import { type LLMModelItemType } from '@fastgpt/global/core/ai/model.d';
import type { CompletionFinishReason, CompletionUsage } from '@fastgpt/global/core/ai/type';
import { getLLMDefaultUsage } from '@fastgpt/global/core/ai/constants';
import { removeDatasetCiteText } from '@fastgpt/global/core/ai/llm/utils';

/* 
  Count response max token
*/
export const computedMaxToken = ({
  maxToken,
  model,
  min
}: {
  maxToken?: number;
  model: LLMModelItemType;
  min?: number;
}) => {
  if (maxToken === undefined) return;

  maxToken = Math.min(maxToken, model.maxResponse);
  return Math.max(maxToken, min || 0);
};

// FastGPT temperature range: [0,10], ai temperature:[0,2],{0,1]……
export const computedTemperature = ({
  model,
  temperature
}: {
  model: LLMModelItemType;
  temperature: number;
}) => {
  if (typeof model.maxTemperature !== 'number') return undefined;
  temperature = +(model.maxTemperature * (temperature / 10)).toFixed(2);
  temperature = Math.max(temperature, 0.01);

  return temperature;
};

// LLM utils
// Parse <think></think> tags to think and answer - unstream response
export const parseReasoningContent = (text: string): [string, string] => {
  const regex = /<think>([\s\S]*?)<\/think>/;
  const match = text.match(regex);

  if (!match) {
    return ['', text];
  }

  const thinkContent = match[1].trim();

  // Add answer (remaining text after think tag)
  const answerContent = text.slice(match.index! + match[0].length);

  return [thinkContent, answerContent];
};

// Parse llm stream part
export const parseLLMStreamResponse = () => {
  let isInThinkTag: boolean | undefined = undefined;
  let startTagBuffer = '';
  let endTagBuffer = '';

  const thinkStartChars = '<think>';
  const thinkEndChars = '</think>';

  let citeBuffer = '';
  const maxCiteBufferLength = 32; // [Object](CITE)总长度为32

  // Buffer
  let buffer_finishReason: CompletionFinishReason = null;
  let buffer_usage: CompletionUsage = getLLMDefaultUsage();
  let buffer_reasoningContent = '';
  let buffer_content = '';

  /* 
    parseThinkTag - 只控制是否主动解析 <think></think>，如果接口已经解析了，则不再解析。
    retainDatasetCite - 
  */
  const parsePart = ({
    part,
    parseThinkTag = true,
    retainDatasetCite = true
  }: {
    part: {
      choices: {
        delta: {
          content?: string | null;
          reasoning_content?: string;
        };
        finish_reason?: CompletionFinishReason;
      }[];
      usage?: CompletionUsage;
    };
    parseThinkTag?: boolean;
    retainDatasetCite?: boolean;
  }): {
    reasoningContent: string;
    content: string; // 原始内容，不去掉 cite
    responseContent: string; // 响应的内容，会去掉 cite
    finishReason: CompletionFinishReason;
  } => {
    const data = (() => {
      buffer_usage = part.usage || buffer_usage;

      const finishReason = part.choices?.[0]?.finish_reason || null;
      buffer_finishReason = finishReason || buffer_finishReason;

      const content = part.choices?.[0]?.delta?.content || '';
      // @ts-ignore
      const reasoningContent = part.choices?.[0]?.delta?.reasoning_content || '';
      const isStreamEnd = !!buffer_finishReason;

      // Parse think
      const { reasoningContent: parsedThinkReasoningContent, content: parsedThinkContent } =
        (() => {
          if (reasoningContent || !parseThinkTag) {
            isInThinkTag = false;
            return { reasoningContent, content };
          }

          // 如果不在 think 标签中，或者有 reasoningContent(接口已解析），则返回 reasoningContent 和 content
          if (isInThinkTag === false) {
            return {
              reasoningContent: '',
              content
            };
          }

          // 检测是否为 think 标签开头的数据
          if (isInThinkTag === undefined) {
            // Parse content think and answer
            startTagBuffer += content;
            // 太少内容时候，暂时不解析
            if (startTagBuffer.length < thinkStartChars.length) {
              if (isStreamEnd) {
                const tmpContent = startTagBuffer;
                startTagBuffer = '';
                return {
                  reasoningContent: '',
                  content: tmpContent
                };
              }
              return {
                reasoningContent: '',
                content: ''
              };
            }

            if (startTagBuffer.startsWith(thinkStartChars)) {
              isInThinkTag = true;
              return {
                reasoningContent: startTagBuffer.slice(thinkStartChars.length),
                content: ''
              };
            }

            // 如果未命中 think 标签，则认为不在 think 标签中，返回 buffer 内容作为 content
            isInThinkTag = false;
            return {
              reasoningContent: '',
              content: startTagBuffer
            };
          }

          // 确认是 think 标签内容，开始返回 think 内容，并实时检测 </think>
          /* 
        检测 </think> 方案。
        存储所有疑似 </think> 的内容，直到检测到完整的 </think> 标签或超出 </think> 长度。
        content 返回值包含以下几种情况:
          abc - 完全未命中尾标签
          abc<th - 命中一部分尾标签
          abc</think> - 完全命中尾标签
          abc</think>abc - 完全命中尾标签
          </think>abc - 完全命中尾标签
          k>abc - 命中一部分尾标签
      */
          // endTagBuffer 专门用来记录疑似尾标签的内容
          if (endTagBuffer) {
            endTagBuffer += content;
            if (endTagBuffer.includes(thinkEndChars)) {
              isInThinkTag = false;
              const answer = endTagBuffer.slice(thinkEndChars.length);
              return {
                reasoningContent: '',
                content: answer
              };
            } else if (endTagBuffer.length >= thinkEndChars.length) {
              // 缓存内容超出尾标签长度，且仍未命中 </think>，则认为本次猜测 </think> 失败，仍处于 think 阶段。
              const tmp = endTagBuffer;
              endTagBuffer = '';
              return {
                reasoningContent: tmp,
                content: ''
              };
            }
            return {
              reasoningContent: '',
              content: ''
            };
          } else if (content.includes(thinkEndChars)) {
            // 返回内容，完整命中</think>，直接结束
            isInThinkTag = false;
            const [think, answer] = content.split(thinkEndChars);
            return {
              reasoningContent: think,
              content: answer
            };
          } else {
            // 无 buffer，且未命中 </think>，开始疑似 </think> 检测。
            for (let i = 1; i < thinkEndChars.length; i++) {
              const partialEndTag = thinkEndChars.slice(0, i);
              // 命中一部分尾标签
              if (content.endsWith(partialEndTag)) {
                const think = content.slice(0, -partialEndTag.length);
                endTagBuffer += partialEndTag;
                return {
                  reasoningContent: think,
                  content: ''
                };
              }
            }
          }

          // 完全未命中尾标签，还是 think 阶段。
          return {
            reasoningContent: content,
            content: ''
          };
        })();

      // Parse datset cite
      if (retainDatasetCite) {
        return {
          reasoningContent: parsedThinkReasoningContent,
          content: parsedThinkContent,
          responseContent: parsedThinkContent,
          finishReason: buffer_finishReason
        };
      }

      // 缓存包含 [ 的字符串，直到超出 maxCiteBufferLength 再一次性返回
      const parseCite = (text: string) => {
        // 结束时，返回所有剩余内容
        if (isStreamEnd) {
          const content = citeBuffer + text;
          citeBuffer = ''; // 清空缓冲区，避免重复输出
          return {
            content: removeDatasetCiteText(content, false)
          };
        }

        // 新内容包含 [，初始化缓冲数据
        if (text.includes('[') || text.includes('【')) {
          const index = text.indexOf('[') !== -1 ? text.indexOf('[') : text.indexOf('【');
          const beforeContent = citeBuffer + text.slice(0, index);
          citeBuffer = text.slice(index);

          // beforeContent 可能是：普通字符串，带 [ 的字符串
          return {
            content: removeDatasetCiteText(beforeContent, false)
          };
        }
        // 处于 Cite 缓冲区，判断是否满足条件
        else if (citeBuffer) {
          citeBuffer += text;

          // 检查缓冲区长度是否达到完整Quote长度或已经流结束
          if (citeBuffer.length >= maxCiteBufferLength) {
            const content = removeDatasetCiteText(citeBuffer, false);
            citeBuffer = '';

            return {
              content
            };
          } else {
            // 暂时不返回内容
            return { content: '' };
          }
        }

        return {
          content: text
        };
      };
      const { content: pasedCiteContent } = parseCite(parsedThinkContent);

      return {
        reasoningContent: parsedThinkReasoningContent,
        content: parsedThinkContent,
        responseContent: pasedCiteContent,
        finishReason: buffer_finishReason
      };
    })();

    buffer_reasoningContent += data.reasoningContent;
    buffer_content += data.content;

    return data;
  };

  const getResponseData = () => {
    return {
      finish_reason: buffer_finishReason,
      usage: buffer_usage,
      reasoningContent: buffer_reasoningContent,
      content: buffer_content
    };
  };

  const updateFinishReason = (finishReason: CompletionFinishReason) => {
    buffer_finishReason = finishReason;
  };

  return {
    parsePart,
    getResponseData,
    updateFinishReason
  };
};