using Microsoft.Data.Sqlite;
using Microsoft.EntityFrameworkCore;
using ProposalSystem.Infrastructure.Data;

namespace ProposalSystem.Tests.Helpers;

/// <summary>
/// Creates SQLite-backed in-memory DbContext instances for tests that require relational
/// features (e.g., ExecuteSqlRawAsync, transactions). The SQLite connection is kept open
/// for the lifetime of the context; disposing the context closes the connection and
/// discards the in-memory database.
///
/// Registers stub Postgres functions (hashtext, pg_advisory_xact_lock) so that
/// production SQL using these functions does not throw in the test environment.
/// </summary>
public static class SqliteDbContextFactory
{
    /// <summary>
    /// Creates a new ProposalDbContext backed by a unique SQLite in-memory database.
    /// The returned context owns the connection; dispose the context to clean up.
    /// </summary>
    public static ProposalDbContext Create()
    {
        var connection = new SqliteConnection("DataSource=:memory:");
        connection.Open();

        // Register Postgres-specific function stubs so ExecuteSqlRawAsync calls
        // like "SELECT pg_advisory_xact_lock(hashtext('...'))" succeed in SQLite.
        RegisterPostgresStubs(connection);

        var options = new DbContextOptionsBuilder<ProposalDbContext>()
            .UseSqlite(connection)
            .Options;

        var context = new ProposalDbContext(options);
        context.Database.EnsureCreated();
        return context;
    }

    /// <summary>
    /// Opens a shared in-memory database and returns the connection plus a factory
    /// for additional contexts over the SAME database — needed by optimistic-
    /// concurrency tests that simulate two competing writers. Callers dispose the
    /// connection after the contexts.
    /// </summary>
    public static (SqliteConnection Connection, Func<ProposalDbContext> ContextFactory) CreateShared()
    {
        var connection = new SqliteConnection("DataSource=:memory:");
        connection.Open();
        RegisterPostgresStubs(connection);

        var options = new DbContextOptionsBuilder<ProposalDbContext>()
            .UseSqlite(connection)
            .Options;

        var first = new ProposalDbContext(options);
        first.Database.EnsureCreated();
        first.Dispose();

        return (connection, () => new ProposalDbContext(options));
    }

    private static void RegisterPostgresStubs(SqliteConnection connection)
    {
        // hashtext(text) -> integer — returns a constant; only needed so SQL parses
        connection.CreateFunction("hashtext", (string _) => 0);

        // pg_advisory_xact_lock(bigint) -> void — no-op in tests
        connection.CreateFunction("pg_advisory_xact_lock", (long _) => 0);
    }
}