using System.Text.RegularExpressions;
using Fleet.Core;
using Fleet.Identity;

namespace Fleet.Server;

/// <summary>注册流程：校验令牌 → 校验持有证明 → 创建节点 → 触发产品挂钩。与 HTTP 无关，便于测试。</summary>
public sealed partial class FleetEnrollmentService
{
    private readonly IFleetStore _store;
    private readonly IEnumerable<IEnrollmentHook> _hooks;
    private readonly IEnumerable<IOperatorTrustSource> _trust;
    private readonly FleetServerOptions _options;
    private readonly TimeProvider _time;

    public FleetEnrollmentService(IFleetStore store, IEnumerable<IEnrollmentHook> hooks, IEnumerable<IOperatorTrustSource> trust, FleetServerOptions options, TimeProvider time)
    {
        _store = store;
        _hooks = hooks;
        _trust = trust;
        _options = options;
        _time = time;
    }

    public async ValueTask<Result<EnrollResponse>> EnrollAsync(EnrollRequest request, string? remoteIp, CancellationToken ct)
    {
        if (string.IsNullOrEmpty(request.JoinToken) || !NamePattern().IsMatch(request.Name))
        {
            return Result<EnrollResponse>.Fail(FleetErrors.InvalidParams, "join_token and a valid name are required");
        }

        if (!TryDecode(request.PublicKey, out byte[] publicKey) || !NodeIdentity.IsValidPublicKey(publicKey)
            || !TryDecode(request.TlsSpki, out byte[] tlsSpki) || tlsSpki.Length != 32
            || !TryDecode(request.TlsPublicKey, out byte[] tlsPublicKey) || !NodeIdentity.IsValidPublicKey(tlsPublicKey)
            || !TryDecode(request.Proof, out byte[] proof))
        {
            return Result<EnrollResponse>.Fail(FleetErrors.InvalidParams, "pubkey, tls_spki, tls_pubkey or proof is malformed");
        }

        // 指纹和完整公钥必须是同一把密钥，否则对端按指纹固定证书、按公钥验签，会各认各的
        if (!System.Security.Cryptography.CryptographicOperations.FixedTimeEquals(NodeIdentity.Fingerprint(tlsPublicKey), tlsSpki))
        {
            return Result<EnrollResponse>.Fail(FleetErrors.InvalidParams, "tls_spki does not match tls_pubkey");
        }

        byte[] tokenHash = TokenHash.Sha256(request.JoinToken);
        JoinTokenRecord? token = await _store.FindJoinTokenAsync(tokenHash, ct);
        long nowMs = _time.GetUtcNow().ToUnixTimeMilliseconds();
        if (token is null || token.RevokedAtMs is not null || token.Uses >= token.MaxUses)
        {
            return Result<EnrollResponse>.Fail(FleetErrors.JoinTokenInvalid, "join token is invalid");
        }

        if (token.ExpiresAtMs <= nowMs)
        {
            return Result<EnrollResponse>.Fail(FleetErrors.JoinTokenExpired, "join token has expired");
        }

        if (!NodeIdentity.Verify(publicKey, proof, SignaturePurpose.Enroll, Convert.ToHexStringLower(tokenHash), request.PublicKey))
        {
            return Result<EnrollResponse>.Fail(FleetErrors.ProofInvalid, "proof of possession does not verify");
        }

        if (!await _store.TryConsumeJoinTokenAsync(token.Id, nowMs, ct))
        {
            return Result<EnrollResponse>.Fail(FleetErrors.JoinTokenInvalid, "join token is invalid");
        }

        // 同名节点已存在时进入 pending，由管理员选择“接管”或“作为新节点”。
        bool nameTaken = await _store.FindEstablishedNodeByNameAsync(request.Name, ct) is not null;
        NodeStatus status = token.AutoApprove && !nameTaken ? NodeStatus.Active : NodeStatus.Pending;

        string prefix = token.Kind.Length > 0 && _options.NodeIdPrefixes.TryGetValue(token.Kind, out string? kindPrefix) ? kindPrefix : _options.NodeIdPrefix;
        var node = new NewNode(
            new NodeId(Ulid.NewPrefixed(prefix, _time)),
            request.Name,
            status,
            publicKey,
            tlsSpki,
            token.Labels,
            request.Meta?.GetRawText(),
            request.NodeVersion,
            nowMs,
            token.Kind,
            tlsPublicKey,
            token.CreatedBy);

        Result<NodeRecord> created = await _store.CreateNodeAsync(node, ct);
        if (!created.TryGet(out NodeRecord? record, out FleetError? error))
        {
            return Result<EnrollResponse>.Fail(error);
        }

        var context = new EnrollmentContext(remoteIp, request.Meta);
        foreach (IEnrollmentHook hook in _hooks)
        {
            await hook.OnEnrolledAsync(record, context, ct);
        }

        return Result<EnrollResponse>.Ok(new EnrollResponse
        {
            NodeId = record.Id.Value,
            Status = record.Status == NodeStatus.Active ? "active" : "pending",
        });
    }

    /// <summary>节点注册之前取：操作员集合的链。码要是有效的；不能用的码不给。</summary>
    public async ValueTask<Result<TrustBundle>> GetTrustAsync(string joinToken, CancellationToken ct)
    {
        JoinTokenRecord? token = await _store.FindJoinTokenAsync(TokenHash.Sha256(joinToken), ct);
        long nowMs = _time.GetUtcNow().ToUnixTimeMilliseconds();
        if (token is null || token.RevokedAtMs is not null || token.Uses >= token.MaxUses)
        {
            return Result<TrustBundle>.Fail(FleetErrors.JoinTokenInvalid, "join token is invalid");
        }

        if (token.ExpiresAtMs <= nowMs)
        {
            return Result<TrustBundle>.Fail(FleetErrors.JoinTokenExpired, "join token has expired");
        }

        var bundle = new TrustBundle();
        foreach (IOperatorTrustSource source in _trust)
        {
            bundle.Chain.AddRange(await source.ChainAsync(ct));
        }

        return Result<TrustBundle>.Ok(bundle);
    }

    private static bool TryDecode(string text, out byte[] data)
    {
        try
        {
            data = Convert.FromBase64String(text);
            return data.Length > 0;
        }
        catch (FormatException)
        {
            data = [];
            return false;
        }
    }

    [GeneratedRegex(@"^[\p{L}\p{M}\p{N}._-]{1,64}$")]
    private static partial Regex NamePattern();
}