import { test, expect, mock, beforeEach } from "bun:test"

// Mock UnauthorizedError to match the SDK's class
class MockUnauthorizedError extends Error {
  constructor(message?: string) {
    super(message ?? "Unauthorized")
    this.name = "UnauthorizedError"
  }
}

// Track what options were passed to each transport constructor
const transportCalls: Array<{
  type: "streamable" | "sse"
  url: string
  options: { authProvider?: unknown }
}> = []

// Controls whether the mock transport simulates a 401 that triggers the SDK
// auth flow (which calls provider.state()) or a simple UnauthorizedError.
let simulateAuthFlow = true

// Mock the transport constructors to simulate OAuth auto-auth on 401
mock.module("@modelcontextprotocol/sdk/client/streamableHttp.js", () => ({
  StreamableHTTPClientTransport: class MockStreamableHTTP {
    authProvider:
      | {
          state?: () => Promise<string>
          redirectToAuthorization?: (url: URL) => Promise<void>
          saveCodeVerifier?: (v: string) => Promise<void>
        }
      | undefined
    constructor(url: URL, options?: { authProvider?: unknown }) {
      this.authProvider = options?.authProvider as typeof this.authProvider
      transportCalls.push({
        type: "streamable",
        url: url.toString(),
        options: options ?? {},
      })
    }
    async start() {
      // Simulate what the real SDK transport does on 401:
      // It calls auth() which eventually calls provider.state(), then
      // provider.redirectToAuthorization(), then throws UnauthorizedError.
      if (simulateAuthFlow && this.authProvider) {
        // The SDK calls provider.state() to get the OAuth state parameter
        if (this.authProvider.state) {
          await this.authProvider.state()
        }
        // The SDK calls saveCodeVerifier before redirecting
        if (this.authProvider.saveCodeVerifier) {
          await this.authProvider.saveCodeVerifier("test-verifier")
        }
        // The SDK calls redirectToAuthorization to redirect the user
        if (this.authProvider.redirectToAuthorization) {
          await this.authProvider.redirectToAuthorization(new URL("https://auth.example.com/authorize?state=test"))
        }
        throw new MockUnauthorizedError()
      }
      throw new MockUnauthorizedError()
    }
    async finishAuth(_code: string) {}
  },
}))

mock.module("@modelcontextprotocol/sdk/client/sse.js", () => ({
  SSEClientTransport: class MockSSE {
    constructor(url: URL, options?: { authProvider?: unknown }) {
      transportCalls.push({
        type: "sse",
        url: url.toString(),
        options: options ?? {},
      })
    }
    async start() {
      throw new Error("Mock SSE transport cannot connect")
    }
  },
}))

// Mock the MCP SDK Client
mock.module("@modelcontextprotocol/sdk/client/index.js", () => ({
  Client: class MockClient {
    async connect(transport: { start: () => Promise<void> }) {
      await transport.start()
    }
  },
}))

// Mock UnauthorizedError in the auth module so instanceof checks work
mock.module("@modelcontextprotocol/sdk/client/auth.js", () => ({
  UnauthorizedError: MockUnauthorizedError,
}))

beforeEach(() => {
  transportCalls.length = 0
  simulateAuthFlow = true
})

// Import modules after mocking
const { MCP } = await import("../../src/mcp/index")
const { Instance } = await import("../../src/project/instance")
const { tmpdir } = await import("../fixture/fixture")

test("first connect to OAuth server shows needs_auth instead of failed", async () => {
  await using tmp = await tmpdir({
    init: async (dir) => {
      await Bun.write(
        `${dir}/opencode.json`,
        JSON.stringify({
          $schema: "https://opencode.ai/config.json",
          mcp: {
            "test-oauth": {
              type: "remote",
              url: "https://example.com/mcp",
            },
          },
        }),
      )
    },
  })

  await Instance.provide({
    directory: tmp.path,
    fn: async () => {
      const result = await MCP.add("test-oauth", {
        type: "remote",
        url: "https://example.com/mcp",
      })

      const serverStatus = result.status as Record<string, { status: string; error?: string }>

      // The server should be detected as needing auth, NOT as failed.
      // Before the fix, provider.state() would throw a plain Error
      // ("No OAuth state saved for MCP server: test-oauth") which was
      // not caught as UnauthorizedError, causing status to be "failed".
      expect(serverStatus["test-oauth"]).toBeDefined()
      expect(serverStatus["test-oauth"].status).toBe("needs_auth")
    },
  })
})

test("state() generates a new state when none is saved", async () => {
  const { McpOAuthProvider } = await import("../../src/mcp/oauth-provider")
  const { McpAuth } = await import("../../src/mcp/auth")

  await using tmp = await tmpdir()

  await Instance.provide({
    directory: tmp.path,
    fn: async () => {
      const provider = new McpOAuthProvider(
        "test-state-gen",
        "https://example.com/mcp",
        {},
        { onRedirect: async () => {} },
      )

      // Ensure no state exists
      const entryBefore = await McpAuth.get("test-state-gen")
      expect(entryBefore?.oauthState).toBeUndefined()

      // state() should generate and return a new state, not throw
      const state = await provider.state()
      expect(typeof state).toBe("string")
      expect(state.length).toBe(64) // 32 bytes as hex

      // The generated state should be persisted
      const entryAfter = await McpAuth.get("test-state-gen")
      expect(entryAfter?.oauthState).toBe(state)
    },
  })
})

test("state() returns existing state when one is saved", async () => {
  const { McpOAuthProvider } = await import("../../src/mcp/oauth-provider")
  const { McpAuth } = await import("../../src/mcp/auth")

  await using tmp = await tmpdir()

  await Instance.provide({
    directory: tmp.path,
    fn: async () => {
      const provider = new McpOAuthProvider(
        "test-state-existing",
        "https://example.com/mcp",
        {},
        { onRedirect: async () => {} },
      )

      // Pre-save a state
      const existingState = "pre-saved-state-value"
      await McpAuth.updateOAuthState("test-state-existing", existingState)

      // state() should return the existing state
      const state = await provider.state()
      expect(state).toBe(existingState)
    },
  })
})