package main

import (
	"fmt"
	"io/ioutil"
	"net/http"
	"os"
	"regexp"
	"strings"
)

var GITDOMAIN = os.Getenv("GITDOMAIN")

func main() {
	// Get the port from command-line arguments
	if len(os.Args) < 2 {
		fmt.Println("Usage: go run main.go <port>")
		return
	}
	port := os.Args[1]

	http.HandleFunc("/", serveFile)
	fmt.Printf("Server is running on :%s\n", port)
	if err := http.ListenAndServe(":"+port, nil); err != nil {
		fmt.Println("Error starting server:", err)
	}
}

func serveFile(w http.ResponseWriter, r *http.Request) {
	// Parse the URL path
	parts := strings.Split(strings.Trim(r.URL.Path, "/"), "/")
	if len(parts) < 3 {
		http.Error(w, "Invalid URL format", http.StatusBadRequest)
		return
	}

	user := parts[0]
	repo := parts[1]
	filePath := strings.Join(parts[2:], "/")

	// Construct the raw file URL
	rawURL := fmt.Sprintf("https://%s/%s/%s/raw/branch/pages/public/%s", GITDOMAIN, user, repo, filePath)

	// Fetch the content from the raw URL
	resp, err := http.Get(rawURL)
	if err != nil || resp.StatusCode != http.StatusOK {
		fmt.Println("Failed to fetch file:", err)
		http.Error(w, "Failed to fetch file", http.StatusNotFound)
		return
	}
	defer resp.Body.Close()

	// Read the content
	content, err := ioutil.ReadAll(resp.Body)
	if err != nil {
		http.Error(w, "Failed to read file content", http.StatusInternalServerError)
		return
	}

	// Determine the content type based on the file extension
	contentType := http.DetectContentType(content)
	if strings.HasSuffix(filePath, ".css") {
		contentType = "text/css"
	} else if strings.HasSuffix(filePath, ".html") {
		contentType = "text/html"
	} else if strings.HasSuffix(filePath, ".js") {
		contentType = "application/javascript"
	} else if strings.HasSuffix(filePath, ".png") {
		contentType = "image/png"
	} else if strings.HasSuffix(filePath, ".jpg") || strings.HasSuffix(filePath, ".jpeg") {
		contentType = "image/jpeg"
	} else if strings.HasSuffix(filePath, ".gif") {
		contentType = "image/gif"
	}

	// Rewrite links in the content
	var rewrittenContent = content
	if contentType == "text/html"{
		rewrittenContent = []byte(rewriteLinks(string(content), user, repo))
	}

	// Set the content type and write the response
	w.Header().Set("Content-Type", contentType)
	w.Write([]byte(rewrittenContent))
}

func rewriteLinks(content, user, repo string) string {
	// Regular expressions to match URLs
	linkRegex := regexp.MustCompile(`(?i)(href|src)="([^"]+)"`)
	replacedContent := linkRegex.ReplaceAllStringFunc(content, func(match string) string {
		// Extract the URL
		submatches := linkRegex.FindStringSubmatch(match)
		if len(submatches) < 3 {
			return match // Return the original match if it doesn't match
		}
		url := submatches[2]

		// Rewrite the URL
		rewrittenURL := rewriteURL(url, user, repo)
		return fmt.Sprintf("%s=\"%s\"", submatches[1], rewrittenURL)
	})

	return replacedContent
}

func rewriteURL(url, user, repo string) string {
	// Check if the URL is relative or absolute
	if strings.HasPrefix(url, "/") {
		// absolute URL, rewrite it
		return fmt.Sprintf("https://%s/%s/%s/raw/branch/pages/public%s", GITDOMAIN, user, repo, url)
	}
	// Return the original URL if it's not relative
	return url
}