package main

import (
	"fmt"
	"io/ioutil"
	"os"
	"path/filepath"
	"regexp"
	"strconv"
	"strings"
)

var pxRegex = regexp.MustCompile(`(\d+\.?\d*)px`)

func pxToRem(pxStr string) string {
	px, err := strconv.ParseFloat(pxStr, 64)
	if err != nil {
		return pxStr + "px"
	}
	if px == 0 {
		return "0"
	}
	rem := px / 16.0
	if rem == float64(int(rem)) {
		return fmt.Sprintf("%drem", int(rem))
	}
	return fmt.Sprintf("%.2frem", rem)
}

func convertFile(filePath string) error {
	content, err := ioutil.ReadFile(filePath)
	if err != nil {
		return err
	}

	original := string(content)
	converted := pxRegex.ReplaceAllStringFunc(original, func(match string) string {
		num := strings.TrimSuffix(match, "px")
		return pxToRem(num)
	})

	if original == converted {
		return nil
	}

	return ioutil.WriteFile(filePath, []byte(converted), 0644)
}

func main() {
	if len(os.Args) < 2 {
		fmt.Println("Usage: go run convert_units.go <directory>")
		os.Exit(1)
	}

	dir := os.Args[1]
	count := 0

	err := filepath.Walk(dir, func(path string, info os.FileInfo, err error) error {
		if err != nil {
			return err
		}
		if !info.IsDir() && strings.HasSuffix(path, ".html") {
			err := convertFile(path)
			if err != nil {
				fmt.Printf("Error converting %s: %v\n", path, err)
				return nil
			}
			count++
			fmt.Printf("Converted: %s\n", path)
		}
		return nil
	})

	if err != nil {
		fmt.Printf("Error walking directory: %v\n", err)
		os.Exit(1)
	}

	fmt.Printf("\nTotal files converted: %d\n", count)
}