import {EntityMetadata} from "../metadata/EntityMetadata";
import {ColumnMetadata} from "../metadata/ColumnMetadata";
import {ForeignKeyMetadata} from "../metadata/ForeignKeyMetadata";
import {Connection} from "../connection/Connection";

/**
 * 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: Connection) {
    }

    // -------------------------------------------------------------------------
    // 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.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: primaryColumn.propertyName + "_ancestor", // todo: naming strategy
                    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: primaryColumn.propertyName + "_descendant",
                    options: {
                        primary: true,
                        length: primaryColumn.length,
                        type: primaryColumn.type,
                    }
                }
            }));
        });

        // 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" // todo: does not work in mssql for some reason
            }),
            new ForeignKeyMetadata({
                entityMetadata: entityMetadata,
                referencedEntityMetadata: parentClosureEntityMetadata,
                columns: [entityMetadata.ownColumns[1]],
                referencedColumns: parentClosureEntityMetadata.primaryColumns,
                // onDelete: "CASCADE" // todo: does not work in mssql for some reason
            }),
        ];

        return entityMetadata;
    }

}