package router

import (
	"compress/gzip"
	"encoding/json"
	"io"
	"io/fs"
	"mime"
	"net/http"
	"path/filepath"
	"strings"

	"github.com/engigu/taskpool/internal/constant"
	"github.com/engigu/taskpool/internal/services"
	"github.com/engigu/taskpool/internal/static"

	"github.com/gin-gonic/gin"
)

// cacheControl 返回设置 Cache-Control header 的中间件
func cacheControl(value string) gin.HandlerFunc {
	return func(c *gin.Context) {
		c.Header("Cache-Control", value)
		c.Next()
	}
}

func openFileWithWebui(filename string) (fs.File, error) {
	webuiSvc := services.NewWebUIService(services.NewSettingsService())
	if customFS := webuiSvc.GetActiveWebUIFS(); customFS != nil {
		// 如果启用了定义的前端包，去取定义的路径
		return customFS.Open(filename)
	}

	// 如果是默认的，取默认路径
	defaultFS := static.GetFS()
	if defaultFS == nil {
		return nil, fs.ErrNotExist
	}
	return defaultFS.Open(filename)
}

func readFileWithWebui(filename string) ([]byte, error) {
	webuiSvc := services.NewWebUIService(services.NewSettingsService())
	if customFS := webuiSvc.GetActiveWebUIFS(); customFS != nil {
		// 如果启用了定义的前端包，去取定义的路径
		return fs.ReadFile(customFS, filename)
	}

	// 如果是默认的，取默认路径
	defaultFS := static.GetFS()
	if defaultFS == nil {
		return nil, fs.ErrNotExist
	}
	return fs.ReadFile(defaultFS, filename)
}

func initStaticRoutes(root *gin.RouterGroup) {

	// 专门处理 /assets 目录下的资源
	root.GET("/assets/*filepath", cacheControl("public, max-age=31536000, immutable"), func(ctx *gin.Context) {
		fullPath := "assets" + ctx.Param("filepath")
		fullPath = strings.TrimPrefix(fullPath, "/")

		isGzipSupported := strings.Contains(ctx.GetHeader("Accept-Encoding"), "gzip")
		gzPath := fullPath + ".gz"

		// 确定 MIME 类型
		ext := filepath.Ext(fullPath)
		contentType := mime.TypeByExtension(ext)
		if contentType == "" {
			switch ext {
			case ".js":
				contentType = "application/javascript"
			case ".css":
				contentType = "text/css"
			case ".svg":
				contentType = "image/svg+xml"
			default:
				contentType = "application/octet-stream"
			}
		}

		// 优先尝试读取 .gz 文件
		if gzFile, err := openFileWithWebui(gzPath); err == nil {
			defer gzFile.Close()
			ctx.Header("Content-Type", contentType)

			if isGzipSupported {
				// 极致性能：流式透传压缩包 (RSS 占用极低)
				ctx.Header("Content-Encoding", "gzip")
				ctx.Status(http.StatusOK)
				io.Copy(ctx.Writer, gzFile)
			} else {
				// 兼容处理：流式解压发送
				gr, _ := gzip.NewReader(gzFile)
				defer gr.Close()
				ctx.Status(http.StatusOK)
				io.Copy(ctx.Writer, gr)
			}
			return
		}

		// 如果没有 .gz，流式读取原文件
		if file, err := openFileWithWebui(fullPath); err == nil {
			defer file.Close()
			ctx.Header("Content-Type", contentType)
			ctx.Status(http.StatusOK)
			io.Copy(ctx.Writer, file)
			return
		}

		ctx.Status(404)
	})

	// logo.svg 等单文件处理
	root.GET("/logo.svg", func(ctx *gin.Context) {
		settings := services.NewSettingsService()
		icon := settings.Get(constant.SectionSite, constant.KeyIcon)
		if icon != "" {
			ctx.Header("Cache-Control", "public, max-age=86400")
			ctx.Data(http.StatusOK, "image/svg+xml", []byte(icon))
			return
		}
		serveSingleFile(ctx, "logo.svg", "image/svg+xml", "public, max-age=86400")
	})

	// PWA 相关路由处理
	initPWARoutes(root)
}

func initPWARoutes(root *gin.RouterGroup) {
	// PWA 相关文件处理
	pwaRootFiles := map[string]string{
		"/sw.js":            "application/javascript",
		"/registerSW.js":    "application/javascript",
		"/favicon.ico":      "image/x-icon",
		"/pwa-icon-192.png": "image/png",
		"/pwa-icon-512.png": "image/png",
	}

	for path, contentType := range pwaRootFiles {
		pPath := path
		pType := contentType
		root.GET(pPath, func(ctx *gin.Context) {
			file := strings.TrimPrefix(pPath, "/")
			serveSingleFile(ctx, file, pType, "public, no-cache")
		})
	}

	// 动态 manifest 处理 (支持由 Go 后端控制标题和图标)
	root.GET("/manifest.webmanifest", handleManifest)

	// 动态匹配 workbox-*.js (Vite PWA 生成的库文件)
	root.GET("/workbox-:hash.js", func(ctx *gin.Context) {
		file := "workbox-" + ctx.Param("hash") + ".js"
		serveSingleFile(ctx, file, "application/javascript", "public, max-age=31536000, immutable")
	})
}

func handleManifest(ctx *gin.Context) {

	// 读取原始 manifest
	data, err := readFileWithWebui("manifest.webmanifest")
	if err != nil {
		ctx.Status(404)
		return
	}

	var manifest map[string]interface{}
	if err := json.Unmarshal(data, &manifest); err != nil {
		// 如果解析失败，回退到原始文件
		ctx.Data(200, "application/manifest+json", data)
		return
	}

	// 注入后端配置的标题
	settings := services.NewSettingsService()
	title := settings.Get(constant.SectionSite, constant.KeyTitle)
	if title != "" {
		manifest["name"] = title
		manifest["short_name"] = title
	}

	// 注入后端配置的图标 (首选 logo.svg)
	manifest["icons"] = []map[string]interface{}{
		{
			"src":     "/logo.svg",
			"sizes":   "any",
			"type":    "image/svg+xml",
			"purpose": "any maskable",
		},
	}

	res, _ := json.Marshal(manifest)
	ctx.Header("Cache-Control", "public, no-cache")
	ctx.Data(200, "application/manifest+json", res)
}

func serveSingleFile(ctx *gin.Context, filename string, contentType string, cache string) {

	if cache != "" {
		ctx.Header("Cache-Control", cache)
	}
	ctx.Header("Content-Type", contentType)

	isGzipSupported := strings.Contains(ctx.GetHeader("Accept-Encoding"), "gzip")

	// 尝试流式发送压缩版
	if gzFile, err := openFileWithWebui(filename + ".gz"); err == nil {
		defer gzFile.Close()
		if isGzipSupported {
			ctx.Header("Content-Encoding", "gzip")
			ctx.Status(200)
			io.Copy(ctx.Writer, gzFile)
		} else {
			gr, _ := gzip.NewReader(gzFile)
			defer gr.Close()
			ctx.Status(200)
			io.Copy(ctx.Writer, gr)
		}
		return
	}

	// 尝试流式发送原版
	if file, err := openFileWithWebui(filename); err == nil {
		defer file.Close()
		ctx.Status(200)
		io.Copy(ctx.Writer, file)
		return
	}

	ctx.Status(404)
}

// serveSPA 注入配置并返回 index.html 给前端渲染
func serveSPA(ctx *gin.Context, urlPrefix string, status int) {

	var data []byte
	// index.html 较小且需要修改字符串，可以一次性读入内存
	if gzFile, err := openFileWithWebui("index.html.gz"); err == nil {
		defer gzFile.Close()
		gr, _ := gzip.NewReader(gzFile)
		data, _ = io.ReadAll(gr)
		gr.Close()
	} else if file, err := openFileWithWebui("index.html"); err == nil {
		defer file.Close()
		data, _ = io.ReadAll(file)
	}

	if data == nil {
		ctx.String(status, "index.html not found.")
		return
	}

	html := string(data)
	baseHref := urlPrefix + "/"
	if urlPrefix == "" {
		baseHref = "/"
	}
	html = strings.Replace(html, "<head>", "<head>\n    <base href=\""+baseHref+"\">", 1)
	configScript := `<script>window.__BASE_URL__ = "` + urlPrefix + `"; window.__API_VERSION__ = "/api/v1";</script>`
	html = strings.Replace(html, "</head>", configScript+"</head>", 1)

	ctx.Header("Content-Type", "text/html; charset=utf-8")
	ctx.Header("Cache-Control", "no-cache, no-store, must-revalidate")
	ctx.Data(status, "text/html; charset=utf-8", []byte(html))
}