/**
 * 移动端聊天服务层
 * 基于 @icos-react/largemodel 的 apiService + messageService 适配
 * 纯浏览器 API，无第三方依赖
 */

import type { ApiConfig, ChatMessage, EventAction, ParaSource, SuggestedQuestion } from '../types';

// ─── Token ───────────────────────────────────────────────────────────────────

/** 解析 Taro / mobile-app 写入的 access_token 信封（含 H5 的 data 包装层） */
function parseTokenEnvelope(raw: string): Record<string, unknown> | null {
  try {
    const parsed: unknown = JSON.parse(raw);
    if (typeof parsed !== 'object' || parsed === null) return null;
    const envelope = parsed as Record<string, unknown>;
    // Taro H5 localStorage：{ "data": "{\"c\":...,\"v\":\"Bearer ...\"}" }
    if (typeof envelope.data === 'string') {
      try {
        const inner: unknown = JSON.parse(envelope.data);
        if (typeof inner === 'object' && inner !== null) {
          return inner as Record<string, unknown>;
        }
      } catch {
        return null;
      }
    }
    return envelope;
  } catch {
    return null;
  }
}

/** 从信封字段 v 取出 Authorization 值（与 mobile-app request.ts 一致） */
function extractTokenFromEnvelopeValue(v: unknown): string | null {
  if (typeof v !== 'string') return null;
  const trimmed = v.trim();
  if (!trimmed) return null;
  // 兼容 v 被二次 JSON 编码："{\"v\":\"\\\"Bearer xxx\\\"\"}"
  if (trimmed.startsWith('"')) {
    try {
      const decoded = JSON.parse(trimmed);
      if (typeof decoded === 'string' && decoded.trim()) {
        return decoded.trim();
      }
    } catch {
      // 非 JSON 字符串，按原值使用
    }
  }
  return trimmed;
}

export function getAuthToken(): string | null {
  try {
    const raw =
      localStorage.getItem('access_token') ||
      localStorage.getItem('token') ||
      sessionStorage.getItem('access_token') ||
      sessionStorage.getItem('token');
    if (!raw) return null;

    const trimmed = raw.trim();
    const envelope = parseTokenEnvelope(trimmed);
    if (envelope && envelope.v != null) {
      return extractTokenFromEnvelopeValue(envelope.v);
    }

    // 已是纯 token 字符串（Bearer xxx 或裸 JWT）
    if (trimmed && !trimmed.startsWith('{')) {
      return trimmed;
    }

    return null;
  } catch {
    return null;
  }
}

// ─── 请求 ────────────────────────────────────────────────────────────────────

export async function sendChatRequest(
  config: ApiConfig,
  message: string,
  sessionId?: string,
  signal?: AbortSignal,
): Promise<Response> {
  const token = getAuthToken();
  const headers: Record<string, string> = {
    'Content-Type': 'application/json',
    ...(config.headers ?? {}),
  };
  if (token) {
    headers['Authorization'] = token.startsWith('Bearer ') ? token : `Bearer ${token}`;
  }

  const body = {
    ...(sessionId ? { bizConversationId: sessionId } : {}),
    conversation_id: '',
    data: {
      inputs: {
        user: message,
      },
    },
    ...(config.body ?? {}),
  };

  return fetch(config.url, {
    method: config.method ?? 'POST',
    headers,
    body: JSON.stringify(body),
    signal,
  });
}

export async function fetchSessionId(
  url = '/mobile/api/cityos/ai/v1/conversation/genBizConversationId',
): Promise<string> {
  const token = getAuthToken();
  const headers: Record<string, string> = { 'Content-Type': 'application/json' };
  if (token) headers['Authorization'] = token.startsWith('Bearer ') ? token : `Bearer ${token}`;

  const res = await fetch(url, { method: 'GET', headers });
  if (!res.ok) throw new Error(`获取会话 ID 失败: ${res.status}`);
  const data = await res.json();
  const id = data?.data ?? data?.bizConversationId ?? data?.sessionId;
  if (!id) throw new Error('服务端返回的会话 ID 为空');
  return id as string;
}

// ─── SSE 流处理 ───────────────────────────────────────────────────────────────

export interface StreamCallbacks {
  onChunk: (text: string) => void;
  onDone: (fullText: string) => void;
  onError: (err: Error) => void;
  onSuggestedQuestions?: (questions: SuggestedQuestion[]) => void;
  onAction?: (actions: EventAction[]) => void;
  onPara?: (para: ParaSource[]) => void;
}

/**
 * 解析单行 SSE data 字段，返回增量文本和可选的推荐问题
 */
function parseSseLine(line: string): {
  text?: string;
  done?: boolean;
  suggestedQuestions?: SuggestedQuestion[];
  actions?: EventAction[];
  para?: ParaSource[];
} {
  if (!line.startsWith('data:')) return {};
  const raw = line.slice(5).trim();
  if (raw === '[DONE]') return { done: true };

  try {
    const json = JSON.parse(raw);

    const isEnd = json?.status === 'END';

    const text: string =
      json?.data?.outputs?.content ??
      json?.answer ??
      json?.content ??
      json?.text ??
      json?.choices?.[0]?.delta?.content ??
      '';

    const suggestedQuestions: SuggestedQuestion[] | undefined =
      json?.suggestedQuestions?.map((q: string, i: number) => ({
        id: `sq-${Date.now()}-${i}`,
        text: q,
      }));

    const rawActions: any[] | undefined =
      json?.data?.outputs?.action ?? json?.data?.actions;
    const actions: EventAction[] | undefined = Array.isArray(rawActions)
      ? rawActions.map((a: any, i: number) => ({
          ...a,
          anchorId: a.anchorId ?? `action-${Date.now()}-${i}`,
        }))
      : undefined;

    const rawPara: any[] | undefined = json?.data?.para;
    const para: ParaSource[] | undefined = Array.isArray(rawPara) && rawPara.length > 0
      ? rawPara.filter((p: any) => p?.title)
      : undefined;

    return { text, suggestedQuestions, actions, para, ...(isEnd ? { done: true } : {}) };
  } catch {
    return { text: raw };
  }
}

/**
 * 消费 SSE 流，通过回调逐步更新 UI
 */
export async function consumeStream(
  response: Response,
  callbacks: StreamCallbacks,
): Promise<void> {
  if (!response.body) {
    callbacks.onError(new Error('Response body is null'));
    return;
  }

  const reader = response.body.getReader();
  const decoder = new TextDecoder();
  let buffer = '';
  let fullText = '';

  try {
    while (true) {
      const { done, value } = await reader.read();
      if (done) break;

      buffer += decoder.decode(value, { stream: true });
      const lines = buffer.split('\n');
      buffer = lines.pop() ?? '';

      for (const line of lines) {
        const { text, done: isDone, suggestedQuestions, actions, para } = parseSseLine(line.trim());
        if (text) {
          fullText += text;
          callbacks.onChunk(fullText);
        }
        if (suggestedQuestions?.length && callbacks.onSuggestedQuestions) {
          callbacks.onSuggestedQuestions(suggestedQuestions);
        }
        if (actions?.length) {
          for (const a of actions) {
            if (a.anchorId) {
              fullText += `\n[ANCHOR:${a.anchorId}]`;
            }
          }
          callbacks.onAction?.(actions);
        }
        if (para?.length && callbacks.onPara) {
          callbacks.onPara(para);
        }
        if (isDone) {
          callbacks.onDone(fullText);
          return;
        }
      }
    }
  } catch (err) {
    callbacks.onError(err instanceof Error ? err : new Error(String(err)));
    return;
  } finally {
    reader.releaseLock();
  }

  callbacks.onDone(fullText);
}

// ─── 消息工厂 ─────────────────────────────────────────────────────────────────

export function createUserMessage(content: string): ChatMessage {
  return {
    id: `user-${Date.now()}`,
    role: 'user',
    content,
    timestamp: Date.now(),
    status: 'success',
  };
}

export function createAssistantMessage(partial = ''): ChatMessage {
  return {
    id: `ai-${Date.now()}`,
    role: 'assistant',
    content: partial,
    timestamp: Date.now(),
    status: 'loading',
  };
}