import { parseApiErrorMessage } from '../../../packages/shared/src/http';
import type { TextStreamOptions } from '../aiTypes';
import {
  type ApiRetryOptions,
  fetchWithApiAuth,
  requestJson,
} from '../apiClient';
import { readCreationAgentSessionFromSse } from './creationAgentSse';

type CreationAgentClientMessages = {
  createSession: string;
  getSession: string;
  sendMessage: string;
  streamIncomplete: string;
  executeAction: string;
};

type CreationAgentClientOptions = {
  apiBase: string;
  messages: CreationAgentClientMessages;
  createSessionTimeoutMs?: number;
  executeActionTimeoutMs?: number;
  readRetry?: ApiRetryOptions;
  writeRetry?: ApiRetryOptions;
};

const DEFAULT_CREATION_AGENT_READ_RETRY: ApiRetryOptions = {
  maxRetries: 1,
  baseDelayMs: 180,
  maxDelayMs: 480,
};

const DEFAULT_CREATION_AGENT_WRITE_RETRY: ApiRetryOptions = {
  maxRetries: 1,
  baseDelayMs: 240,
  maxDelayMs: 640,
  retryUnsafeMethods: true,
};

function buildJsonPostInit(payload: unknown): RequestInit {
  return {
    method: 'POST',
    headers: { 'Content-Type': 'application/json' },
    body: JSON.stringify(payload),
  };
}

async function openCreationAgentSsePost(
  url: string,
  payload: unknown,
  fallbackMessage: string,
  signal?: AbortSignal,
) {
  const response = await fetchWithApiAuth(url, {
    ...buildJsonPostInit(payload),
    signal,
  });

  if (!response.ok) {
    const responseText = await response.text();
    throw new Error(parseApiErrorMessage(responseText, fallbackMessage));
  }

  if (!response.body) {
    throw new Error('streaming response body is unavailable');
  }

  return response;
}

/**
 * 三类作品创作 Agent 都遵循同一组 HTTP/SSE 端点形状。
 * 这里统一请求骨架，玩法 client 只保留路径、类型与中文错误文案差异。
 */
export function createCreationAgentClient<
  TCreateSessionPayload,
  TCreateSessionResponse,
  TGetSessionResponse,
  TSession,
  TSendMessagePayload,
  TSendMessageResponse,
  TExecuteActionPayload,
  TExecuteActionResponse,
>({
  apiBase,
  messages,
  createSessionTimeoutMs = 15000,
  executeActionTimeoutMs,
  readRetry = DEFAULT_CREATION_AGENT_READ_RETRY,
  writeRetry = DEFAULT_CREATION_AGENT_WRITE_RETRY,
}: CreationAgentClientOptions) {
  const createSession = (
    payload: TCreateSessionPayload,
  ): Promise<TCreateSessionResponse> =>
    requestJson<TCreateSessionResponse>(
      apiBase,
      buildJsonPostInit(payload),
      messages.createSession,
      {
        retry: writeRetry,
        timeoutMs: createSessionTimeoutMs,
      },
    );

  const getSession = (sessionId: string): Promise<TGetSessionResponse> =>
    requestJson<TGetSessionResponse>(
      `${apiBase}/${encodeURIComponent(sessionId)}`,
      { method: 'GET' },
      messages.getSession,
      {
        retry: readRetry,
      },
    );

  const sendMessage = (
    sessionId: string,
    payload: TSendMessagePayload,
  ): Promise<TSendMessageResponse> =>
    requestJson<TSendMessageResponse>(
      `${apiBase}/${encodeURIComponent(sessionId)}/messages`,
      buildJsonPostInit(payload),
      messages.sendMessage,
      {
        retry: writeRetry,
      },
    );

  const streamMessage = async (
    sessionId: string,
    payload: TSendMessagePayload,
    options: TextStreamOptions = {},
  ): Promise<TSession> => {
    const response = await openCreationAgentSsePost(
      `${apiBase}/${encodeURIComponent(sessionId)}/messages/stream`,
      payload,
      messages.sendMessage,
      options.signal,
    );

    return readCreationAgentSessionFromSse<TSession>(response, {
      ...options,
      fallbackMessage: messages.sendMessage,
      incompleteMessage: messages.streamIncomplete,
    });
  };

  const executeAction = (
    sessionId: string,
    payload: TExecuteActionPayload,
  ): Promise<TExecuteActionResponse> =>
    requestJson<TExecuteActionResponse>(
      `${apiBase}/${encodeURIComponent(sessionId)}/actions`,
      buildJsonPostInit(payload),
      messages.executeAction,
      {
        retry: writeRetry,
        timeoutMs: executeActionTimeoutMs,
      },
    );

  return {
    createSession,
    getSession,
    sendMessage,
    streamMessage,
    executeAction,
  };
}