package service

import (
	"bytes"
	"context"
	"encoding/json"
	"fmt"
	"io"
	"net/http"
	"time"

	"go.uber.org/zap"
	"github.com/topfans/backend/pkg/logger"
)

// MinimaxClient MiniMax 图像生成 HTTP 客户端
type MinimaxClient struct {
	APIURL     string
	APIKey     string
	HTTPClient *http.Client
}

// NewMinimaxClient 创建 MiniMax 客户端
func NewMinimaxClient(apiURL, apiKey string) *MinimaxClient {
	return &MinimaxClient{
		APIURL: apiURL,
		APIKey: apiKey,
		HTTPClient: &http.Client{
			Timeout: 60 * time.Second,
		},
	}
}

// SubjectReference 人像参考（图生图）
type SubjectReference struct {
	Type      string `json:"type"`       // "character"
	ImageFile string `json:"image_file"` // URL 或 data: URL
}

// ImageGenReq 文生图/图生图请求
type ImageGenReq struct {
	Model            string             `json:"model"`
	Prompt           string             `json:"prompt"`
	AspectRatio      string             `json:"aspect_ratio"`
	N                int                `json:"n"`
	ResponseFormat   string             `json:"response_format"`
	SubjectReference []SubjectReference `json:"subject_reference,omitempty"`
}

// ImageGenResp 文生图响应
type ImageGenResp struct {
	ID    string `json:"id"`
	Data  struct {
		ImageURLs []string `json:"image_urls"`
	} `json:"data"`
	BaseResp struct {
		StatusCode int    `json:"status_code"`
		StatusMsg  string `json:"status_msg"`
	} `json:"base_resp"`
}

// GenerateImage 文生图（无参考图）
func (c *MinimaxClient) GenerateImage(ctx context.Context, prompt string) (string, error) {
	return c.GenerateImageWithSubject(ctx, prompt, "")
}

// GenerateImageWithSubject 图生图 — 将人物抠图作为 subject_reference 传给 MiniMax
// 这样 AI 生成的背景图会自然地融合人物主体
func (c *MinimaxClient) GenerateImageWithSubject(ctx context.Context, prompt, subjectImageURL string) (string, error) {
	req := ImageGenReq{
		Model:          "image-01",
		Prompt:         prompt,
		AspectRatio:    "3:4",
		N:              1,
		ResponseFormat: "url",
	}

	if subjectImageURL != "" {
		req.SubjectReference = []SubjectReference{
			{Type: "character", ImageFile: subjectImageURL},
		}
	}

	body, err := json.Marshal(req)
	if err != nil {
		return "", fmt.Errorf("marshal minimax request: %w", err)
	}

	httpReq, err := http.NewRequestWithContext(ctx, "POST", c.APIURL, bytes.NewReader(body))
	if err != nil {
		return "", fmt.Errorf("create minimax request: %w", err)
	}

	httpReq.Header.Set("Authorization", fmt.Sprintf("Bearer %s", c.APIKey))
	httpReq.Header.Set("Content-Type", "application/json")

	resp, err := c.HTTPClient.Do(httpReq)
	if err != nil {
		return "", fmt.Errorf("minimax http: %w", err)
	}
	defer resp.Body.Close()

	respBody, _ := io.ReadAll(resp.Body)

	var genResp ImageGenResp
	if err := json.Unmarshal(respBody, &genResp); err != nil {
		return "", fmt.Errorf("parse minimax response: %w, body=%s", err, string(respBody))
	}

	if genResp.BaseResp.StatusCode != 0 {
		return "", fmt.Errorf("minimax error: code=%d msg=%s", genResp.BaseResp.StatusCode, genResp.BaseResp.StatusMsg)
	}

	if len(genResp.Data.ImageURLs) == 0 {
		return "", fmt.Errorf("minimax returned no images")
	}

	logger.Logger.Info("MiniMax generated image",
		zap.String("prompt_preview", prompt[:minLen(60, len(prompt))]),
		zap.Bool("with_subject", subjectImageURL != ""),
	)

	return genResp.Data.ImageURLs[0], nil
}

func minLen(a, b int) int {
	if a < b {
		return a
	}
	return b
}