import {EntityMetadata} from "./EntityMetadata";
import {IndexMetadataArgs} from "../metadata-args/IndexMetadataArgs";

/**
 * Index metadata contains all information about table's index.
 */
export class IndexMetadata {

    // ---------------------------------------------------------------------
    // Public Properties
    // ---------------------------------------------------------------------

    /**
     * Entity metadata of the class to which this index is applied.
     */
    entityMetadata: EntityMetadata;

    // ---------------------------------------------------------------------
    // Readonly Properties
    // ---------------------------------------------------------------------

    /**
     * Indicates if this index must be unique.
     */
    readonly isUnique: boolean;

    /**
     * Target class to which metadata is applied.
     */
    readonly target?: Function|string;
    
    // ---------------------------------------------------------------------
    // Private Properties
    // ---------------------------------------------------------------------

    /**
     * Composite index name.
     */
    private readonly _name: string|undefined;

    /**
     * Columns combination to be used as index.
     */
    private readonly _columns: ((object: any) => any[])|string[];

    // ---------------------------------------------------------------------
    // Constructor
    // ---------------------------------------------------------------------

    constructor(args: IndexMetadataArgs) {
        this.target = args.target;
        this._columns = args.columns;
        this._name = args.name;
        this.isUnique = args.unique;
    }

    // ---------------------------------------------------------------------
    // Accessors
    // ---------------------------------------------------------------------

    /**
     * Gets index's name.
     */
    get name() {
        return this.entityMetadata.namingStrategy.indexName(this._name, this.entityMetadata.table.name, this.columns);
    }

    /**
     * Gets the table name on which index is applied.
     */
    get tableName() {
        return this.entityMetadata.table.name;
    }

    /**
     * Gets the column names which are in this index.
     */
    get columns(): string[] {
        
        // if columns already an array of string then simply return it
        let columnPropertyNames: string[] = [];
        if (this._columns instanceof Array) {
            columnPropertyNames = this._columns;
        } else {
            // if columns is a function that returns array of field names then execute it and get columns names from it
            const propertiesMap = this.entityMetadata.createPropertiesMap();
            columnPropertyNames = this._columns(propertiesMap).map((i: any) => String(i));
        }

        const columns = this.entityMetadata.columns.filter(column => columnPropertyNames.indexOf(column.propertyName) !== -1);
        const missingColumnNames = columnPropertyNames.filter(columnPropertyName => !this.entityMetadata.columns.find(column => column.propertyName === columnPropertyName));
        if (missingColumnNames.length > 0) {
            // console.log(this.entityMetadata.columns);
            throw new Error(`Index ${this._name ? "\"" + this._name + "\" " : ""}contains columns that are missing in the entity: ` + missingColumnNames.join(", "));
        }

        return columns.map(column => column.name);
    }
    
}