next-chat/app/client/platforms/google.ts

import { Google, REQUEST_TIMEOUT_MS } from "@/app/constant";
import { ChatOptions, getHeaders, LLMApi, LLMModel, LLMUsage } from "../api";
import { useAccessStore, useAppConfig, useChatStore } from "@/app/store";
import {
  EventStreamContentType,
  fetchEventSource,
} from "@fortaine/fetch-event-source";
import { prettyObject } from "@/app/utils/format";
import { getClientConfig } from "@/app/config/client";
import Locale from "../../locales";
import { getServerSideConfig } from "@/app/config/server";
export class GeminiProApi implements LLMApi {
  extractMessage(res: any) {
    console.log("[Response] gemini-pro response: ", res);

    return (
      res?.candidates?.at(0)?.content?.parts.at(0)?.text ||
      res?.error?.message ||
      ""
    );
  }
  async chat(options: ChatOptions): Promise<void> {
    const apiClient = this;
    const messages = options.messages.map((v) => ({
      role: v.role.replace("assistant", "model").replace("system", "user"),
      parts: [{ text: v.content }],
    }));

    // google requires that role in neighboring messages must not be the same
    for (let i = 0; i < messages.length - 1; ) {
      // Check if current and next item both have the role "model"
      if (messages[i].role === messages[i + 1].role) {
        // Concatenate the 'parts' of the current and next item
        messages[i].parts = messages[i].parts.concat(messages[i + 1].parts);
        // Remove the next item
        messages.splice(i + 1, 1);
      } else {
        // Move to the next item
        i++;
      }
    }

    const modelConfig = {
      ...useAppConfig.getState().modelConfig,
      ...useChatStore.getState().currentSession().mask.modelConfig,
      ...{
        model: options.config.model,
      },
    };
    const requestPayload = {
      contents: messages,
      generationConfig: {
        // stopSequences: [
        //   "Title"
        // ],
        temperature: modelConfig.temperature,
        maxOutputTokens: modelConfig.max_tokens,
        topP: modelConfig.top_p,
        // "topK": modelConfig.top_k,
      },
    };

    console.log("[Request] google payload: ", requestPayload);

    const shouldStream = !!options.config.stream;
    const controller = new AbortController();
    options.onController?.(controller);
    try {
      const chatPath = this.path(Google.ChatPath);
      const chatPayload = {
        method: "POST",
        body: JSON.stringify(requestPayload),
        signal: controller.signal,
        headers: getHeaders(),
      };

      // make a fetch request
      const requestTimeoutId = setTimeout(
        () => controller.abort(),
        REQUEST_TIMEOUT_MS,
      );
      if (shouldStream) {
        let responseText = "";
        let remainText = "";
        let streamChatPath = chatPath.replace(
          "generateContent",
          "streamGenerateContent",
        );
        let finished = false;
        const finish = () => {
          finished = true;
          options.onFinish(responseText + remainText);
        };

        // animate response to make it looks smooth
        function animateResponseText() {
          if (finished || controller.signal.aborted) {
            responseText += remainText;
            finish();
            return;
          }

          if (remainText.length > 0) {
            const fetchCount = Math.max(1, Math.round(remainText.length / 60));
            const fetchText = remainText.slice(0, fetchCount);
            responseText += fetchText;
            remainText = remainText.slice(fetchCount);
            options.onUpdate?.(responseText, fetchText);
          }

          requestAnimationFrame(animateResponseText);
        }

        // start animaion
        animateResponseText();
        fetch(streamChatPath, chatPayload)
          .then((response) => {
            const reader = response?.body?.getReader();
            const decoder = new TextDecoder();
            let partialData = "";

            return reader?.read().then(function processText({
              done,
              value,
            }): Promise<any> {
              if (done) {
                console.log("Stream complete");
                // options.onFinish(responseText + remainText);
                finished = true;
                return Promise.resolve();
              }

              partialData += decoder.decode(value, { stream: true });

              try {
                let data = JSON.parse(ensureProperEnding(partialData));
                console.log(data);
                let fetchText = apiClient.extractMessage(data[data.length - 1]);
                console.log("[Response Animation] fetchText: ", fetchText);
                remainText += fetchText;
              } catch (error) {
                // skip error message when parsing json
              }

              return reader.read().then(processText);
            });
          })
          .catch((error) => {
            console.error("Error:", error);
          });
      } else {
        const res = await fetch(chatPath, chatPayload);
        clearTimeout(requestTimeoutId);

        const resJson = await res.json();

        if (resJson?.promptFeedback?.blockReason) {
          // being blocked
          options.onError?.(
            new Error(
              "Message is being blocked for reason: " +
                resJson.promptFeedback.blockReason,
            ),
          );
        }
        const message = this.extractMessage(resJson);
        options.onFinish(message);
      }
    } catch (e) {
      console.log("[Request] failed to make a chat request", e);
      options.onError?.(e as Error);
    }
  }
  usage(): Promise<LLMUsage> {
    throw new Error("Method not implemented.");
  }
  async models(): Promise<LLMModel[]> {
    return [];
  }
  path(path: string): string {
    return "/api/google/" + path;
  }
}

function ensureProperEnding(str: string) {
  if (str.startsWith("[") && !str.endsWith("]")) {
    return str + "]";
  }
  return str;
}