/**
 * Tests for the resumable, deletion-aware enumeration variants on `Client`:
 * `collectionsSince` and `filesSince`.
 *
 * The whole-account methods `listCollections` / `listFiles` always start at
 * `sinceTime: 0` and hide deletions. The cache refresh needs the opposite:
 * start from a saved cursor, learn what was deleted, and get back a cursor to
 * resume from next time. These two methods provide that.
 *
 * The return shape keeps live records and tombstones apart — `collections` /
 * `files` are decrypted live records, `deleted` is a plain list of the ids the
 * server tombstoned. A tombstone carries no decryptable key or metadata, so it
 * is a bare id rather than a hollowed-out `Collection` / `EnteFile`.
 *
 * All tests inject a fake `fetch` and drive a real `Client` (built with
 * `Client.fromJSON`) so the decryption path runs for real. Live rows are built
 * with libsodium exactly as the server would encrypt them; tombstone rows carry
 * only the fields the code reads (`id`, `updationTime`, `isDeleted`), because
 * they are never decrypted.
 */

import sodium from "libsodium-wrappers-sumo";
import { beforeAll, describe, expect, it } from "vitest";
import { init, toBase64 } from "../../src/crypto/index.js";
import { Client, type ClientSnapshot } from "../../src/client.js";

// ---------------------------------------------------------------------------
// Fixtures
// ---------------------------------------------------------------------------

const USER_ID = 42;

interface Keys {
    masterKey: Uint8Array;
    publicKey: Uint8Array;
    secretKey: Uint8Array;
}

const buildKeys = (): Keys => {
    const kp = sodium.crypto_box_keypair();
    return {
        masterKey: sodium.crypto_secretbox_keygen(),
        publicKey: kp.publicKey,
        secretKey: kp.privateKey,
    };
};

const snapshotFor = (keys: Keys): ClientSnapshot => ({
    email: "user@example.com",
    userID: USER_ID,
    token: "test-token",
    masterKey: toBase64(keys.masterKey),
    secretKey: toBase64(keys.secretKey),
    publicKey: toBase64(keys.publicKey),
});

const secretboxEncrypt = (
    plaintext: Uint8Array,
    key: Uint8Array,
): { ciphertext: Uint8Array; nonce: Uint8Array } => {
    const nonce = sodium.randombytes_buf(sodium.crypto_secretbox_NONCEBYTES);
    return {
        ciphertext: sodium.crypto_secretbox_easy(plaintext, nonce, key),
        nonce,
    };
};

/** An owned collection row as the server sends it, keyed under the master key. */
const ownedCollectionRow = (
    masterKey: Uint8Array,
    opts: { id: number; name: string; updationTime: number },
): Record<string, unknown> => {
    const collectionKey = sodium.crypto_secretbox_keygen();
    const { ciphertext: encKey, nonce: keyNonce } = secretboxEncrypt(
        collectionKey,
        masterKey,
    );
    const { ciphertext: encName, nonce: nameNonce } = secretboxEncrypt(
        new TextEncoder().encode(opts.name),
        collectionKey,
    );
    return {
        id: opts.id,
        owner: { id: USER_ID },
        encryptedKey: toBase64(encKey),
        keyDecryptionNonce: toBase64(keyNonce),
        encryptedName: toBase64(encName),
        nameDecryptionNonce: toBase64(nameNonce),
        type: "album",
        updationTime: opts.updationTime,
    };
};

/** A live file row inside a collection, keyed under that collection's key. */
const fileRow = (
    collectionKey: Uint8Array,
    opts: { id: number; title: string; updationTime: number },
): Record<string, unknown> => {
    const fileKey = sodium.crypto_secretbox_keygen();
    const { ciphertext: encFileKey, nonce: fileKeyNonce } = secretboxEncrypt(
        fileKey,
        collectionKey,
    );
    const metadata = {
        title: opts.title,
        fileType: 0,
        creationTime: opts.updationTime,
        modificationTime: opts.updationTime,
    };
    const push =
        sodium.crypto_secretstream_xchacha20poly1305_init_push(fileKey);
    const encMeta = sodium.crypto_secretstream_xchacha20poly1305_push(
        push.state,
        new TextEncoder().encode(JSON.stringify(metadata)),
        null,
        sodium.crypto_secretstream_xchacha20poly1305_TAG_FINAL,
    );
    return {
        id: opts.id,
        collectionID: 1,
        ownerID: USER_ID,
        encryptedKey: toBase64(encFileKey),
        keyDecryptionNonce: toBase64(fileKeyNonce),
        metadata: {
            encryptedData: toBase64(encMeta),
            decryptionHeader: toBase64(push.header),
        },
        file: { decryptionHeader: toBase64(sodium.randombytes_buf(24)) },
        thumbnail: { decryptionHeader: toBase64(sodium.randombytes_buf(24)) },
        updationTime: opts.updationTime,
    };
};

/** A tombstone row. Never decrypted, so only these fields are ever read. */
const tombstoneRow = (
    id: number,
    updationTime: number,
): Record<string, unknown> => ({
    id,
    updationTime,
    isDeleted: true,
});

const jsonResponse = (body: unknown): Response =>
    new Response(JSON.stringify(body), {
        status: 200,
        headers: { "content-type": "application/json" },
    });

/**
 * A fetch that serves canned responses in order and records the `sinceTime`
 * query parameter each request carried, so tests can prove the cursor is
 * threaded from one page (and one call) to the next.
 */
const recordingFetch = (
    ...responses: Response[]
): { fetch: typeof globalThis.fetch; sinceTimes: (string | null)[] } => {
    const sinceTimes: (string | null)[] = [];
    let i = 0;
    const fake = async (input: RequestInfo | URL): Promise<Response> => {
        const url =
            typeof input === "string"
                ? input
                : input instanceof URL
                  ? input.href
                  : input.url;
        sinceTimes.push(new URL(url).searchParams.get("sinceTime"));
        if (i >= responses.length) {
            throw new Error(`recordingFetch: no response for call #${i}`);
        }
        return responses[i++]!;
    };
    return { fetch: fake as typeof globalThis.fetch, sinceTimes };
};

// ---------------------------------------------------------------------------
// Tests
// ---------------------------------------------------------------------------

describe("Client.filesSince", () => {
    beforeAll(async () => {
        await init();
        await sodium.ready;
    });

    it("pages from the given cursor, decrypts live rows, and collects tombstones", async () => {
        const keys = buildKeys();
        const collectionKey = sodium.crypto_secretbox_keygen();

        // Page 1 mixes a live file and a tombstone; the tombstone has the
        // higher updationTime, so it — not the live row — sets the cursor the
        // second page must be fetched from.
        const { fetch, sinceTimes } = recordingFetch(
            jsonResponse({
                diff: [
                    fileRow(collectionKey, {
                        id: 1001,
                        title: "first.jpg",
                        updationTime: 100,
                    }),
                    tombstoneRow(1002, 150),
                ],
                hasMore: true,
            }),
            jsonResponse({
                diff: [
                    fileRow(collectionKey, {
                        id: 1003,
                        title: "second.jpg",
                        updationTime: 200,
                    }),
                ],
                hasMore: false,
            }),
        );
        const client = Client.fromJSON(snapshotFor(keys), { fetch });

        const { files, deleted, cursor } = await client.filesSince({
            collectionID: 1,
            collectionKey,
            sinceTime: 0,
        });

        expect(files.map((f) => f.id)).toEqual([1001, 1003]);
        expect(files.map((f) => f.metadata.title)).toEqual([
            "first.jpg",
            "second.jpg",
        ]);
        expect(deleted).toEqual([1002]);
        expect(cursor).toBe(200);
        // First request started at the caller's cursor; the second resumed
        // from the max updationTime seen on the first page (the tombstone's).
        expect(sinceTimes).toEqual(["0", "150"]);
    });

    it("fetches only newer rows when the returned cursor is passed back in", async () => {
        const keys = buildKeys();
        const collectionKey = sodium.crypto_secretbox_keygen();

        const { fetch, sinceTimes } = recordingFetch(
            jsonResponse({ diff: [], hasMore: false }),
        );
        const client = Client.fromJSON(snapshotFor(keys), { fetch });

        const result = await client.filesSince({
            collectionID: 1,
            collectionKey,
            sinceTime: 200,
        });

        expect(result.files).toEqual([]);
        expect(result.deleted).toEqual([]);
        // An empty diff advances nothing: the cursor falls back to the input.
        expect(result.cursor).toBe(200);
        expect(sinceTimes).toEqual(["200"]);
    });

    it("stops and throws when the server claims more but does not advance (#7)", async () => {
        const keys = buildKeys();
        const collectionKey = sodium.crypto_secretbox_keygen();

        // hasMore is true, but the page's max updationTime (50) does not exceed
        // the cursor the request was made with (50). Following hasMore here
        // would refetch this same page forever.
        const { fetch, sinceTimes } = recordingFetch(
            jsonResponse({ diff: [tombstoneRow(1, 50)], hasMore: true }),
            jsonResponse({ diff: [tombstoneRow(1, 50)], hasMore: true }),
        );
        const client = Client.fromJSON(snapshotFor(keys), { fetch });

        await expect(
            client.filesSince({
                collectionID: 1,
                collectionKey,
                sinceTime: 50,
            }),
        ).rejects.toThrow(/not advance|non-advancing/i);
        // It gave up after the first page rather than looping.
        expect(sinceTimes).toEqual(["50"]);
    });
});

describe("Client.collectionsSince", () => {
    beforeAll(async () => {
        await init();
        await sodium.ready;
    });

    it("decrypts live collections, collects tombstones, and returns a cursor", async () => {
        const keys = buildKeys();

        const { fetch, sinceTimes } = recordingFetch(
            jsonResponse({
                collections: [
                    ownedCollectionRow(keys.masterKey, {
                        id: 1,
                        name: "Vacation",
                        updationTime: 100,
                    }),
                    tombstoneRow(3, 150),
                ],
            }),
        );
        const client = Client.fromJSON(snapshotFor(keys), { fetch });

        const { collections, deleted, cursor } = await client.collectionsSince({
            sinceTime: 0,
        });

        expect(collections.map((c) => c.id)).toEqual([1]);
        expect(collections[0]!.name).toBe("Vacation");
        expect(deleted).toEqual([3]);
        // The tombstone's updationTime advances the cursor too, so the next
        // sync starts after it rather than seeing it again.
        expect(cursor).toBe(150);
        expect(sinceTimes).toEqual(["0"]);
    });

    it("falls back to the input cursor on an empty response", async () => {
        const keys = buildKeys();

        const { fetch, sinceTimes } = recordingFetch(
            jsonResponse({ collections: [] }),
        );
        const client = Client.fromJSON(snapshotFor(keys), { fetch });

        const result = await client.collectionsSince({ sinceTime: 150 });

        expect(result.collections).toEqual([]);
        expect(result.deleted).toEqual([]);
        expect(result.cursor).toBe(150);
        expect(sinceTimes).toEqual(["150"]);
    });
});

describe("Client list wrappers still hide deletions", () => {
    beforeAll(async () => {
        await init();
        await sodium.ready;
    });

    it("listFiles drops tombstones and returns only live files", async () => {
        const keys = buildKeys();
        const collectionKey = sodium.crypto_secretbox_keygen();

        const { fetch, sinceTimes } = recordingFetch(
            jsonResponse({
                diff: [
                    fileRow(collectionKey, {
                        id: 7,
                        title: "keep.jpg",
                        updationTime: 100,
                    }),
                    tombstoneRow(8, 150),
                ],
                hasMore: false,
            }),
        );
        const client = Client.fromJSON(snapshotFor(keys), { fetch });

        const files = await client.listFiles(1, collectionKey);

        expect(files.map((f) => f.id)).toEqual([7]);
        // The wrapper starts a full enumeration from zero.
        expect(sinceTimes).toEqual(["0"]);
    });
});