import { BASE_URL } from "../../constant/base";

/// 请求流式数据的API
const API = '/agent/assistant/chat';

/**
 * 获取AI聊天流式信息（仅微信小程序支持）
 * @param {Object} params 请求参数
 * @param {Function} onChunk 回调，每收到一段数据触发
 * @returns {Promise}
 */
function agentChatStream(params, onChunk) {
    return new Promise((resolve, reject) => {
        const token = uni.getStorageSync('token');
        let hasError = false;

        console.log("发送请求内容: ", params)
        // #ifdef MP-WEIXIN
        const requestTask = uni.request({
            url: BASE_URL + API, // 替换为你的接口地址
            method: 'POST',
            data: params,
            enableChunked: true,
            header: {
                Accept: 'text/event-stream',
                'Content-Type': 'application/json',
                Authorization: `Bearer ${token}`, // 如需token可加
            },
            responseType: 'arraybuffer',
            success(res) {
                resolve(res.data);
            },
            fail(err) {
				console.log("====> ", JSON.stringify(err))
                reject(err);
            },
			complete(res) {
				if(res.statusCode !== 200) {
                    console.log("====> ", JSON.stringify(res))

                    if (onChunk) {
                        onChunk({ error: true, message: '服务器错误', detail: res });
                    }
					reject(res);
				}
			}
        });

        requestTask.onHeadersReceived(res => {
            console.log('onHeadersReceived', res);
            const status = res.statusCode || (res.header && res.header.statusCode);
            if (status && status !== 200) {
                hasError = true;
                if (onChunk) {
                    onChunk({ error: true, message: `服务器错误(${status})`, detail: res });
                }
                requestTask.abort && requestTask.abort();
            }
        });

        requestTask.onChunkReceived(res => {
            if (hasError) return;
            const base64 = uni.arrayBufferToBase64(res.data);
            let data = '';
            try {
                data = decodeURIComponent(escape(weAtob(base64)));
            } catch (e) {
                // 某些平台可能不支持 atob，可以直接用 base64
                data = base64;
            }
            const messages = parseSSEChunk(data);
            messages.forEach(msg => {
                if (onChunk) onChunk(msg);
            });
        });
        // #endif
    });
}

// window.atob兼容性处理
const weAtob = (string) => {
  const b64re =
    /^(?:[A-Za-z\d+/]{4})*?(?:[A-Za-z\d+/]{2}(?:==)?|[A-Za-z\d+/]{3}=?)?$/;
  const b64 =
    'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=';

  // 去除空白字符
  string = String(string).replace(/[\t\n\f\r ]+/g, '');

  // 验证 Base64 编码
  if (!b64re.test(string)) {
    throw new TypeError(
      // eslint-disable-next-line quotes
      "Failed to execute 'atob' on 'Window': The string to be decoded is not correctly encoded."
    );
  }

  // 填充字符
  string += '=='.slice(2 - (string.length & 3));

  let bitmap,
    result = '',
    r1,
    r2,
    i = 0;

  for (; i < string.length;) {
    bitmap =
      (b64.indexOf(string.charAt(i++)) << 18) |
      (b64.indexOf(string.charAt(i++)) << 12) |
      ((r1 = b64.indexOf(string.charAt(i++))) << 6) |
      (r2 = b64.indexOf(string.charAt(i++)));

    if (r1 === 64) {
      result += String.fromCharCode((bitmap >> 16) & 255);
    } else if (r2 === 64) {
      result += String.fromCharCode(
        (bitmap >> 16) & 255,
        (bitmap >> 8) & 255
      );
    } else {
      result += String.fromCharCode(
        (bitmap >> 16) & 255,
        (bitmap >> 8) & 255,
        bitmap & 255
      );
    }
  }
  return result;
};


// 解析SSE分段数据
function parseSSEChunk(raw) {
    // 拆分为多段
    const lines = raw.split('\n\n');
    const results = [];
    lines.forEach(line => {
        // 只处理包含 data: 的行
        const dataMatch = line.match(/data:(\{.*\})/);
        if (dataMatch && dataMatch[1]) {
            try {
                const obj = JSON.parse(dataMatch[1]);
                results.push(obj);
            } catch (e) {
                // 解析失败忽略
            }
        }
    });
    return results;
}

export { agentChatStream }