using Microsoft.EntityFrameworkCore;
using ZB.MOM.WW.ScadaBridge.Commons.Entities.Deployment;
using ZB.MOM.WW.ScadaBridge.Commons.Entities.Instances;
using ZB.MOM.WW.ScadaBridge.Commons.Entities.Sites;
using ZB.MOM.WW.ScadaBridge.Commons.Entities.Templates;
using ZB.MOM.WW.ScadaBridge.ConfigurationDatabase.Repositories;
using ZB.MOM.WW.ScadaBridge.ConfigurationDatabase.Tests.Migrations;
using Xunit;

namespace ZB.MOM.WW.ScadaBridge.ConfigurationDatabase.Tests.Repositories;

/// <summary>
/// SQL Server integration coverage for the notify-and-fetch <see cref="PendingDeployment"/>
/// staging store's <b>same-DeploymentId re-stage</b> path. The SQLite in-memory fixture
/// (<c>PendingDeploymentRepositoryTests</c>) covers the logic, but the delete-before-insert
/// ordering that lets <see cref="DeploymentManagerRepository.StagePendingIfAbsentAsync"/>
/// re-stage an instance's OWN <c>DeploymentId</c> over an expired row depends on EF emitting
/// the DELETE before the INSERT within a single <c>SaveChanges</c> — against the production
/// UNIQUE index on <c>DeploymentId</c>. SQLite's constraint timing differs from SQL Server's
/// (SQLite defers/relaxes within a transaction where SQL Server enforces per-statement), so
/// this class asserts the behaviour against the real migrated schema via
/// <see cref="MsSqlMigrationFixture"/> rather than the SQLite provider.
/// </summary>
public class PendingDeploymentRepositoryIntegrationTests : IClassFixture<MsSqlMigrationFixture>
{
    private readonly MsSqlMigrationFixture _fixture;

    public PendingDeploymentRepositoryIntegrationTests(MsSqlMigrationFixture fixture)
    {
        _fixture = fixture;
    }

    [SkippableFact]
    public async Task StagePendingIfAbsent_ExpiredRowSameDeploymentId_ReStages_NoUniqueViolation()
    {
        Skip.IfNot(_fixture.Available, _fixture.SkipReason);

        var instanceId = await SeedInstanceAsync("ReStageInst");
        var now = DateTimeOffset.UtcNow;

        // Seed an EXPIRED pending row carrying DeploymentId "D1". A startup reconcile re-stages
        // the DeployedConfigSnapshot's OWN DeploymentId, so the fresh row reuses "D1" — the exact
        // collision the unique index would reject if the DELETE didn't precede the INSERT.
        await using (var seedContext = CreateContext())
        {
            seedContext.Set<PendingDeployment>().Add(new PendingDeployment(
                "D1", instanceId, "rev-old", "{\"old\":true}", "tok-old",
                now.AddMinutes(-20), now.AddMinutes(-10)));
            await seedContext.SaveChangesAsync();
        }

        // Re-stage "D1" over the expired row. Against the real UNIQUE index on DeploymentId this
        // MUST succeed (EF orders delete-before-insert in the single SaveChanges) rather than
        // throwing SqlException 2627/2601.
        await using (var context = CreateContext())
        {
            var repo = new DeploymentManagerRepository(context);
            var staged = await repo.StagePendingIfAbsentAsync(
                instanceId, "D1", "rev-new", "{\"new\":true}", "tok-new",
                now, now.AddMinutes(10));
            Assert.True(staged);
        }

        // Exactly one row for "D1" survives — the fresh one.
        await using (var readContext = CreateContext())
        {
            var rows = await readContext.Set<PendingDeployment>()
                .Where(p => p.DeploymentId == "D1")
                .ToListAsync();
            Assert.Single(rows);
            Assert.Equal("tok-new", rows[0].Token);
            Assert.Equal("{\"new\":true}", rows[0].ConfigurationJson);
            Assert.True(rows[0].ExpiresAtUtc > now);
        }
    }

    [SkippableFact]
    public async Task AddPendingDeployment_NewDeployDifferentId_SupersedesPriorRow_OnRealSqlServer()
    {
        Skip.IfNot(_fixture.Available, _fixture.SkipReason);

        var instanceId = await SeedInstanceAsync("SupersedeInst");
        var now = DateTimeOffset.UtcNow;

        await using (var context = CreateContext())
        {
            var repo = new DeploymentManagerRepository(context);
            await repo.AddPendingDeploymentAsync(new PendingDeployment(
                "dep-A", instanceId, "rev-a", "{\"v\":1}", "tok-a", now, now.AddMinutes(5)));
            await repo.SaveChangesAsync();
        }

        // A newer deploy for the SAME instance with a DIFFERENT DeploymentId must replace the
        // prior row (delete-then-insert under the per-instance operation lock) with no FK or
        // unique conflict on real SQL Server.
        await using (var context = CreateContext())
        {
            var repo = new DeploymentManagerRepository(context);
            await repo.AddPendingDeploymentAsync(new PendingDeployment(
                "dep-B", instanceId, "rev-b", "{\"v\":2}", "tok-b", now, now.AddMinutes(5)));
            await repo.SaveChangesAsync();
        }

        await using (var readContext = CreateContext())
        {
            var rows = await readContext.Set<PendingDeployment>()
                .Where(p => p.InstanceId == instanceId)
                .ToListAsync();
            Assert.Single(rows);
            Assert.Equal("dep-B", rows[0].DeploymentId);
            Assert.Equal("{\"v\":2}", rows[0].ConfigurationJson);
        }
    }

    /// <summary>
    /// Seeds an Instance (with its required Site + Template) against the fixture database and
    /// returns its generated id. The PendingDeployment → Instance FK requires a real parent row.
    /// </summary>
    private async Task<int> SeedInstanceAsync(string uniqueName)
    {
        await using var context = CreateContext();
        var site = new Site($"Site-{uniqueName}", $"S-{uniqueName}");
        var template = new Template($"T-{uniqueName}");
        context.Sites.Add(site);
        context.Templates.Add(template);
        await context.SaveChangesAsync();

        var instance = new Instance(uniqueName) { SiteId = site.Id, TemplateId = template.Id };
        context.Instances.Add(instance);
        await context.SaveChangesAsync();
        return instance.Id;
    }

    private ScadaBridgeDbContext CreateContext()
    {
        var options = new DbContextOptionsBuilder<ScadaBridgeDbContext>()
            .UseSqlServer(_fixture.ConnectionString)
            .Options;
        return new ScadaBridgeDbContext(options);
    }
}