package main

type Day4Offset struct {
	x int
	y int
}

func Day4IsWordValid(lines []string, x int, y int, table []Day4Offset, word string) bool {
	for i, offset := range table {
		y := y + offset.y
		if y < 0 {
			return false
		}
		if y >= len(lines) {
			return false
		}

		x := x + offset.x
		if x < 0 {
			return false
		}
		if x >= len(lines[y]) {
			return false
		}

		if lines[y][x] != word[i] {
			return false
		}
	}

	return true
}

func Day4Part1(lines []string) error {
	offsetTables := [][]Day4Offset{
		[]Day4Offset{
			Day4Offset{ x: 0, y: 0, },
			Day4Offset{ x: 1, y: 0, },
			Day4Offset{ x: 2, y: 0, },
			Day4Offset{ x: 3, y: 0, },
		},
		[]Day4Offset{
			Day4Offset{ x: 0, y: 0, },
			Day4Offset{ x: 0, y: 1, },
			Day4Offset{ x: 0, y: 2, },
			Day4Offset{ x: 0, y: 3, },
		},
		[]Day4Offset{
			Day4Offset{ x: 0, y: 0, },
			Day4Offset{ x: 1, y: 1, },
			Day4Offset{ x: 2, y: 2, },
			Day4Offset{ x: 3, y: 3, },
		},
		[]Day4Offset{
			Day4Offset{ x:  0, y: 0, },
			Day4Offset{ x: -1, y: 1, },
			Day4Offset{ x: -2, y: 2, },
			Day4Offset{ x: -3, y: 3, },
		},
	}

	answer := 0
	for y := range len(lines) {
		for x := range len(lines[y]) {
			for _, table := range offsetTables {
				if Day4IsWordValid(lines, x, y, table, "XMAS") {
					answer += 1
				}

				if Day4IsWordValid(lines, x, y, table, "SAMX") {
					answer += 1
				}
			}
		}
	}

	println(answer)

	return nil
}

func Day4Part2(lines []string) error {
	table1 := []Day4Offset{
		Day4Offset{ x: 0, y: 0, },
		Day4Offset{ x: 1, y: 1, },
		Day4Offset{ x: 2, y: 2, },
	}

	table2 := []Day4Offset{
		Day4Offset{ x: 2, y: 0, },
		Day4Offset{ x: 1, y: 1, },
		Day4Offset{ x: 0, y: 2, },
	}

	answer := 0
	for y := range len(lines) {
		for x := range len(lines[y]) {
			diagonal1 := Day4IsWordValid(lines, x, y, table1, "MAS") || Day4IsWordValid(lines, x, y, table1, "SAM")
			diagonal2 := Day4IsWordValid(lines, x, y, table2, "MAS") || Day4IsWordValid(lines, x, y, table2, "SAM")

			if diagonal1 && diagonal2 {
				answer += 1
			}
		}
	}

	println(answer)

	return nil
}