package main

import (
	"bufio"
	"fmt"
	"os"
	"strconv"
	"time"
)

func mustAtoi(line string) int {
	i, _ := strconv.Atoi(line)
	return i
}

func main() {
	start := time.Now()
	partOne()
	duration := time.Since(start)
	partTwo()
	duration2 := time.Since(start)
	fmt.Printf("p1: %s, p2: %s\n", duration, duration2-duration)
}

func makeScanner(test bool) *bufio.Scanner {
	var f *os.File
	if test {
		f, _ = os.Open("inputs/testinput")
	} else {
		f, _ = os.Open("inputs/input")
	}
	reader := bufio.NewReader(f)
	return bufio.NewScanner(reader)
}

type targetArea struct {
	startx int
	endx   int
	starty int
	endy   int
}

func ParseInput(line string) targetArea {
	target := targetArea{}
	acc := ""
	for i := 0; i < len(line); i++ {
		switch line[i] {
		case '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '-':
			acc += string(line[i])
		case '.':
			i++ // skip the second .
			if target.startx == 0 {
				target.startx = mustAtoi(acc)
			} else {
				target.starty = mustAtoi(acc)
			}
			acc = ""
		case ',':
			target.endx = mustAtoi(acc)
			acc = ""
		default: // all other characters do nothing
		}
		target.endy = mustAtoi(acc)
	}
	return target
}

func InTarget(x, y int, target targetArea) bool {
	return x >= target.startx && x <= target.endx && y <= target.endy && y >= target.starty
}

func BeyondTarget(x, y int, target targetArea) bool {
	return x > target.endx || y < target.starty
}

type probe struct {
	xvelocity int
	yvelocity int
	x         int
	y         int
	maxy      int
}

func (p *probe) Step() {
	p.x += p.xvelocity
	p.y += p.yvelocity
	if p.xvelocity > 0 {
		p.xvelocity--
	} else if p.xvelocity < 0 {
		p.xvelocity++
	}
	p.yvelocity--
	if p.y > p.maxy {
		p.maxy = p.y
	}
}

func partOne() {
	scanner := makeScanner(false)

	// read line
	scanner.Scan()
	line := scanner.Text()
	target := ParseInput(line)
	highestArc := 0
	for j := 1; j < 50; j++ {
		for k := 1; k < 100; k++ {
			initx := j
			inity := k
			p := &probe{
				xvelocity: initx,
				yvelocity: inity,
			}
			for {
				p.Step()
				if InTarget(p.x, p.y, target) {
					if p.maxy > highestArc {
						highestArc = p.maxy
					}
				}
				if BeyondTarget(p.x, p.y, target) {
					break
				}
			}
		}
	}
	fmt.Println(highestArc)
}

func partTwo() {
	scanner := makeScanner(false)

	// read line
	scanner.Scan()
	line := scanner.Text()
	target := ParseInput(line)
	hits := 0
	for j := 0; j < 1000; j++ {
		for k := -200; k < 1000; k++ {
			initx := j
			inity := k
			p := &probe{
				xvelocity: initx,
				yvelocity: inity,
			}
			for {
				p.Step()
				if InTarget(p.x, p.y, target) {
					hits++
					break
				}
				if BeyondTarget(p.x, p.y, target) {
					break
				}
			}
		}
	}
	fmt.Println(hits)
}