package main

import (
	"bufio"
	"fmt"
	"io/ioutil"
	"os"
)

var (
	hadError bool = false
)

func main() {
	if len(os.Args) > 2 {
		fmt.Println("Usage: pj1-go [script]")
		os.Exit(64)
	} else if len(os.Args) == 2 {
		runFile(os.Args[0])
	} else {
		runPrompt()
	}
}

func runFile(path string) {
	bytes, err := ioutil.ReadFile(path)
	if err != nil {
		fmt.Println(err)
		return
	}
	run(string(bytes[:]))

	if hadError {
		os.Exit(65)
	}
}

func runPrompt() {
	scanner := bufio.NewScanner(os.Stdin)
	for {
		fmt.Print("> ")
		if !scanner.Scan() {
			break
		}
		line := scanner.Text()
		fmt.Println(line)
		run(line)

		hadError = false
	}
	if err := scanner.Err(); err != nil {
		fmt.Fprintln(os.Stderr, "reading standard input:", err)
	}
}

func run(source string) {
	lexer := NewLexer(source)
	lexer.ScanTokens()
	var tokens []Token = lexer.tokens

	for _, token := range tokens {
		fmt.Println(token)
	}
}

// TODO: might have to rename
func error(line int, msg string) {
	report(line, "", msg)
	hadError = true
}

func report(line int, where string, msg string) {
	fmt.Fprintln(os.Stderr, "[line "+fmt.Sprint(line)+"] Error"+where+": "+msg)
}