using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using static StellaOps.Localization.T;

namespace StellaOps.Provcache;

public sealed partial class VeriKeyBuilder
{
    /// <summary>
    /// Sets the VEX hash set hash (sorted aggregation of VEX statement hashes).
    /// </summary>
    /// <param name="vexHashSetHash">The pre-computed VEX hash set hash.</param>
    /// <returns>This builder for fluent chaining.</returns>
    public VeriKeyBuilder WithVexHashSet(string vexHashSetHash)
    {
        if (string.IsNullOrWhiteSpace(vexHashSetHash))
            throw new ArgumentException(_t("common.provcache.vex_hash_required"), nameof(vexHashSetHash));

        _vexHashSetHash = NormalizeHash(vexHashSetHash);
        return this;
    }

    /// <summary>
    /// Computes VEX hash set from individual VEX statement hashes.
    /// Hashes are sorted lexicographically before aggregation for determinism.
    /// </summary>
    /// <param name="vexStatementHashes">Individual VEX statement hashes.</param>
    /// <returns>This builder for fluent chaining.</returns>
    public VeriKeyBuilder WithVexStatementHashes(IEnumerable<string> vexStatementHashes)
    {
        ArgumentNullException.ThrowIfNull(vexStatementHashes);

        var sortedHashes = vexStatementHashes
            .Where(h => !string.IsNullOrWhiteSpace(h))
            .Select(NormalizeHash)
            .Order(StringComparer.Ordinal)
            .ToList();

        if (sortedHashes.Count == 0)
        {
            _vexHashSetHash = ComputeHash(Encoding.UTF8.GetBytes("empty-vex-set"));
        }
        else
        {
            var concatenated = string.Join("|", sortedHashes);
            _vexHashSetHash = ComputeHash(Encoding.UTF8.GetBytes(concatenated));
        }

        return this;
    }
}