// Copyright 2025 BackendServerTemplate Authors. All rights reserved.
// Use of this source code is governed by a MIT-style
// license that can be found in the LICENSE file.

package mod

import (
	"fmt"
	"github.com/SongZihuan/BackendServerTemplate/tool/utils/cleanstringutils"
	"log"
	"os"
	"regexp"
	"strings"
	"sync"
)

const FileGoMod = "./go.mod"
const module = "module"

var validModuleNameRegex = regexp.MustCompile(`^[a-zA-Z0-9]+([./-]?[a-zA-Z0-9]+)*$`)

var once sync.Once
var goModuleName string = ""

func GetGoModuleName() (string, error) {
	var err error

	once.Do(func() {
		goModuleName, err = getGoModuleName()
	})
	if goModuleName == "" && err == nil {
		err = fmt.Errorf("go module name not found")
	}

	return goModuleName, err
}

func getGoModuleName() (string, error) {
	log.Println("generate: find the go mod name")
	defer log.Println("generate: find the go mod name finish")

	dat, err := os.ReadFile(FileGoMod)
	if err != nil {
		return "", err
	}

	goMod := strings.TrimPrefix(cleanstringutils.GetString(string(dat)), "\n")

	moduleLine := strings.TrimSpace(strings.Split(goMod, "\n")[0])

	if !strings.Contains(moduleLine, module) && len(moduleLine) > len(module) {
		return "", fmt.Errorf("go.mod error: %s not found", module)
	}

	moduleName := cleanstringutils.GetStringOneLine(moduleLine[len(module):])
	if !IsValidGoModuleName(moduleName) {
		return "", fmt.Errorf("go.mod error: '%s' is not a valid go module name", moduleName)
	}

	log.Printf("generate: go mod name get: %s\n", moduleName)
	return moduleName, nil
}

func IsValidGoModuleName(name string) bool {
	return validModuleNameRegex.MatchString(name)
}