/* ============================================================
   errors.js — the API error type and FastAPI `detail` unwrapping.

   Lifted verbatim from the original src/api.js. FastAPI returns errors as
   {detail: ...} where `detail` is a string for HTTPException and an array of
   {loc, msg, type} objects for request-validation failures — parseDetail
   already handles both shapes, so it moves unchanged.
   ============================================================ */

export class ApiError extends Error {
  constructor(message, status, body) {
    super(message)
    this.name = 'ApiError'
    this.status = status
    this.body = body
  }
}

/** Raised when the refresh token itself is rejected — the session is over. */
export class SessionExpiredError extends Error {
  constructor(message = 'Your session has expired. Please sign in again.') {
    super(message)
    this.name = 'SessionExpiredError'
  }
}

export function parseDetail(detail) {
  if (detail == null || detail === '') return null
  if (typeof detail === 'string') return detail
  if (Array.isArray(detail)) {
    return detail
      .map((item) => {
        if (typeof item === 'string') return item
        if (item && typeof item === 'object') {
          return item.msg || item.message || JSON.stringify(item)
        }
        return String(item)
      })
      .filter(Boolean)
      .join('; ')
  }
  if (typeof detail === 'object') {
    return detail.msg || detail.message || JSON.stringify(detail)
  }
  return String(detail)
}

export function friendlyAuthError(err, fallback = 'Something went wrong. Please try again.') {
  if (!(err instanceof ApiError)) {
    return err?.message || fallback
  }
  const fromServer = parseDetail(err.body?.detail)
  switch (err.status) {
    case 429:
      return fromServer || 'Too many attempts. Please wait a moment and try again.'
    case 404:
      return fromServer || 'No account found for that email.'
    case 400:
      return fromServer || 'Please check your details and try again.'
    case 401:
      return fromServer || 'Incorrect email or password.'
    case 403:
      return fromServer || 'Your Approval is at Pending'
    case 409:
      return fromServer || 'An account with that email already exists.'
    case 502:
      return fromServer || 'Email service is temporarily unavailable. Please try again later.'
    default:
      return fromServer || err.message || fallback
  }
}