package main

import (
	"bufio"
	"io"
	"log"
	"os"
	"strconv"
	"strings"
)

type callback interface {
	moveTo(x, y float32)
	lineTo(x, y float32)
	draw(argb uint32)
}

func xy(args []string) (float32, float32) {
	x, err := strconv.ParseFloat(args[0], 32)
	if err != nil {
		log.Fatal(err)
	}
	y, err := strconv.ParseFloat(args[1], 32)
	if err != nil {
		log.Fatal(err)
	}
	return float32(x), float32(y)
}

func argb(s string) uint32 {
	i, err := strconv.ParseInt(s, 0, 64)
	if err != nil {
		log.Fatal(err)
	}
	return uint32(i)
}

func parse(cb callback) {
	file, err := os.Open("draw-cmds.txt")
	if err != nil {
		log.Fatal(err)
	}
	defer file.Close()
	r := bufio.NewReader(file)
	for {
		s, err := r.ReadString('\n')
		if err != nil {
			if err == io.EOF {
				break
			}
			log.Fatal(err)
		}
		s = strings.TrimSpace(s)
		if s[0] == '#' {
			continue
		}
		a := strings.Split(strings.TrimSpace(s[1:]), " ")
		switch s[0] {
		case 'm':
			x, y := xy(a)
			cb.moveTo(x, y)
		case 'l':
			x, y := xy(a)
			cb.lineTo(x, y)
		case 'd':
			cb.draw(argb(a[0]))
		}
	}
}