package main

import (
	"database/sql"
	"image"
	"log"
	"net/http"
	"os"
	"runtime"

	"regexp"
	"strconv"

	"github.com/chai2010/webp"
	"github.com/disintegration/imaging"
	_ "github.com/go-sql-driver/mysql"
	giftowebp "github.com/sizeofint/gif-to-webp"
	"github.com/spf13/viper"
)

func init() {
	// 设置日志格式
	log.SetFlags(log.Ldate | log.Ltime | log.Lshortfile)
}

// 实现一个 web api 服务(获取指定尺寸的图片)
func main() {
	runtime.GOMAXPROCS(runtime.NumCPU())

	// 读取配置文件yaml
	viper.SetConfigName("config") // 设置配置文件的名字
	viper.SetConfigType("yaml")   // 设置配置文件的格式
	viper.AddConfigPath("./data") // 设置配置文件所在的路径
	if err := viper.ReadInConfig(); err != nil {
		log.Println("读取配置文件失败", err)
		return
	}
	user := viper.Get("mysql.user").(string)
	password := viper.Get("mysql.password").(string)
	host := viper.Get("mysql.host").(string)
	port := viper.Get("mysql.port").(int)
	database := viper.Get("mysql.database").(string)
	sqlconf := user + ":" + password + "@tcp(" + host + ":" + strconv.Itoa(port) + ")/" + database + "?charset=utf8mb4&parseTime=True&loc=Local"

	// 连接数据库
	db, err := sql.Open("mysql", sqlconf)
	if err != nil {
		log.Println("连接数据库失败", err)
		return
	}

	// 从 web_images 表读取图片 id, version, width, height, format
	rows, err := db.Query("SELECT id, width, height, content FROM web_images WHERE id = 8888")
	if err != nil {
		log.Println("查询数据库失败", err)
		return
	}
	defer rows.Close()

	// 遍历查询结果
	for rows.Next() {
		var id, width, height, content string
		if err = rows.Scan(&id, &width, &height, &content); err != nil {
			log.Println("读取数据库失败", err)
			return
		}
		log.Println(id, width, height, content)
	}

	http.HandleFunc("/img/", func(w http.ResponseWriter, r *http.Request) {

		// URL 格式: /img/{id}-{version}@{倍图}{宽度}.{格式}
		reg := regexp.MustCompile(`^/img/([0-9a-zA-Z]+)-([0-9a-zA-Z]+)@([0-9]{1,4})x([0-9]{1,4}).(jpg|jpeg|png|webp)$`)
		matches := reg.FindStringSubmatch(r.URL.Path)
		if len(matches) != 6 {
			log.Println("URL 格式错误", matches)
			w.WriteHeader(http.StatusBadRequest)
			return
		}

		// 正则表达式获取参数
		id, version, multiple_str, width_str, format := matches[1], matches[2], matches[3], matches[4], matches[5]
		multiple, err := strconv.Atoi(multiple_str)
		if err != nil {
			log.Println("倍图参数错误", multiple_str)
			w.WriteHeader(http.StatusBadRequest)
			return
		}

		width, err := strconv.Atoi(width_str)
		if err != nil {
			log.Println("宽度参数错误", width_str)
			w.WriteHeader(http.StatusBadRequest)
			return
		}

		log.Println(id, version, multiple, width, format)

		// 打開輸入文件
		file, err := os.Open("data/test.gif")
		if err != nil {
			log.Println("打开文件失败", err)
			w.WriteHeader(http.StatusBadRequest)
			return
		}
		defer file.Close()

		// 將輸入文件解碼為 image.Image
		img, ext, err := image.Decode(file)
		if err != nil {
			log.Println("解码图像失败", err)
			w.WriteHeader(http.StatusBadRequest)
			return
		}

		// 如果是 GIF 格式的动态图片，直接返回
		if ext == "gif" {
			var gifBin, webpBuf []byte
			if gifBin, err = os.ReadFile("data/test.gif"); err != nil {
				log.Println("读取文件失败", err)
				w.WriteHeader(http.StatusBadRequest)
				return
			}
			converter := giftowebp.NewConverter()
			converter.LoopCompatibility = false // 是否兼容循环动画
			converter.WebPConfig.SetLossless(0) // 0 有损压缩 1无损压缩
			converter.WebPConfig.SetMethod(6)   // 压缩速度 0-6 0最快 6质量最好
			converter.WebPConfig.SetQuality(10) // 压缩质量 0-100
			converter.WebPAnimEncoderOptions.SetKmin(9)
			converter.WebPAnimEncoderOptions.SetKmax(17)
			if webpBuf, err = converter.Convert(gifBin); err != nil {
				log.Println("编码图像失败", err.Error())
				w.WriteHeader(http.StatusBadRequest)
				return
			}
			w.Write(webpBuf)
			return
		}

		// 將圖像轉換為 RGBA 格式（如果尚未採用該格式）
		if _, ok := img.(*image.RGBA); !ok {
			img = imaging.Clone(img)
		}

		// 將圖像調整為指定宽度的 WebP 格式並將其寫入輸出到瀏覽器(高度自适应)
		if err = webp.Encode(w, imaging.Resize(img, multiple*width, 0, imaging.Lanczos), &webp.Options{Quality: 80}); err != nil {
			log.Println("编码图像失败", err.Error())
			w.WriteHeader(http.StatusBadRequest)
			return
		}
	})
	log.Println("Server is running at http://localhost:6001")
	http.ListenAndServe(":6001", nil)
}