/**
 * The example script `examples/download-albums.ts` (issue #144), run twice
 * against a stand-in account, as a user would run it twice.
 *
 * The account has two albums sharing one photo, and one of its photos is a
 * live photo whose image is a HEIC with EXIF. The first run puts every
 * original at its save path, writes each photo's metadata beside it and each
 * album's photos under `albums/`. Before the second run the account gains an
 * album holding a new photo. The second run downloads that photo and writes
 * its files and the new album's, and fetches nothing else and changes no
 * other file.
 */

import { describe, it, expect, beforeEach, afterEach } from "vitest";
import {
    existsSync,
    mkdtempSync,
    readdirSync,
    readFileSync,
    rmSync,
    statSync,
    utimesSync,
    writeFileSync,
} from "node:fs";
import { tmpdir } from "node:os";
import { join } from "node:path";

import { downloadAlbums } from "../../examples/download-albums.js";
import { Library, type ContentSource } from "../../src/index.js";
import type { CollectionsPage, FilesPage } from "../../src/client.js";
import type { Collection, EnteFile } from "../../src/model/types.js";
import { HEIC_WITH_EXIF } from "../exif-heic.js";
import {
    asLivePhoto,
    cdnSource,
    livePhotoHash,
    livePhotoZip,
    VIDEO,
} from "../live-photo.js";

const USER_ID = 7;

// Every photo is taken at noon local time on 2026-03-01, so the machine's time
// zone cannot move it to another day; it is saved in the folder `DAY`. Ente
// stores times in microseconds.
const TAKEN_MS = new Date(2026, 2, 1, 12).getTime();
const DAY = join("2026", "2026-03", "2026-03-01");

const collection = (id: number, name: string): Collection => ({
    id,
    ownerID: USER_ID,
    key: new Uint8Array([id]),
    name,
    type: "album",
    updationTime: 1,
    isShared: false,
});

const file = (id: number, collectionID: number): EnteFile => ({
    id,
    collectionID,
    ownerID: USER_ID,
    key: new Uint8Array([id]),
    metadata: {
        title: `file-${id}.jpg`,
        fileType: "image",
        creationTime: TAKEN_MS * 1000,
        modificationTime: TAKEN_MS * 1000,
    },
    file: { decryptionHeader: "aGVhZGVy" },
    thumbnail: { decryptionHeader: "dGh1bWI=" },
    updationTime: 1,
});

let root: string;

beforeEach(() => {
    root = mkdtempSync(join(tmpdir(), "quak-download-albums-"));
});

afterEach(() => {
    if (root && existsSync(root))
        rmSync(root, { recursive: true, force: true });
});

// Every file and directory under `dir`, by path.
const entries = (dir: string): string[] =>
    readdirSync(dir, { recursive: true, encoding: "utf-8" });

// Set the modification time of everything under `dir` to the epoch, so that
// anything written there afterwards has a later one, however soon it comes.
const backdate = (dir: string): void => {
    for (const name of entries(dir)) utimesSync(join(dir, name), 0, 0);
};

// The modification time of everything under `dir`, by path.
const mtimes = (dir: string): Map<string, number> =>
    new Map(
        entries(dir).map((name) => [name, statSync(join(dir, name)).mtimeMs]),
    );

const readJSON = (path: string): unknown =>
    JSON.parse(readFileSync(path, "utf-8"));

describe("examples/download-albums.ts", () => {
    it("downloads every album's photos with their metadata, and on a second run only what the account gained", async () => {
        // Album 1, "Trip", holds photos 1 and 2. Album 2, "Family", holds
        // photo 2 and photo 3, a live photo.
        const live = await asLivePhoto(
            file(3, 2),
            livePhotoZip({ "image.heic": HEIC_WITH_EXIF, "video.mov": VIDEO }),
            livePhotoHash(HEIC_WITH_EXIF, VIDEO),
        );
        const collections = [collection(1, "Trip"), collection(2, "Family")];
        const filesByAlbum = new Map<number, EnteFile[]>([
            [1, [file(1, 1), file(2, 1)]],
            [2, [file(2, 2), live.file]],
        ]);
        const client = {
            whoami: () => ({ email: "u@example.com", userID: USER_ID }),
            collectionsSince: async (): Promise<CollectionsPage> => ({
                collections: [...collections],
                deleted: [],
                cursor: 1,
            }),
            filesSince: async (args: {
                collectionID: number;
            }): Promise<FilesPage> => ({
                files: filesByAlbum.get(args.collectionID) ?? [],
                deleted: [],
                cursor: 1,
            }),
        };

        // Photo 3 comes from a stand-in server, encrypted as Ente serves a
        // live photo. Any other original is a few bytes naming its photo.
        // `calls` counts every fetch, thumbnails included.
        const server = cdnSource(new Map([[3, live.body]]));
        let calls = 0;
        const source: ContentSource = {
            original: async (args) => {
                calls++;
                if (args.file.id === 3) return server.original(args);
                const bytes = `original-${args.file.id}`;
                writeFileSync(args.destination, bytes);
                return { bytesWritten: bytes.length };
            },
            thumbnail: async (args) => {
                calls++;
                return server.thumbnail(args);
            },
        };

        const dir = join(root, "photos");
        const open = (): Promise<Library> =>
            Library.open({
                client,
                cacheDirectory: join(root, "cache"),
                downloadDirectory: dir,
                contentSource: source,
                refreshIntervalSeconds: 3600,
                precacheThumbnails: false,
                precacheOriginals: false,
            });

        const first = await open();
        // The cache already holds photo 1's original, so its record names a
        // cache path, which the metadata leaves out. download() copies it
        // from the cache rather than fetching it again.
        await first.photos.byID({ fileID: 1 })!.original();
        expect(await downloadAlbums(first, dir)).toEqual({
            downloaded: 3,
            alreadyLocal: 0,
        });
        await first.close();
        expect(calls).toBe(3);

        // Each original at its save path, a live photo as its image, its video
        // and the file naming them, and each photo's metadata beside it.
        const day = join(dir, DAY);
        expect(readdirSync(day).sort()).toEqual([
            "2026-03-01.1.jpg",
            "2026-03-01.1.jpg.json",
            "2026-03-01.2.jpg",
            "2026-03-01.2.jpg.json",
            "2026-03-01.3.heic",
            "2026-03-01.3.heic.json",
            "2026-03-01.3.livephoto.json",
            "2026-03-01.3.mov",
        ]);
        expect(readFileSync(join(day, "2026-03-01.1.jpg"), "utf-8")).toBe(
            "original-1",
        );
        expect(readFileSync(join(day, "2026-03-01.2.jpg"), "utf-8")).toBe(
            "original-2",
        );
        expect(readFileSync(join(day, "2026-03-01.3.heic"))).toEqual(
            Buffer.from(HEIC_WITH_EXIF),
        );
        expect(readFileSync(join(day, "2026-03-01.3.mov"))).toEqual(
            Buffer.from(VIDEO),
        );

        // The metadata is the photo's record and its EXIF fields. The
        // originals of photos 1 and 2 are not image data, so they have no
        // EXIF fields. Photo 3's image holds a camera, an exposure and a
        // position, and the date it was taken is written as an ISO 8601
        // string. `record` holds the fields the three records share.
        const record = {
            takenAt: TAKEN_MS,
            modifiedAt: TAKEN_MS,
            fileType: "image",
            isArchived: false,
            isHidden: false,
        };
        expect(readJSON(join(day, "2026-03-01.1.jpg.json"))).toEqual({
            ...record,
            fileID: 1,
            albumIDs: [1],
            title: "file-1.jpg",
            exif: {},
        });
        expect(readJSON(join(day, "2026-03-01.2.jpg.json"))).toEqual({
            ...record,
            fileID: 2,
            albumIDs: [1, 2],
            title: "file-2.jpg",
            exif: {},
        });
        expect(readJSON(join(day, "2026-03-01.3.heic.json"))).toEqual({
            ...record,
            fileID: 3,
            albumIDs: [2],
            title: "file-3.jpg",
            fileType: "livePhoto",
            hash: livePhotoHash(HEIC_WITH_EXIF, VIDEO),
            exif: {
                make: "Canon",
                model: "EOS R5",
                lensModel: "RF50mm F1.8 STM",
                dateTimeOriginal: "2021-07-15T14:30:00.000Z",
                offsetTimeOriginal: "+02:00",
                exposureTime: 1 / 250,
                fNumber: 2.8,
                iso: 400,
                focalLength: 50,
                orientation: 6,
                gpsLatitude: 40 + 26 / 60 + 46 / 3600,
                gpsLongitude: -(79 + 58 / 60 + 56 / 3600),
                gpsAltitude: -12.5,
            },
        });

        // Each album's photos, newest first, by save path relative to `dir`.
        // Photo 2 is in both.
        expect(readdirSync(join(dir, "albums")).sort()).toEqual([
            "1.json",
            "2.json",
        ]);
        expect(readJSON(join(dir, "albums", "1.json"))).toEqual({
            collectionID: 1,
            name: "Trip",
            savePaths: [
                join(DAY, "2026-03-01.2.jpg"),
                join(DAY, "2026-03-01.1.jpg"),
            ],
        });
        expect(readJSON(join(dir, "albums", "2.json"))).toEqual({
            collectionID: 2,
            name: "Family",
            savePaths: [
                join(DAY, "2026-03-01.3.heic"),
                join(DAY, "2026-03-01.2.jpg"),
            ],
        });

        // Before the second run the account gains album 3, "Garden", holding
        // a new photo 4. The second run, with a newly opened library, opens
        // the cache written by the first and still downloads photo 4. It finds
        // the other photos already local and fetches nothing else.
        collections.push(collection(3, "Garden"));
        filesByAlbum.set(3, [file(4, 3)]);
        backdate(dir);
        const before = mtimes(dir);
        const second = await open();
        expect(await downloadAlbums(second, dir)).toEqual({
            downloaded: 1,
            alreadyLocal: 3,
        });
        await second.close();
        expect(calls).toBe(4);
        expect(readFileSync(join(day, "2026-03-01.4.jpg"), "utf-8")).toBe(
            "original-4",
        );
        expect(readJSON(join(dir, "albums", "3.json"))).toEqual({
            collectionID: 3,
            name: "Garden",
            savePaths: [join(DAY, "2026-03-01.4.jpg")],
        });

        // The second run adds only photo 4's files and album 3's, and
        // rewrites, renames or removes no file from the first run. The two
        // directories that gain a file are the only other changes.
        const after = mtimes(dir);
        expect(
            [...after.keys()].filter((name) => !before.has(name)).sort(),
        ).toEqual([
            join(DAY, "2026-03-01.4.jpg"),
            join(DAY, "2026-03-01.4.jpg.json"),
            join("albums", "3.json"),
        ]);
        for (const [name, mtime] of before) {
            if (name === DAY || name === "albums") continue;
            expect(after.get(name), name).toBe(mtime);
        }
    });
});