import { describe, it, expect, vi, beforeEach } from 'vitest';
import type { SchedulerClient, CreateScheduleInput, CreateScheduleOutput } from '../src/client.js';
import { buildReminderTools } from '../src/tools.js';
import type { AuthContext } from '@sh-mcp/shared';

// ---------------------------------------------------------------------------
// Helpers
// ---------------------------------------------------------------------------

/** Returns a Date that is `offsetMs` milliseconds in the future. */
function futureDate(offsetMs = 5 * 60 * 1000): Date {
  return new Date(Date.now() + offsetMs);
}

/** AuthContext with ops:tasks scope — the happy-path identity. */
function makeCtx(overrides: Partial<AuthContext> = {}): AuthContext {
  return {
    sub: 'lauren@seahavenind.com',
    scopes: ['ops:read', 'ops:tasks'],
    aud: 'sh-mcp-ops',
    ...overrides,
  };
}

/** Build a mock SchedulerClient whose createSchedule can be controlled per-test. */
function makeMockClient(
  impl?: (input: CreateScheduleInput) => Promise<CreateScheduleOutput>,
): SchedulerClient {
  return {
    createSchedule: vi.fn(
      impl ??
        (async (input: CreateScheduleInput): Promise<CreateScheduleOutput> => ({
          scheduleArn: `arn:aws:scheduler:us-east-1:328440206208:schedule/default/${input.scheduleName}`,
        })),
    ),
  };
}

// ---------------------------------------------------------------------------
// Suite
// ---------------------------------------------------------------------------

describe('create_reminder', () => {
  let mockClient: SchedulerClient;
  let createReminder: ReturnType<typeof buildReminderTools>[0];

  beforeEach(() => {
    mockClient = makeMockClient();
    [createReminder] = buildReminderTools({ client: mockClient });
  });

  // -------------------------------------------------------------------------
  // Tool definition contract
  // -------------------------------------------------------------------------

  describe('tool definition', () => {
    it('has the correct name', () => {
      expect(createReminder.name).toBe('create_reminder');
    });

    it('is in the ops tier', () => {
      expect(createReminder.tier).toBe('ops');
    });

    it('requires the ops:tasks scope', () => {
      expect(createReminder.requiredScope).toBe('ops:tasks');
    });

    it('has a non-empty description', () => {
      expect(createReminder.description.length).toBeGreaterThan(10);
    });

    it('input schema declares remind_at and message as required', () => {
      const schema = createReminder.inputSchema as {
        required: string[];
        properties: Record<string, unknown>;
      };
      expect(schema.required).toContain('remind_at');
      expect(schema.required).toContain('message');
    });
  });

  // -------------------------------------------------------------------------
  // Happy path
  // -------------------------------------------------------------------------

  describe('happy path', () => {
    it('creates a schedule and returns a confirmation', async () => {
      const remindAt = futureDate(10 * 60 * 1000).toISOString();
      const ctx = makeCtx();

      const result = await createReminder.handler(
        { remind_at: remindAt, message: 'Pick up the dry cleaning' },
        ctx,
      );

      expect(result.remind_at).toBe(new Date(remindAt).toISOString());
      expect(result.reminder_id).toMatch(/^sh-reminder-/);
      expect(result.confirmation).toContain('Pick up the dry cleaning');
    });

    it('passes the message and sub in the schedule payload', async () => {
      const remindAt = futureDate(10 * 60 * 1000).toISOString();
      const ctx = makeCtx();

      await createReminder.handler({ remind_at: remindAt, message: 'Follow up with vendor' }, ctx);

      const calls = (mockClient.createSchedule as ReturnType<typeof vi.fn>).mock.calls;
      expect(calls).toHaveLength(1);
      const [callInput] = calls[0] as [CreateScheduleInput];
      expect(callInput.payload['sub']).toBe('lauren@seahavenind.com');
      expect(callInput.payload['message']).toBe('Follow up with vendor');
    });

    it('defaults recipient to the calling user sub when not provided', async () => {
      const remindAt = futureDate(10 * 60 * 1000).toISOString();
      const ctx = makeCtx();

      await createReminder.handler({ remind_at: remindAt, message: 'Check email' }, ctx);

      const [callInput] = (mockClient.createSchedule as ReturnType<typeof vi.fn>).mock.calls[0] as [
        CreateScheduleInput,
      ];
      expect(callInput.payload['recipient']).toBe('lauren@seahavenind.com');
    });

    it('resolves recipient to sub when "me" is passed explicitly', async () => {
      const remindAt = futureDate(10 * 60 * 1000).toISOString();
      const ctx = makeCtx();

      await createReminder.handler(
        { remind_at: remindAt, message: 'Standup in 5', recipient: 'me' },
        ctx,
      );

      const [callInput] = (mockClient.createSchedule as ReturnType<typeof vi.fn>).mock.calls[0] as [
        CreateScheduleInput,
      ];
      expect(callInput.payload['recipient']).toBe('lauren@seahavenind.com');
    });

    it('forwards a custom channel recipient unchanged', async () => {
      const remindAt = futureDate(10 * 60 * 1000).toISOString();
      const ctx = makeCtx();

      await createReminder.handler(
        { remind_at: remindAt, message: 'Team standup', recipient: 'C01234567' },
        ctx,
      );

      const [callInput] = (mockClient.createSchedule as ReturnType<typeof vi.fn>).mock.calls[0] as [
        CreateScheduleInput,
      ];
      expect(callInput.payload['recipient']).toBe('C01234567');
    });

    it('scheduleAt is the ISO string of remind_at', async () => {
      const remindAt = futureDate(30 * 60 * 1000).toISOString();
      const ctx = makeCtx();

      await createReminder.handler({ remind_at: remindAt, message: 'Check metrics' }, ctx);

      const [callInput] = (mockClient.createSchedule as ReturnType<typeof vi.fn>).mock.calls[0] as [
        CreateScheduleInput,
      ];
      expect(callInput.scheduleAt).toBe(new Date(remindAt).toISOString());
    });
  });

  // -------------------------------------------------------------------------
  // Scope enforcement
  // -------------------------------------------------------------------------

  describe('scope enforcement', () => {
    it('throws when ops:tasks scope is missing', async () => {
      const ctx = makeCtx({ scopes: ['ops:read'] });
      const remindAt = futureDate(10 * 60 * 1000).toISOString();

      await expect(
        createReminder.handler({ remind_at: remindAt, message: 'Unauthorized' }, ctx),
      ).rejects.toThrow();
    });

    it('throws when scopes array is empty', async () => {
      const ctx = makeCtx({ scopes: [] });
      const remindAt = futureDate(10 * 60 * 1000).toISOString();

      await expect(
        createReminder.handler({ remind_at: remindAt, message: 'No scopes' }, ctx),
      ).rejects.toThrow();
    });

    it('succeeds when only ops:tasks is present (minimal grant)', async () => {
      const ctx = makeCtx({ scopes: ['ops:tasks'] });
      const remindAt = futureDate(10 * 60 * 1000).toISOString();

      await expect(
        createReminder.handler({ remind_at: remindAt, message: 'Minimal scope' }, ctx),
      ).resolves.toBeDefined();
    });
  });

  // -------------------------------------------------------------------------
  // Input validation
  // -------------------------------------------------------------------------

  describe('input validation', () => {
    it('rejects an invalid remind_at string', async () => {
      const ctx = makeCtx();

      await expect(
        createReminder.handler({ remind_at: 'not-a-date', message: 'Bad date' }, ctx),
      ).rejects.toThrow(/invalid remind_at/);
    });

    it('rejects a remind_at that is in the past', async () => {
      const ctx = makeCtx();
      const past = new Date(Date.now() - 60_000).toISOString();

      await expect(
        createReminder.handler({ remind_at: past, message: 'Past date' }, ctx),
      ).rejects.toThrow(/at least 1 minute in the future/);
    });

    it('rejects a remind_at less than 1 minute in the future', async () => {
      const ctx = makeCtx();
      const tooSoon = new Date(Date.now() + 30_000).toISOString();

      await expect(
        createReminder.handler({ remind_at: tooSoon, message: 'Too soon' }, ctx),
      ).rejects.toThrow(/at least 1 minute in the future/);
    });
  });

  // -------------------------------------------------------------------------
  // Empty / minimal result
  // -------------------------------------------------------------------------

  describe('edge cases', () => {
    it('handles a single-character message without truncating confirmation', async () => {
      const ctx = makeCtx();
      const remindAt = futureDate(10 * 60 * 1000).toISOString();

      const result = await createReminder.handler({ remind_at: remindAt, message: 'A' }, ctx);

      expect(result.confirmation).toContain('"A"');
    });

    it('truncates long messages in the confirmation with ellipsis', async () => {
      const ctx = makeCtx();
      const remindAt = futureDate(10 * 60 * 1000).toISOString();
      const longMessage = 'x'.repeat(200);

      const result = await createReminder.handler(
        { remind_at: remindAt, message: longMessage },
        ctx,
      );

      expect(result.confirmation).toContain('…');
    });

    it('schedule name is within EventBridge name length limit (64 chars)', async () => {
      const ctx = makeCtx({
        sub: 'a-very-long-user-sub-that-exceeds-typical-length@seahavenind.com',
      });
      const remindAt = futureDate(10 * 60 * 1000).toISOString();

      const result = await createReminder.handler(
        { remind_at: remindAt, message: 'Name length check' },
        ctx,
      );

      expect(result.reminder_id.length).toBeLessThanOrEqual(64);
    });
  });

  // -------------------------------------------------------------------------
  // Error path
  // -------------------------------------------------------------------------

  describe('error handling', () => {
    it('surfaces a generic scheduler error to the caller', async () => {
      const failingClient = makeMockClient(async () => {
        throw new Error('Scheduler internal error');
      });
      const [failTool] = buildReminderTools({ client: failingClient });
      const ctx = makeCtx();
      const remindAt = futureDate(10 * 60 * 1000).toISOString();

      await expect(
        failTool.handler({ remind_at: remindAt, message: 'Will fail' }, ctx),
      ).rejects.toThrow('Scheduler internal error');
    });
  });

  // -------------------------------------------------------------------------
  // Throttle / retry simulation
  // -------------------------------------------------------------------------

  describe('throttle / retry', () => {
    it('surfaces a ThrottlingException from the scheduler', async () => {
      let callCount = 0;
      const throttlingClient = makeMockClient(async () => {
        callCount += 1;
        const err = Object.assign(new Error('Rate exceeded'), {
          name: 'ThrottlingException',
          $fault: 'client',
        });
        throw err;
      });
      const [throttleTool] = buildReminderTools({ client: throttlingClient });
      const ctx = makeCtx();
      const remindAt = futureDate(10 * 60 * 1000).toISOString();

      await expect(
        throttleTool.handler({ remind_at: remindAt, message: 'Throttled' }, ctx),
      ).rejects.toThrow('Rate exceeded');

      // The tool itself does not retry — retries are the transport/server layer's
      // responsibility. Assert the client was called exactly once.
      expect(callCount).toBe(1);
    });

    it('surfaces a ConflictException when a schedule name already exists', async () => {
      const conflictClient = makeMockClient(async () => {
        const err = Object.assign(new Error('Schedule already exists with this name'), {
          name: 'ConflictException',
        });
        throw err;
      });
      const [conflictTool] = buildReminderTools({ client: conflictClient });
      const ctx = makeCtx();
      const remindAt = futureDate(10 * 60 * 1000).toISOString();

      await expect(
        conflictTool.handler({ remind_at: remindAt, message: 'Duplicate' }, ctx),
      ).rejects.toThrow('Schedule already exists');
    });
  });
});