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import type { ModelSchema } from "./model.ts";import { DataTypes, RelationshipType } from "./data-types.ts";import { PivotModel } from "./model-pivot.ts";
type PrimaryKeyOption = {  primaryKey?: string;};
type ForeignKeyOption = {  foreignKey?: string;};
type RelationshipOptions = PrimaryKeyOption & ForeignKeyOption;
export const Relationships = {  /** Define a one-to-one or one-to-many relationship field for a given model. */  _belongsToField(model: ModelSchema): RelationshipType {    return {      type: DataTypes.INTEGER,      relationship: {        kind: "single",        model,      },    };  },
  /** Define a one-to-one or one-to-many relationship for a given model. */  belongsTo(    modelA: ModelSchema,    modelB: ModelSchema,    options?: ForeignKeyOption,  ) {    const foreignKey = options?.foreignKey;    const modelAFieldName = foreignKey || `${modelB.name.toLowerCase()}Id`;    modelA.fields[modelAFieldName] = this._belongsToField(modelB);  },
  /** Add corresponding fields to each model for a one-to-one relationship. */  oneToOne(    modelA: ModelSchema,    modelB: ModelSchema,    options?: RelationshipOptions,  ) {    const primaryKey = options?.primaryKey;    const foreignKey = options?.foreignKey;
    const modelAFieldName = primaryKey || `${modelB.name.toLowerCase()}Id`;    const modelBFieldName = foreignKey || `${modelA.name.toLowerCase()}Id`;
    modelA.fields[modelAFieldName] = this._belongsToField(modelB);    modelB.fields[modelBFieldName] = this._belongsToField(modelA);  },
  /** Generate a many-to-many pivot model for two given models.   *    *     const AirportFlight = Relationships.manyToMany(Airport, Flight);   */  manyToMany(    modelA: ModelSchema,    modelB: ModelSchema,    options?: RelationshipOptions,  ): ModelSchema {    const primaryKey = options?.primaryKey;    const foreignKey = options?.foreignKey;
    const pivotClassName = `${modelA.table}_${modelB.table}`;    const modelAFieldName = primaryKey || `${modelA.name.toLowerCase()}Id`;    const modelBFieldName = foreignKey || `${modelB.name.toLowerCase()}Id`;
    class PivotClass extends PivotModel {      static table = pivotClassName;
      static fields = {        id: {          primaryKey: true,          autoIncrement: true,        },        [modelAFieldName]: Relationships._belongsToField(modelA),        [modelBFieldName]: Relationships._belongsToField(modelB),      };
      static _pivotsModels = {        [modelA.name]: modelA,        [modelB.name]: modelB,      };
      static _pivotsFields = {        [modelA.name]: modelAFieldName,        [modelB.name]: modelBFieldName,      };    }
    modelA.pivot[modelB.name] = PivotClass;    modelB.pivot[modelA.name] = PivotClass;
    return PivotClass;  },};