using ItWorx.KnowledgeHub.Infrastructure.Operations;
using ItWorx.KnowledgeHub.Infrastructure.Persistence;
using ItWorx.KnowledgeHub.IntegrationTests.Infrastructure;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.Diagnostics.HealthChecks;

namespace ItWorx.KnowledgeHub.IntegrationTests.Operations;

/// <summary>Proves M7-A05 ("Health endpoints distinguish liveness, readiness and
/// degraded dependencies") against real PostgreSQL and a real filesystem, not mocks.
/// </summary>
[Collection(PostgresTestGroup.Name)]
public sealed class HealthCheckTests(PostgresContainerFixture postgres)
{
    [Fact]
    public async Task A_fully_migrated_reachable_database_is_healthy()
    {
        await using var target = await RestoreTargetDatabase.CreateAsync(postgres);
        var options = new DbContextOptionsBuilder<KnowledgeHubDbContext>()
            .UseNpgsql(target.ConnectionString, npgsql => npgsql.MigrationsAssembly(typeof(KnowledgeHubDbContext).Assembly.GetName().Name))
            .UseSnakeCaseNamingConvention()
            .Options;
        await using var db = new KnowledgeHubDbContext(options);
        var check = new DatabaseHealthCheck(db);

        var result = await check.CheckHealthAsync(new HealthCheckContext());

        Assert.Equal(HealthStatus.Healthy, result.Status);
    }

    [Fact]
    public async Task An_unreachable_database_is_unhealthy_not_a_thrown_exception()
    {
        var options = new DbContextOptionsBuilder<KnowledgeHubDbContext>()
            .UseNpgsql("Host=127.0.0.1;Port=1;Database=does-not-exist;Username=nobody;Password=nothing;Timeout=1")
            .UseSnakeCaseNamingConvention()
            .Options;
        await using var db = new KnowledgeHubDbContext(options);
        var check = new DatabaseHealthCheck(db);

        var result = await check.CheckHealthAsync(new HealthCheckContext());

        Assert.Equal(HealthStatus.Unhealthy, result.Status);
    }

    [Fact]
    public async Task A_database_with_pending_migrations_is_unhealthy()
    {
        var databaseName = $"health_unmigrated_{Guid.NewGuid():N}";
        await using (var admin = new Npgsql.NpgsqlConnection(postgres.AdminConnectionString))
        {
            await admin.OpenAsync();
            await using var create = new Npgsql.NpgsqlCommand($"CREATE DATABASE \"{databaseName}\"", admin);
            await create.ExecuteNonQueryAsync();
        }

        try
        {
            var connectionString = new Npgsql.NpgsqlConnectionStringBuilder(postgres.AdminConnectionString) { Database = databaseName }.ConnectionString;
            var options = new DbContextOptionsBuilder<KnowledgeHubDbContext>()
                .UseNpgsql(connectionString, npgsql => npgsql.MigrationsAssembly(typeof(KnowledgeHubDbContext).Assembly.GetName().Name))
                .UseSnakeCaseNamingConvention()
                .Options;
            await using var db = new KnowledgeHubDbContext(options);
            var check = new DatabaseHealthCheck(db);

            // Reachable, but never migrated — must never be reported ready.
            var result = await check.CheckHealthAsync(new HealthCheckContext());

            Assert.Equal(HealthStatus.Unhealthy, result.Status);
        }
        finally
        {
            await using var admin = new Npgsql.NpgsqlConnection(postgres.AdminConnectionString);
            await admin.OpenAsync();
            await using var drop = new Npgsql.NpgsqlCommand($"DROP DATABASE IF EXISTS \"{databaseName}\" WITH (FORCE)", admin);
            await drop.ExecuteNonQueryAsync();
        }
    }

    [Fact]
    public async Task All_writable_configured_paths_are_healthy()
    {
        var root = Path.Combine(Path.GetTempPath(), "ikh-health-writable", Guid.NewGuid().ToString("N"));
        var configuration = new ConfigurationBuilder()
            .AddInMemoryCollection(new Dictionary<string, string?>
            {
                ["KnowledgeHub:Paths:Data"] = Path.Combine(root, "data"),
                ["KnowledgeHub:Paths:Attachments"] = Path.Combine(root, "attachments")
            })
            .Build();
        var check = new StorageHealthCheck(configuration);

        try
        {
            var result = await check.CheckHealthAsync(new HealthCheckContext());

            Assert.Equal(HealthStatus.Healthy, result.Status);
        }
        finally
        {
            if (Directory.Exists(root))
            {
                Directory.Delete(root, recursive: true);
            }
        }
    }

    [Fact]
    public async Task A_path_that_cannot_be_created_as_a_directory_is_unhealthy()
    {
        var blockingFile = Path.Combine(Path.GetTempPath(), $"ikh-health-blocking-{Guid.NewGuid():N}.tmp");
        await File.WriteAllBytesAsync(blockingFile, [1]);

        try
        {
            // A configured path that collides with an existing *file* can never become
            // a writable directory — a real, not simulated, storage failure.
            var configuration = new ConfigurationBuilder()
                .AddInMemoryCollection(new Dictionary<string, string?> { ["KnowledgeHub:Paths:Data"] = blockingFile })
                .Build();
            var check = new StorageHealthCheck(configuration);

            var result = await check.CheckHealthAsync(new HealthCheckContext());

            Assert.Equal(HealthStatus.Unhealthy, result.Status);
        }
        finally
        {
            File.Delete(blockingFile);
        }
    }
}