import { describe, it, expect, vi, beforeEach } from "vitest";
import express from "express";
import request from "supertest";
import { getPoolStats } from "../services/browser.js";
import { pool } from "../services/db.js";

let app: express.Express;

beforeEach(async () => {
  vi.clearAllMocks();

  // Default: healthy DB
  const mockClient = {
    query: vi.fn()
      .mockResolvedValueOnce({ rows: [{ 1: 1 }] }) // SELECT 1
      .mockResolvedValueOnce({ rows: [{ version: "PostgreSQL 17.4 on x86_64" }] }), // SELECT version()
    release: vi.fn(),
  };
  vi.mocked(pool.connect).mockResolvedValue(mockClient as any);

  vi.mocked(getPoolStats).mockReturnValue({
    poolSize: 16,
    totalPages: 16,
    availablePages: 14,
    queueDepth: 0,
    pdfCount: 5,
    restarting: false,
    uptimeMs: 60000,
    browsers: [],
  });

  const { healthRouter } = await import("../routes/health.js");
  app = express();
  app.use("/health", healthRouter);
});

describe("GET /health", () => {
  it("returns 200 with status ok when DB is healthy", async () => {
    const res = await request(app).get("/health");
    expect(res.status).toBe(200);
    expect(res.body.status).toBe("ok");
    expect(res.body.database.status).toBe("ok");
  });

  it("returns 503 with status degraded on DB error", async () => {
    vi.mocked(pool.connect).mockRejectedValue(new Error("Connection refused"));
    const res = await request(app).get("/health");
    expect(res.status).toBe(503);
    expect(res.body.status).toBe("degraded");
    expect(res.body.database.status).toBe("error");
  });

  it("includes pool stats", async () => {
    const res = await request(app).get("/health");
    expect(res.body.pool).toMatchObject({
      size: 16,
      available: 14,
      queueDepth: 0,
      pdfCount: 5,
    });
  });

  it("includes version", async () => {
    const res = await request(app).get("/health");
    expect(res.body.version).toBeDefined();
    expect(typeof res.body.version).toBe("string");
  });

  it("returns 503 when client.query() throws and releases client with destroy flag", async () => {
    const mockRelease = vi.fn();
    const mockClient = {
      query: vi.fn().mockRejectedValue(new Error("Query failed")),
      release: mockRelease,
    };
    vi.mocked(pool.connect).mockResolvedValue(mockClient as any);

    const res = await request(app).get("/health");
    
    expect(res.status).toBe(503);
    expect(res.body.status).toBe("degraded");
    expect(res.body.database.status).toBe("error");
    expect(res.body.database.message).toContain("Query failed");
    
    // Verify client.release(true) was called to destroy the bad connection
    expect(mockRelease).toHaveBeenCalledWith(true);
  });

  it("returns 503 when database health check times out (timeout race wins)", async () => {
    // Make pool.connect() hang longer than HEALTH_CHECK_TIMEOUT_MS (3000ms)
    const mockClient = {
      query: vi.fn(),
      release: vi.fn(),
    };
    
    vi.mocked(pool.connect).mockImplementation(() => 
      new Promise((resolve) => {
        // Resolve after 5000ms, which is longer than the 3000ms timeout
        setTimeout(() => resolve(mockClient as any), 5000);
      })
    );

    const res = await request(app).get("/health");

    expect(res.status).toBe(503);
    expect(res.body.status).toBe("degraded");
    expect(res.body.database.status).toBe("error");
    expect(res.body.database.message).toContain("Database health check timed out");
  });

  it("returns PostgreSQL for version string without PostgreSQL match", async () => {
    const mockClient = {
      query: vi.fn()
        .mockResolvedValueOnce({ rows: [{ 1: 1 }] }) // SELECT 1
        .mockResolvedValueOnce({ rows: [{ version: "MySQL 8.0.33" }] }), // No PostgreSQL in version string
      release: vi.fn(),
    };
    vi.mocked(pool.connect).mockResolvedValue(mockClient as any);

    const res = await request(app).get("/health");

    expect(res.status).toBe(200);
    expect(res.body.status).toBe("ok");
    expect(res.body.database.status).toBe("ok");
    expect(res.body.database.version).toBe("PostgreSQL"); // fallback when no regex match
  });

  it("returns 503 when non-Error is thrown in catch block", async () => {
    // Make pool.connect() throw a non-Error object
    vi.mocked(pool.connect).mockRejectedValue("String error message");

    const res = await request(app).get("/health");

    expect(res.status).toBe(503);
    expect(res.body.status).toBe("degraded");
    expect(res.body.database.status).toBe("error");
    expect(res.body.database.message).toBe("Database connection failed");
  });
});