package loader

import (
	"fmt"
	"image"
	"image/png"
	"net/http"
	"strings"
	"time"

	// 支持 JPEG 解码
	_ "image/jpeg"
)

var httpClient = &http.Client{
	Timeout: 30 * time.Second,
}

// LoadImage 从 URL 下载并解码图片，返回 image.Image
func LoadImage(url string) (image.Image, error) {
	url = strings.TrimSpace(url)
	if url == "" {
		return nil, fmt.Errorf("empty URL")
	}

	resp, err := httpClient.Get(url)
	if err != nil {
		return nil, fmt.Errorf("download failed: %w", err)
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusOK {
		return nil, fmt.Errorf("download returned HTTP %d", resp.StatusCode)
	}

	img, _, err := image.Decode(resp.Body)
	if err != nil {
		return nil, fmt.Errorf("decode failed: %w", err)
	}

	return img, nil
}

// LoadDecodePNG 下载并强制解码为 PNG（获取 alpha 通道）
func LoadDecodePNG(url string) (image.Image, error) {
	url = strings.TrimSpace(url)
	if url == "" {
		return nil, fmt.Errorf("empty URL")
	}

	resp, err := httpClient.Get(url)
	if err != nil {
		return nil, fmt.Errorf("download failed: %w", err)
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusOK {
		return nil, fmt.Errorf("download returned HTTP %d", resp.StatusCode)
	}

	img, err := png.Decode(resp.Body)
	if err != nil {
		// Fallback: try standard image decode
		return LoadImage(url)
	}

	return img, nil
}