package cohere

import (
	"bufio"
	"encoding/json"
	"fmt"
	"github.com/gin-gonic/gin"
	"io"
	"net/http"
	"one-api/common"
	"one-api/dto"
	"one-api/service"
	"strings"
)

func requestOpenAI2Cohere(textRequest dto.GeneralOpenAIRequest) *CohereRequest {
	cohereReq := CohereRequest{
		Model:       textRequest.Model,
		ChatHistory: []ChatHistory{},
		Message:     "",
		Stream:      textRequest.Stream,
		MaxTokens:   textRequest.GetMaxTokens(),
	}
	if cohereReq.MaxTokens == 0 {
		cohereReq.MaxTokens = 4000
	}
	for _, msg := range textRequest.Messages {
		if msg.Role == "user" {
			cohereReq.Message = msg.StringContent()
		} else {
			var role string
			if msg.Role == "assistant" {
				role = "CHATBOT"
			} else if msg.Role == "system" {
				role = "SYSTEM"
			} else {
				role = "USER"
			}
			cohereReq.ChatHistory = append(cohereReq.ChatHistory, ChatHistory{
				Role:    role,
				Message: msg.StringContent(),
			})
		}
	}
	return &cohereReq
}

func stopReasonCohere2OpenAI(reason string) string {
	switch reason {
	case "COMPLETE":
		return "stop"
	case "MAX_TOKENS":
		return "max_tokens"
	default:
		return reason
	}
}

func cohereStreamHandler(c *gin.Context, resp *http.Response, modelName string, promptTokens int) (*dto.OpenAIErrorWithStatusCode, *dto.Usage) {
	responseId := fmt.Sprintf("chatcmpl-%s", common.GetUUID())
	createdTime := common.GetTimestamp()
	usage := &dto.Usage{}
	responseText := ""
	scanner := bufio.NewScanner(resp.Body)
	scanner.Split(func(data []byte, atEOF bool) (advance int, token []byte, err error) {
		if atEOF && len(data) == 0 {
			return 0, nil, nil
		}
		if i := strings.Index(string(data), "\n"); i >= 0 {
			return i + 1, data[0:i], nil
		}
		if atEOF {
			return len(data), data, nil
		}
		return 0, nil, nil
	})
	dataChan := make(chan string)
	stopChan := make(chan bool)
	go func() {
		for scanner.Scan() {
			data := scanner.Text()
			dataChan <- data
		}
		stopChan <- true
	}()
	service.SetEventStreamHeaders(c)
	c.Stream(func(w io.Writer) bool {
		select {
		case data := <-dataChan:
			data = strings.TrimSuffix(data, "\r")
			var cohereResp CohereResponse
			err := json.Unmarshal([]byte(data), &cohereResp)
			if err != nil {
				common.SysError("error unmarshalling stream response: " + err.Error())
				return true
			}
			var openaiResp dto.ChatCompletionsStreamResponse
			openaiResp.Id = responseId
			openaiResp.Created = createdTime
			openaiResp.Object = "chat.completion.chunk"
			openaiResp.Model = modelName
			if cohereResp.IsFinished {
				finishReason := stopReasonCohere2OpenAI(cohereResp.FinishReason)
				openaiResp.Choices = []dto.ChatCompletionsStreamResponseChoice{
					{
						Delta:        dto.ChatCompletionsStreamResponseChoiceDelta{},
						Index:        0,
						FinishReason: &finishReason,
					},
				}
				if cohereResp.Response != nil {
					usage.PromptTokens = cohereResp.Response.Meta.BilledUnits.InputTokens
					usage.CompletionTokens = cohereResp.Response.Meta.BilledUnits.OutputTokens
				}
			} else {
				openaiResp.Choices = []dto.ChatCompletionsStreamResponseChoice{
					{
						Delta: dto.ChatCompletionsStreamResponseChoiceDelta{
							Role:    "assistant",
							Content: &cohereResp.Text,
						},
						Index: 0,
					},
				}
				responseText += cohereResp.Text
			}
			jsonStr, err := json.Marshal(openaiResp)
			if err != nil {
				common.SysError("error marshalling stream response: " + err.Error())
				return true
			}
			c.Render(-1, common.CustomEvent{Data: "data: " + string(jsonStr)})
			return true
		case <-stopChan:
			c.Render(-1, common.CustomEvent{Data: "data: [DONE]"})
			return false
		}
	})
	if usage.PromptTokens == 0 {
		usage, _ = service.ResponseText2Usage(responseText, modelName, promptTokens)
	}
	return nil, usage
}

func cohereHandler(c *gin.Context, resp *http.Response, modelName string, promptTokens int) (*dto.OpenAIErrorWithStatusCode, *dto.Usage) {
	createdTime := common.GetTimestamp()
	responseBody, err := io.ReadAll(resp.Body)
	if err != nil {
		return service.OpenAIErrorWrapper(err, "read_response_body_failed", http.StatusInternalServerError), nil
	}
	err = resp.Body.Close()
	if err != nil {
		return service.OpenAIErrorWrapper(err, "close_response_body_failed", http.StatusInternalServerError), nil
	}
	var cohereResp CohereResponseResult
	err = json.Unmarshal(responseBody, &cohereResp)
	if err != nil {
		return service.OpenAIErrorWrapper(err, "unmarshal_response_body_failed", http.StatusInternalServerError), nil
	}
	usage := dto.Usage{}
	usage.PromptTokens = cohereResp.Meta.BilledUnits.InputTokens
	usage.CompletionTokens = cohereResp.Meta.BilledUnits.OutputTokens
	usage.TotalTokens = cohereResp.Meta.BilledUnits.InputTokens + cohereResp.Meta.BilledUnits.OutputTokens

	var openaiResp dto.TextResponse
	openaiResp.Id = cohereResp.ResponseId
	openaiResp.Created = createdTime
	openaiResp.Object = "chat.completion"
	openaiResp.Model = modelName
	openaiResp.Usage = usage

	content, _ := json.Marshal(cohereResp.Text)
	openaiResp.Choices = []dto.OpenAITextResponseChoice{
		{
			Index:        0,
			Message:      dto.Message{Content: content, Role: "assistant"},
			FinishReason: stopReasonCohere2OpenAI(cohereResp.FinishReason),
		},
	}

	jsonResponse, err := json.Marshal(openaiResp)
	if err != nil {
		return service.OpenAIErrorWrapper(err, "marshal_response_body_failed", http.StatusInternalServerError), nil
	}
	c.Writer.Header().Set("Content-Type", "application/json")
	c.Writer.WriteHeader(resp.StatusCode)
	_, err = c.Writer.Write(jsonResponse)
	return nil, &usage
}
