using Microsoft.EntityFrameworkCore;
using Microsoft.Data.Sqlite;

namespace ClaudeDo.Data.Tests;

// Sibling migrations branched off the same parent have silently dropped each other's columns
// during a SQLite table rebuild before (see docs/explore-notes). Every other Data.Tests fixture
// uses EnsureCreated, which skips the migration chain entirely, so nothing else in the suite
// would catch that. This compares the schema the migration chain actually produces against the
// schema EnsureCreated builds from today's model.
public sealed class MigrationSchemaDriftTests : IDisposable
{
    private readonly string _migratedDbPath;
    private readonly string _modelDbPath;

    public MigrationSchemaDriftTests()
    {
        _migratedDbPath = Path.Combine(Path.GetTempPath(), $"claudedo_drift_migrated_{Guid.NewGuid():N}.db");
        _modelDbPath = Path.Combine(Path.GetTempPath(), $"claudedo_drift_model_{Guid.NewGuid():N}.db");
    }

    public void Dispose()
    {
        SqliteConnection.ClearAllPools();
        foreach (var path in new[] { _migratedDbPath, _modelDbPath })
            foreach (var suffix in new[] { "", "-wal", "-shm" })
                try { File.Delete(path + suffix); } catch { }
    }

    [Fact]
    public void Migrated_schema_has_the_same_columns_as_the_current_model()
    {
        using (var migrated = new ClaudeDoDbContext(OptionsFor(_migratedDbPath)))
            ClaudeDoDbContext.MigrateAndConfigure(migrated);
        using (var model = new ClaudeDoDbContext(OptionsFor(_modelDbPath)))
            model.Database.EnsureCreated();

        var migratedColumns = ReadColumnsByTable(_migratedDbPath);
        var modelColumns = ReadColumnsByTable(_modelDbPath);

        var mismatches = new List<string>();
        foreach (var (table, expectedColumns) in modelColumns)
        {
            if (!migratedColumns.TryGetValue(table, out var actualColumns))
            {
                mismatches.Add($"{table}: missing from migrated schema entirely");
                continue;
            }

            var missingInMigrated = expectedColumns.Except(actualColumns).ToList();
            var extraInMigrated = actualColumns.Except(expectedColumns).ToList();
            if (missingInMigrated.Count > 0 || extraInMigrated.Count > 0)
            {
                mismatches.Add(
                    $"{table}: missing-in-migrated=[{string.Join(", ", missingInMigrated)}] " +
                    $"extra-in-migrated=[{string.Join(", ", extraInMigrated)}]");
            }
        }

        Assert.True(mismatches.Count == 0, "Schema drift between migrated DB and current model:\n" + string.Join("\n", mismatches));
    }

    private static DbContextOptions<ClaudeDoDbContext> OptionsFor(string dbPath) =>
        new DbContextOptionsBuilder<ClaudeDoDbContext>()
            .UseSqlite($"Data Source={dbPath}")
            .Options;

    private static Dictionary<string, HashSet<string>> ReadColumnsByTable(string dbPath)
    {
        using var conn = new SqliteConnection($"Data Source={dbPath}");
        conn.Open();

        var tables = new List<string>();
        using (var cmd = conn.CreateCommand())
        {
            cmd.CommandText = "SELECT name FROM sqlite_master WHERE type='table' AND name != '__EFMigrationsHistory' AND name NOT LIKE 'sqlite_%'";
            using var reader = cmd.ExecuteReader();
            while (reader.Read())
                tables.Add(reader.GetString(0));
        }

        var result = new Dictionary<string, HashSet<string>>();
        foreach (var table in tables)
        {
            var columns = new HashSet<string>();
            using var cmd = conn.CreateCommand();
            cmd.CommandText = $"PRAGMA table_info(\"{table}\")";
            using var reader = cmd.ExecuteReader();
            while (reader.Read())
                columns.Add(reader.GetString(reader.GetOrdinal("name")));
            result[table] = columns;
        }

        return result;
    }
}