import { InclusionFilter } from '@loopback/filter';
import { Options } from '../common-types';
import { Entity } from '../model';
import { TypeResolver } from '../type-resolver';
export declare enum RelationType {
    belongsTo = "belongsTo",
    hasOne = "hasOne",
    hasMany = "hasMany",
    embedsOne = "embedsOne",
    embedsMany = "embedsMany",
    referencesOne = "referencesOne",
    referencesMany = "referencesMany"
}
export interface RelationDefinitionBase {
    /**
     * The type of the relation, must be one of RelationType values.
     */
    type: RelationType;
    /**
     * True for relations targeting multiple instances (e.g. HasMany),
     * false for relations with a single target (e.g. BelongsTo, HasOne).
     * This property is needed by OpenAPI/JSON Schema generator.
     */
    targetsMany: boolean;
    /**
     * The relation name, typically matching the name of the accessor property
     * defined on the source model. For example "orders" or "customer".
     */
    name: string;
    /**
     * The source model of this relation.
     *
     * E.g. when a Customer has many Order instances, then Customer is the source.
     */
    source: typeof Entity;
    /**
     * The target model of this relation.
     *
     * E.g. when a Customer has many Order instances, then Order is the target.
     */
    target: TypeResolver<Entity, typeof Entity>;
}
/**
 * HasManyDefinition defines one-to-many relations and also possible defines
 * many-to-many relations with through models.
 */
export interface HasManyDefinition extends RelationDefinitionBase {
    type: RelationType.hasMany;
    targetsMany: true;
    /**
     * keyTo: The foreign key used by the target model for this relation.
     * keyFrom: The source key used by the source model for this relation.
     *
     * E.g. when a Customer has many Order instances, then keyTo is "customerId".
     * Note that "customerId" is the default FK assumed by the framework, users
     * can provide a custom FK name by setting "keyTo".
     * And Customer.id is keyFrom. keyFrom defaults to the id property of a model.
     * Users can provide a custom source key name by setting "keyTo".
     *
     */
    keyTo?: string;
    keyFrom?: string;
    /**
     * With current architecture design, polymorphic type cannot be supported without through
     * Consider using Source-hasMany->Through->hasOne->Target(polymorphic) for one-to-many relations
     */
    /**
     * Description of the through model of the hasManyThrough relation.
     *
     * A `hasManyThrough` relation defines a many-to-many connection with another model.
     * This relation indicates that the declaring model can be matched with zero or more
     * instances of another model by proceeding through a third model.
     *
     * E.g a Category has many Products, and a Product can have many Categories.
     * CategoryProductLink can be the through model.
     * Such a through model has information of foreign keys of the source model(Category) and the target model(Product).
     *
     * Warning: The hasManyThrough interface is experimental and is subject to change.
     * If backwards-incompatible changes are made, a new major version may not be
     * released.
     */
    through?: {
        /**
         * The through model of this relation.
         *
         * E.g. when a Category has many CategoryProductLink instances and a Product has many CategoryProductLink instances,
         * then CategoryProductLink is through.
         */
        model: TypeResolver<Entity, typeof Entity>;
        /**
         * The foreign key of the source model defined in the through model, e.g. CategoryProductLink#categoryId
         */
        keyFrom?: string;
        /**
         * The foreign key of the target model defined in the through model, e.g. CategoryProductLink#productId
         */
        keyTo?: string;
        /**
         * The polymorphism of the target model. The discriminator is a key of *through* model.
         * If the target model is not polymorphic, then the value should be left undefined or false;
         * If the key on through model indicating the concrete class of the through instance is default
         * i.e. camelCase(classNameOf(targetModelInstance)) + "Id"
         * then the discriminator field can be undefined
         *
         * With current architecture design, polymorphic type cannot be supported without through
         * Consider using Source hasMany Through hasOne Target(polymorphic)
         * or Source hasMany Through belongsTo Target(polymorphic) for one-to-many relations
         */
        polymorphic?: boolean | {
            discriminator: string;
        };
    };
}
export interface BelongsToDefinition extends RelationDefinitionBase {
    type: RelationType.belongsTo;
    targetsMany: false;
    keyFrom?: string;
    keyTo?: string;
    /**
     * The polymorphism of the target model. The discriminator is a key of source model.
     * If the target model is not polymorphic, then the value should be left undefined or false;
     * If the key on source model indicating the concrete class of the target instance is default
     * i.e. camelCase(classNameOf(throughModelInstance)) + "Id"
     * Then the discriminator field can be undefined
     */
    polymorphic?: boolean | {
        discriminator: string;
    };
}
export interface HasOneDefinition extends RelationDefinitionBase {
    type: RelationType.hasOne;
    targetsMany: false;
    /**
     * keyTo: The foreign key used by the target model for this relation.
     * keyFrom: The source key used by the source model for this relation.
     *
     * E.g. when a Customer has one Address instance, then keyTo is "customerId".
     * Note that "customerId" is the default FK assumed by the framework, users
     * can provide a custom FK name by setting "keyTo".
     * And Customer.id is keyFrom. keyFrom defaults to the id property of a model.
     * Users can provide a custom source key name by setting "keyTo".
     */
    keyTo?: string;
    keyFrom?: string;
    /**
     * The polymorphism of the target model. The discriminator is a key of source model.
     * If the target model is not polymorphic, then the value should be left undefined or false;
     * If the key on source model indicating the concrete class of the target instance is default
     * i.e. camelCase(classNameOf(throughModelInstance)) + "Id"
     * Then the discriminator field can be undefined
     */
    polymorphic?: boolean | {
        discriminator: string;
    };
}
export interface ReferencesManyDefinition extends RelationDefinitionBase {
    type: RelationType.referencesMany;
    targetsMany: true;
    /**
     * keyTo: The foreign key used by the target model for this relation.
     * keyFrom: The source key used by the source model for this relation.
     *
     * TODO(bajtos) Add relation description.
     *
     */
    keyTo?: string;
    keyFrom?: string;
}
/**
 * A union type describing all possible Relation metadata objects.
 */
export declare type RelationMetadata = HasManyDefinition | BelongsToDefinition | HasOneDefinition | ReferencesManyDefinition | RelationDefinitionBase;
export { Getter } from '@loopback/core';
/**
 * @returns An array of resolved values, the items must be ordered in the same
 * way as `sourceEntities`. The resolved value can be one of:
 * - `undefined` when no target model(s) were found
 * - `Entity` for relations targeting a single model
 * - `Entity[]` for relations targeting multiple models
 */
export declare type InclusionResolver<S extends Entity, T extends Entity> = (
/**
 * List of source models as returned by the first database query.
 */
sourceEntities: S[], 
/**
 * Inclusion requested by the user (e.g. scope constraints to apply).
 */
inclusion: InclusionFilter, 
/**
 * Generic options object, e.g. carrying the Transaction object.
 */
options?: Options) => Promise<(T | undefined)[] | (T[] | undefined)[]>;