package advent

import java.awt.Point
import kotlin.math.abs
import kotlin.math.max
import kotlin.math.min

class Day3 {

    private class Line(
        val x1 : Int,
        val y1 : Int,
        val x2 : Int,
        val y2 : Int
    ) {
        fun isHorizontal() = y1 == y2

        override fun toString() = "[$x1, $y1] -> [$x2, $y2]"
    }

    private class Step(
        val direction : String,
        val steps : Int

    ) {
        override fun toString() = "$direction$steps"
    }

    companion object {

        private fun getInput() : Pair<List<Step>, List<Step>> {
            val lines = javaClass
                .getResource("/Day3Input")
                .readText()
                .lines()
                .map { line ->
                    line.split(',').map { Step(it.substring(0, 1), it.substring(1).toInt()) }
                }
            return Pair(lines[0], lines[1])
        }

        private fun getWire(steps : List<Step>) : MutableList<Line> {
            var (x, y) = Pair(0, 0)
            val lines = mutableListOf<Line>()
            for (step in steps) {
                val (x0, y0) = Pair(x, y)
                when (step.direction) {
                    "U" -> y -= step.steps
                    "D" -> y += step.steps
                    "L" -> x -= step.steps
                    "R" -> x += step.steps
                }
                lines.add(Line(min(x0, x), min(y0, y), max(x0, x), max(y0, y)))
            }
            return lines
        }

        private fun areLinesIntersecting(line1 : Line, line2 : Line) : Point? {
            val hLine : Line
            val vLine : Line
            if (line1.isHorizontal() && !line2.isHorizontal()) {
                hLine = line1
                vLine = line2
            } else if (!line1.isHorizontal() && line2.isHorizontal()) {
                hLine = line2
                vLine = line1
            } else {
                return null
            }
            if (hLine.y1 >= vLine.y1 && hLine.y1 <= vLine.y2 && vLine.x1 >= hLine.x1 && vLine.x1 <= hLine.x2) {
                return Point(vLine.x1, hLine.y1)
            }
            return null
        }

        private fun getIntersections(wire1 : List<Line>, wire2 : List<Line>) : MutableList<Point> {
            val intersections = mutableListOf<Point>()
            for (line1 in wire1) {
                for (line2 in wire2) {
                    areLinesIntersecting(line1, line2)?.let { intersections.add(it) }
                }
            }
            return intersections
        }

        @JvmStatic
        fun main(args : Array<String>) {
            val input = getInput()
            val wire1 = getWire(input.first)
            val wire2 = getWire(input.second)
            val intersections = getIntersections(wire1, wire2)
            var closestDistance= Int.MAX_VALUE
            intersections.forEach {
                val distance = abs(it.x) + abs(it.y)
                if (distance in 1 until closestDistance) {
                    closestDistance = distance
                }
            }
            println(closestDistance)
        }

    }


}