import { utils } from "./utils";

/**
 * The base class for dealing with queries.
 */
export class QueryBase {
    selectProperties: string[];
    expandProperties: string[];

    constructor() {
        this.selectProperties = null;
        this.expandProperties = null;
    }

    /**
    * Selects which fields will be returned when querying the service.
    */
    select(...properties: string[]): QueryBase {
        properties = properties ?? [];

        this.validatePropertyPaths(properties);

        return this.clone((newObj: QueryBase) => {
            newObj.selectProperties = properties.filter((prop, index, props) => props.indexOf(prop) === index);
        });
    }

    /**
    * Selects which navigation properties will be returned when querying the service.
    */
    expand(...properties: string[]): QueryBase {
        properties = properties ?? [];
        this.validatePropertyPaths(properties);

        return this.clone((newObj: QueryBase) => {
            newObj.expandProperties = properties.filter((prop, index, props) => props.indexOf(prop) === index);
        });
    }

    protected validatePropertyPaths(propPaths: string[], allowNested = false) {
        for (let i = 0; i < propPaths.length; i++) {
            const member = propPaths[i];
            if (!utils.isString(member)) {
                throw new Error("Invalid argument in clause");
            }

            if (!allowNested && member.indexOf(".") > -1) {
                throw new Error("Invalid argument in clause");
            }
        }
    }

    protected clone(setter: Function = null) {
        const newObj = utils.clone(this, new QueryBase(), setter);
        return newObj;
    }
}