import type {
  ConfirmCreativePuzzleTemplateRequest,
  CreateCreativeAgentSessionRequest,
  CreativeAgentSessionResponse,
  CreativeAgentSessionSnapshot,
  CreativeAgentSseEvent,
  CreativeDraftEditStreamRequest,
  StreamCreativeAgentMessageRequest,
} from '../../../packages/shared/src/contracts/creativeAgent';
import { parseApiErrorMessage } from '../../../packages/shared/src/http';
import type { TextStreamOptions } from '../aiTypes';
import { fetchWithApiAuth, requestJson } from '../apiClient';
import {
  readCreativeAgentResultFromSse,
  readCreativeAgentSessionFromSse,
} from './creativeAgentSse';

const CREATIVE_AGENT_API_BASE = '/api/runtime/creative-agent/sessions';

export type CreativeAgentStreamOptions = TextStreamOptions & {
  onEvent?: (event: CreativeAgentSseEvent) => void;
};

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

async function openCreativeAgentSsePost(
  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;
}

export async function createCreativeAgentSession(
  payload: CreateCreativeAgentSessionRequest = {},
) {
  return requestJson<CreativeAgentSessionResponse>(
    CREATIVE_AGENT_API_BASE,
    buildJsonPostInit(payload),
    '创建智能创作会话失败',
    {
      retry: {
        maxRetries: 1,
        baseDelayMs: 240,
        maxDelayMs: 640,
        retryUnsafeMethods: true,
      },
      timeoutMs: 15000,
    },
  );
}

export async function getCreativeAgentSession(sessionId: string) {
  return requestJson<CreativeAgentSessionResponse>(
    `${CREATIVE_AGENT_API_BASE}/${encodeURIComponent(sessionId)}`,
    { method: 'GET' },
    '读取智能创作会话失败',
  );
}

export async function streamCreativeAgentMessage(
  sessionId: string,
  payload: StreamCreativeAgentMessageRequest,
  options: CreativeAgentStreamOptions = {},
) {
  const response = await openCreativeAgentSsePost(
    `${CREATIVE_AGENT_API_BASE}/${encodeURIComponent(sessionId)}/messages/stream`,
    payload,
    '发送智能创作消息失败',
    options.signal,
  );

  return readCreativeAgentSessionFromSse(response, {
    ...options,
    fallbackMessage: '发送智能创作消息失败',
    incompleteMessage: '智能创作消息流式结果不完整',
  });
}

export async function confirmCreativePuzzleTemplate(
  sessionId: string,
  payload: ConfirmCreativePuzzleTemplateRequest,
) {
  return requestJson<CreativeAgentSessionResponse>(
    `${CREATIVE_AGENT_API_BASE}/${encodeURIComponent(sessionId)}/confirm-template`,
    buildJsonPostInit(payload),
    '确认拼图模板失败',
    {
      retry: {
        maxRetries: 1,
        baseDelayMs: 240,
        maxDelayMs: 640,
        retryUnsafeMethods: true,
      },
    },
  );
}

export async function streamCreativeDraftEdit(
  sessionId: string,
  payload: CreativeDraftEditStreamRequest,
  options: CreativeAgentStreamOptions = {},
) {
  const response = await openCreativeAgentSsePost(
    `${CREATIVE_AGENT_API_BASE}/${encodeURIComponent(sessionId)}/draft-edits/stream`,
    payload,
    '修改拼图草稿失败',
    options.signal,
  );

  return requestCreativeDraftEditResultFromSse(response, options);
}

export async function cancelCreativeAgentSession(sessionId: string) {
  return requestJson<CreativeAgentSessionResponse>(
    `${CREATIVE_AGENT_API_BASE}/${encodeURIComponent(sessionId)}/cancel`,
    buildJsonPostInit({}),
    '取消智能创作会话失败',
  );
}

async function requestCreativeDraftEditResultFromSse(
  response: Response,
  options: CreativeAgentStreamOptions,
) {
  const result = await readCreativeAgentResultFromSse(response, {
    ...options,
    fallbackMessage: '修改拼图草稿失败',
    incompleteMessage: '智能创作修改结果不完整',
  });

  if (result.draftEditResult) {
    return result.draftEditResult;
  }

  // 中文注释：后端如果暂时只返回 session，调用方仍能用 session 做保底收尾。
  return result.session as CreativeAgentSessionSnapshot;
}

export const creativeAgentClient = {
  createSession: createCreativeAgentSession,
  getSession: getCreativeAgentSession,
  streamMessage: streamCreativeAgentMessage,
  confirmTemplate: confirmCreativePuzzleTemplate,
  streamDraftEdit: streamCreativeDraftEdit,
  cancelSession: cancelCreativeAgentSession,
};