using Insight.Database;
using System.Data;

namespace Database.Core.DataDefinitionLanguage
{
    public interface IDbSetup
    {
        void CreateSystem(string schema = null);
    }

    /// <summary>
    /// This is by purpose not async await
    /// </summary>
    public class SetupIdentitySystem : IDbSetup
    {
        readonly IDbConnection _db;
        IDbTransaction _transaction = null;
        string _schema;

        public SetupIdentitySystem(IDbConnection db)
        {
            _db = db;
        }

        /// <summary>
        /// Creates the system tables in the specified schema within a transaction.
        /// </summary>
        /// <param name="schema">The schema name where the tables will be created.</param>
        public void CreateSystem(string schema = null)
        {

            using (_transaction = _db.BeginTransaction())
            {
                try
                {
                    CreateUsersTable();
                    CreateTenantsTable();
                    CreateUserTenantsTable();
                    SetupRLS();

                    _transaction.Commit();
                }
                catch (Exception ex)
                {
                    _transaction.Rollback();
                    throw new InvalidOperationException("Failed to create system tables.", ex);
                }
            }
        }
        private void ExecuteSql(string sql)
        {
            if (string.IsNullOrEmpty(sql))
                throw new ArgumentNullException(nameof(sql));

            _db.ExecuteSql(sql);
        }


        /// <summary>
        /// Creates the users table
        /// </summary>
        public void CreateUsersTable()
        {
            var sql = @"
                CREATE TABLE IF NOT EXISTS users (
                    id SERIAL PRIMARY KEY,
                    email VARCHAR(256) NOT NULL UNIQUE,
                    password_hash VARCHAR(256) NOT NULL,
                    security_stamp VARCHAR(36) NOT NULL,
                    email_confirmed BOOLEAN NOT NULL DEFAULT FALSE,
                    access_failed_count INTEGER NOT NULL DEFAULT 0,
                    lockout_enabled BOOLEAN NOT NULL DEFAULT TRUE,
                    lockout_end TIMESTAMPTZ NULL,
                    is_active BOOLEAN NOT NULL DEFAULT TRUE,
                    created_at TIMESTAMPTZ NOT NULL DEFAULT CURRENT_TIMESTAMP,
                    last_login_at TIMESTAMPTZ NULL
                );";

            ExecuteSql(sql);

        }

        /// <summary>
        /// Creates the tenants table
        /// </summary>
        public void CreateTenantsTable()
        {
            var sql = @"
                CREATE TABLE IF NOT EXISTS tenants (
                    id SERIAL PRIMARY KEY,
                    connection_string VARCHAR(500) NOT NULL,
                    is_active BOOLEAN NOT NULL DEFAULT TRUE,
                    created_by INTEGER NOT NULL REFERENCES users(id),
                    created_at TIMESTAMPTZ NOT NULL DEFAULT CURRENT_TIMESTAMP
                );";

            ExecuteSql(sql);

        }

        /// <summary>
        /// Creates the user_tenants table
        /// </summary>
        public void CreateUserTenantsTable()
        {
            var sql = @"
                CREATE TABLE IF NOT EXISTS user_tenants (
                    user_id INTEGER NOT NULL REFERENCES users(id),
                    tenant_id INTEGER NOT NULL REFERENCES tenants(id),
                    pin_code VARCHAR(10) NULL,
                    created_at TIMESTAMPTZ NOT NULL DEFAULT CURRENT_TIMESTAMP,
                    PRIMARY KEY (user_id, tenant_id)
                );";

            ExecuteSql(sql);

        }

        /// <summary>
        /// Sets up Row Level Security (RLS) for the tenants and user_tenants tables.
        /// </summary>
        public void SetupRLS()
        {
            var sql = new[]
                {
                    "ALTER TABLE tenants ENABLE ROW LEVEL SECURITY;",
                    "ALTER TABLE user_tenants ENABLE ROW LEVEL SECURITY;",
                    "DROP POLICY IF EXISTS tenant_access ON tenants;",
                    @"CREATE POLICY tenant_access ON tenants
                        USING (id IN (
                            SELECT tenant_id 
                            FROM user_tenants 
                            WHERE user_id = current_setting('app.user_id', TRUE)::INTEGER
                        ));",
                    "DROP POLICY IF EXISTS user_tenant_access ON user_tenants;",
                    @"CREATE POLICY user_tenant_access ON user_tenants
                        USING (user_id = current_setting('app.user_id', TRUE)::INTEGER);"
                };

            foreach (var statement in sql)
            {
                ExecuteSql(statement);
            }
        }


    }
}