package main

import (
	"flag"
	"fmt"
	"log"
	"os"
	"os/exec"
	"strings"
)

var commandEnvDescription = "load environment variable from .env file"

func commandEnv(args []string) {
	var flagSet = flag.NewFlagSet("env", flag.ContinueOnError)
	envFilePath := flagSet.String("file", ".env", "the file contains environment variables to parse")
	printToScreen := flagSet.Bool("print", false, "wethear or not print to screen")
	_ = printToScreen
	printWithExport := flagSet.Bool("export", false, "wethear or not add `export` prefix to each variable when printing")
	flagSet.Parse(args[1:])
	_, err := parseEnvFileAndSetEnv(*envFilePath, *printToScreen, *printWithExport)
	if err != nil {
		fmt.Printf("%v", err)
		os.Exit(2)
	}
	if len(flagSet.Args()) > 0 {
		cmd := exec.Command(flagSet.Args()[0], flagSet.Args()[1:]...)
		var out strings.Builder
		cmd.Stdout = &out
		err = cmd.Run()
		if err != nil {
			log.Fatal(err)
		}
		fmt.Printf(out.String())
	}

}

func parseEnvFileAndSetEnv(filePath string, printToScreen, printWithExport bool) (string, error) {
	raw, err := os.ReadFile(filePath)
	if err != nil {
		return "", fmt.Errorf("read from %v has error: %w", filePath, err)
	}
	rawLines := strings.Split(string(raw), "\n")
	for i, line := range rawLines {
		trimedLine := strings.TrimSpace(line)
		if strings.HasPrefix(trimedLine, "#") {
			continue
		}
		if trimedLine == "" {
			continue
		}
		parts := strings.Split(trimedLine, "=")
		if len(parts) != 2 {
			return "", fmt.Errorf("line %v is malformed: `%v`", i+1, trimedLine)
		}
		if strings.TrimSpace(parts[0]) != parts[0] {
			return "", fmt.Errorf("line %v is malformed: between variable name and `=` can't has any space", i+1)
		}
		if strings.TrimSpace(parts[1]) != parts[1] {
			return "", fmt.Errorf("line %v is malformed: between `=` and value can't has any space", i+1)
		}
		os.Setenv(parts[0], parts[1])
		if printToScreen {
			s := fmt.Sprintf("%v=%v\n", parts[0], parts[1])
			if printWithExport {
				s = fmt.Sprintf("export %v", s)
			}
			fmt.Print(s)
		}

	}
	return "", nil
}