import { describe, expect, test, vi } from "vitest";

import { createMarketBatchLoader } from "../src/content/market/batch-loader";

describe("market batch loader", () => {
  test("puts current-page rows into loading before the request resolves", async () => {
    const deferred = createDeferred();
    const row = createRowRecorder("111");
    const loader = createMarketBatchLoader({
      apiClient: {
        loadAuthorAseInfo: vi.fn(() => deferred.promise)
      },
      concurrency: 4
    });

    const loadPromise = loader.loadRows({
      listSeq: 1,
      rows: [row.row]
    });

    expect(row.states[0]).toMatchObject({
      authorId: "111",
      listSeq: 1,
      state: "loading"
    });

    deferred.resolve({
      rates: {
        personalVideoAfterSearchRate: "0.02% - 0.1%",
        singleVideoAfterSearchRate: "<0.02%"
      },
      success: true
    });
    await loadPromise;
  });

  test("reuses the success cache for repeated authorIds", async () => {
    const apiClient = {
      loadAuthorAseInfo: vi.fn(async () => ({
        rates: {
          personalVideoAfterSearchRate: "0.02% - 0.1%",
          singleVideoAfterSearchRate: "<0.02%"
        },
        success: true as const
      }))
    };
    const firstRow = createRowRecorder("111");
    const secondRow = createRowRecorder("111");
    const loader = createMarketBatchLoader({
      apiClient,
      concurrency: 4
    });

    await loader.loadRows({
      listSeq: 1,
      rows: [firstRow.row]
    });
    await loader.loadRows({
      listSeq: 2,
      rows: [secondRow.row]
    });

    expect(apiClient.loadAuthorAseInfo).toHaveBeenCalledTimes(1);
    expect(secondRow.states.at(-1)).toMatchObject({
      source: "cache",
      state: "success"
    });
  });

  test("deduplicates in-flight requests for the same authorId", async () => {
    const deferred = createDeferred();
    const firstRow = createRowRecorder("111");
    const secondRow = createRowRecorder("111");
    const apiClient = {
      loadAuthorAseInfo: vi.fn(() => deferred.promise)
    };
    const loader = createMarketBatchLoader({
      apiClient,
      concurrency: 4
    });

    const loadPromise = loader.loadRows({
      listSeq: 1,
      rows: [firstRow.row, secondRow.row]
    });

    expect(apiClient.loadAuthorAseInfo).toHaveBeenCalledTimes(1);

    deferred.resolve({
      rates: {
        personalVideoAfterSearchRate: "0.02% - 0.1%",
        singleVideoAfterSearchRate: "<0.02%"
      },
      success: true
    });
    await loadPromise;
  });

  test("honors the concurrency cap", async () => {
    const deferreds = new Map([
      ["111", createDeferred()],
      ["222", createDeferred()],
      ["333", createDeferred()]
    ]);
    const started: string[] = [];
    const loader = createMarketBatchLoader({
      apiClient: {
        loadAuthorAseInfo: vi.fn((authorId: string) => {
          started.push(authorId);
          return deferreds.get(authorId)!.promise;
        })
      },
      concurrency: 2
    });

    const loadPromise = loader.loadRows({
      listSeq: 1,
      rows: [createRowRecorder("111").row, createRowRecorder("222").row, createRowRecorder("333").row]
    });

    expect(started).toEqual(["111", "222"]);

    deferreds.get("111")!.resolve(successResult());
    await tick();
    expect(started).toEqual(["111", "222", "333"]);

    deferreds.get("222")!.resolve(successResult());
    deferreds.get("333")!.resolve(successResult());
    await loadPromise;
  });

  test("renders failed rows as error states", async () => {
    const row = createRowRecorder("111");
    const loader = createMarketBatchLoader({
      apiClient: {
        loadAuthorAseInfo: vi.fn(async () => ({
          reason: "request-failed",
          success: false as const
        }))
      },
      concurrency: 4
    });

    await loader.loadRows({
      listSeq: 1,
      rows: [row.row]
    });

    expect(row.states.at(-1)).toMatchObject({
      reason: "request-failed",
      retryable: true,
      state: "error"
    });
  });

  test("retries the whole row when the provided retry handler is invoked", async () => {
    const row = createRowRecorder("111");
    const apiClient = {
      loadAuthorAseInfo: vi
        .fn()
        .mockResolvedValueOnce({
          reason: "request-failed",
          success: false as const
        })
        .mockResolvedValueOnce(successResult())
    };
    const loader = createMarketBatchLoader({
      apiClient,
      concurrency: 4
    });

    await loader.loadRows({
      listSeq: 1,
      rows: [row.row]
    });

    expect(row.retry).toBeTypeOf("function");
    await row.retry?.();

    expect(apiClient.loadAuthorAseInfo).toHaveBeenCalledTimes(2);
    expect(row.states.at(-2)).toMatchObject({
      state: "loading"
    });
    expect(row.states.at(-1)).toMatchObject({
      state: "success"
    });
  });
});

function createRowRecorder(authorId: string | null) {
  const states: unknown[] = [];
  let retry: (() => Promise<void> | void) | undefined;

  return {
    row: {
      authorId,
      render(
        state: unknown,
        options?: { onRetry?: () => Promise<void> | void }
      ) {
        states.push(state);
        retry = options?.onRetry;
      }
    },
    get retry() {
      return retry;
    },
    states
  };
}

function createDeferred<T = unknown>() {
  let resolve!: (value: T) => void;
  const promise = new Promise<T>((nextResolve) => {
    resolve = nextResolve;
  });

  return { promise, resolve };
}

function successResult() {
  return {
    rates: {
      personalVideoAfterSearchRate: "0.02% - 0.1%",
      singleVideoAfterSearchRate: "<0.02%"
    },
    success: true as const
  };
}

function tick() {
  return new Promise((resolve) => {
    setTimeout(resolve, 0);
  });
}