import { RelationCountMetadataArgs } from "../metadata-args/RelationCountMetadataArgs"
import { EntityMetadata } from "./EntityMetadata"
import { RelationMetadata } from "./RelationMetadata"
import { SelectQueryBuilder } from "../query-builder/SelectQueryBuilder"
import { TypeORMError } from "../error"

/**
 * Contains all information about entity's relation count.
 */
export class RelationCountMetadata {
    // ---------------------------------------------------------------------
    // Public Properties
    // ---------------------------------------------------------------------

    /**
     * Entity metadata where this column metadata is.
     */
    entityMetadata: EntityMetadata

    /**
     * Relation which needs to be counted.
     */
    relation: RelationMetadata

    /**
     * Relation name which need to count.
     */
    relationNameOrFactory: string | ((object: any) => any)

    /**
     * Target class to which metadata is applied.
     */
    target: Function | string

    /**
     * Target's property name to which this metadata is applied.
     */
    propertyName: string

    /**
     * Alias of the joined (destination) table.
     */
    alias?: string

    /**
     * Extra condition applied to "ON" section of join.
     */
    queryBuilderFactory?: (
        qb: SelectQueryBuilder<any>,
    ) => SelectQueryBuilder<any>

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

    constructor(options: {
        entityMetadata: EntityMetadata
        args: RelationCountMetadataArgs
    }) {
        this.entityMetadata = options.entityMetadata
        this.target = options.args.target
        this.propertyName = options.args.propertyName
        this.relationNameOrFactory = options.args.relation
        this.alias = options.args.alias
        this.queryBuilderFactory = options.args.queryBuilderFactory
    }

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

    /**
     * Builds some depend relation count metadata properties.
     * This builder method should be used only after entity metadata, its properties map and all relations are build.
     */
    build() {
        const propertyPath =
            typeof this.relationNameOrFactory === "function"
                ? this.relationNameOrFactory(this.entityMetadata.propertiesMap)
                : this.relationNameOrFactory
        const relation =
            this.entityMetadata.findRelationWithPropertyPath(propertyPath)
        if (!relation)
            throw new TypeORMError(
                `Cannot find relation ${propertyPath}. Wrong relation specified for @RelationCount decorator.`,
            )

        this.relation = relation
    }
}