const std = @import("std");

pub const title = "Day 03: Lobby";

pub fn run(_: std.mem.Allocator) !void {
    const input = @embedFile("./input/day03.txt");
    var lines = std.mem.tokenizeScalar(u8, input, '\n');

    var accumulator: u64 = 0;

    const nr_of_digits = 12;

    while (lines.next()) |line| {
        var joltage: u64 = 0;

        var start: usize = 0;
        for (0..nr_of_digits) |i| {
            const end = line.len - (nr_of_digits - i) + 1;

            std.debug.print("checking {d} to {d}\n", .{start, end});

            var digit: u8 = 0;
            for (line[start..end], start..) |c, di| {
                const d = try std.fmt.charToDigit(c, 10);
                if (d > digit) {
                    digit = d;
                    start = di + 1;
                }
            }
            std.debug.print("digit = {d}\n", .{digit});

            joltage += digit * std.math.pow(u64, 10, nr_of_digits - (i + 1));
        }

        std.debug.print("joltage = {d}\n", .{joltage});
        accumulator += joltage;
    }

    var buffer: [8]u8 = undefined;
    var stdout_writer = std.fs.File.stdout().writer(&buffer);
    const stdout = &stdout_writer.interface;

    try stdout.print("{d}\n", .{accumulator});

    try stdout.flush();
}