sbd2-frontend/src/lib/api/client.ts

import { API_CONFIG } from './config'
import { createApiError, NetworkError, TimeoutError } from './errors'
import type { ApiClient, ApiRequestConfig, HttpMethod } from './types'
import { authEvents, AUTH_EVENTS } from '../events'

export class BaseApiClient implements ApiClient {
  private refreshPromise: Promise<void> | null = null
  private baseURL: string

  constructor(baseURL: string = API_CONFIG.BASE_URL) {
    this.baseURL = baseURL
  }

  private buildURL(endpoint: string, params?: Record<string, string | number | boolean | undefined>): string {
    let url: URL
    
    if (this.baseURL) {
      // Full base URL provided
      url = new URL(endpoint, this.baseURL)
    } else {
      // Use relative URL (for reverse proxy)
      url = new URL(endpoint, window.location.origin)
    }
    
    if (params) {
      Object.entries(params).forEach(([key, value]) => {
        if (value !== undefined) {
          url.searchParams.append(key, String(value))
        }
      })
    }
    
    return this.baseURL ? url.toString() : url.pathname + url.search
  }

  private async request<T>(
    method: HttpMethod,
    endpoint: string,
    data?: unknown,
    config: ApiRequestConfig = {}
  ): Promise<T> {
    const {
      params,
      skipAuth = false,
      timeout = API_CONFIG.TIMEOUT,
      headers: customHeaders,
      ...fetchConfig
    } = config

    const url = this.buildURL(endpoint, params)
    const headers: Record<string, string> = {
      'Content-Type': 'application/json',
      ...(customHeaders as Record<string, string>),
    }

    const requestConfig: RequestInit = {
      method,
      headers,
      credentials: skipAuth ? 'omit' : 'include',
      ...fetchConfig,
    }

    if (data && ['POST', 'PUT', 'PATCH'].includes(method)) {
      if (data instanceof FormData) {
        // Remove Content-Type header for FormData to let browser set it with boundary
        delete headers['Content-Type']
        requestConfig.body = data
      } else {
        requestConfig.body = JSON.stringify(data)
      }
    }

    const controller = new AbortController()
    const timeoutId = setTimeout(() => controller.abort(), timeout)
    requestConfig.signal = controller.signal

    try {
      const response = await fetch(url, requestConfig)
      clearTimeout(timeoutId)

      if (!response.ok) {
        if (response.status === 401 && !skipAuth) {
          try {
            await this.handleTokenRefresh()
            // Retry the original request
            const retryResponse = await fetch(url, requestConfig)
            
            if (!retryResponse.ok) {
              const errorData = await this.safeParseJSON(retryResponse)
              throw createApiError(retryResponse, errorData)
            }
            
            return await this.safeParseJSON(retryResponse) as T
          } catch (refreshError) {
            this.handleAuthenticationFailure()
            throw refreshError
          }
        }
        
        const errorData = await this.safeParseJSON(response)
        throw createApiError(response, errorData)
      }

      // Handle empty responses (204 No Content, etc.)
      if (response.status === 204 || response.headers.get('content-length') === '0') {
        return {} as T
      }

      return await this.safeParseJSON(response) as T
    } catch (error) {
      clearTimeout(timeoutId)
      
      if ((error as Error).name === 'AbortError') {
        throw new TimeoutError()
      }
      
      if (error instanceof TypeError && error.message.includes('fetch')) {
        throw new NetworkError()
      }
      
      throw error
    }
  }

  private async safeParseJSON(response: Response): Promise<unknown> {
    try {
      const text = await response.text()
      return text ? JSON.parse(text) : {}
    } catch {
      return {}
    }
  }

  private async handleTokenRefresh(): Promise<void> {
    if (this.refreshPromise) {
      await this.refreshPromise
      return
    }

    this.refreshPromise = this.performTokenRefresh()
    
    try {
      await this.refreshPromise
    } finally {
      this.refreshPromise = null
    }
  }

  private async performTokenRefresh(): Promise<void> {
    const response = await fetch(`${this.baseURL}${API_CONFIG.ENDPOINTS.AUTH.REFRESH}`, {
      method: 'POST',
      headers: { 'Content-Type': 'application/json' },
      credentials: 'include',
    })

    if (!response.ok) {
      throw createApiError(response, await this.safeParseJSON(response))
    }

    // Emit token refresh event for socket reconnection (reactive refresh)
    authEvents.emit(AUTH_EVENTS.TOKEN_REFRESHED)
  }

  private handleAuthenticationFailure(): void {
    // Only redirect if we're not already on auth pages to prevent infinite loops
    const currentPath = window.location.pathname
    const authPaths = ['/login', '/register', '/auth/callback']
    
    if (!authPaths.includes(currentPath)) {
      window.location.href = '/login'
    }
  }

  // Public API methods
  async get<T>(endpoint: string, config?: ApiRequestConfig): Promise<T> {
    return this.request<T>('GET', endpoint, undefined, config)
  }

  async post<T>(endpoint: string, data?: unknown, config?: ApiRequestConfig): Promise<T> {
    return this.request<T>('POST', endpoint, data, config)
  }

  async put<T>(endpoint: string, data?: unknown, config?: ApiRequestConfig): Promise<T> {
    return this.request<T>('PUT', endpoint, data, config)
  }

  async patch<T>(endpoint: string, data?: unknown, config?: ApiRequestConfig): Promise<T> {
    return this.request<T>('PATCH', endpoint, data, config)
  }

  async delete<T>(endpoint: string, config?: ApiRequestConfig): Promise<T> {
    return this.request<T>('DELETE', endpoint, undefined, config)
  }

  // Utility methods
  setBaseURL(baseURL: string): void {
    this.baseURL = baseURL
  }

  getBaseURL(): string {
    return this.baseURL
  }
}

// Default API client instance
export const apiClient = new BaseApiClient()