import { describe, it, expect } from 'vitest';
import { EventQueue } from '../src/queue.js';
import {
  TaskType,
  Complexity,
  Harness,
  Provider,
  Outcome,
  TaskCompletionEvent,
} from '../src/types/events.js';

function makeEvent(id: string): TaskCompletionEvent {
  return {
    instance_id: 'test-instance',
    event_id: id,
    schema_version: '1.0',
    timestamp: new Date().toISOString(),
    task_duration_ms: 1000,
    task_type: TaskType.IMPLEMENTATION,
    complexity: Complexity.MEDIUM,
    harness: Harness.CLAUDE_CODE,
    model: 'claude-3-opus',
    provider: Provider.ANTHROPIC,
    estimated_input_tokens: 1000,
    estimated_output_tokens: 500,
    actual_input_tokens: 1100,
    actual_output_tokens: 550,
    estimated_cost_usd_micros: 50000,
    actual_cost_usd_micros: 55000,
    quality_gate_passed: true,
    quality_gates_run: [],
    quality_gates_failed: [],
    context_compactions: 0,
    context_rotations: 0,
    context_utilization_final: 0.5,
    outcome: Outcome.SUCCESS,
    retry_count: 0,
  };
}

describe('EventQueue', () => {
  it('should enqueue and drain events', () => {
    const queue = new EventQueue(10);
    const event = makeEvent('e1');

    queue.enqueue(event);
    expect(queue.size).toBe(1);
    expect(queue.isEmpty).toBe(false);

    const drained = queue.drain(10);
    expect(drained).toHaveLength(1);
    expect(drained[0].event_id).toBe('e1');
    expect(queue.isEmpty).toBe(true);
  });

  it('should respect maxSize with FIFO eviction', () => {
    const queue = new EventQueue(3);

    queue.enqueue(makeEvent('e1'));
    queue.enqueue(makeEvent('e2'));
    queue.enqueue(makeEvent('e3'));
    expect(queue.size).toBe(3);

    // Adding a 4th should evict the oldest (e1)
    queue.enqueue(makeEvent('e4'));
    expect(queue.size).toBe(3);

    const drained = queue.drain(10);
    expect(drained.map((e) => e.event_id)).toEqual(['e2', 'e3', 'e4']);
  });

  it('should drain up to maxItems', () => {
    const queue = new EventQueue(10);
    queue.enqueue(makeEvent('e1'));
    queue.enqueue(makeEvent('e2'));
    queue.enqueue(makeEvent('e3'));

    const drained = queue.drain(2);
    expect(drained).toHaveLength(2);
    expect(drained.map((e) => e.event_id)).toEqual(['e1', 'e2']);
    expect(queue.size).toBe(1);
  });

  it('should remove drained items from the queue', () => {
    const queue = new EventQueue(10);
    queue.enqueue(makeEvent('e1'));
    queue.enqueue(makeEvent('e2'));

    queue.drain(1);
    expect(queue.size).toBe(1);

    const remaining = queue.drain(10);
    expect(remaining[0].event_id).toBe('e2');
  });

  it('should report isEmpty correctly', () => {
    const queue = new EventQueue(5);
    expect(queue.isEmpty).toBe(true);

    queue.enqueue(makeEvent('e1'));
    expect(queue.isEmpty).toBe(false);

    queue.drain(1);
    expect(queue.isEmpty).toBe(true);
  });

  it('should report size correctly', () => {
    const queue = new EventQueue(10);
    expect(queue.size).toBe(0);

    queue.enqueue(makeEvent('e1'));
    expect(queue.size).toBe(1);

    queue.enqueue(makeEvent('e2'));
    expect(queue.size).toBe(2);

    queue.drain(1);
    expect(queue.size).toBe(1);
  });

  it('should return empty array when draining empty queue', () => {
    const queue = new EventQueue(5);
    const drained = queue.drain(10);
    expect(drained).toEqual([]);
  });

  it('should prepend events to the front of the queue', () => {
    const queue = new EventQueue(10);
    queue.enqueue(makeEvent('e3'));

    queue.prepend([makeEvent('e1'), makeEvent('e2')]);
    expect(queue.size).toBe(3);

    const drained = queue.drain(10);
    expect(drained.map((e) => e.event_id)).toEqual(['e1', 'e2', 'e3']);
  });

  it('should respect maxSize when prepending', () => {
    const queue = new EventQueue(3);
    queue.enqueue(makeEvent('e3'));
    queue.enqueue(makeEvent('e4'));

    // Only 1 slot available, so only first event should be prepended
    queue.prepend([makeEvent('e1'), makeEvent('e2')]);
    expect(queue.size).toBe(3);

    const drained = queue.drain(10);
    expect(drained.map((e) => e.event_id)).toEqual(['e1', 'e3', 'e4']);
  });
});