using System.Data.Common;
using Data.SeaHavenIndustries;
using Microsoft.Data.Sqlite;
using Microsoft.EntityFrameworkCore;
using Microsoft.EntityFrameworkCore.Diagnostics;
using SeaHaven.DataServices.Implementation;

namespace SeaHavenIndustries.Tests;

public sealed class UpliftDataServiceTransactionTests
{
    [Theory]
    [InlineData("Cannot insert duplicate key row with unique index 'IX_DispatchUpliftRequests_DispatchId'.", true)]
    [InlineData("Cannot insert duplicate key row with unique index 'IX_DispatchUpliftRequests_DispatchId_RequestKey'.", false)]
    public void IsActiveDispatchIndexViolationMessage_MatchesOnlyTheActiveDispatchIndex(
        string message,
        bool expected)
    {
        Assert.Equal(expected, UpliftDataService.IsActiveDispatchIndexViolationMessage(message));
    }

    [Fact]
    public async Task SaveChangesAsync_ActiveUpliftOnSameDispatch_MapsConcurrentInsertConflict()
    {
        await using var connection = new SqliteConnection("DataSource=:memory:");
        await connection.OpenAsync();
        var options = new DbContextOptionsBuilder<ApplicationDbContext>()
            .UseSqlite(connection)
            .Options;

        await using var context = new ApplicationDbContext(options);
        await context.Database.EnsureCreatedAsync();
        context.Vendors.Add(new Vendor { Id = 1, CompanyName = "Acme HVAC" });
        context.Dispatches.Add(new Dispatch
        {
            Id = 10,
            VendorId = 1,
            DispatchNumber = "DIS-10",
            Status = "Scheduled",
        });
        await context.SaveChangesAsync();

        var data = new UpliftDataService(context);
        await data.StageAsync(new DispatchUpliftRequest
        {
            DispatchId = 10,
            RequestedNTE = 1500m,
            Status = "Pending",
            RequiredTier = 1,
            NotificationStatus = "Pending",
        }, CancellationToken.None);
        await data.SaveChangesAsync(CancellationToken.None);

        // The database index is the final guard when competing requests pass
        // their dispatch-scoped active-request checks.
        var exception = await Assert.ThrowsAsync<SeaHaven.DataServices.Exceptions.UpliftDispatchConflictException>(
            () => data.ExecuteWorkOrderMutationAsync(
                2,
                async cancellationToken =>
                {
                    await data.StageAsync(new DispatchUpliftRequest
                    {
                        DispatchId = 10,
                        RequestedNTE = 1700m,
                        Status = "Pending",
                        RequiredTier = 1,
                        NotificationStatus = "Pending",
                    }, cancellationToken);
                    await data.SaveChangesAsync(cancellationToken);
                    return true;
                },
                CancellationToken.None));
        Assert.Equal("An active uplift request already exists for this dispatch.", exception.Message);
        Assert.Equal(1, await context.DispatchUpliftRequests.CountAsync());
    }

    [Fact]
    public async Task SaveChangesAsync_RequestKeyConflict_IsNotMappedToActiveDispatchConflict()
    {
        await using var connection = new SqliteConnection("DataSource=:memory:");
        await connection.OpenAsync();
        var options = new DbContextOptionsBuilder<ApplicationDbContext>()
            .UseSqlite(connection)
            .Options;

        await using var context = new ApplicationDbContext(options);
        await context.Database.EnsureCreatedAsync();
        context.Vendors.Add(new Vendor { Id = 1, CompanyName = "Acme HVAC" });
        context.Dispatches.Add(new Dispatch
        {
            Id = 10,
            VendorId = 1,
            DispatchNumber = "DIS-10",
            Status = "Scheduled",
        });
        await context.SaveChangesAsync();

        var data = new UpliftDataService(context);
        await data.StageAsync(new DispatchUpliftRequest
        {
            DispatchId = 10,
            RequestKey = "same-key",
            RequestedNTE = 1500m,
            Status = "Approved",
            RequiredTier = 1,
            NotificationStatus = "Sent",
        }, CancellationToken.None);
        await data.SaveChangesAsync(CancellationToken.None);
        await data.StageAsync(new DispatchUpliftRequest
        {
            DispatchId = 10,
            RequestKey = "same-key",
            RequestedNTE = 1700m,
            Status = "Approved",
            RequiredTier = 1,
            NotificationStatus = "Sent",
        }, CancellationToken.None);

        await Assert.ThrowsAsync<DbUpdateException>(
            () => data.SaveChangesAsync(CancellationToken.None));
    }

    [Fact]
    public async Task ExecuteWorkOrderMutationAsync_ReleasesGate_WhenTransactionInitializationFails()
    {
        await using var connection = new SqliteConnection("DataSource=:memory:");
        await connection.OpenAsync();

        var failingOptions = new DbContextOptionsBuilder<ApplicationDbContext>()
            .UseSqlite(connection)
            .AddInterceptors(new ThrowOnceTransactionInterceptor())
            .Options;

        await using (var failedContext = new ApplicationDbContext(failingOptions))
        {
            var failedService = new UpliftDataService(failedContext);

            await Assert.ThrowsAsync<InvalidOperationException>(() =>
                failedService.ExecuteWorkOrderMutationAsync(
                    387,
                    _ => Task.FromResult(true),
                    CancellationToken.None));
        }

        var retryOptions = new DbContextOptionsBuilder<ApplicationDbContext>()
            .UseSqlite(connection)
            .Options;
        await using var retryContext = new ApplicationDbContext(retryOptions);
        var retryService = new UpliftDataService(retryContext);

        var retry = retryService.ExecuteWorkOrderMutationAsync(
            387,
            _ => Task.FromResult("entered"),
            CancellationToken.None);

        Assert.Equal("entered", await retry.WaitAsync(TimeSpan.FromSeconds(1)));
    }

    private sealed class ThrowOnceTransactionInterceptor : DbTransactionInterceptor
    {
        private int _remaining = 1;

        public override InterceptionResult<DbTransaction> TransactionStarting(
            DbConnection connection,
            TransactionStartingEventData eventData,
            InterceptionResult<DbTransaction> result)
        {
            ThrowOnce();
            return base.TransactionStarting(connection, eventData, result);
        }

        public override ValueTask<InterceptionResult<DbTransaction>> TransactionStartingAsync(
            DbConnection connection,
            TransactionStartingEventData eventData,
            InterceptionResult<DbTransaction> result,
            CancellationToken cancellationToken = default)
        {
            ThrowOnce();
            return base.TransactionStartingAsync(connection, eventData, result, cancellationToken);
        }

        private void ThrowOnce()
        {
            if (Interlocked.Exchange(ref _remaining, 0) == 1)
                throw new InvalidOperationException("Forced transaction initialization failure");
        }
    }
}