using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Logging;
using Gpulse.WCT.DataAnalyzer.Core.Infrastructure.LocalData;
using Gpulse.WCT.DataAnalyzer.Core.Domain.Local;

namespace Gpulse.WCT.DataAnalyzer.Core.Application;

/// <summary>
/// 维度表管理服务 - 负责维度表的CRUD操作（并发安全版本）
/// </summary>
public class DimensionService
{
    private readonly WctMinerDbContext _context;
    private readonly ILogger<DimensionService> _logger;

    public DimensionService(WctMinerDbContext context, ILogger<DimensionService> logger)
    {
        _context = context;
        _logger = logger;
    }

    /// <summary>
    /// 获取或创建TX面板维度（并发安全）
    /// </summary>
    public async Task<TxPanel> GetOrCreateTxPanelAsync(string name)
    {
        return await GetOrCreateDimensionAsync(
            () => _context.TxPanels.AsNoTracking().FirstOrDefaultAsync(p => p.Name == name),
            () => new TxPanel { Name = name },
            entity => _context.TxPanels.Add(entity),
            name,
            "TX Panel"
        );
    }

    /// <summary>
    /// 获取或创建TX硬件版本维度（并发安全）
    /// </summary>
    public async Task<TxHardware> GetOrCreateTxHardwareAsync(string version)
    {
        return await GetOrCreateDimensionAsync(
            () => _context.TxHardwares.AsNoTracking().FirstOrDefaultAsync(h => h.Version == version),
            () => new TxHardware { Version = version },
            entity => _context.TxHardwares.Add(entity),
            version,
            "TX Hardware"
        );
    }

    /// <summary>
    /// 获取或创建TX软件版本维度（并发安全）
    /// </summary>
    public async Task<TxSoftware> GetOrCreateTxSoftwareAsync(string version)
    {
        return await GetOrCreateDimensionAsync(
            () => _context.TxSoftwares.AsNoTracking().FirstOrDefaultAsync(s => s.Version == version),
            () => new TxSoftware { Version = version },
            entity => _context.TxSoftwares.Add(entity),
            version,
            "TX Software"
        );
    }

    /// <summary>
    /// 获取或创建RX类型维度（并发安全）
    /// </summary>
    public async Task<RxType> GetOrCreateRxTypeAsync(string name)
    {
        return await GetOrCreateDimensionAsync(
            () => _context.RxTypes.AsNoTracking().FirstOrDefaultAsync(r => r.Name == name),
            () => new RxType { Name = name },
            entity => _context.RxTypes.Add(entity),
            name,
            "RX Type"
        );
    }

    /// <summary>
    /// 通用的并发安全 GetOrCreate 模式
    /// </summary>
    private async Task<T> GetOrCreateDimensionAsync<T>(
        Func<Task<T?>> findExisting,
        Func<T> createNew,
        Action<T> addToContext,
        string identifier,
        string dimensionName) where T : class
    {
        const int maxRetries = 3;

        for (int attempt = 0; attempt < maxRetries; attempt++)
        {
            // 使用 AsNoTracking 避免 ChangeTracker 缓存
            var existing = await findExisting();

            if (existing != null) return existing;

            var newEntity = createNew();
            addToContext(newEntity);

            try
            {
                await _context.SaveChangesAsync();
                _logger.LogDebug("创建新 {DimensionName} 维度: {Identifier}", dimensionName, identifier);
                return newEntity;
            }
            catch (DbUpdateException ex) when (IsUniqueConstraintViolation(ex))
            {
                // Detach 实体以避免 ChangeTracker 问题
                _context.Entry(newEntity).State = EntityState.Detached;
                _logger.LogDebug("{DimensionName} 并发创建冲突，重试: {Identifier}", dimensionName, identifier);

                if (attempt < maxRetries - 1)
                {
                    // 随机退避，减少并发冲突
                    await Task.Delay(Random.Shared.Next(5, 20));
                }
            }
        }

        // 最后一次尝试：必然存在（唯一约束已生效）
        var finalEntity = await findExisting();
        if (finalEntity == null)
        {
            // 极端情况：重试全部失败但数据不存在，抛出异常
            throw new InvalidOperationException($"无法获取或创建 {dimensionName} 维度: {identifier}");
        }
        return finalEntity;
    }

    /// <summary>
    /// 检测 SQLite 唯一约束违反错误
    /// </summary>
    private static bool IsUniqueConstraintViolation(DbUpdateException ex)
    {
        return ex.InnerException is Microsoft.Data.Sqlite.SqliteException sqliteEx
            && sqliteEx.SqliteErrorCode == 19; // SQLITE_CONSTRAINT
    }
}