/**
 * Unit tests for QueueManager
 *
 * Tests core queue operations, status management, and pub/sub functionality.
 */

import { describe, it, expect, beforeEach, vi } from 'vitest';
import { QueueManager } from '$lib/server/queue/QueueManager';

describe('QueueManager', () => {
	let queueManager: QueueManager;

	beforeEach(() => {
		// Create fresh instance for each test
		queueManager = new QueueManager();
	});

	describe('enqueue', () => {
		it('should enqueue items with unique IDs', () => {
			const item1 = queueManager.enqueue('https://instagram.com/p/test1');
			const item2 = queueManager.enqueue('https://instagram.com/p/test2');

			expect(item1.id).toBeTruthy();
			expect(item2.id).toBeTruthy();
			expect(item1.id).not.toBe(item2.id);
		});

		it('should create items with pending status', () => {
			const item = queueManager.enqueue('https://instagram.com/p/test');

			expect(item.status).toBe('pending');
			expect(item.enqueuedAt).toBeTruthy();
			expect(item.logs).toEqual([]);
			expect(item.progressEvents).toEqual([]);
			expect(item.retryCount).toBe(0);
			expect(item.maxRetries).toBe(3);
		});

		it('should notify subscribers when enqueueing', () => {
			const callback = vi.fn();
			queueManager.subscribe(callback);

			const item = queueManager.enqueue('https://instagram.com/p/test');

			expect(callback).toHaveBeenCalledWith(
				expect.objectContaining({
					itemId: item.id,
					status: 'pending'
				})
			);
		});
	});

	describe('dequeue', () => {
		it('should dequeue oldest pending item first (FIFO)', () => {
			const item1 = queueManager.enqueue('https://instagram.com/p/test1');
			const item2 = queueManager.enqueue('https://instagram.com/p/test2');

			const dequeued1 = queueManager.dequeue();
			expect(dequeued1?.id).toBe(item1.id);

			const dequeued2 = queueManager.dequeue();
			expect(dequeued2?.id).toBe(item2.id);
		});

		it('should return null when queue is empty', () => {
			const item = queueManager.dequeue();
			expect(item).toBeNull();
		});

		it('should mark dequeued item as in_progress', () => {
			const enqueuedItem = queueManager.enqueue('https://instagram.com/p/test');

			const dequeuedItem = queueManager.dequeue();

			expect(dequeuedItem?.status).toBe('in_progress');
			expect(dequeuedItem?.currentPhase).toBe('extraction');
			expect(dequeuedItem?.startedAt).toBeTruthy();
		});

		it('should skip non-pending items', () => {
			const item1 = queueManager.enqueue('https://instagram.com/p/test1');
			const item2 = queueManager.enqueue('https://instagram.com/p/test2');

			// Dequeue first item
			queueManager.dequeue();

			// Second item should be next
			const dequeued = queueManager.dequeue();
			expect(dequeued?.id).toBe(item2.id);
		});
	});

	describe('updateStatus', () => {
		it('should update item status', () => {
			const item = queueManager.enqueue('https://instagram.com/p/test');

			queueManager.updateStatus(item.id, 'in_progress', { phase: 'parsing' });

			const updated = queueManager.get(item.id);
			expect(updated?.status).toBe('in_progress');
			expect(updated?.currentPhase).toBe('parsing');
		});

		it('should set completedAt for terminal statuses', () => {
			const item = queueManager.enqueue('https://instagram.com/p/test');

			queueManager.updateStatus(item.id, 'success');

			const updated = queueManager.get(item.id);
			expect(updated?.completedAt).toBeTruthy();
		});

		it('should merge additional data into item', () => {
			const item = queueManager.enqueue('https://instagram.com/p/test');

			queueManager.updateStatus(item.id, 'success', {
				recipe: { name: 'Test Recipe' },
				tandoorRecipeId: 123
			});

			const updated = queueManager.get(item.id);
			expect(updated?.recipe).toEqual({ name: 'Test Recipe' });
			expect(updated?.tandoorRecipeId).toBe(123);
		});

		it('should handle error data', () => {
			const item = queueManager.enqueue('https://instagram.com/p/test');

			const errorData = {
				error: {
					phase: 'extraction' as const,
					message: 'Failed to load page',
					recoverable: true,
					timestamp: new Date().toISOString()
				}
			};

			queueManager.updateStatus(item.id, 'unhealthy', errorData);

			const updated = queueManager.get(item.id);
			expect(updated?.error).toEqual(errorData.error);
		});
	});

	describe('addProgressEvent', () => {
		it('should add progress events to item', () => {
			const item = queueManager.enqueue('https://instagram.com/p/test');

			const event = {
				type: 'status',
				message: 'Extracting...',
				timestamp: new Date().toISOString()
			};

			queueManager.addProgressEvent(item.id, event);

			const updated = queueManager.get(item.id);
			expect(updated?.progressEvents).toHaveLength(1);
			expect(updated?.progressEvents[0]).toEqual(event);
		});

		it('should add event message to logs', () => {
			const item = queueManager.enqueue('https://instagram.com/p/test');

			queueManager.addProgressEvent(item.id, {
				type: 'status',
				message: 'Test message',
				timestamp: new Date().toISOString()
			});

			const updated = queueManager.get(item.id);
			expect(updated?.logs).toContain('Test message');
		});

		it('should notify subscribers with event data', () => {
			const callback = vi.fn();
			queueManager.subscribe(callback);

			const item = queueManager.enqueue('https://instagram.com/p/test');
			callback.mockClear(); // Clear enqueue notification

			const event = { type: 'status', message: 'Test', timestamp: new Date().toISOString() };
			queueManager.addProgressEvent(item.id, event);

			expect(callback).toHaveBeenCalledWith(
				expect.objectContaining({
					itemId: item.id,
					data: { event }
				})
			);
		});
	});

	describe('remove', () => {
		it('should remove items by ID', () => {
			const item = queueManager.enqueue('https://instagram.com/p/test');

			const removed = queueManager.remove(item.id);

			expect(removed).toBe(true);
			expect(queueManager.get(item.id)).toBeUndefined();
		});

		it('should return false for non-existent items', () => {
			const removed = queueManager.remove('non-existent-id');
			expect(removed).toBe(false);
		});

		it('should notify subscribers when removing', () => {
			const callback = vi.fn();
			queueManager.subscribe(callback);

			const item = queueManager.enqueue('https://instagram.com/p/test');
			callback.mockClear();

			queueManager.remove(item.id);

			expect(callback).toHaveBeenCalledWith(
				expect.objectContaining({
					itemId: item.id,
					data: { removed: true }
				})
			);
		});
	});

	describe('retry', () => {
		it('should retry failed items', () => {
			const item = queueManager.enqueue('https://instagram.com/p/test');
			queueManager.updateStatus(item.id, 'error');

			const retried = queueManager.retry(item.id);

			expect(retried).toBe(true);

			const updated = queueManager.get(item.id);
			expect(updated?.status).toBe('pending');
			expect(updated?.retryCount).toBe(1);
			expect(updated?.error).toBeUndefined();
			expect(updated?.currentPhase).toBeUndefined();
		});

		it('should not retry items in progress', () => {
			const item = queueManager.enqueue('https://instagram.com/p/test');
			queueManager.updateStatus(item.id, 'in_progress');

			const retried = queueManager.retry(item.id);

			expect(retried).toBe(false);
			expect(queueManager.get(item.id)?.status).toBe('in_progress');
		});

		it('should increment retry count', () => {
			const item = queueManager.enqueue('https://instagram.com/p/test');
			queueManager.updateStatus(item.id, 'error');

			queueManager.retry(item.id);
			queueManager.retry(item.id);

			expect(queueManager.get(item.id)?.retryCount).toBe(2);
		});
	});

	describe('getAll', () => {
		it('should return all queue items', () => {
			queueManager.enqueue('https://instagram.com/p/test1');
			queueManager.enqueue('https://instagram.com/p/test2');
			queueManager.enqueue('https://instagram.com/p/test3');

			const items = queueManager.getAll();

			expect(items).toHaveLength(3);
		});

		it('should return empty array when queue is empty', () => {
			const items = queueManager.getAll();
			expect(items).toEqual([]);
		});
	});

	describe('get', () => {
		it('should return item by ID', () => {
			const item = queueManager.enqueue('https://instagram.com/p/test');

			const retrieved = queueManager.get(item.id);

			expect(retrieved?.id).toBe(item.id);
			expect(retrieved?.url).toBe(item.url);
		});

		it('should return undefined for non-existent ID', () => {
			const item = queueManager.get('non-existent-id');
			expect(item).toBeUndefined();
		});
	});

	describe('subscribe', () => {
		it('should notify subscribers of updates', () => {
			const callback = vi.fn();
			queueManager.subscribe(callback);

			queueManager.enqueue('https://instagram.com/p/test');

			expect(callback).toHaveBeenCalled();
		});

		it('should return unsubscribe function', () => {
			const callback = vi.fn();
			const unsubscribe = queueManager.subscribe(callback);

			queueManager.enqueue('https://instagram.com/p/test1');
			expect(callback).toHaveBeenCalledTimes(1);

			unsubscribe();
			callback.mockClear();

			queueManager.enqueue('https://instagram.com/p/test2');
			expect(callback).not.toHaveBeenCalled();
		});

		it('should handle subscriber errors gracefully', () => {
			const goodCallback = vi.fn();
			const badCallback = vi.fn(() => {
				throw new Error('Subscriber error');
			});

			queueManager.subscribe(goodCallback);
			queueManager.subscribe(badCallback);

			// Should not throw despite bad callback
			expect(() => {
				queueManager.enqueue('https://instagram.com/p/test');
			}).not.toThrow();

			// Good callback should still be called
			expect(goodCallback).toHaveBeenCalled();
		});

		it('should support multiple subscribers', () => {
			const callback1 = vi.fn();
			const callback2 = vi.fn();
			const callback3 = vi.fn();

			queueManager.subscribe(callback1);
			queueManager.subscribe(callback2);
			queueManager.subscribe(callback3);

			queueManager.enqueue('https://instagram.com/p/test');

			expect(callback1).toHaveBeenCalled();
			expect(callback2).toHaveBeenCalled();
			expect(callback3).toHaveBeenCalled();
		});
	});

	describe('deduplication', () => {
		it('should return existing item when enqueueing duplicate URL', () => {
			const url = 'https://instagram.com/p/ABC123';
			const firstItem = queueManager.enqueue(url);
			const secondItem = queueManager.enqueue(url);

			expect(secondItem.id).toBe(firstItem.id);
			expect(queueManager.getAll()).toHaveLength(1);
		});

		it('should find item by URL', () => {
			const url = 'https://instagram.com/p/TEST123';
			const item = queueManager.enqueue(url);

			const found = queueManager.findByUrl(url);
			expect(found?.id).toBe(item.id);
		});

		it('should return undefined when URL not found', () => {
			const found = queueManager.findByUrl('https://instagram.com/p/NOTFOUND');
			expect(found).toBeUndefined();
		});
	});
});