package static

import (
	"errors"
	"fmt"
	"io"
	"io/fs"
	"net/http"
	"os"
	"strings"

	"github.com/OpenListTeam/OpenList/v4/drivers/base"
	"github.com/OpenListTeam/OpenList/v4/internal/conf"
	"github.com/OpenListTeam/OpenList/v4/internal/setting"
	"github.com/OpenListTeam/OpenList/v4/pkg/utils"
	"github.com/OpenListTeam/OpenList/v4/public"
	"github.com/gin-gonic/gin"
)

var static fs.FS

func initStatic() {
	utils.Log.Debug("Initializing static file system...")
	if conf.Conf.DistDir == "" {
		dist, err := fs.Sub(public.Public, "dist")
		if err != nil {
			utils.Log.Fatalf("failed to read dist dir: %v", err)
		}
		static = dist
		utils.Log.Debug("Using embedded dist directory")
		return
	}
	static = os.DirFS(conf.Conf.DistDir)
	utils.Log.Infof("Using custom dist directory: %s", conf.Conf.DistDir)
}

func replaceStrings(content string, replacements map[string]string) string {
	for old, new := range replacements {
		content = strings.Replace(content, old, new, 1)
	}
	return content
}

func initIndex() {
	utils.Log.Debug("Initializing index.html...")
	siteConfig := getSiteConfig()
	if conf.Conf.DistDir != "" || (conf.Conf.Cdn != "" && (conf.WebVersion == "" || conf.WebVersion == "beta" || conf.WebVersion == "dev")) {
		utils.Log.Infof("Fetching index.html from CDN: %s/index.html...", conf.Conf.Cdn)
		resp, err := base.RestyClient.R().
			SetHeader("Accept", "text/html").
			Get(fmt.Sprintf("%s/index.html", siteConfig.Cdn))
		if err != nil {
			utils.Log.Fatalf("failed to fetch index.html from CDN: %v", err)
		}
		if resp.StatusCode() != http.StatusOK {
			utils.Log.Fatalf("failed to fetch index.html from CDN, status code: %d", resp.StatusCode())
		}
		conf.RawIndexHtml = string(resp.Body())
		utils.Log.Info("Successfully fetched index.html from CDN")
	} else {
		utils.Log.Debug("Reading index.html from static files system...")
		indexFile, err := static.Open("index.html")
		if err != nil {
			if errors.Is(err, fs.ErrNotExist) {
				utils.Log.Fatalf("index.html not exist, you may forget to put dist of frontend to public/dist")
			}
			utils.Log.Fatalf("failed to read index.html: %v", err)
		}
		defer func() {
			_ = indexFile.Close()
		}()
		index, err := io.ReadAll(indexFile)
		if err != nil {
			utils.Log.Fatalf("failed to read dist/index.html")
		}
		conf.RawIndexHtml = string(index)
		utils.Log.Debug("Successfully read index.html from static files system")
	}
	utils.Log.Debug("Replacing placeholders in index.html...")
	replaceMap := map[string]string{
		"cdn: undefined":       fmt.Sprintf("cdn: '%s'", siteConfig.Cdn),
		"base_path: undefined": fmt.Sprintf("base_path: '%s'", siteConfig.BasePath),
	}
	conf.RawIndexHtml = replaceStrings(conf.RawIndexHtml, replaceMap)
	UpdateIndex()
}

func UpdateIndex() {
	utils.Log.Debug("Updating index.html with settings...")
	favicon := setting.GetStr(conf.Favicon)
	title := setting.GetStr(conf.SiteTitle)
	customizeHead := setting.GetStr(conf.CustomizeHead)
	customizeBody := setting.GetStr(conf.CustomizeBody)
	mainColor := setting.GetStr(conf.MainColor)
	utils.Log.Debug("Applying replacements for default pages...")
	replaceMap1 := map[string]string{
		"https://cdn.oplist.org/gh/OpenListTeam/Logo@main/logo.svg": favicon,
		"Loading...":            title,
		"main_color: undefined": fmt.Sprintf("main_color: '%s'", mainColor),
	}
	conf.ManageHtml = replaceStrings(conf.RawIndexHtml, replaceMap1)
	utils.Log.Debug("Applying replacements for manage pages...")
	replaceMap2 := map[string]string{
		"<!-- customize head -->": customizeHead,
		"<!-- customize body -->": customizeBody,
	}
	conf.IndexHtml = replaceStrings(conf.ManageHtml, replaceMap2)
	utils.Log.Debug("Index.html update completed")
}

func Static(r *gin.RouterGroup, noRoute func(handlers ...gin.HandlerFunc)) {
	utils.Log.Debug("Setting up static routes...")
	initStatic()
	initIndex()
	folders := []string{"assets", "images", "streamer", "static"}
	if conf.Conf.Cdn == "" {
		utils.Log.Debug("Setting up static file serving...")
		r.Use(func(c *gin.Context) {
			for _, folder := range folders {
				if strings.HasPrefix(c.Request.RequestURI, fmt.Sprintf("/%s/", folder)) {
					c.Header("Cache-Control", "public, max-age=15552000")
				}
			}
		})
		for _, folder := range folders {
			sub, err := fs.Sub(static, folder)
			if err != nil {
				utils.Log.Fatalf("can't find folder: %s", folder)
			}
			utils.Log.Debugf("Setting up route for folder: %s", folder)
			r.StaticFS(fmt.Sprintf("/%s/", folder), http.FS(sub))
		}
	} else {
		// Ensure static file redirected to CDN
		for _, folder := range folders {
			r.GET(fmt.Sprintf("/%s/*filepath", folder), func(c *gin.Context) {
				filepath := c.Param("filepath")
				c.Redirect(http.StatusFound, fmt.Sprintf("%s/%s%s", conf.Conf.Cdn, folder, filepath))
			})
		}
	}

	utils.Log.Debug("Setting up catch-all route...")
	noRoute(func(c *gin.Context) {
		if c.Request.Method != "GET" && c.Request.Method != "POST" {
			c.Status(405)
			return
		}
		c.Header("Content-Type", "text/html")
		c.Status(200)
		if strings.HasPrefix(c.Request.URL.Path, "/@manage") {
			_, _ = c.Writer.WriteString(conf.ManageHtml)
		} else {
			_, _ = c.Writer.WriteString(conf.IndexHtml)
		}
		c.Writer.Flush()
		c.Writer.WriteHeaderNow()
	})
}