using System;
using System.Threading;
using System.Threading.Tasks;

namespace Aging.ResourceContracts
{
    /// <summary>与现有 OwnerType 数值对齐：Production=0, Maintenance=1。</summary>
    public enum OwnerTypeV3 { Production = 0, Maintenance = 1 }

    /// <summary>MVP 相位：Free 可用 / Active 持有 / RecoveryRequired 过期待回收（INV-03）。</summary>
    public enum LeasePhase { Free = 0, Active = 1, RecoveryRequired = 2 }

    /// <summary>每资源一张租约凭证；栅栏=(AuthorityId, Epoch, ResourceKey, LeaseId, Generation)。</summary>
    public sealed class LeaseGrant
    {
        public string AuthorityId { get; }
        public string ResourceKey { get; }
        public string LeaseId { get; }
        public string OwnerId { get; }
        public OwnerTypeV3 OwnerType { get; }
        public long Epoch { get; }
        public long Generation { get; }
        public long ExpiresUtcMs { get; }

        public LeaseGrant(string authorityId, string resourceKey, string leaseId,
            string ownerId, OwnerTypeV3 ownerType, long epoch, long generation, long expiresUtcMs)
        {
            AuthorityId = authorityId; ResourceKey = resourceKey; LeaseId = leaseId;
            OwnerId = ownerId; OwnerType = ownerType; Epoch = epoch;
            Generation = generation; ExpiresUtcMs = expiresUtcMs;
        }
    }

    public sealed class AcquireRequest
    {
        public string OwnerId { get; set; } = "";
        public OwnerTypeV3 OwnerType { get; set; }
        /// <summary>boot_id + pid，同机进程区分。</summary>
        public string ProcessInstanceId { get; set; } = "";
        public string MachineName { get; set; } = Environment.MachineName;
        public int HostProcessId { get; set; } = System.Diagnostics.Process.GetCurrentProcess().Id;
        /// <summary>申请理由（维护会话填操作员与原因，进 lease_history）。</summary>
        public string Reason { get; set; } = "";
        /// <summary>Ordinals 升序、去重后申请（组申请 = 单事务全有全无）。</summary>
        public string[] ResourceKeys { get; set; } = new string[0];
        public int WaitTimeoutMs { get; set; } = 1000;
        public int TtlSeconds { get; set; } = 30;
    }

    public enum AcquireResultCode { Acquired, Reused, ConflictHeld, RecoveryBlocked, Timeout }

    public sealed class ConflictInfo
    {
        public string OwnerId { get; set; } = "";
        public OwnerTypeV3 OwnerType { get; set; }
        public string MachineName { get; set; } = "";
        public int HostProcessId { get; set; }
        public string Reason { get; set; } = "";
        public long ExpiresUtcMs { get; set; }
    }

    public sealed class AcquireOutcome
    {
        public AcquireResultCode Code { get; set; }
        public LeaseGrant[] Grants { get; set; } = new LeaseGrant[0];
        public ConflictInfo? Holder { get; set; }
        /// <summary>RecoveryBlocked 时指向 recovery_checkpoint 的键。</summary>
        public string? RecoveryCheckpointKey { get; set; }
    }

    /// <summary>租约协调器：仲裁域唯一入口。实现方：DbLeaseStore。</summary>
    public interface ILeaseCoordinator
    {
        /// <summary>权威域当前 epoch（重启后递增，旧 Grant 自动失效）。</summary>
        long CurrentEpoch { get; }

        AcquireOutcome Acquire(AcquireRequest request);
        /// <summary>同 LeaseId+Generation 续期；返回 false=已被回收/超越（本地须熔断）。</summary>
        bool Renew(LeaseGrant grant, int extendSeconds);
        bool Release(LeaseGrant grant, string note);
        ConflictInfo? ProbeConflict(string resourceKey);
        LeasePhase PhaseOf(string resourceKey);
        int SweepExpired();
        /// <summary>RecoveryRequired → Free：宿主完成读回探测后登记证据并放行。</summary>
        bool ApproveRecovery(string resourceKey, string readbackJson, string approvedBy);
        /// <summary>测试用：强制提升 epoch，使所有活跃 Grant 失效。</summary>
        void BumpEpochForTest(string reason);
    }
}