import { EntityMetadata } from '../metadata/EntityMetadata';
import { ColumnMetadata } from '../metadata/ColumnMetadata';
import { ForeignKeyMetadata } from '../metadata/ForeignKeyMetadata';
import { DataSource } from '../data-source/DataSource';
import { IndexMetadata } from '../metadata/IndexMetadata';

/**
 * Creates EntityMetadata for junction tables of the closure entities.
 * Closure junction tables are tables generated by closure entities.
 */
export class ClosureJunctionEntityMetadataBuilder {
	// -------------------------------------------------------------------------
	// Constructor
	// -------------------------------------------------------------------------

	constructor(private connection: DataSource) {}

	// -------------------------------------------------------------------------
	// Public Methods
	// -------------------------------------------------------------------------

	/**
	 * Builds EntityMetadata for the closure junction of the given closure entity.
	 */
	build(parentClosureEntityMetadata: EntityMetadata) {
		// create entity metadata itself
		const entityMetadata = new EntityMetadata({
			parentClosureEntityMetadata: parentClosureEntityMetadata,
			connection: this.connection,
			args: {
				target: '',
				name:
					parentClosureEntityMetadata.treeOptions &&
					parentClosureEntityMetadata.treeOptions.closureTableName
						? parentClosureEntityMetadata.treeOptions.closureTableName
						: parentClosureEntityMetadata.tableNameWithoutPrefix,
				type: 'closure-junction',
			},
		});
		entityMetadata.build();

		// create ancestor and descendant columns for new closure junction table
		parentClosureEntityMetadata.primaryColumns.forEach((primaryColumn) => {
			entityMetadata.ownColumns.push(
				new ColumnMetadata({
					connection: this.connection,
					entityMetadata: entityMetadata,
					closureType: 'ancestor',
					referencedColumn: primaryColumn,
					args: {
						target: '',
						mode: 'virtual',
						propertyName:
							parentClosureEntityMetadata.treeOptions &&
							parentClosureEntityMetadata.treeOptions.ancestorColumnName
								? parentClosureEntityMetadata.treeOptions.ancestorColumnName(primaryColumn)
								: primaryColumn.propertyName + '_ancestor',
						options: {
							primary: true,
							length: primaryColumn.length,
							type: primaryColumn.type,
						},
					},
				}),
			);
			entityMetadata.ownColumns.push(
				new ColumnMetadata({
					connection: this.connection,
					entityMetadata: entityMetadata,
					closureType: 'descendant',
					referencedColumn: primaryColumn,
					args: {
						target: '',
						mode: 'virtual',
						propertyName:
							parentClosureEntityMetadata.treeOptions &&
							parentClosureEntityMetadata.treeOptions.descendantColumnName
								? parentClosureEntityMetadata.treeOptions.descendantColumnName(primaryColumn)
								: primaryColumn.propertyName + '_descendant',
						options: {
							primary: true,
							length: primaryColumn.length,
							type: primaryColumn.type,
						},
					},
				}),
			);
		});

		entityMetadata.ownIndices = [
			new IndexMetadata({
				entityMetadata: entityMetadata,
				columns: [entityMetadata.ownColumns[0]],
				args: {
					target: entityMetadata.target,
					synchronize: true,
				},
			}),
			new IndexMetadata({
				entityMetadata: entityMetadata,
				columns: [entityMetadata.ownColumns[1]],
				args: {
					target: entityMetadata.target,
					synchronize: true,
				},
			}),
		];

		// if tree level column was defined by a closure entity then add it to the junction columns as well
		if (parentClosureEntityMetadata.treeLevelColumn) {
			entityMetadata.ownColumns.push(
				new ColumnMetadata({
					connection: this.connection,
					entityMetadata: entityMetadata,
					args: {
						target: '',
						mode: 'virtual',
						propertyName: 'level',
						options: {
							type: this.connection.driver.mappedDataTypes.treeLevel,
						},
					},
				}),
			);
		}

		// create junction table foreign keys
		entityMetadata.foreignKeys = [
			new ForeignKeyMetadata({
				entityMetadata: entityMetadata,
				referencedEntityMetadata: parentClosureEntityMetadata,
				columns: [entityMetadata.ownColumns[0]],
				referencedColumns: parentClosureEntityMetadata.primaryColumns,
				onDelete: 'CASCADE',
			}),
			new ForeignKeyMetadata({
				entityMetadata: entityMetadata,
				referencedEntityMetadata: parentClosureEntityMetadata,
				columns: [entityMetadata.ownColumns[1]],
				referencedColumns: parentClosureEntityMetadata.primaryColumns,
				onDelete: 'CASCADE',
			}),
		];

		return entityMetadata;
	}
}