sample :: #string END
..@@.@@@@.
@@@.@.@.@@
@@@@@.@.@@
@.@@@@..@.
@@.@@@@.@@
.@@@@@@@.@
.@.@.@.@@@
@.@@@.@@@@
.@@@@@@@@.
@.@.@@@.@.
END

main :: () {
    print("@: %\n", #char "@");
    print(".: %\n", #char ".");
    content := read_entire_file("day4.input");

    solve_first(content);
    solve_second(content);
}

solve_first :: (input: string) {
    all_lines := split(input, #char "\n");
    lines: [..]string;
    for line: all_lines {
        if line.count == 0 continue;
        array_add(*lines, line);
    }
    assert(lines[0].count != 0);
    line_length := lines[0].count;
    removable := 0;
    for line, line_index: lines {
        if line.count == 0 continue;
        for char, char_index: line {
            if char == #char "." continue;
            surrounding_chars: [8]u8;
            surrounding_chars_index := 0;
            for dy: -1..1 {
                for dx: -1..1 {
                    if dx == 0 && dy == 0 continue;
                    defer surrounding_chars_index += 1;
                    x := char_index + dx;
                    if x < 0 || line.count <= x continue;
                    y := line_index + dy;
                    if y < 0 || lines.count <= y continue;
                    surrounding_chars[surrounding_chars_index] = lines[y][x];
                }
            }
            if array_count(surrounding_chars, (char: u8) -> bool { return char == #char "@"; }) < 4 {
                removable += 1;
            }
        }
    }
    print("%\n", removable);
}

Point :: struct {
    line_index: int;
    char_index: int;
}

solve_second :: (input: string) {
    all_lines := split(input, #char "\n");
    lines: [..][..]u8;
    array_reserve(*lines, all_lines.count);
    for line: all_lines {
        if line.count == 0 continue;
        chars: [..]u8;
        array_reserve(*chars, line.count);
        for line {
            array_add(*chars, it);
        }
        array_add(*lines, chars);
    }
    assert(lines[0].count != 0);
    line_length := lines[0].count;
    removed := 0;
    any_removed := true;
    while any_removed {
        any_removed = false;
        points_to_remove: [..]Point;
        points_to_remove.allocator = temp;
        array_reserve(*points_to_remove, line_length);
	defer reset_temporary_storage();
	for line, line_index: lines {
	    if line.count == 0 continue;
	    for char, char_index: line {
		if char == #char "." continue;
		surrounding_chars: [8]u8;
                surrounding_chars_index := 0;
                for dy: -1..1 {
                    for dx: -1..1 {
                        if dx == 0 && dy == 0 continue;
                        defer surrounding_chars_index += 1;
                        x := char_index + dx;
                        if x < 0 || line.count <= x continue;
                        y := line_index + dy;
                        if y < 0 || lines.count <= y continue;
                        surrounding_chars[surrounding_chars_index] = lines[y][x];
                    }
                }
                if array_count(surrounding_chars, (char: u8) -> bool { return char == #char "@"; }) < 4 {
                    removed += 1;
                    any_removed = true;
                    array_add(*points_to_remove, .{line_index=line_index, char_index=char_index});
                }
            }
        }

        for points_to_remove {
            lines[it.line_index][it.char_index] = #char ".";
        }
    }
    print("%\n", removed);
}


array_count :: (arr: []$T, f: (t: T) -> bool) -> int {
    total := 0;
    for arr {
        if f(it) total += 1;
    }
    return total;
}

#import "Basic";
#import "File";
#import "String";