package service

import (
	"bytes"
	"context"
	"fmt"
	"io"
	"mime/multipart"
	"net/http"
	"strings"
	"time"
)

// SegmentHTTPClient 自部署抠图 HTTP 服务（如 rembg s → POST /api/remove）
type SegmentHTTPClient struct {
	endpoint string
	client   *http.Client
}

func NewSegmentHTTPClient(endpoint string) *SegmentHTTPClient {
	return &SegmentHTTPClient{
		endpoint: strings.TrimSpace(endpoint),
		client:   &http.Client{Timeout: 120 * time.Second},
	}
}

func (c *SegmentHTTPClient) enabled() bool {
	return c.endpoint != ""
}

// RemoveBackground 上传图片字节，返回透明 PNG
func (c *SegmentHTTPClient) RemoveBackground(ctx context.Context, imageData []byte, contentType string) ([]byte, error) {
	if !c.enabled() {
		return nil, fmt.Errorf("抠图 HTTP 地址未配置")
	}
	if len(imageData) == 0 {
		return nil, fmt.Errorf("图片为空")
	}

	ext := "jpg"
	if strings.Contains(strings.ToLower(contentType), "png") {
		ext = "png"
	}

	var buf bytes.Buffer
	w := multipart.NewWriter(&buf)
	part, err := w.CreateFormFile("image", "upload."+ext)
	if err != nil {
		return nil, err
	}
	if _, err := part.Write(imageData); err != nil {
		return nil, err
	}
	_ = w.WriteField("scene", "portrait")
	if err := w.Close(); err != nil {
		return nil, err
	}

	req, err := http.NewRequestWithContext(ctx, http.MethodPost, c.endpoint, &buf)
	if err != nil {
		return nil, err
	}
	req.Header.Set("Content-Type", w.FormDataContentType())

	res, err := c.client.Do(req)
	if err != nil {
		return nil, err
	}
	defer res.Body.Close()

	raw, err := io.ReadAll(io.LimitReader(res.Body, maxSegmentImageBytes*4))
	if err != nil {
		return nil, err
	}
	if res.StatusCode < 200 || res.StatusCode >= 300 {
		return nil, fmt.Errorf("抠图 HTTP %d: %s", res.StatusCode, truncate(string(raw), 240))
	}

	ct := strings.ToLower(res.Header.Get("Content-Type"))
	if strings.Contains(ct, "image/") {
		return raw, nil
	}
	return nil, fmt.Errorf("抠图 HTTP 返回非图片内容")
}