import { AppError } from '@/lib/error-model';
import { hostApiFetch } from '@/lib/host-api';
import {
  IMAGE_PROMPT_MUSEUM_API_PATH,
  type PromptMuseumEntry,
  type PromptMuseumListQuery,
  type PromptMuseumPage,
} from '../../shared/image-prompt-museum';

type PromptMuseumEnvelope<T> = {
  success?: boolean;
  status?: number;
  code?: string;
  error?: string;
  data?: T;
};

type PromptMuseumMedia = {
  dataBase64: string;
  mimeType: string;
};

const PROMPT_MUSEUM_MEDIA_URL_PATTERN = /^\/api\/image-prompt-museum\/[A-Za-z0-9][A-Za-z0-9._:-]{0,127}\/media\/(?:thumbnail|[0-9]+)$/;
const PROMPT_MUSEUM_MEDIA_MIME_TYPES = new Set([
  'image/avif',
  'image/gif',
  'image/jpeg',
  'image/png',
  'image/webp',
]);
const MAX_MEDIA_BASE64_LENGTH = Math.ceil((10 * 1024 * 1024) / 3) * 4;

export class PromptMuseumApiError extends Error {
  readonly status: number;
  readonly code: string;

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

function errorStatus(error: unknown): number {
  if (error instanceof AppError && typeof error.details?.status === 'number') {
    return error.details.status;
  }
  return 502;
}

function errorCode(error: unknown, status: number): string {
  if (error instanceof AppError && typeof error.details?.backendCode === 'string') {
    return error.details.backendCode;
  }
  if (status === 401) return 'PROMPT_MUSEUM_AUTH_REQUIRED';
  if (status === 404) return 'PROMPT_MUSEUM_NOT_FOUND';
  return 'PROMPT_MUSEUM_REQUEST_FAILED';
}

function createQuery(query: PromptMuseumListQuery): string {
  const params = new URLSearchParams();
  const values: Array<[string, string | undefined]> = [
    ['q', query.q],
    ['use_case', query.useCase],
    ['style', query.style],
    ['subject', query.subject],
    ['language', query.language],
    ['model', query.model],
    ['cursor', query.cursor],
    ['limit', query.limit === undefined ? undefined : String(query.limit)],
  ];
  for (const [key, value] of values) {
    if (value?.trim()) params.set(key, value.trim());
  }
  const encoded = params.toString();
  return encoded ? `?${encoded}` : '';
}

async function requestData<T>(path: string): Promise<T> {
  let response: PromptMuseumEnvelope<T>;
  try {
    response = await hostApiFetch<PromptMuseumEnvelope<T>>(path);
  } catch (error) {
    const status = errorStatus(error);
    throw new PromptMuseumApiError(
      status,
      errorCode(error, status),
      error instanceof Error ? error.message : '提示词博物馆请求失败',
    );
  }

  if (!response.success || response.data === undefined) {
    throw new PromptMuseumApiError(
      response.status ?? 502,
      response.code ?? 'PROMPT_MUSEUM_REQUEST_FAILED',
      response.error ?? '提示词博物馆请求失败',
    );
  }
  return response.data;
}

export async function fetchPromptMuseumPage(query: PromptMuseumListQuery = {}): Promise<PromptMuseumPage> {
  return await requestData(`${IMAGE_PROMPT_MUSEUM_API_PATH}${createQuery(query)}`);
}

export async function fetchPromptMuseumEntry(entryId: string): Promise<PromptMuseumEntry> {
  return await requestData(`${IMAGE_PROMPT_MUSEUM_API_PATH}/${encodeURIComponent(entryId)}`);
}

export async function fetchPromptMuseumMedia(mediaUrl: string): Promise<string> {
  if (!PROMPT_MUSEUM_MEDIA_URL_PATTERN.test(mediaUrl)) {
    throw new PromptMuseumApiError(400, 'PROMPT_MUSEUM_INVALID_MEDIA_URL', '提示词图片地址无效');
  }
  const localPath = mediaUrl.replace('/api/image-prompt-museum/', `${IMAGE_PROMPT_MUSEUM_API_PATH}/`);
  const payload = await hostApiFetch<PromptMuseumMedia>(localPath);
  const mimeType = typeof payload?.mimeType === 'string' ? payload.mimeType.trim().toLowerCase() : '';
  const dataBase64 = typeof payload?.dataBase64 === 'string' ? payload.dataBase64 : '';
  if (
    !PROMPT_MUSEUM_MEDIA_MIME_TYPES.has(mimeType)
    || !dataBase64
    || dataBase64.length > MAX_MEDIA_BASE64_LENGTH
    || !/^[A-Za-z0-9+/]*={0,2}$/.test(dataBase64)
    || dataBase64.length % 4 === 1
  ) {
    throw new PromptMuseumApiError(502, 'PROMPT_MUSEUM_INVALID_MEDIA_RESPONSE', '提示词图片返回了无效数据');
  }
  return `data:${mimeType};base64,${dataBase64}`;
}