// API Client for CLQMS
// Wrapper around fetch for making API calls to the backend

import { browser } from '$app/environment';
import { PUBLIC_API_BASE_URL, PUBLIC_API_BASE_URL_PROD } from '$env/static/public';

const API_BASE_URL = browser 
  ? (import.meta.env.DEV ? PUBLIC_API_BASE_URL : PUBLIC_API_BASE_URL_PROD)
  : PUBLIC_API_BASE_URL;

interface ApiError {
  message: string;
  status: number;
  code?: string;
}

interface ApiResponse<T> {
  data: T | null;
  error: ApiError | null;
  success: boolean;
}

class ApiClient {
  private baseUrl: string;
  private defaultHeaders: Record<string, string>;

  constructor(baseUrl: string = API_BASE_URL) {
    this.baseUrl = baseUrl.replace(/\/$/, '');
    this.defaultHeaders = {
      'Content-Type': 'application/json',
      'Accept': 'application/json'
    };
  }

  private async request<T>(
    endpoint: string,
    options: RequestInit = {}
  ): Promise<ApiResponse<T>> {
    const url = `${this.baseUrl}/${endpoint.replace(/^\//, '')}`;
    
    const config: RequestInit = {
      ...options,
      headers: {
        ...this.defaultHeaders,
        ...options.headers
      },
      credentials: 'include'
    };

    try {
      const response = await fetch(url, config);
      
      if (!response.ok) {
        const errorData = await response.json().catch(() => ({}));
        return {
          data: null,
          error: {
            message: errorData.message || `HTTP Error: ${response.status}`,
            status: response.status,
            code: errorData.code
          },
          success: false
        };
      }

      const contentType = response.headers.get('content-type');
      let data: T;
      
      if (contentType?.includes('application/json')) {
        data = await response.json();
      } else {
        data = await response.text() as unknown as T;
      }

      return {
        data,
        error: null,
        success: true
      };

    } catch (error) {
      return {
        data: null,
        error: {
          message: error instanceof Error ? error.message : 'Network error',
          status: 0
        },
        success: false
      };
    }
  }

  async get<T>(endpoint: string, headers?: Record<string, string>): Promise<ApiResponse<T>> {
    return this.request<T>(endpoint, { method: 'GET', headers });
  }

  async post<T>(
    endpoint: string,
    body: unknown,
    headers?: Record<string, string>
  ): Promise<ApiResponse<T>> {
    return this.request<T>(endpoint, {
      method: 'POST',
      body: JSON.stringify(body),
      headers
    });
  }

  async patch<T>(
    endpoint: string,
    body: unknown,
    headers?: Record<string, string>
  ): Promise<ApiResponse<T>> {
    return this.request<T>(endpoint, {
      method: 'PATCH',
      body: JSON.stringify(body),
      headers
    });
  }

  async put<T>(
    endpoint: string,
    body: unknown,
    headers?: Record<string, string>
  ): Promise<ApiResponse<T>> {
    return this.request<T>(endpoint, {
      method: 'PUT',
      body: JSON.stringify(body),
      headers
    });
  }

  async delete<T>(endpoint: string, headers?: Record<string, string>): Promise<ApiResponse<T>> {
    return this.request<T>(endpoint, { method: 'DELETE', headers });
  }
}

export const api = new ApiClient();
export type { ApiResponse, ApiError };