using ErsatzTV.Application.Search.Queries;
using ErsatzTV.Core.Api.Search;
using ErsatzTV.Core.Domain;
using ErsatzTV.Infrastructure;
using ErsatzTV.Infrastructure.Data;
using ErsatzTV.Infrastructure.MySql.Data;
using ErsatzTV.Infrastructure.Sqlite.Data;
using LanguageExt;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Logging.Abstractions;
using MySqlConnector;
using NUnit.Framework;
using Shouldly;

namespace ErsatzTV.Tests.Integration;

/// <summary>
///     ersatztv#668, EXECUTED on both providers. The bug was a collation/fold difference, so it lives exactly
///     where a single-provider test cannot see it: SQLite's <c>LOWER()</c> folds ASCII only and UNDER-matched
///     a stored <c>Édith</c>, while MySQL's is Unicode-aware and reaches it unaided. (Its column collation
///     is accent-INsensitive, but the executed comparison is not — see the method docstring below.)
///     <para>
///         <see cref="ErsatzTV.Tests.Application.Search.GetSearchFieldValuesHandlerTests" /> covers the
///         SQLite semantics in depth against in-memory SQLite, and
///         <c>SearchFieldValuesQueryShapeTests</c> pins the generated SQL for both providers without a
///         server. Neither can show that a REAL MySQL server returns the accented value — the fix's central
///         claim is "on both providers", and on MySQL that rests on the server's Unicode-aware
///         <c>LOWER()</c> rather than on any code this repo owns — explicitly NOT on its collation, which
///         the executed comparison bypasses. That is precisely the kind of assumption worth executing.
///     </para>
///     <para>
///         MySQL needs a live server via <c>ETV_TEST_MYSQL_CONNECTION</c>. Without it the MySQL fixture
///         <b>ignores</b> — a visible skip, never a silent pass. Setting <c>ETV_REQUIRE_MYSQL_TESTS=1</c>
///         turns that skip into a hard failure, so an ARMED lane cannot degrade into "connected to nothing
///         and passed".
///     </para>
///     <para>
///         <b>CI does not currently arm it</b>, so in CI this half SKIPS. Running MySQL fixtures against the
///         live service was implemented and then removed as non-deterministic — see the note in
///         <c>.gitea/workflows/docker-build.yml</c>; re-arming is tracked by ersatztv#627. Do not read the
///         REQUIRE variable above as a guarantee that something enforces this today: nothing does. This
///         mirrors <see cref="LibraryFolderDedupeMigrationTests" /> deliberately; the two fixtures share the
///         contract, not code, because their setup needs differ.
///     </para>
/// </summary>
[TestFixture(TestProvider.Sqlite)]
[TestFixture(TestProvider.MySql)]
[NonParallelizable]
public class SearchFieldValuesProviderTests(TestProvider provider)
{
    private const string MySqlConnectionVariable = "ETV_TEST_MYSQL_CONNECTION";
    private const string MySqlRequiredVariable = "ETV_REQUIRE_MYSQL_TESTS";

    private string _databasePath = null!;
    private string? _mySqlConnectionString;
    private DbContextOptions<TvContext> _options = null!;

    [SetUp]
    public async Task SetUp()
    {
        if (provider is TestProvider.Sqlite)
        {
            TvContext.IsSqlite = true;
            TvContext.LastInsertedRowId = "last_insert_rowid()";
            TvContext.CaseInsensitiveCollation = "NOCASE";
            TvContext.IsUniqueConstraintViolation = SqliteErrorClassifier.IsUniqueConstraintViolation;
            TvContext.RegisterUnicodeCaseFunctions = SqliteUnicodeFunctions.Register;

            _databasePath = Path.Combine(Path.GetTempPath(), $"etv668-{Guid.NewGuid():N}.sqlite3");
            _options = new DbContextOptionsBuilder<TvContext>()
                .UseSqlite($"Data Source={_databasePath}")
                .Options;
        }
        else
        {
            string? baseConnectionString = Environment.GetEnvironmentVariable(MySqlConnectionVariable);
            if (string.IsNullOrWhiteSpace(baseConnectionString))
            {
                string message =
                    $"{MySqlConnectionVariable} is not set, so the MySql half of the #668 facet-value fixture "
                    + "cannot run. This endpoint's correctness is collation-dependent and therefore "
                    + "provider-specific, so the coverage is not optional in CI.";

                if (IsTrue(Environment.GetEnvironmentVariable(MySqlRequiredVariable)))
                {
                    Assert.Fail($"{message} {MySqlRequiredVariable} is set, so this is a failure, not a skip.");
                }

                Assert.Ignore($"{message} Set it to run this locally.");
            }

            // A database of our own with a name that has never been used, so isolation does not depend on a
            // wipe succeeding. Dropped and its pool cleared in TearDown.
            _mySqlConnectionString =
                new MySqlConnectionStringBuilder(baseConnectionString) { Database = $"etv668_{Guid.NewGuid():N}" }
                    .ConnectionString;

            TvContext.IsSqlite = false;
            TvContext.LastInsertedRowId = "last_insert_id()";
            TvContext.CaseInsensitiveCollation = "utf8mb4_general_ci";
            TvContext.IsUniqueConstraintViolation = MySqlErrorClassifier.IsUniqueConstraintViolation;

            // Explicitly the no-op: MySQL's own LOWER() is Unicode-aware, so the handler must reach the
            // accented value WITHOUT any custom fold. Wiring SQLite's here would mask that.
            TvContext.RegisterUnicodeCaseFunctions = static _ => { };

            _options = new DbContextOptionsBuilder<TvContext>()
                .UseMySql(_mySqlConnectionString, ServerVersion.AutoDetect(_mySqlConnectionString))
                .Options;
        }

        // Schema creation deliberately does NOT happen here: NUnit skips [TearDown] when [SetUp] throws, so
        // a failure part-way through EnsureCreatedAsync would strand the created database (and its pooled
        // connection) with nothing to drop it. The test body creates it instead, matching the sibling
        // fixture, whose SetUp likewise cannot strand one.
    }

    [TearDown]
    public async Task TearDown()
    {
        if (provider is TestProvider.Sqlite)
        {
            Microsoft.Data.Sqlite.SqliteConnection.ClearAllPools();
            foreach (string path in new[] { _databasePath, $"{_databasePath}-wal", $"{_databasePath}-shm" })
            {
                if (File.Exists(path))
                {
                    File.Delete(path);
                }
            }

            return;
        }

        if (_mySqlConnectionString is not null)
        {
            await using (TvContext context = Create(_options))
            {
                await context.Database.EnsureDeletedAsync();
            }

            // MySqlConnector keys pools by connection string; a fresh database name means a fresh pool, and
            // leaving it uncleared leaks a server thread per test until max_connections is exhausted.
            await using var probe = new MySqlConnection(_mySqlConnectionString);
            await MySqlConnection.ClearPoolAsync(probe);

            _mySqlConnectionString = null;
        }
    }

    /// <summary>
    ///     The #668 headline, executed: a stored value whose prefix carries an UPPERCASE non-ASCII character
    ///     is reachable from both casings of the query, on whichever provider this fixture is running.
    ///     <para>
    ///         Negative controls: "Zulu" (trivially unrelated) and "Edith" (unaccented, the near miss).
    ///         <b>Be precise about what "Edith" does and does not prove.</b> It was added expecting MySQL to
    ///         OVER-match it — the column collation is <c>utf8mb4_0900_ai_ci</c>, so <c>é</c> equals <c>e</c>
    ///         — which would have made the in-memory ordinal filter load-bearing here. Measured against a
    ///         live 8.4 server, it does not: deleting that filter leaves this test green, because the driver
    ///         binds the LIKE pattern with a BINARY collation and the executed comparison is therefore
    ///         accent-SENSITIVE. (A literal pattern typed by hand DOES over-match — a different query from
    ///         the one the handler runs.) So the row pins the accent-sensitive result on both providers and
    ///         documents the near miss; it does NOT exercise an over-match correction, because with the
    ///         CURRENT driver there is nothing to correct. That is a driver-contingent fact, not a law: a
    ///         driver or protocol change that made the pattern ci-collated would restore the over-match, and
    ///         the ordinal filter — which stays regardless — would then be doing real work here.
    ///     </para>
    /// </summary>
    [TestCase("é", TestName = "Uppercase_Accent_Reachable_From_Lowercase_Query")]
    [TestCase("É", TestName = "Uppercase_Accent_Reachable_From_Uppercase_Query")]
    public async Task Stored_Uppercase_Accent_Is_Reachable(string query)
    {
        await using (TvContext context = Create(_options))
        {
            await context.Database.EnsureCreatedAsync();
            context.Set<Genre>().AddRange(
                new Genre { Name = "Édith" },
                new Genre { Name = "Edith" },
                new Genre { Name = "Zulu" });
            await context.SaveChangesAsync();
        }

        var handler = new GetSearchFieldValuesHandler(new TestDbContextFactory(_options));

        Option<SearchFieldValuesResponseModel> result = await handler.Handle(
            new GetSearchFieldValues("genre", query, 50),
            CancellationToken.None);

        result.IsSome.ShouldBeTrue();
        result.IfSome(r => r.Values.ShouldBe(new List<string> { "Édith" }));
    }

    private static bool IsTrue(string? value) =>
        value is "1" || string.Equals(value, "true", StringComparison.OrdinalIgnoreCase);

    private static TvContext Create(DbContextOptions<TvContext> options) =>
        new(
            options,
            NullLoggerFactory.Instance,
            new SlowQueryInterceptor(NullLogger<SlowQueryInterceptor>.Instance));

    private sealed class TestDbContextFactory(DbContextOptions<TvContext> options) : IDbContextFactory<TvContext>
    {
        public TvContext CreateDbContext() => Create(options);
    }
}