package main

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

var DEBUG = false

func args() {
	filename := os.Args[1]
	f, err := os.Open(filename)
	if err != nil {
		fmt.Fprintln(os.Stderr, "unable to read file ", filename)
		os.Exit(1)
	}
	defer f.Close()

	c := make(chan token, 32)
	go lex(bufio.NewReader(f), c)

	for s := range c {
		fmt.Printf("%11s %s\n", s.t, s.lexeme)
	}
}

func main() {
	if len(os.Args) > 1 {
		args()
		return
	}

	r := bufio.NewReader(os.Stdin)
	for {
		fmt.Print("> ")
		line, prefix, err := r.ReadLine()
		if prefix {
			fmt.Println("(prefix)")
		}
		switch err {
		case nil:
			break
		case io.EOF:
			fmt.Print("\n")
			return
		default:
			fmt.Println("error: ", err)
			continue
		}

		c := make(chan token, 32)
		go lexs(string(line)+"\n", c)
		for s := range c {
			fmt.Printf("%11s %s\n", s.t, s.lexeme)
		}
	}
}