using Database.Common;
using Insight.Database;
using System;
using System.Data;
using System.Threading.Tasks;

namespace Database.IdentitySystem
{
    public class DbSetup
    {
        readonly IDbConnection _db;
        IDbTransaction _transaction = null;
        string _schema;

        public DbSetup(IDbConnection db)
        {
            _db = db ?? throw new ArgumentNullException(nameof(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 async Task CreateSystem(string schema)
        {
            _schema = schema;

            if (!Validations.IsValidSchemaName(schema))
                throw new ArgumentException("Invalid schema name", nameof(schema));

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

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

            await _db.ExecuteAsync(sql).ConfigureAwait(false);
        }


        /// <summary>
        /// Creates the users table in the ptmain schema.
        /// </summary>
        public async Task CreateUsersTable()
        {
            var sql = @"
                CREATE TABLE IF NOT EXISTS ptmain.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
                );";

            await ExecuteSqlAsync(sql).ConfigureAwait(false);

        }

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

            await ExecuteSqlAsync(sql).ConfigureAwait(false);

        }

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

            await ExecuteSqlAsync(sql).ConfigureAwait(false);

        }

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

            foreach (var statement in sql)
            {
                await ExecuteSqlAsync(statement).ConfigureAwait(false);
            }
        }


    }
}