package main

import (
	"bufio"
	"fmt"
	"os"
	"strconv"
	"strings"
	"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 coord struct {
	x int
	y int
}

func getRange(start, end int) []int {
	if start > end {
		s := make([]int, start-end+1)
		for i := range s {
			s[i] = start
			start--
		}
		return s
	}
	if end > start {
		s := make([]int, end-start+1)
		for i := range s {
			s[i] = start
			start++
		}
		return s
	}
	return []int{}
}

func printCave(cave map[coord]int, xmin, xmax, depth int, floor bool) {
	for _, d := range getRange(0, depth) {
		fmt.Printf("%3d ", d)
		for _, x := range getRange(xmin, xmax) {
			if d == 0 && x == 500 {
				fmt.Print("+")
			} else if score, ok := cave[coord{x: x, y: d}]; ok {
				if score == 1 {
					fmt.Print("#")
				} else if score == 2 {
					fmt.Print("o")
				}
			} else {
				fmt.Print(".")
			}
		}
		fmt.Printf("\n")
	}
	if floor {
		fmt.Printf("%3d ", depth+1)
		for range getRange(xmin, xmax) {
			fmt.Print("#")
		}
		fmt.Printf("\n")
	}
}

// return value is false if sand reached max depth
func addSand(cave map[coord]int, depth int, floor bool) bool {
	x := 500
	y := 0
	for {
		if y > depth {
			if floor {
				// made it to the floor, come to rest
				cave[coord{x: x, y: y}] = 2
				return true
			}
			return false
		}
		if _, blocked := cave[coord{x: x, y: y + 1}]; !blocked {
			y += 1
			continue
		}
		if _, blocked := cave[coord{x: x - 1, y: y + 1}]; !blocked {
			y += 1
			x -= 1
			continue
		}
		if _, blocked := cave[coord{x: x + 1, y: y + 1}]; !blocked {
			y += 1
			x += 1
			continue
		}
		// filled the cavern, return false
		if y == 0 {
			cave[coord{x: x, y: y}] = 2
			return false
		}
		// blocked in all directions, come to rest
		cave[coord{x: x, y: y}] = 2
		return true
	}
}

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

	cave := map[coord]int{}
	maxx, minx, depth := 0, 1000, 0

	for scanner.Scan() {
		line := scanner.Text()
		coords := strings.Split(line, " -> ")
		prevx, prevy := 0, 0
		for _, i := range coords {
			x, y, _ := strings.Cut(i, ",")
			if prevx == 0 && prevy == 0 {
				prevx, prevy = mustAtoi(x), mustAtoi(y)
				continue
			}
			if prevx == mustAtoi(x) {
				for _, curry := range getRange(prevy, mustAtoi(y)) {
					cave[coord{x: prevx, y: curry}] = 1
				}
				prevy = mustAtoi(y)
			} else if prevy == mustAtoi(y) {
				for _, currx := range getRange(prevx, mustAtoi(x)) {
					cave[coord{x: currx, y: prevy}] = 1
				}
				prevx = mustAtoi(x)
			}
			if mustAtoi(x) > maxx {
				maxx = mustAtoi(x)
			} else if mustAtoi(x) < minx {
				minx = mustAtoi(x)
			}
			if mustAtoi(y) > depth {
				depth = mustAtoi(y)
			}
		}
	}
	for addSand(cave, depth, false) {
	}
	printCave(cave, minx-1, maxx+1, depth+1, false)
	score := 0
	for _, c := range cave {
		if c == 2 {
			score++
		}
	}
	fmt.Println(score)
}

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

	cave := map[coord]int{}
	maxx, minx, depth := 0, 1000, 0

	for scanner.Scan() {
		line := scanner.Text()
		coords := strings.Split(line, " -> ")
		prevx, prevy := 0, 0
		for _, i := range coords {
			x, y, _ := strings.Cut(i, ",")
			if prevx == 0 && prevy == 0 {
				prevx, prevy = mustAtoi(x), mustAtoi(y)
				continue
			}
			if prevx == mustAtoi(x) {
				for _, curry := range getRange(prevy, mustAtoi(y)) {
					cave[coord{x: prevx, y: curry}] = 1
				}
				prevy = mustAtoi(y)
			} else if prevy == mustAtoi(y) {
				for _, currx := range getRange(prevx, mustAtoi(x)) {
					cave[coord{x: currx, y: prevy}] = 1
				}
				prevx = mustAtoi(x)
			}
			if mustAtoi(x) > maxx {
				maxx = mustAtoi(x)
			} else if mustAtoi(x) < minx {
				minx = mustAtoi(x)
			}
			if mustAtoi(y) > depth {
				depth = mustAtoi(y)
			}
		}
	}
	for addSand(cave, depth, true) {
	}
	printCave(cave, minx-1, maxx+1, depth+1, true)
	score := 0
	for _, c := range cave {
		if c == 2 {
			score++
		}
	}
	fmt.Println(score)
}