exec.go

package main

import (
	"bufio"
	"errors"
	"fmt"
	"os"
	"os/exec"
	"strings"

	"github.com/eiannone/keyboard"
)

const maxAliasFileSize = 1 << 20

var alias = map[string][]string{}

func init() {
	setupAlias()
}

// Executes the given inputs
func execInput(input string) {
	input = strings.TrimSuffix(input, "\n")

	input = strings.TrimSpace(input)

	args := strings.Split(input, " ")

	program := strings.TrimSpace(args[0])

	switch program {
	case "cd":
		if len(args) < 2 {
			fmt.Fprintln(os.Stderr, ErrNoPath.Error())
			return
		}

		os.Chdir(args[1])
		return

	case "exit":
		keyboard.Close()
		os.Exit(0)
	}

	split := 0
	for _, v := range args[1:] {
		v = strings.TrimSpace(v)
		if v != "" {
			args[split] = v
			split++
		}
	}

	if _, ok := alias[program]; ok {
		key := program
		program = alias[program][0]
		args = append(alias[key][1:], args[:split]...)
	} else {
		args = args[:split]
	}

	cmd := exec.Command(program, args...)

	cmd.Stderr = os.Stderr
	cmd.Stdout = os.Stdout

	err := cmd.Run()

	if err != nil {
		if errors.Is(err, exec.ErrNotFound) {
			fmt.Printf("%s: %v\n", program, ErrCommantNotFound)
		}
	}

}

// Populates alias map from alias file
func setupAlias() {
	file, err := os.Open("alias")
	if err != nil {
		return
	}

	defer file.Close()

	fi, err := file.Stat()
	if err != nil {
		return
	}

	if maxAliasFileSize < fi.Size() {
		panic("alias file is too large!")
	}

	reader := bufio.NewReader(file)

	for {
		line, _, err := reader.ReadLine()
		if err != nil {
			return
		}

		keyValue := strings.Split(string(line), "=")

		if len(keyValue) != 2 {
			continue
		}

		key := strings.TrimSpace(keyValue[0])

		values := strings.Split(keyValue[1], " ")

		var args = []string{}

		for _, v := range values {
			v = strings.TrimSpace(v)
			if v != "" {
				args = append(args, v)
			}
		}

		alias[key] = args
	}
}