module day4.part2.main;

import std;

void main()
{
    readText("input").parsePassports.countValidPassports.writeln;
}

alias Passport = string[string];

auto parsePassports(string input)
{
    return input.splitter("\n\n").map!(passport => passport.splitter().map!((entry) {
            auto keyAndValue = entry.split(':');
            return tuple(keyAndValue[0], keyAndValue[1]);
        }).assocArray);
}

enum Field : string
{
    birthYear = "byr",
    issueYear = "iyr",
    expirationYear = "eyr",
    height = "hgt",
    hairColor = "hcl",
    eyeColor = "ecl",
    passportID = "pid",
    countryID = "cid",
}

bool isValidYear(int min, int max)(string yr)
{
    if (yr.length != 4 || yr.canFind!(not!isDigit))
        return false;
    auto year = yr.to!int;
    return year >= min && year <= max;

}

alias isValidBirthYear = isValidYear!(1920, 2002);
alias isValidIssueYear = isValidYear!(2010, 2020);
alias isValidExpirationYear = isValidYear!(2020, 2030);

bool isValidHeight(string hgt)
{
    auto match = hgt.matchFirst(r"^(\d+)(cm|in)$");
    if (!match || match.length != 3)
        return false;

    auto number = match[1].to!int;
    switch (match[2])
    {
    case "cm":
        return number >= 150 && number <= 193;
        break;
    case "in":
        return number >= 59 && number <= 76;
    default:
        return false;
    }
}

bool isValidHairColor(string hcl)
{
    return hcl.matchFirst(r"^#[0-9a-f]{6}$").to!bool;
}

bool isValidEyeColor(string ecl)
{
    return ["amb", "blu", "brn", "gry", "grn", "hzl", "oth"].canFind(ecl);
}

bool isValidPassportID(string pid)
{
    return pid.matchFirst(r"^\d{9}$").to!bool;
}

enum requiredFields = [
        Field.birthYear, Field.issueYear, Field.expirationYear, Field.height,
        Field.hairColor, Field.eyeColor, Field.passportID
    ];

bool isValidPassport(Passport passport)
{
    return requiredFields.all!(field => field in passport)
        && isValidBirthYear(passport[Field.birthYear])
        && isValidIssueYear(passport[Field.issueYear])
        && isValidExpirationYear(passport[Field.expirationYear])
        && isValidHeight(passport[Field.height])
        && isValidHairColor(passport[Field.hairColor])
        && isValidEyeColor(passport[Field.eyeColor])
        && isValidPassportID(passport[Field.passportID]);
}

auto countValidPassports(R)(R r) if (isInputRange!R && is(ElementType!R == Passport))
{
    return r.filter!isValidPassport.count;
}

unittest
{
    auto input = `eyr:1972 cid:100
hcl:#18171d ecl:amb hgt:170 pid:186cm iyr:2018 byr:1926

iyr:2019
hcl:#602927 eyr:1967 hgt:170cm
ecl:grn pid:012533040 byr:1946

hcl:dab227 iyr:2012
ecl:brn hgt:182cm pid:021572410 eyr:2020 byr:1992 cid:277

hgt:59cm ecl:zzz
eyr:2038 hcl:74454a iyr:2023
pid:3556412378 byr:2007`;

    auto passPorts = input.parsePassports;
    assert(passPorts.countValidPassports == 0);
}

unittest
{
    auto input = `pid:087499704 hgt:74in ecl:grn iyr:2012 eyr:2030 byr:1980
hcl:#623a2f

eyr:2029 ecl:blu cid:129 byr:1989
iyr:2014 pid:896056539 hcl:#a97842 hgt:165cm

hcl:#888785
hgt:164cm byr:2001 iyr:2015 cid:88
pid:545766238 ecl:hzl
eyr:2022

iyr:2010 hgt:158cm hcl:#b6652a ecl:blu byr:1944 eyr:2021 pid:093154719`;

    auto passPorts = input.parsePassports;
    assert(passPorts.countValidPassports == 4);
}