package main

import "core:math"
import "core:slice"
import "core:strconv"
import "core:strings"
import "core:bytes"
import "core:fmt"
import "core:os"

import "../util"

Row :: struct { min: i64, max: i64 }
Column :: struct { min: i64, max: i64 }

part_1 :: proc(lines: []string) {
    result: i64 = 0

    for line in lines {
        row := Row{ min = 0, max = 127 }
        col := Column{ min = 0, max = 7 }
        for letter in line {
            switch letter {
            case 'B':
                row.min += (row.max - row.min + 1) / 2
            case 'F':
                row.max -= (row.max - row.min + 1) / 2
            case 'R':
                col.min += (col.max - col.min + 1) / 2
            case 'L':
                col.max -= (col.max - col.min + 1) / 2
            }
        }

        id := row.max * 8 + col.max
        result = max(result, id)
    }

    fmt.printfln("Part 1: %d", result)
}

part_2 :: proc(lines: []string) {
    result: i64 = 0
    seats := [dynamic]i64{}

    for line in lines {
        row := Row{ min = 0, max = 127 }
        col := Column{ min = 0, max = 7 }
        for letter in line {
            switch letter {
            case 'B':
                row.min += (row.max - row.min + 1) / 2
            case 'F':
                row.max -= (row.max - row.min + 1) / 2
            case 'R':
                col.min += (col.max - col.min + 1) / 2
            case 'L':
                col.max -= (col.max - col.min + 1) / 2
            }
        }
        append(&seats, row.max * 8 + col.max)
    }

    slice.sort(seats[:])
    for seat, idx in seats[1:len(seats)-1] {
        if seat - 1 != seats[idx] {
            result = seat - 1
            break
        }
    }

    fmt.printfln("Part 2: %d", result)
}

main :: proc() {
    context.allocator = context.temp_allocator
    defer free_all(context.temp_allocator)

    INPUT :: #load("input.txt", string)
    lines := strings.split(INPUT, "\n")
    lines = lines[:len(lines)-1]

    part_1(lines)
    part_2(lines)
}