import { supabase } from '../lib/supabase'

const API_BASE = import.meta.env['VITE_API_URL'] ?? ''

// Refresh token if it expires within this many seconds
const TOKEN_EXPIRY_BUFFER_SECONDS = 60

export class ApiError extends Error {
  status: number

  constructor(status: number, message: string) {
    super(message)
    this.name = 'ApiError'
    this.status = status
  }
}

function isTokenExpiringSoon(expiresAt: number): boolean {
  const nowSeconds = Math.floor(Date.now() / 1000)
  return expiresAt - nowSeconds < TOKEN_EXPIRY_BUFFER_SECONDS
}

async function getValidAccessToken(): Promise<string | null> {
  const { data } = await supabase.auth.getSession()
  const session = data.session

  if (!session) {
    return null
  }

  // If token is expired or expiring soon, refresh it
  if (isTokenExpiringSoon(session.expires_at ?? 0)) {
    const { data: refreshed, error } = await supabase.auth.refreshSession()
    if (error || !refreshed.session) {
      return null
    }
    return refreshed.session.access_token
  }

  return session.access_token
}

async function getAuthHeaders(): Promise<Record<string, string>> {
  const token = await getValidAccessToken()
  if (token) {
    return { Authorization: `Bearer ${token}` }
  }
  return {}
}

async function request<T>(path: string, options?: RequestInit, isRetry = false): Promise<T> {
  const authHeaders = await getAuthHeaders()
  const res = await fetch(`${API_BASE}/api/v1${path}`, {
    ...options,
    headers: {
      'Content-Type': 'application/json',
      ...authHeaders,
      ...options?.headers,
    },
  })

  // On 401, try refreshing the token and retry once
  if (res.status === 401 && !isRetry) {
    const { data: refreshed, error } = await supabase.auth.refreshSession()
    if (!error && refreshed.session) {
      return request<T>(path, options, true)
    }
  }

  if (!res.ok) {
    const body = await res.json().catch(() => ({}))
    throw new ApiError(res.status, body.detail ?? res.statusText)
  }

  if (res.status === 204) return undefined as T
  return res.json()
}

export const api = {
  get: <T>(path: string) => request<T>(path),

  post: <T>(path: string, body: unknown) =>
    request<T>(path, {
      method: 'POST',
      body: JSON.stringify(body),
    }),

  patch: <T>(path: string, body: unknown) =>
    request<T>(path, {
      method: 'PATCH',
      body: JSON.stringify(body),
    }),

  put: <T>(path: string, body: unknown) =>
    request<T>(path, {
      method: 'PUT',
      body: JSON.stringify(body),
    }),

  del: <T = void>(path: string) => request<T>(path, { method: 'DELETE' }),
}