package gemini

import (
	"encoding/json"
	"errors"
	"fmt"
	"io"
	"net/http"
	"strings"
	"time"

	"github.com/gin-gonic/gin"
	"github.com/songquanpeng/one-api/common/config"
	"github.com/songquanpeng/one-api/common/helper"
	channelhelper "github.com/songquanpeng/one-api/relay/adaptor"
	"github.com/songquanpeng/one-api/relay/adaptor/openai"
	"github.com/songquanpeng/one-api/relay/meta"
	"github.com/songquanpeng/one-api/relay/model"
	"github.com/songquanpeng/one-api/relay/relaymode"
)

type Adaptor struct {
}

func (a *Adaptor) Init(meta *meta.Meta) {
}

func (a *Adaptor) GetRequestURL(meta *meta.Meta) (string, error) {
	defaultVersion := config.GeminiVersion
	modelLower := strings.ToLower(meta.ActualModelName)
	if strings.Contains(modelLower, "gemini-1.5") ||
		strings.Contains(modelLower, "gemini-2.") ||
		strings.Contains(modelLower, "gemini-3.") {
		defaultVersion = "v1beta"
	}

	version := helper.AssignOrDefault(meta.Config.APIVersion, defaultVersion)

	modelName := meta.ActualModelName

	switch meta.Mode {
	case relaymode.ImagesEdits:
		// Image editing uses :predict (same as generation) with referenceImages in instances[]
		if strings.Contains(modelName, "/") {
			return fmt.Sprintf("%s/v1/%s:predict", meta.BaseURL, publisherModelPath(modelName)), nil
		}
		return fmt.Sprintf("%s/v1beta/models/%s:predict", meta.BaseURL, modelName), nil
	case relaymode.ImagesGenerations:
		// Imagen 3+ models use :generateImages endpoint
		if isImagen3Model(modelName) {
			return fmt.Sprintf("%s/v1/models/%s:generateImages", meta.BaseURL, publisherModelPath(modelName)), nil
		}
		// Publisher models (e.g. klingai/kling-v2, volcengine/doubao-*) use v1 :predict
		if strings.Contains(modelName, "/") {
			return fmt.Sprintf("%s/v1/%s:predict", meta.BaseURL, publisherModelPath(modelName)), nil
		}
		// Legacy imagegeneration models (no publisher prefix) use v1beta :predict
		return fmt.Sprintf("%s/v1beta/models/%s:predict", meta.BaseURL, modelName), nil
	case relaymode.Embeddings:
		return fmt.Sprintf("%s/%s/models/%s:batchEmbedContents", meta.BaseURL, version, modelName), nil
	}

	action := "generateContent"
	if meta.IsStream {
		action = "streamGenerateContent?alt=sse"
	}
	return fmt.Sprintf("%s/%s/%s:%s", meta.BaseURL, version, publisherModelPath(modelName), action), nil
}

func (a *Adaptor) SetupRequestHeader(c *gin.Context, req *http.Request, meta *meta.Meta) error {
	channelhelper.SetupCommonRequestHeader(c, req, meta)
	req.Header.Set("x-goog-api-key", meta.APIKey)
	return nil
}

func (a *Adaptor) ConvertRequest(c *gin.Context, relayMode int, request *model.GeneralOpenAIRequest) (any, error) {
	if request == nil {
		return nil, errors.New("request is nil")
	}
	switch relayMode {
	case relaymode.Embeddings:
		geminiEmbeddingRequest := ConvertEmbeddingRequest(*request)
		return geminiEmbeddingRequest, nil
	default:
		geminiRequest := ConvertRequest(*request)
		return geminiRequest, nil
	}
}

func (a *Adaptor) ConvertImageRequest(request *model.ImageRequest) (any, error) {
	if request == nil {
		return nil, errors.New("request is nil")
	}
	n := request.N
	if n <= 0 {
		n = 1
	}
	// If an image is provided, convert to :editImage format (image-to-image)
	if request.Image != nil {
		imageStr, ok := request.Image.(string)
		if !ok {
			return nil, errors.New("image field must be a base64 string or data URL")
		}
		// Strip data URL prefix if present (e.g. "data:image/png;base64,")
		base64Data := imageStr
		if idx := strings.Index(imageStr, ";base64,"); idx != -1 {
			base64Data = imageStr[idx+8:]
		}
		return EditImageRequest{
			Instances: []EditImageInstance{
				{
					Prompt: request.Prompt,
					ReferenceImages: []ReferenceImageItem{
						{
							ReferenceType: "REFERENCE_TYPE_RAW",
							ReferenceId:   1,
							ReferenceImage: ReferenceImageData{
								BytesBase64Encoded: base64Data,
							},
						},
					},
				},
			},
		}, nil
	}
	if isImagen3Model(request.Model) {
		return GenerateImagesRequest{
			Prompt:         request.Prompt,
			NumberOfImages: n,
			AspectRatio:    sizeToAspectRatio(request.Size),
		}, nil
	}
	return ImagenRequest{
		Instances: []ImagenInstance{{Prompt: request.Prompt}},
		Parameters: ImagenParameters{
			SampleCount: n,
			AspectRatio: sizeToAspectRatio(request.Size),
		},
	}, nil
}

// publisherModelPath converts publisher/model names to the correct Vertex AI URL path segment.
// Google's own models (gemini/, google/) keep the raw /models/publisher/model format.
// Third-party publisher models use /publishers/{pub}/models/{model} format.
func publisherModelPath(modelName string) string {
	if idx := strings.Index(modelName, "/"); idx != -1 {
		publisher := modelName[:idx]
		model := modelName[idx+1:]
		if publisher == "gemini" || publisher == "google" {
			return fmt.Sprintf("models/%s", modelName)
		}
		return fmt.Sprintf("publishers/%s/models/%s", publisher, model)
	}
	return fmt.Sprintf("models/%s", modelName)
}

// isImagen3Model returns true for image-generation-only models that use the :generateImages endpoint.
func isImagen3Model(modelName string) bool {
	lower := strings.ToLower(modelName)
	return strings.HasPrefix(lower, "imagen-3") ||
		strings.HasPrefix(lower, "imagen-4") ||
		strings.Contains(lower, "imagegeneration@00")
}
func sizeToAspectRatio(size string) string {
	switch size {
	case "1792x1024":
		return "16:9"
	case "1024x1792":
		return "9:16"
	case "1024x1024", "":
		return "1:1"
	default:
		return "1:1"
	}
}

func (a *Adaptor) DoRequest(c *gin.Context, meta *meta.Meta, requestBody io.Reader) (*http.Response, error) {
	return channelhelper.DoRequestHelper(a, c, meta, requestBody)
}

func (a *Adaptor) DoResponse(c *gin.Context, resp *http.Response, meta *meta.Meta) (usage *model.Usage, err *model.ErrorWithStatusCode) {
	if meta.IsStream {
		err, usage, meta.GenerationId = StreamHandler(c, resp)
		if usage != nil {
			usage.PromptTokens = meta.PromptTokens
		}
	} else {
		switch meta.Mode {
		case relaymode.Embeddings:
			err, usage = EmbeddingHandler(c, resp)
		case relaymode.ImagesGenerations, relaymode.ImagesEdits:
			err = ImagenHandler(c, resp)
		default:
			err, usage = Handler(c, resp, meta.PromptTokens, meta.ActualModelName)
		}
	}
	return
}

// ImagenHandler converts a Google Imagen predict/generateImages response to OpenAI image response format.
// Handles both Vertex AI format (predictions[].bytesBase64Encoded) and OpenAI format (data[].b64_json).
func ImagenHandler(c *gin.Context, resp *http.Response) *model.ErrorWithStatusCode {
	responseBody, readErr := io.ReadAll(resp.Body)
	resp.Body.Close()
	if readErr != nil {
		return openai.ErrorWrapper(readErr, "read_response_body_failed", http.StatusInternalServerError)
	}

	fmt.Printf("[ImagenHandler] raw response body: %s\n", string(responseBody))

	// Safety check: empty response
	if len(responseBody) == 0 || string(responseBody) == "{}" || string(responseBody) == "null" {
		return openai.ErrorWrapper(
			fmt.Errorf("upstream returned empty response body"),
			"empty_response_body",
			http.StatusBadGateway,
		)
	}

	data := make([]openai.ImageData, 0)

	// Format 1: :generateImages / :editImage → generatedImages[].image.imageBytes
	var generateResp GenerateImagesResponse
	if err := json.Unmarshal(responseBody, &generateResp); err == nil {
		if generateResp.Error != nil {
			return openai.ErrorWrapper(
				fmt.Errorf("%s", generateResp.Error.Message),
				"imagen_error",
				http.StatusInternalServerError,
			)
		}
		for _, img := range generateResp.GeneratedImages {
			if img.Image.ImageBytes != "" {
				data = append(data, openai.ImageData{B64Json: img.Image.ImageBytes})
			}
		}
	}

	// Format 2: legacy :predict → predictions[].bytesBase64Encoded or predictions[].gcsUri
	if len(data) == 0 {
		var imagenResp ImagenResponse
		if err := json.Unmarshal(responseBody, &imagenResp); err == nil {
			if imagenResp.Error != nil {
				return openai.ErrorWrapper(
					fmt.Errorf("%s", imagenResp.Error.Message),
					"imagen_error",
					http.StatusInternalServerError,
				)
			}
			for _, p := range imagenResp.Predictions {
				if p.BytesBase64Encoded != "" {
					data = append(data, openai.ImageData{B64Json: p.BytesBase64Encoded})
				} else if p.GcsUri != "" {
					data = append(data, openai.ImageData{Url: p.GcsUri})
				}
			}
		}
	}

	// Format 3: OpenAI format data[].b64_json — used by models like openai/gpt-image-*
	if len(data) == 0 {
		var openaiImgResp struct {
			Data []struct {
				B64Json string `json:"b64_json"`
				URL     string `json:"url"`
			} `json:"data"`
		}
		if err := json.Unmarshal(responseBody, &openaiImgResp); err == nil {
			for _, item := range openaiImgResp.Data {
				data = append(data, openai.ImageData{B64Json: item.B64Json, Url: item.URL})
			}
		}
	}
	if len(data) == 0 {
		return openai.ErrorWrapper(
			fmt.Errorf("upstream returned no image data (response: %s)", string(responseBody)),
			"no_image_data",
			http.StatusBadGateway,
		)
	}

	openaiResp := openai.ImageResponse{
		Created: time.Now().Unix(),
		Data:    data,
	}

	jsonBytes, err := json.Marshal(openaiResp)
	if err != nil {
		return openai.ErrorWrapper(err, "marshal_response_failed", http.StatusInternalServerError)
	}

	c.Writer.Header().Set("Content-Type", "application/json")
	c.Writer.WriteHeader(http.StatusOK)
	c.Writer.Write(jsonBytes)
	return nil
}

func (a *Adaptor) GetModelList() []string {
	return ModelList
}

func (a *Adaptor) GetChannelName() string {
	return "google gemini"
}