package palm

import (
	"encoding/json"
	"io"
	"net/http"
	"one-api/common"
	"one-api/constant"
	"one-api/dto"
	relaycommon "one-api/relay/common"
	"one-api/relay/helper"
	"one-api/service"
	"one-api/types"

	"github.com/gin-gonic/gin"
)

// https://developers.generativeai.google/api/rest/generativelanguage/models/generateMessage#request-body
// https://developers.generativeai.google/api/rest/generativelanguage/models/generateMessage#response-body

func responsePaLM2OpenAI(response *PaLMChatResponse) *dto.OpenAITextResponse {
	fullTextResponse := dto.OpenAITextResponse{
		Choices: make([]dto.OpenAITextResponseChoice, 0, len(response.Candidates)),
	}
	for i, candidate := range response.Candidates {
		choice := dto.OpenAITextResponseChoice{
			Index: i,
			Message: dto.Message{
				Role:    "assistant",
				Content: candidate.Content,
			},
			FinishReason: "stop",
		}
		fullTextResponse.Choices = append(fullTextResponse.Choices, choice)
	}
	return &fullTextResponse
}

func streamResponsePaLM2OpenAI(palmResponse *PaLMChatResponse) *dto.ChatCompletionsStreamResponse {
	var choice dto.ChatCompletionsStreamResponseChoice
	if len(palmResponse.Candidates) > 0 {
		choice.Delta.SetContentString(palmResponse.Candidates[0].Content)
	}
	choice.FinishReason = &constant.FinishReasonStop
	var response dto.ChatCompletionsStreamResponse
	response.Object = "chat.completion.chunk"
	response.Model = "palm2"
	response.Choices = []dto.ChatCompletionsStreamResponseChoice{choice}
	return &response
}

func palmStreamHandler(c *gin.Context, resp *http.Response) (*types.NewAPIError, string) {
	responseText := ""
	responseId := helper.GetResponseID(c)
	createdTime := common.GetTimestamp()
	dataChan := make(chan string)
	stopChan := make(chan bool)
	go func() {
		responseBody, err := io.ReadAll(resp.Body)
		if err != nil {
			common.SysError("error reading stream response: " + err.Error())
			stopChan <- true
			return
		}
		common.CloseResponseBodyGracefully(resp)
		var palmResponse PaLMChatResponse
		err = json.Unmarshal(responseBody, &palmResponse)
		if err != nil {
			common.SysError("error unmarshalling stream response: " + err.Error())
			stopChan <- true
			return
		}
		fullTextResponse := streamResponsePaLM2OpenAI(&palmResponse)
		fullTextResponse.Id = responseId
		fullTextResponse.Created = createdTime
		if len(palmResponse.Candidates) > 0 {
			responseText = palmResponse.Candidates[0].Content
		}
		jsonResponse, err := json.Marshal(fullTextResponse)
		if err != nil {
			common.SysError("error marshalling stream response: " + err.Error())
			stopChan <- true
			return
		}
		dataChan <- string(jsonResponse)
		stopChan <- true
	}()
	helper.SetEventStreamHeaders(c)
	c.Stream(func(w io.Writer) bool {
		select {
		case data := <-dataChan:
			c.Render(-1, common.CustomEvent{Data: "data: " + data})
			return true
		case <-stopChan:
			c.Render(-1, common.CustomEvent{Data: "data: [DONE]"})
			return false
		}
	})
	common.CloseResponseBodyGracefully(resp)
	return nil, responseText
}

func palmHandler(c *gin.Context, info *relaycommon.RelayInfo, resp *http.Response) (*dto.Usage, *types.NewAPIError) {
	responseBody, err := io.ReadAll(resp.Body)
	if err != nil {
		return nil, types.NewOpenAIError(err, types.ErrorCodeReadResponseBodyFailed, http.StatusInternalServerError)
	}
	common.CloseResponseBodyGracefully(resp)
	var palmResponse PaLMChatResponse
	err = json.Unmarshal(responseBody, &palmResponse)
	if err != nil {
		return nil, types.NewOpenAIError(err, types.ErrorCodeBadResponseBody, http.StatusInternalServerError)
	}
	if palmResponse.Error.Code != 0 || len(palmResponse.Candidates) == 0 {
		return nil, types.WithOpenAIError(types.OpenAIError{
			Message: palmResponse.Error.Message,
			Type:    palmResponse.Error.Status,
			Param:   "",
			Code:    palmResponse.Error.Code,
		}, resp.StatusCode)
	}
	fullTextResponse := responsePaLM2OpenAI(&palmResponse)
	completionTokens := service.CountTextToken(palmResponse.Candidates[0].Content, info.UpstreamModelName)
	usage := dto.Usage{
		PromptTokens:     info.PromptTokens,
		CompletionTokens: completionTokens,
		TotalTokens:      info.PromptTokens + completionTokens,
	}
	fullTextResponse.Usage = usage
	jsonResponse, err := common.Marshal(fullTextResponse)
	if err != nil {
		return nil, types.NewError(err, types.ErrorCodeBadResponseBody)
	}
	c.Writer.Header().Set("Content-Type", "application/json")
	c.Writer.WriteHeader(resp.StatusCode)
	common.IOCopyBytesGracefully(c, resp, jsonResponse)
	return &usage, nil
}
