const std = @import("std");
const Io = std.Io;

const shared = @import("shared.zig");
const print = shared.print;

pub fn insertIfNotSmallest(allocator: std.mem.Allocator, list: *std.ArrayList(Result), value: u8, index: usize) !void {
    for (list.items) |result| {
        if (value > result.value) {
            try list.append(allocator, .{ .index = index, .value = value });
            break;
        }
    }

    std.mem.sort(Result, list.items, {}, Result.compareValues);
}

const Result = struct {
    index: usize,
    value: u8,

    pub fn compareValues(_: void, lhs: @This(), rhs: @This()) bool {
        return lhs.value > rhs.value;
    }

    pub fn compareIndex(_: void, lhs: @This(), rhs: @This()) bool {
        return lhs.index < rhs.index;
    }
};

pub fn selectNLargest(comptime N: usize, allocator: std.mem.Allocator, line: []const u8) ![N]usize {
    var list: std.ArrayList(Result) = .empty;
    try list.appendNTimes(allocator, .{ .index = line.len, .value = 0 }, N);
    defer list.deinit(allocator);

    for (line, 0..) |x, i| {
        try insertIfNotSmallest(allocator, &list, x, i);

        while (list.items.len > 2) {
            _ = list.pop();
        }
    }

    std.mem.sort(Result, list.items, {}, Result.compareIndex);

    var rv: [N]usize = .{ line.len, line.len };
    for (0..N) |i| {
        rv[i] = list.items[i].index;
    }
    return rv;
}

pub fn main(init: std.process.Init) !void {
    try shared.sharedInit(init);
    const allocator: std.mem.Allocator = init.arena.allocator();
    const bytes = shared.loadBytesArg(allocator);

    var lineIter = std.mem.tokenizeScalar(u8, bytes, '\n');

    var part1: i64 = 0;
    var digits: std.ArrayList(u8) = .empty;
    defer digits.deinit(allocator);

    while (lineIter.next()) |l| {
        const line = shared.trim(l);
        const x = try selectNLargest(2, allocator, line);
        digits.clearRetainingCapacity();
        for (0..x.len) |i| {
            try digits.append(allocator, line[x[i]]);
        }
        print("{s}", .{digits.items});
        part1 += try std.fmt.parseInt(i64, digits.items, 10);
    }

    print("part1 {d}", .{part1});
}