Invercargill-Sql/src/migrations/column-builder.vala

using Invercargill.DataStructures;
using InvercargillSql.Orm;

namespace InvercargillSql.Migrations {
    
    /**
     * Column builder for migrations that provides a fluent API for configuring column definitions.
     *
     * This builder is used within migration operations to configure column properties.
     * All configuration methods return this builder for method chaining.
     *
     * Example usage within a migration:
     * {{{
     * b.create_table("users")
     *     .column<int64>("id", c => c.type_int().primary_key().auto_increment())
     *     .column<string>("email", c => c.type_text().not_null().unique())
     *     .execute();
     * }}}
     */
    public class MigrationColumnBuilder : Object {
        private MigrationBuilder? _migration_parent;
        private TableBuilder? _table_parent;
        private AlterTableBuilder? _alter_parent;
        private ColumnDefinition _column;
        private string? _table_name;
        
        // Index support
        private bool _should_create_index = false;
        private string? _index_name = null;
        
        // Foreign key support
        private ForeignKeyBuilder? _fk_builder = null;
        
        /**
         * Protected constructor for subclasses like ForeignKeyBuilder.
         */
        protected MigrationColumnBuilder.for_subclass() {
            _column = new ColumnDefinition();
        }
        
        /**
         * Creates a new MigrationColumnBuilder with a MigrationBuilder parent.
         *
         * @param parent the parent MigrationBuilder to return to after configuration
         * @param table_name the name of the table this column belongs to
         * @param column the column definition being configured
         */
        internal MigrationColumnBuilder(MigrationBuilder parent, string table_name, ColumnDefinition column) {
            _migration_parent = parent;
            _table_name = table_name;
            _column = column;
        }
        
        /**
         * Creates a new MigrationColumnBuilder with a TableBuilder parent.
         *
         * @param parent the parent TableBuilder to return to after configuration
         * @param column the column definition being configured
         */
        internal MigrationColumnBuilder.for_table(TableBuilder parent, ColumnDefinition column) {
            _table_parent = parent;
            _column = column;
        }
        
        /**
         * Creates a new MigrationColumnBuilder with an AlterTableBuilder parent.
         *
         * @param parent the parent AlterTableBuilder to return to after configuration
         * @param table_name the name of the table this column belongs to
         * @param column the column definition being configured
         */
        internal MigrationColumnBuilder.for_alter(AlterTableBuilder parent, string table_name, ColumnDefinition column) {
            _alter_parent = parent;
            _table_name = table_name;
            _column = column;
        }
        
        /**
         * Sets the column type to INTEGER.
         * 
         * @return this builder for method chaining
         */
        public MigrationColumnBuilder type_int() {
            _column.column_type = ColumnType.INT_64;
            return this;
        }
        
        /**
         * Sets the column type to TEXT.
         * 
         * @return this builder for method chaining
         */
        public MigrationColumnBuilder type_text() {
            _column.column_type = ColumnType.TEXT;
            return this;
        }
        
        /**
         * Sets the column type to REAL.
         * 
         * @return this builder for method chaining
         */
        public MigrationColumnBuilder type_real() {
            _column.column_type = ColumnType.DECIMAL;
            return this;
        }
        
        /**
         * Sets the column type to BLOB.
         * 
         * @return this builder for method chaining
         */
        public MigrationColumnBuilder type_blob() {
            _column.column_type = ColumnType.BINARY;
            return this;
        }
        
        /**
         * Sets the column type to DATETIME.
         * 
         * @return this builder for method chaining
         */
        public MigrationColumnBuilder type_datetime() {
            _column.column_type = ColumnType.DATETIME;
            return this;
        }
        
        /**
         * Sets the column type to BOOLEAN.
         * 
         * @return this builder for method chaining
         */
        public MigrationColumnBuilder type_boolean() {
            _column.column_type = ColumnType.BOOLEAN;
            return this;
        }
        
        /**
         * Marks this column as the primary key.
         * 
         * Only one column per table should be marked as primary key.
         * 
         * @return this builder for method chaining
         */
        public MigrationColumnBuilder primary_key() {
            _column.is_primary_key = true;
            return this;
        }
        
        /**
         * Marks this column as NOT NULL.
         * 
         * @return this builder for method chaining
         */
        public MigrationColumnBuilder not_null() {
            _column.is_required = true;
            return this;
        }
        
        /**
         * Marks this column as UNIQUE.
         * 
         * @return this builder for method chaining
         */
        public MigrationColumnBuilder unique() {
            _column.is_unique = true;
            return this;
        }
        
        /**
         * Marks this column as auto-incrementing.
         * 
         * Typically used for integer primary keys.
         * 
         * @return this builder for method chaining
         */
        public MigrationColumnBuilder auto_increment() {
            _column.auto_increment = true;
            return this;
        }
        
        /**
         * Sets a default value for this column.
         * 
         * @param value the default value to use when inserting records
         * @return this builder for method chaining
         */
        public MigrationColumnBuilder default_value<T>(T value) {
            _column.default_value = new Invercargill.NativeElement<T>(value);
            return this;
        }
        
        /**
         * Marks this column to use the current timestamp as default.
         * 
         * Only applicable to DATETIME columns.
         * 
         * @return this builder for method chaining
         */
        public MigrationColumnBuilder default_now() {
            _column.default_now = true;
            return this;
        }
        
        /**
         * Adds a foreign key reference to another table.
         *
         * This method creates a ForeignKeyBuilder that allows configuring the FK
         * constraint with methods like .name(), .on_delete_cascade(), etc.
         * The ForeignKeyBuilder extends MigrationColumnBuilder, so column methods
         * can still be called after FK configuration.
         *
         * Example:
         * {{{
         * t.column<int64?>("user_id")
         *     .not_null()
         *     .references("users", "id")
         *         .name("fk_orders_users")
         *         .on_delete_cascade()
         *     .indexed();  // Can continue with column methods
         * }}}
         *
         * @param table the referenced table name
         * @param column the referenced column name in the foreign table
         * @return a ForeignKeyBuilder for configuring the FK constraint
         */
        public ForeignKeyBuilder references(string table, string column) {
            _fk_builder = new ForeignKeyBuilder(this, table, column);
            return _fk_builder;
        }
        
        /**
         * Marks this column to have an index created for it.
         *
         * The index uniqueness is automatically inferred from the column's is_unique property.
         * If a custom index name is needed, pass it as the name parameter.
         *
         * Example:
         * {{{
         * // Basic index with auto-generated name (idx_{table}_{column})
         * t.column<string>("email").not_null().indexed();
         *
         * // Unique index - uniqueness inferred from column's unique() flag
         * t.column<string>("email").unique().indexed();
         *
         * // Index with custom name
         * t.column<string>("email").indexed("idx_users_email_address");
         * }}}
         *
         * @param name optional custom index name; if null, auto-generated as idx_{table}_{column}
         * @return this builder for method chaining
         */
        public MigrationColumnBuilder indexed(string? name = null) {
            _should_create_index = true;
            _index_name = name;
            return this;
        }
        
        /**
         * Whether an index should be created for this column.
         * TableBuilder uses this to determine if an index operation is needed.
         */
        public bool should_create_index { get { return _should_create_index; } }
        
        /**
         * The custom index name, or null if auto-generation should be used.
         * Auto-generated format: idx_{table}_{column}
         */
        public string? index_name { get { return _index_name; } }
        
        /**
         * The ForeignKeyBuilder if a foreign key was configured via references().
         * TableBuilder uses this to collect FK constraints from column definitions.
         */
        public ForeignKeyBuilder? fk_builder { get { return _fk_builder; } }
        
        /**
         * Returns to the parent MigrationBuilder.
         *
         * This method navigates through the parent chain to find the MigrationBuilder.
         *
         * @return the parent MigrationBuilder
         */
        internal virtual MigrationBuilder return_to_migration() {
            if (_migration_parent != null) return _migration_parent;
            if (_table_parent != null) return _table_parent.return_to_migration();
            if (_alter_parent != null) return _alter_parent.return_to_migration();
            assert_not_reached();
        }
    }
}