import axios from 'axios';
import type { AxiosInstance, AxiosRequestConfig, AxiosError } from 'axios';
import { APIException } from '$lib/types';

/**
 * API Client Configuration
 */
const getAPIBaseURL = (): string => {
	const apiUrl = import.meta.env?.VITE_API_BASE_URL || 'https://api.csgow.tf';

	// Check if we're running on the server (SSR) or in production
	// On the server, we must use the actual API URL, not the proxy
	if (import.meta.env.SSR || import.meta.env.PROD) {
		return apiUrl;
	}

	// In development mode on the client, use the Vite proxy to avoid CORS issues
	// The proxy will forward /api requests to VITE_API_BASE_URL
	return '/api';
};

const API_BASE_URL = getAPIBaseURL();
const API_TIMEOUT = Number(import.meta.env?.VITE_API_TIMEOUT) || 10000;

// Log the API configuration
if (import.meta.env.DEV) {
	if (import.meta.env.SSR) {
		console.log('[API Client] SSR mode - using direct API URL:', API_BASE_URL);
	} else {
		console.log('[API Client] Browser mode - using Vite proxy');
		console.log('[API Client] Frontend requests: /api/*');
		console.log(
			'[API Client] Proxy target:',
			import.meta.env?.VITE_API_BASE_URL || 'https://api.csgow.tf'
		);
	}
}

/**
 * Base API Client
 * Provides centralized HTTP communication with error handling
 */
class APIClient {
	private client: AxiosInstance;
	private abortControllers: Map<string, AbortController>;

	constructor() {
		this.client = axios.create({
			baseURL: API_BASE_URL,
			timeout: API_TIMEOUT,
			headers: {
				'Content-Type': 'application/json',
				Accept: 'application/json'
			}
		});

		this.abortControllers = new Map();

		// Request interceptor
		this.client.interceptors.request.use(
			(config) => {
				// Add request ID for tracking
				const requestId = `${config.method}_${config.url}_${Date.now()}`;
				config.headers['X-Request-ID'] = requestId;
				return config;
			},
			(error) => Promise.reject(error)
		);

		// Response interceptor for error handling
		this.client.interceptors.response.use(
			(response) => response,
			(error: AxiosError) => {
				const apiError = this.handleError(error);
				return Promise.reject(apiError);
			}
		);
	}

	/**
	 * Handle API errors and convert to APIException
	 */
	private handleError(error: AxiosError): APIException {
		// Network error (no response from server)
		if (!error.response) {
			if (error.code === 'ECONNABORTED' || error.message.includes('timeout')) {
				return APIException.timeout('Request timed out. Please try again.');
			}
			return APIException.networkError(
				'Unable to connect to the server. Please check your internet connection.'
			);
		}

		// Server responded with error status
		const { status, data } = error.response;
		return APIException.fromResponse(status, data);
	}

	/**
	 * GET request
	 */
	async get<T>(url: string, config?: AxiosRequestConfig): Promise<T> {
		const response = await this.client.get<T>(url, config);
		return response.data;
	}

	/**
	 * POST request
	 */
	async post<T>(url: string, data?: unknown, config?: AxiosRequestConfig): Promise<T> {
		const response = await this.client.post<T>(url, data, config);
		return response.data;
	}

	/**
	 * PUT request
	 */
	async put<T>(url: string, data?: unknown, config?: AxiosRequestConfig): Promise<T> {
		const response = await this.client.put<T>(url, data, config);
		return response.data;
	}

	/**
	 * DELETE request
	 */
	async delete<T>(url: string, config?: AxiosRequestConfig): Promise<T> {
		const response = await this.client.delete<T>(url, config);
		return response.data;
	}

	/**
	 * Cancelable GET request
	 * Automatically cancels previous request with same key
	 */
	async getCancelable<T>(url: string, key: string, config?: AxiosRequestConfig): Promise<T> {
		// Cancel previous request with same key
		if (this.abortControllers.has(key)) {
			this.abortControllers.get(key)?.abort();
		}

		// Create new abort controller
		const controller = new AbortController();
		this.abortControllers.set(key, controller);

		try {
			const response = await this.client.get<T>(url, {
				...config,
				signal: controller.signal
			});
			this.abortControllers.delete(key);
			return response.data;
		} catch (error) {
			this.abortControllers.delete(key);
			throw error;
		}
	}

	/**
	 * Cancel a specific request by key
	 */
	cancelRequest(key: string): void {
		const controller = this.abortControllers.get(key);
		if (controller) {
			controller.abort();
			this.abortControllers.delete(key);
		}
	}

	/**
	 * Cancel all pending requests
	 */
	cancelAllRequests(): void {
		this.abortControllers.forEach((controller) => controller.abort());
		this.abortControllers.clear();
	}

	/**
	 * Get base URL for constructing full URLs
	 */
	getBaseURL(): string {
		return API_BASE_URL;
	}
}

/**
 * Singleton API client instance
 */
export const apiClient = new APIClient();

/**
 * Export for testing/mocking
 */
export { APIClient };