} already local, in ${dir}`,
        );
    } finally {
        await lib.close();
    }
}

// Run main() when node runs this file, not when a test imports it. argv[1] is
// the path as given, and import.meta.url has symlinks resolved.
const script = process.argv[1];
if (script && pathToFileURL(realpathSync(script)).href === import.meta.url) {
    await main();
}