package main

import (
	"bufio"
	"bytes"
	"fmt"
	"io"
	"log"
	"unicode"
)

type groundpipe struct {
	value byte // value of the pipe

	// byte slices should be sorted to allow for easier comparison
	north []byte // valid byte set for a pipe to the north
	south []byte // valid byte set for a pipe to the south
	east  []byte // valid byte set for a pipe to the east
	west  []byte // valid byte set for a pipe to the west
}

type day10 struct{}

func scanmaze(r io.Reader) ([][]groundpipe, int, int) {
	layers := make([][]groundpipe, 0)
	row, col := 0, 0
	buf := bufio.NewReader(r)

	for next := true; next; {
		bts, err := buf.ReadBytes('\n')
		next = !reachedeof(err)

		layers = append(layers, make([]groundpipe, 0))
		end := len(layers) - 1

		for i, b := range bytes.TrimFunc(bts, unicode.IsSpace) {
			pipe := groundpipe{value: b}
			switch b {
			case '|':
				pipe.north = []byte("7F|")
				pipe.south = []byte("JL|")
				// pipe.east = []byte("")
				// pipe.west = []byte("")
			case '-':
				// pipe.north = []byte("")
				// pipe.south = []byte("")
				pipe.east = []byte("-7J")
				pipe.west = []byte("-FL")
			case 'L':
				pipe.north = []byte("7F|")
				// pipe.south = []byte("")
				pipe.east = []byte("-7J")
				// pipe.west = []byte("")
			case 'J':
				pipe.north = []byte("7F|")
				// pipe.south = []byte("")
				// pipe.east = []byte("")
				pipe.west = []byte("-FL")
			case '7':
				// pipe.north = []byte("")
				pipe.south = []byte("JL|")
				// pipe.east = []byte("")
				pipe.west = []byte("-FL")
			case 'F':
				// pipe.north = []byte("")
				pipe.south = []byte("JL|")
				pipe.east = []byte("-7J")
				// pipe.west = []byte("")
			case 'S':
				row, col = end, i
			default:
				// ignoring '.' and '\n'
				continue
			}
			layers[end] = append(layers[end], pipe)
		}
	}

	return layers, row, col
}

func (d day10) solve1(r io.Reader) string {
	_, startx, starty := scanmaze(r)
	log.Printf("x: %d; y: %d", startx, starty)
	farthest := 0

	return fmt.Sprintf("%d", farthest)
}

func (d day10) solve2(r io.Reader) string {
	return "incomplete"
}