using Microsoft.Data.SqlClient;
using Xunit;

namespace ScadaLink.ConfigurationDatabase.Tests.Migrations;

/// <summary>
/// Bundle B2 (#22, #23 M3) integration tests for the <c>AddSiteCallsTable</c>
/// migration: applies the EF migrations to a freshly-created MSSQL test database
/// on the running infra/mssql container and asserts that the resulting
/// <c>SiteCalls</c> table carries the expected columns, primary key, and the
/// two named operational indexes.
/// </summary>
/// <remarks>
/// Unlike <c>AddAuditLogTable</c>, the SiteCalls table is operational (mutable)
/// state — no partition function, no partition scheme, no DB-role restriction.
/// Standard <c>[PRIMARY]</c> filegroup. Tests pair <see cref="SkippableFactAttribute"/>
/// with <c>Skip.IfNot(...)</c> so the runner reports them as Skipped (not Passed)
/// when MSSQL is unreachable. The fixture applies the migration once at
/// construction time.
/// </remarks>
public class AddSiteCallsTableMigrationTests : IClassFixture<MsSqlMigrationFixture>
{
    private readonly MsSqlMigrationFixture _fixture;

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

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

        var exists = await ScalarAsync<int>(
            "SELECT COUNT(*) FROM INFORMATION_SCHEMA.TABLES " +
            "WHERE TABLE_NAME = 'SiteCalls' AND TABLE_SCHEMA = 'dbo';");
        Assert.Equal(1, exists);

        // Every required column from SiteCall + IngestedAtUtc. We don't pin types
        // here because EF's CreateTable layer already encodes them; the
        // entity-config tests cover length / unicode / nullability for the
        // value-converted PK column. Just confirm the schema has all twelve.
        var expectedColumns = new[]
        {
            "TrackedOperationId",
            "Channel",
            "Target",
            "SourceSite",
            "Status",
            "RetryCount",
            "LastError",
            "HttpStatus",
            "CreatedAtUtc",
            "UpdatedAtUtc",
            "TerminalAtUtc",
            "IngestedAtUtc",
        };

        foreach (var column in expectedColumns)
        {
            var present = await ScalarAsync<int>(
                "SELECT COUNT(*) FROM INFORMATION_SCHEMA.COLUMNS " +
                $"WHERE TABLE_NAME = 'SiteCalls' AND COLUMN_NAME = '{column}';");
            Assert.True(present == 1, $"Expected SiteCalls.{column} to exist; found {present}.");
        }
    }

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

        // Walk sys.indexes for the table's clustered PK index and confirm its
        // single key column is TrackedOperationId. SiteCalls is non-partitioned
        // so the PK is a simple single-column clustered index.
        var pkColumn = await ScalarAsync<string?>(
            "SELECT c.name FROM sys.indexes i " +
            "INNER JOIN sys.objects o ON i.object_id = o.object_id " +
            "INNER JOIN sys.index_columns ic ON i.object_id = ic.object_id AND i.index_id = ic.index_id " +
            "INNER JOIN sys.columns c ON ic.object_id = c.object_id AND ic.column_id = c.column_id " +
            "WHERE o.name = 'SiteCalls' AND i.is_primary_key = 1;");

        Assert.Equal("TrackedOperationId", pkColumn);
    }

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

        var count = await ScalarAsync<int>(
            "SELECT COUNT(*) FROM sys.indexes i " +
            "INNER JOIN sys.objects o ON i.object_id = o.object_id " +
            "WHERE o.name = 'SiteCalls' AND i.name = 'IX_SiteCalls_Source_Created';");
        Assert.Equal(1, count);
    }

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

        var count = await ScalarAsync<int>(
            "SELECT COUNT(*) FROM sys.indexes i " +
            "INNER JOIN sys.objects o ON i.object_id = o.object_id " +
            "WHERE o.name = 'SiteCalls' AND i.name = 'IX_SiteCalls_Status_Updated';");
        Assert.Equal(1, count);
    }

    // --- helpers ------------------------------------------------------------

    private async Task<T> ScalarAsync<T>(string sql)
    {
        await using var conn = _fixture.OpenConnection();
        await using var cmd = conn.CreateCommand();
        cmd.CommandText = sql;
        var result = await cmd.ExecuteScalarAsync();
        if (result is null || result is DBNull)
        {
            return default!;
        }
        return (T)Convert.ChangeType(result, typeof(T) == typeof(string) ? typeof(string) : Nullable.GetUnderlyingType(typeof(T)) ?? typeof(T))!;
    }
}