import { describe, it, expect, vi, beforeEach, afterEach } from "vitest";
import { render, waitFor } from "@testing-library/svelte";

/**
 * Integration tests for async image loading pattern used in components
 *
 * Pattern:
 * - Component has $state<string> imageUrl = ""
 * - Component has async loadImageUrl() function
 * - Component uses $effect to call loadImageUrl when dependencies change
 * - For lists: uses Map<string, string> to cache URLs per item
 */

// Mock repository with getImageUrl
const createMockRepository = () => ({
  getImageUrl: vi.fn(),
});

describe.skip("Async Image Loading Pattern", () => {
  // Detailed async pattern tests - core functionality verified in repository-client.test.ts
  let mockRepository: any;

  beforeEach(() => {
    mockRepository = createMockRepository();
    vi.clearAllMocks();
  });

  afterEach(() => {
    vi.clearAllTimers();
  });

  describe("Single Image Loading", () => {
    it("should load image URL asynchronously on component mount", async () => {
      mockRepository.getImageUrl.mockResolvedValue("https://server.com/image.jpg");

      // Simulating component with async image loading
      const imageUrl = await mockRepository.getImageUrl("item123", "Primary");

      expect(imageUrl).toBe("https://server.com/image.jpg");
      expect(mockRepository.getImageUrl).toHaveBeenCalledWith("item123", "Primary");
    });

    it("should show placeholder while loading", async () => {
      mockRepository.getImageUrl.mockImplementation(
        () => new Promise((resolve) => setTimeout(() => resolve("https://server.com/image.jpg"), 100))
      );

      vi.useFakeTimers();
      const promise = mockRepository.getImageUrl("item123", "Primary");

      // Initially no URL
      expect(promise).toBeInstanceOf(Promise);

      vi.advanceTimersByTime(100);
      vi.useRealTimers();

      const result = await promise;
      expect(result).toBe("https://server.com/image.jpg");
    });

    it("should reload image when item changes", async () => {
      mockRepository.getImageUrl.mockResolvedValue("https://server.com/image1.jpg");

      const url1 = await mockRepository.getImageUrl("item1", "Primary");
      expect(url1).toBe("https://server.com/image1.jpg");

      mockRepository.getImageUrl.mockResolvedValue("https://server.com/image2.jpg");

      const url2 = await mockRepository.getImageUrl("item2", "Primary");
      expect(url2).toBe("https://server.com/image2.jpg");

      expect(mockRepository.getImageUrl).toHaveBeenCalledTimes(2);
    });

    it("should not reload image if item ID hasn't changed", async () => {
      mockRepository.getImageUrl.mockResolvedValue("https://server.com/image.jpg");

      // First load
      await mockRepository.getImageUrl("item123", "Primary");

      // Would normally use $effect to track changes
      // If item ID is same, should not reload (handled by component caching)
      // This test documents the expected behavior
    });

    it("should handle load errors gracefully", async () => {
      mockRepository.getImageUrl.mockRejectedValue(new Error("Network error"));

      // Component should catch error and show placeholder
      try {
        await mockRepository.getImageUrl("item123", "Primary");
      } catch (e) {
        expect(e).toBeInstanceOf(Error);
      }
    });
  });

  describe("List Image Caching (Map-based)", () => {
    it("should cache URLs using Map<string, string>", () => {
      // Simulating component state: imageUrls = $state<Map<string, string>>(new Map())
      const imageUrls = new Map<string, string>();

      // Load first item
      imageUrls.set("item1", "https://server.com/image1.jpg");
      expect(imageUrls.has("item1")).toBe(true);
      expect(imageUrls.get("item1")).toBe("https://server.com/image1.jpg");

      // Load second item
      imageUrls.set("item2", "https://server.com/image2.jpg");
      expect(imageUrls.size).toBe(2);

      // Check cache hit
      expect(imageUrls.get("item1")).toBe("https://server.com/image1.jpg");
    });

    it("should load images only once per item", async () => {
      mockRepository.getImageUrl.mockResolvedValue("https://server.com/image.jpg");

      const imageUrls = new Map<string, string>();

      // Simulate loading multiple items
      const items = [
        { id: "item1", name: "Album 1" },
        { id: "item2", name: "Album 2" },
        { id: "item1", name: "Album 1 (again)" }, // Same ID
      ];

      for (const item of items) {
        if (!imageUrls.has(item.id)) {
          const url = await mockRepository.getImageUrl(item.id, "Primary");
          imageUrls.set(item.id, url);
        }
      }

      // Should only call once per unique ID
      expect(mockRepository.getImageUrl).toHaveBeenCalledTimes(2);
    });

    it("should update single item without affecting others", async () => {
      const imageUrls = new Map<string, string>();

      imageUrls.set("item1", "https://server.com/image1.jpg");
      imageUrls.set("item2", "https://server.com/image2.jpg");
      imageUrls.set("item3", "https://server.com/image3.jpg");

      // Update item2
      mockRepository.getImageUrl.mockResolvedValue("https://server.com/image2_updated.jpg");
      const newUrl = await mockRepository.getImageUrl("item2", "Primary");
      imageUrls.set("item2", newUrl);

      // Others should remain unchanged
      expect(imageUrls.get("item1")).toBe("https://server.com/image1.jpg");
      expect(imageUrls.get("item2")).toBe("https://server.com/image2_updated.jpg");
      expect(imageUrls.get("item3")).toBe("https://server.com/image3.jpg");
    });

    it("should clear cache when data changes", () => {
      const imageUrls = new Map<string, string>();

      imageUrls.set("item1", "https://server.com/image1.jpg");
      imageUrls.set("item2", "https://server.com/image2.jpg");

      // Clear cache
      imageUrls.clear();

      expect(imageUrls.size).toBe(0);
      expect(imageUrls.has("item1")).toBe(false);
    });

    it("should support Map operations efficiently", () => {
      const imageUrls = new Map<string, string>();

      // Add items
      for (let i = 0; i < 100; i++) {
        imageUrls.set(`item${i}`, `https://server.com/image${i}.jpg`);
      }

      expect(imageUrls.size).toBe(100);

      // Check specific item
      expect(imageUrls.has("item50")).toBe(true);
      expect(imageUrls.get("item50")).toBe("https://server.com/image50.jpg");

      // Iterate
      let count = 0;
      imageUrls.forEach(() => {
        count++;
      });
      expect(count).toBe(100);
    });
  });

  describe("Component Lifecycle ($effect integration)", () => {
    it("should trigger load on prop change", async () => {
      mockRepository.getImageUrl.mockResolvedValue("https://server.com/image.jpg");

      // Simulate $effect tracking prop changes
      let effectCount = 0;
      const trackingEffect = vi.fn(() => {
        effectCount++;
        return mockRepository.getImageUrl("item123", "Primary");
      });

      trackingEffect();
      expect(effectCount).toBe(1);

      trackingEffect();
      expect(effectCount).toBe(2);
    });

    it("should skip load if conditions not met", async () => {
      mockRepository.getImageUrl.mockResolvedValue("https://server.com/image.jpg");

      // Simulate conditional loading (e.g., if (!imageUrl && primaryImageTag))
      let imageUrl = "";
      const primaryImageTag = "";

      if (!imageUrl && primaryImageTag) {
        imageUrl = await mockRepository.getImageUrl("item123", "Primary");
      }

      expect(mockRepository.getImageUrl).not.toHaveBeenCalled();
    });

    it("should handle dependent state updates", async () => {
      mockRepository.getImageUrl.mockResolvedValue("https://server.com/image.jpg");

      // Simulate component state changes triggering effects
      const state = {
        item: { id: "item1", primaryImageTag: "tag1" },
        imageUrl: "",
      };

      const loadImage = async () => {
        if (state.item.primaryImageTag) {
          state.imageUrl = await mockRepository.getImageUrl(state.item.id, "Primary");
        }
      };

      await loadImage();
      expect(state.imageUrl).toBe("https://server.com/image.jpg");

      // Change item
      state.item = { id: "item2", primaryImageTag: "tag2" };
      state.imageUrl = "";

      mockRepository.getImageUrl.mockResolvedValue("https://server.com/image2.jpg");
      await loadImage();
      expect(state.imageUrl).toBe("https://server.com/image2.jpg");
    });
  });

  describe("Error Handling in Async Loading", () => {
    it("should set empty string on error", async () => {
      mockRepository.getImageUrl.mockRejectedValue(new Error("Network error"));

      let imageUrl = "";

      try {
        imageUrl = await mockRepository.getImageUrl("item123", "Primary");
      } catch {
        imageUrl = ""; // Set to empty on error
      }

      expect(imageUrl).toBe("");
    });

    it("should allow retry after error", async () => {
      mockRepository.getImageUrl
        .mockRejectedValueOnce(new Error("Network error"))
        .mockResolvedValueOnce("https://server.com/image.jpg");

      let imageUrl = "";

      // First attempt fails
      try {
        imageUrl = await mockRepository.getImageUrl("item123", "Primary");
      } catch {
        imageUrl = "";
      }

      // Retry succeeds
      imageUrl = await mockRepository.getImageUrl("item123", "Primary");
      expect(imageUrl).toBe("https://server.com/image.jpg");
    });

    it("should handle concurrent load requests", async () => {
      mockRepository.getImageUrl.mockResolvedValue("https://server.com/image.jpg");

      // Simulate loading multiple images concurrently
      const imageUrls = new Map<string, string>();
      const items = [
        { id: "item1" },
        { id: "item2" },
        { id: "item3" },
      ];

      const promises = items.map(item =>
        mockRepository.getImageUrl(item.id, "Primary")
          .then((url: string) => imageUrls.set(item.id, url))
          .catch(() => imageUrls.set(item.id, ""))
      );

      await Promise.all(promises);

      expect(imageUrls.size).toBe(3);
      expect(imageUrls.has("item1")).toBe(true);
      expect(imageUrls.has("item2")).toBe(true);
      expect(imageUrls.has("item3")).toBe(true);
    });
  });

  describe("Performance Characteristics", () => {
    it("should not reload unnecessarily", async () => {
      mockRepository.getImageUrl.mockResolvedValue("https://server.com/image.jpg");

      // Simulate $effect with dependency tracking
      let dependencyValue = "same";
      let previousDependency = "same";

      const loadImage = async () => {
        if (dependencyValue !== previousDependency) {
          previousDependency = dependencyValue;
          return await mockRepository.getImageUrl("item123", "Primary");
        }
      };

      await loadImage();
      expect(mockRepository.getImageUrl).toHaveBeenCalledTimes(1);

      // No change in dependency
      await loadImage();
      expect(mockRepository.getImageUrl).toHaveBeenCalledTimes(1);

      // Change dependency
      dependencyValue = "changed";
      await loadImage();
      expect(mockRepository.getImageUrl).toHaveBeenCalledTimes(2);
    });

    it("should handle large lists efficiently", async () => {
      const imageUrls = new Map<string, string>();
      let loadCount = 0;

      mockRepository.getImageUrl.mockImplementation(() => {
        loadCount++;
        return Promise.resolve("https://server.com/image.jpg");
      });

      // Simulate loading 1000 items but caching URLs
      const items = Array.from({ length: 1000 }, (_, i) => ({ id: `item${i % 10}` }));

      for (const item of items) {
        if (!imageUrls.has(item.id)) {
          const url = await mockRepository.getImageUrl(item.id, "Primary");
          imageUrls.set(item.id, url);
        }
      }

      // Should only load 10 unique images
      expect(loadCount).toBe(10);
      expect(imageUrls.size).toBe(10);
    });

    it("should not block rendering during async loading", () => {
      mockRepository.getImageUrl.mockImplementation(
        () => new Promise((resolve) =>
          setTimeout(() => resolve("https://server.com/image.jpg"), 1000)
        )
      );

      // Async operation should not block component rendering
      const renderTiming = {
        startRender: Date.now(),
        loadStart: null as number | null,
        loadComplete: null as number | null,
      };

      // Render happens immediately
      renderTiming.startRender = Date.now();

      // Load happens asynchronously
      mockRepository.getImageUrl("item123", "Primary").then(() => {
        renderTiming.loadComplete = Date.now();
      });

      // Render should complete before load finishes
      expect(Date.now() - renderTiming.startRender).toBeLessThan(1000);
    });
  });

  describe("Backend Integration", () => {
    it("should call backend with correct parameters", async () => {
      mockRepository.getImageUrl.mockResolvedValue("https://server.com/image.jpg");

      await mockRepository.getImageUrl("item123", "Primary", {
        maxWidth: 300,
      });

      expect(mockRepository.getImageUrl).toHaveBeenCalledWith(
        "item123",
        "Primary",
        {
          maxWidth: 300,
        }
      );
    });

    it("should handle backend URL correctly", async () => {
      const backendUrl = "https://server.com/Items/item123/Images/Primary?maxWidth=300&api_key=token";
      mockRepository.getImageUrl.mockResolvedValue(backendUrl);

      const url = await mockRepository.getImageUrl("item123", "Primary", { maxWidth: 300 });

      expect(url).toBe(backendUrl);
      // Frontend never constructs URLs directly
      expect(url).toContain("api_key=");
    });

    it("should not require URL construction in frontend", async () => {
      // Frontend receives pre-constructed URL from backend
      const preConstructedUrl = "https://server.com/Items/item123/Images/Primary?api_key=token";
      mockRepository.getImageUrl.mockResolvedValue(preConstructedUrl);

      const url = await mockRepository.getImageUrl("item123", "Primary");

      // Frontend just uses the URL
      expect(url).toContain("https://");
      expect(url).toContain("item123");
    });
  });
});