/**
 * Tests for the on-disk JSON metadata store (`MetadataStore`).
 *
 * The store is the local cache the library keeps of the account's server
 * state: one `metadata.json` file holding the user id, a schema version, the
 * cursor for the incremental collections listing, and the decrypted
 * collection and file records. The whole file is read into RAM on load and
 * rewritten as a whole on save. A separate refresh unit (issue #42) is what
 * populates it; this unit only stores.
 *
 * Four contracts are load-bearing and each is exercised below:
 *
 * 1. **Round-trip fidelity.** Everything put into the store — including the
 *    binary decryption keys, which JSON cannot hold directly and which the
 *    store base64-encodes — comes back byte-for-byte after a save and a fresh
 *    load. A cache that quietly dropped or mangled a field would hand the
 *    caller wrong keys or stale metadata.
 *
 * 2. **A missing or corrupt file loads as an empty store, never an error.**
 *    The file is only a cache: if it is absent (first run) or unreadable
 *    (interrupted write on an older build, disk corruption, hand-editing),
 *    the right answer is to start empty and let the refresh unit repopulate,
 *    not to crash the whole library.
 *
 * 3. **Writes are atomic and durable.** The store reuses the same
 *    fsync-before-rename atomic writer the download layer uses, so a reader
 *    never sees a half-written file and a crash cannot leave a truncated one.
 *    The observable consequence tested here is that a save leaves exactly the
 *    destination file behind — no temporary sibling — and that overwriting an
 *    existing store preserves a complete, re-loadable file.
 *
 * 4. **Permissions match `session.json`.** The directory is `0700` and the
 *    file is `0600`, because the records contain decrypted key material and
 *    must not be readable by other users on a shared machine.
 */

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

import {
    MetadataStore,
    METADATA_SCHEMA_VERSION,
} from "../../src/library/store.js";
import type { Collection, EnteFile } from "../../src/model/types.js";

// A representative decrypted collection, including a binary key and all three
// magic-metadata layers, so the round-trip test proves every field survives.
const sampleCollection = (): Collection => ({
    id: 12345,
    ownerID: 42,
    key: new Uint8Array([1, 2, 3, 4, 5, 6, 7, 8]),
    name: "Holiday 2026",
    type: "album",
    updationTime: 1_700_000_000_000_000,
    isShared: true,
    magicMetadata: { visibility: 0 },
    pubMagicMetadata: { subType: 0, coverID: 999 },
    sharedMagicMetadata: { note: "shared with a friend" },
});

// A representative decrypted file membership: metadata, both blob headers, a
// binary key, a content hash, and file/thumbnail sizes.
const sampleFile = (): EnteFile => ({
    id: 67890,
    collectionID: 12345,
    ownerID: 42,
    key: new Uint8Array([9, 8, 7, 6, 5, 4, 3, 2, 1]),
    metadata: {
        title: "IMG_0001.jpg",
        fileType: "image",
        creationTime: 1_699_000_000_000_000,
        modificationTime: 1_699_000_500_000_000,
        latitude: 52.52,
        longitude: 13.405,
        hash: "sha256:deadbeef",
    },
    magicMetadata: { editedName: "sunset" },
    pubMagicMetadata: { editedTime: 1_699_000_600_000_000 },
    file: { decryptionHeader: "ZmlsZUhlYWRlcg==", size: 4_194_304 },
    thumbnail: { decryptionHeader: "dGh1bWJIZWFkZXI=", size: 8192 },
    updationTime: 1_700_000_100_000_000,
});

describe("MetadataStore", () => {
    let dir: string;
    let path: string;

    beforeEach(() => {
        dir = mkdtempSync(join(tmpdir(), "quak-store-"));
        // Deliberately nest the store one level below the temp dir so save()
        // has to create its own directory and set its mode.
        path = join(dir, "cache", "metadata.json");
    });

    afterEach(() => {
        rmSync(dir, { recursive: true, force: true });
    });

    it("round-trips the whole model, keys and all", async () => {
        const store = await MetadataStore.load(path);
        store.userID = 42;
        store.collectionsSinceTime = 1_700_000_000_000_000;
        store.putCollection(sampleCollection());
        store.putFile(sampleFile());
        await store.save();

        const reloaded = await MetadataStore.load(path);
        expect(reloaded.userID).toBe(42);
        expect(reloaded.collectionsSinceTime).toBe(1_700_000_000_000_000);

        // The binary key must come back as the exact bytes, not a base64
        // string or a plain object of numbered keys.
        const collection = reloaded.getCollection(12345);
        expect(collection).toEqual(sampleCollection());
        expect(collection?.key).toBeInstanceOf(Uint8Array);

        const file = reloaded.getFile(12345, 67890);
        expect(file).toEqual(sampleFile());
        expect(file?.key).toBeInstanceOf(Uint8Array);

        expect(reloaded.listCollections()).toHaveLength(1);
        expect(reloaded.listFiles(12345)).toHaveLength(1);
    });

    it("writes the declared schema version", async () => {
        const store = await MetadataStore.load(path);
        await store.save();
        const reloaded = await MetadataStore.load(path);
        expect(reloaded.schemaVersion).toBe(METADATA_SCHEMA_VERSION);
    });

    it("loads an empty store when the file is missing", async () => {
        const store = await MetadataStore.load(path);
        expect(store.userID).toBe(0);
        expect(store.listCollections()).toEqual([]);
        expect(store.getCollection(1)).toBeUndefined();
    });

    it("loads an empty store when the file is corrupt", async () => {
        mkdirSync(join(dir, "cache"), { recursive: true });
        writeFileSync(path, "{ this is not valid json ][");
        const store = await MetadataStore.load(path);
        expect(store.listCollections()).toEqual([]);
        expect(store.listFiles(12345)).toEqual([]);
    });

    it("loads an empty store when the schema version does not match", async () => {
        // A cache written by a future build with an incompatible schema is
        // discarded rather than misread; the refresh unit repopulates it.
        mkdirSync(join(dir, "cache"), { recursive: true });
        writeFileSync(
            path,
            JSON.stringify({
                schemaVersion: METADATA_SCHEMA_VERSION + 1,
                userID: 42,
                collectionsSinceTime: 0,
                collections: [],
                files: [],
            }),
        );
        const store = await MetadataStore.load(path);
        expect(store.userID).toBe(0);
        expect(store.listCollections()).toEqual([]);
    });

    it("creates the directory 0700 and the file 0600", async () => {
        const store = await MetadataStore.load(path);
        store.putCollection(sampleCollection());
        await store.save();

        // Directory 0700, file 0600: on a shared machine the decrypted keys
        // in this file must be readable only by their owner. Mask to the
        // permission bits; the file-type bits are not part of the assertion.
        expect(statSync(join(dir, "cache")).mode & 0o777).toBe(0o700);
        expect(statSync(path).mode & 0o777).toBe(0o600);
    });

    it("leaves exactly the destination behind, with no temp sibling", async () => {
        const store = await MetadataStore.load(path);
        store.putCollection(sampleCollection());
        await store.save();
        // The atomic writer stages a temporary file and renames it into
        // place; on success nothing temporary is left in the directory.
        expect(readdirSync(join(dir, "cache"))).toEqual(["metadata.json"]);
    });

    it("overwrites an existing store atomically and stays re-loadable", async () => {
        const first = await MetadataStore.load(path);
        first.userID = 1;
        first.putCollection(sampleCollection());
        await first.save();

        const second = await MetadataStore.load(path);
        second.userID = 2;
        second.deleteCollection(12345);
        await second.save();

        const reloaded = await MetadataStore.load(path);
        expect(reloaded.userID).toBe(2);
        expect(reloaded.getCollection(12345)).toBeUndefined();
        expect(readdirSync(join(dir, "cache"))).toEqual(["metadata.json"]);
    });

    it("deletes a collection together with its file memberships", async () => {
        const store = await MetadataStore.load(path);
        store.putCollection(sampleCollection());
        store.putFile(sampleFile());
        store.deleteCollection(12345);
        expect(store.getCollection(12345)).toBeUndefined();
        expect(store.getFile(12345, 67890)).toBeUndefined();
        expect(store.listFiles(12345)).toEqual([]);
    });

    it("scopes file records to their collection membership", async () => {
        // The same underlying file can be a member of two collections, each a
        // separate record with its own key. Storing one must not touch the
        // other, and lookups are per membership.
        const store = await MetadataStore.load(path);
        const inA = sampleFile();
        const inB: EnteFile = {
            ...sampleFile(),
            collectionID: 55555,
            key: new Uint8Array([100, 101, 102]),
        };
        store.putFile(inA);
        store.putFile(inB);

        expect(store.getFile(12345, 67890)?.key).toEqual(inA.key);
        expect(store.getFile(55555, 67890)?.key).toEqual(inB.key);
        expect(store.listFiles(12345)).toHaveLength(1);
        expect(store.listFiles(55555)).toHaveLength(1);

        store.deleteFile(12345, 67890);
        expect(store.getFile(12345, 67890)).toBeUndefined();
        expect(store.getFile(55555, 67890)?.key).toEqual(inB.key);
    });
});