package openai

import (
	"bufio"
	"bytes"
	"fmt"
	"io"
	"net/http"
	"strings"

	"github.com/QuantumNous/new-api/common"
	"github.com/QuantumNous/new-api/constant"
	"github.com/QuantumNous/new-api/logger"
	relaycommon "github.com/QuantumNous/new-api/relay/common"
	"github.com/QuantumNous/new-api/relay/helper"
	"github.com/QuantumNous/new-api/relaykit/dto"
	"github.com/QuantumNous/new-api/relaykit/relayconvert"
	"github.com/QuantumNous/new-api/relaykit/types"
	"github.com/QuantumNous/new-api/service"

	"github.com/gin-gonic/gin"
	"github.com/tidwall/gjson"
	"github.com/tidwall/sjson"
)

func OaiResponsesHandler(c *gin.Context, info *relaycommon.RelayInfo, resp *http.Response) (*dto.Usage, *types.NewAPIError) {
	defer service.CloseResponseBodyGracefully(resp)
	if strings.HasPrefix(strings.ToLower(resp.Header.Get("Content-Type")), "text/event-stream") {
		body, err := readBufferedResponsesSSE(resp.Body)
		if err != nil {
			return nil, types.NewOpenAIError(err, types.ErrorCodeBadResponseBody, http.StatusBadGateway)
		}
		converted := *resp
		converted.Header = resp.Header.Clone()
		converted.Header.Set("Content-Type", "application/json")
		converted.Header.Del("Content-Length")
		converted.Body = io.NopCloser(bytes.NewReader(body))
		converted.ContentLength = int64(len(body))
		return OaiResponsesHandler(c, info, &converted)
	}

	// read response body
	var responsesResponse dto.OpenAIResponsesResponse
	responseBody, err := io.ReadAll(resp.Body)
	if err != nil {
		return nil, types.NewOpenAIError(err, types.ErrorCodeReadResponseBodyFailed, http.StatusInternalServerError)
	}
	err = common.Unmarshal(responseBody, &responsesResponse)
	if err != nil {
		return nil, types.NewOpenAIError(err, types.ErrorCodeBadResponseBody, http.StatusInternalServerError)
	}
	if oaiError := responsesResponse.GetOpenAIError(); oaiError != nil && oaiError.Type != "" {
		return nil, types.WithOpenAIError(*oaiError, resp.StatusCode)
	}

	info.ObserveResponseModel(responsesResponse.Model)
	responseBody = rewriteSGLangResponsesCreatedAt(info, responseBody, "created_at", responsesResponse.CreatedAt)

	// 写入新的 response body
	service.IOCopyBytesGracefully(c, resp, responseBody)

	// compute usage
	usage := &dto.Usage{}
	service.ApplyResponsesUsage(usage, responsesResponse.Usage)
	// Count actual tool invocations from Output (not tool declarations).
	for _, output := range responsesResponse.Output {
		switch output.Type {
		case dto.BuildInCallWebSearchCall:
			info.CountBillableToolCall(dto.BuildInCallWebSearchCall, "")
		case dto.BuildInCallFileSearchCall:
			info.CountBillableToolCall(dto.BuildInCallFileSearchCall, "")
		case dto.BuildInCallFunctionCall:
			info.CountBillableToolCall(dto.BuildInCallFunctionCall, output.Name)
		}
	}

	imageCounter := &relaycommon.ImageGenerationCallCounter{}
	if !relaycommon.IsNonBillableResponsesStatus(responsesResponse.Status) {
		for i := range responsesResponse.Output {
			idx := i
			imageCounter.Observe(&responsesResponse.Output[i], &idx)
		}
	}
	imageCounter.Commit(info)

	return usage, nil
}

// Some upstreams return SSE even for stream=false. Require a terminal response
// and reuse JSON delivery and settlement so upstream usage is charged once.
func readBufferedResponsesSSE(body io.Reader) ([]byte, error) {
	scanner := helper.NewStreamScanner(body)
	scanner.Split(bufio.ScanLines)
	accumulator := relayconvert.NewResponsesBufferedAccumulator()
	var data []string
	for scanner.Scan() {
		line := strings.TrimSuffix(scanner.Text(), "\r")
		if payload, ok := strings.CutPrefix(line, "data:"); ok {
			data = append(data, strings.TrimPrefix(payload, " "))
		}
		if line != "" || len(data) == 0 {
			continue
		}
		payload := strings.Join(data, "\n")
		data = nil
		if payload == "[DONE]" {
			break
		}
		var event dto.ResponsesStreamResponse
		if err := common.UnmarshalJsonStr(payload, &event); err != nil {
			return nil, err
		}
		accumulator.ProcessEvent(&event)
		switch event.Type {
		case "error", "response.error", "response.failed", "response.cancelled", "response.canceled":
			return nil, fmt.Errorf("responses stream ended with %s", event.Type)
		case "response.completed", "response.done", "response.incomplete":
			if event.Response == nil {
				return nil, fmt.Errorf("responses terminal event has no response")
			}
			result := []byte(gjson.Get(payload, "response").Raw)
			if len(event.Response.Output) == 0 {
				accumulator.SupplementResponseOutput(event.Response)
				if len(event.Response.Output) != 0 {
					output, err := common.Marshal(event.Response.Output)
					if err != nil {
						return nil, err
					}
					return sjson.SetRawBytes(result, "output", output)
				}
			}
			return result, nil
		}
	}
	if err := scanner.Err(); err != nil {
		return nil, err
	}
	return nil, fmt.Errorf("responses stream ended without a terminal response")
}

func OaiResponsesStreamHandler(c *gin.Context, info *relaycommon.RelayInfo, resp *http.Response) (*dto.Usage, *types.NewAPIError) {
	if resp == nil || resp.Body == nil {
		logger.LogError(c, "invalid response or response body")
		return nil, types.NewError(fmt.Errorf("invalid response"), types.ErrorCodeBadResponse)
	}

	defer service.CloseResponseBodyGracefully(resp)

	accumulator := service.NewResponsesUsageAccumulator(info)

	helper.StreamScannerHandler(c, resp, info, func(data string, sr *helper.StreamResult) {

		// 检查当前数据是否包含 completed 状态和 usage 信息
		var streamResponse dto.ResponsesStreamResponse
		if err := common.UnmarshalJsonStr(data, &streamResponse); err != nil {
			logger.LogError(c, "failed to unmarshal stream response: "+err.Error())
			sr.Error(err)
			return
		}
		if streamResponse.Response != nil {
			data = string(rewriteSGLangResponsesCreatedAt(info, []byte(data), "response.created_at", streamResponse.Response.CreatedAt))
		}
		sendResponsesStreamData(c, streamResponse, data)
		accumulator.Observe(&streamResponse)
	})

	common.SetContextKey(c, constant.ContextKeyResponseStreamStatus, info.StreamStatus)
	info.StreamStatus.RequireTerminal()
	return accumulator.Finish(), nil
}

func rewriteSGLangResponsesCreatedAt(info *relaycommon.RelayInfo, payload []byte, path string, createdAt dto.IntValue) []byte {
	if info.GetChannelType() != constant.ChannelTypeSGLang {
		return payload
	}
	if !gjson.GetBytes(payload, path).Exists() {
		return payload
	}
	patched, err := sjson.SetBytes(payload, path, int(createdAt))
	if err != nil {
		return payload
	}
	return patched
}