using System.Security.Cryptography;
using System.Text;

namespace NeonSprawl.Server.Game.Contracts;

/// <summary>Id normalization for contract instance stores (NEO-146).</summary>
public static class ContractInstanceIds
{
    /// <summary>Trim + lowercase; empty when input is null/whitespace.</summary>
    public static string NormalizePlayerId(string? playerId)
    {
        var trimmed = playerId?.Trim();
        if (string.IsNullOrEmpty(trimmed))
        {
            return string.Empty;
        }

        return trimmed.ToLowerInvariant();
    }

    /// <summary>Trim + lowercase; empty when input is null/whitespace.</summary>
    public static string NormalizeContractInstanceId(string? contractInstanceId) => NormalizePlayerId(contractInstanceId);

    /// <summary>Trim + lowercase; empty when input is null/whitespace.</summary>
    public static string NormalizeTemplateId(string? templateId) => NormalizePlayerId(templateId);

    /// <summary>Trim; empty when input is null/whitespace (seed bucket casing preserved).</summary>
    public static string NormalizeSeedBucket(string? seedBucket)
    {
        var trimmed = seedBucket?.Trim();
        return string.IsNullOrEmpty(trimmed) ? string.Empty : trimmed;
    }

    /// <summary>Composite store key for <paramref name="playerId"/> + <paramref name="contractInstanceId"/>.</summary>
    public static string MakeInstanceKey(string? playerId, string? contractInstanceId)
    {
        var p = NormalizePlayerId(playerId);
        var i = NormalizeContractInstanceId(contractInstanceId);
        if (p.Length == 0 || i.Length == 0)
        {
            return string.Empty;
        }

        return $"{p}\0{i}";
    }

    /// <summary>
    /// Deterministic contract instance id from normalized seed inputs (NEO-147).
    /// Format: <c>ci_{32 lowercase hex}</c> from SHA-256 of <c>{playerId}|{templateId}|{seedBucket}</c>.
    /// </summary>
    public static string MakeDeterministicInstanceId(string? playerId, string? templateId, string? seedBucket)
    {
        var p = NormalizePlayerId(playerId);
        var t = NormalizeTemplateId(templateId);
        var b = NormalizeSeedBucket(seedBucket);
        if (p.Length == 0 || t.Length == 0 || b.Length == 0)
        {
            return string.Empty;
        }

        var payload = $"{p}|{t}|{b}";
        var hash = SHA256.HashData(Encoding.UTF8.GetBytes(payload));
        return $"ci_{Convert.ToHexStringLower(hash.AsSpan(0, 16))}";
    }
}