package imglib

import (
	"bytes"
	"encoding/base64"
	"fmt"
	"image"
	_ "image/jpeg"
	_ "image/png"
	"os"
	"strings"
	"time"

	"github.com/valyala/fasthttp"
)

// ImageInput 统一图片输入源，支持三种加载方式
type ImageInput struct {
	FilePath string // 磁盘文件路径
	URL      string // 网络 URL（http/https）
	Base64   string // Base64 编码的图片数据（可带 data:image/xxx;base64, 前缀）
}

// NewImageInputFromFile 从文件路径创建输入源
func NewImageInputFromFile(path string) ImageInput {
	return ImageInput{FilePath: path}
}

// NewImageInputFromURL 从网络 URL 创建输入源
func NewImageInputFromURL(url string) ImageInput {
	return ImageInput{URL: url}
}

// NewImageInputFromBase64 从 Base64 字符串创建输入源
func NewImageInputFromBase64(b64 string) ImageInput {
	return ImageInput{Base64: b64}
}

// Load 加载图片，返回解码后的 image.Image 和格式名称
func (in ImageInput) Load() (image.Image, string, error) {
	switch {
	case in.Base64 != "":
		return loadImageFromBase64(in.Base64)
	case in.URL != "":
		return loadImageFromURL(in.URL, 120)
	case in.FilePath != "":
		return loadImageFromFile(in.FilePath)
	default:
		return nil, "", fmt.Errorf("ImageInput 未设置任何输入源（FilePath/URL/Base64 均为空）")
	}
}

// loadImageFromFile 从磁盘文件加载图片
func loadImageFromFile(path string) (image.Image, string, error) {
	file, err := os.Open(path)
	if err != nil {
		return nil, "", fmt.Errorf("打开图片文件失败: %v", err)
	}
	defer file.Close()

	img, format, err := image.Decode(file)
	if err != nil {
		return nil, "", fmt.Errorf("解码图片失败: %v", err)
	}
	return img, format, nil
}

// loadImageFromURL 从网络 URL 加载图片
func loadImageFromURL(url string, timeout int) (image.Image, string, error) {
	if timeout <= 0 {
		timeout = 120
	}

	req := fasthttp.AcquireRequest()
	resp := fasthttp.AcquireResponse()
	defer fasthttp.ReleaseRequest(req)
	defer fasthttp.ReleaseResponse(resp)

	req.SetRequestURI(url)
	req.Header.SetMethod("GET")
	req.Header.Set("User-Agent", "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36")
	req.Header.Set("Accept", "image/avif,image/webp,image/apng,image/*,*/*;q=0.8")

	client := &fasthttp.Client{
		ReadTimeout:  time.Duration(timeout) * time.Second,
		WriteTimeout: time.Duration(timeout) * time.Second,
	}

	err := client.Do(req, resp)
	if err != nil {
		return nil, "", fmt.Errorf("请求失败: %v", err)
	}

	body := resp.Body()
	imgData := make([]byte, len(body))
	copy(imgData, body)

	img, format, err := image.Decode(bytes.NewReader(imgData))
	if err != nil {
		return nil, "", fmt.Errorf("解码图片失败: %v", err)
	}
	return img, format, nil
}

// loadImageFromBase64 从 Base64 字符串加载图片
func loadImageFromBase64(b64 string) (image.Image, string, error) {
	b64 = strings.TrimPrefix(b64, "data:image/jpeg;base64,")
	b64 = strings.TrimPrefix(b64, "data:image/jpg;base64,")
	b64 = strings.TrimPrefix(b64, "data:image/png;base64,")
	b64 = strings.TrimPrefix(b64, "data:image/gif;base64,")
	b64 = strings.TrimPrefix(b64, "data:image/webp;base64,")

	imgData, err := base64.StdEncoding.DecodeString(b64)
	if err != nil {
		return nil, "", fmt.Errorf("解码 base64 失败: %v", err)
	}

	img, format, err := image.Decode(bytes.NewReader(imgData))
	if err != nil {
		return nil, "", fmt.Errorf("解码 base64 图片失败: %v", err)
	}
	return img, format, nil
}