using Yarn.Unity;

namespace NightclubArcadia.Dialogue
{
    /// <summary>
    /// Deterministically turns the player's real name into an unrelated club
    /// alias. Same input name always yields the same alias (hash-seeded pick
    /// from two word pools), but the alias carries no resemblance to the
    /// input — it's a stage name, not a nickname derived from it.
    ///
    /// Used from Yarn as a smart variable (see $player_alias in Common.yarn)
    /// or directly: {alias_name($player_name)}
    /// </summary>
    public static class AliasNameGenerator
    {
        static readonly string[] FirstWords =
        {
            "Midnight", "Velvet", "Neon", "Crimson", "Static", "Amber",
            "Obsidian", "Electric", "Hollow", "Silver", "Violet", "Iron",
            "Phantom", "Copper", "Glass", "Ashen",
        };

        static readonly string[] SecondWords =
        {
            "Vex", "Wilde", "Sable", "Rook", "Marlowe", "Cross",
            "Vane", "Thorn", "Rye", "Blaze", "Faye", "Quinn",
            "Storm", "Reyes", "Lark", "Doyle",
        };

        [YarnFunction("alias_name")]
        public static string AliasName(string realName)
        {
            if (string.IsNullOrEmpty(realName))
            {
                realName = "unknown";
            }

            var hash = Fnv1aHash(realName);
            var first = FirstWords[hash % (uint)FirstWords.Length];
            var second = SecondWords[(hash / (uint)FirstWords.Length) % (uint)SecondWords.Length];
            return $"{first} {second}";
        }

        // FNV-1a: simple, stable across platforms and .NET versions (unlike
        // string.GetHashCode, which is not guaranteed stable run-to-run).
        static uint Fnv1aHash(string value)
        {
            const uint offsetBasis = 2166136261;
            const uint prime = 16777619;

            var hash = offsetBasis;
            foreach (var c in value)
            {
                hash ^= c;
                hash *= prime;
            }

            return hash;
        }
    }
}