/*
 * Copyright (c) 2021 <NAME>
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */
package days

import utils.*
import kotlin.math.absoluteValue
import kotlin.math.sign

fun main() {
    data class Point(val x: Int, val y: Int)
    data class Segment(val start: Point, val end: Point)

    fun Point.diff(other: Point, selector: (Point) -> Int): IntRange =
        minOf(selector(this), selector(other))..maxOf(selector(this), selector(other))

    val segments = readInput().map { it.split(" -> ") }
        .map { (start, end) ->
            Segment(
                start.split(",").let { (x, y) -> Point(x.toInt(), y.toInt()) },
                end.split(",").let { (x, y) -> Point(x.toInt(), y.toInt()) }
            )
        }

    fun part1(): Int {
        val grid = Array(segments.maxOf { maxOf(it.start.y, it.end.y) } + 1) {
            IntArray( segments.maxOf { maxOf(it.start.x, it.end.x) } + 1)
        }

        for (segment in segments) {
            if (segment.start.x == segment.end.x) {
                segment.start.diff(segment.end, Point::y).forEach { y ->
                    grid[y][segment.start.x]++
                }
            } else if (segment.start.y == segment.end.y) {
                segment.start.diff(segment.end, Point::x).forEach { x ->
                    grid[segment.start.y][x]++
                }
            }
        }

        return grid.flatMap { it.filter { it > 1 } }.count()
    }

    fun part2(): Int {
        val grid = Array(segments.maxOf { maxOf(it.start.y, it.end.y) } + 1) {
            IntArray( segments.maxOf { maxOf(it.start.x, it.end.x) } + 1)
        }

        for (segment in segments) {
            val dX = (segment.end.x - segment.start.x).sign
            val dY = (segment.end.y - segment.start.y).sign

            for (t in 0..maxOf((segment.start.x - segment.end.x).absoluteValue, (segment.start.y - segment.end.y).absoluteValue)) {
                grid[segment.start.y + t * dY][segment.start.x + t * dX]++
            }
        }

        return grid.flatMap { it.filter { it > 1 } }.count()
    }

    println("Part 1: ${part1()}")
    println("Part 2: ${part2()}")
}