import {CsvStringifier} from './abstract';
import {FieldStringifier} from '../field-stringifier';
import {Field, ObjectHeaderItem, ObjectStringifierHeader} from '../record';
import {isObject, ObjectMap} from '../lang/object';

export class ObjectCsvStringifier extends CsvStringifier<ObjectMap<Field>> {
    private readonly header: ObjectStringifierHeader;

    constructor(fieldStringifier: FieldStringifier, header: ObjectStringifierHeader, recordDelimiter?: string) {
        super(fieldStringifier, recordDelimiter);
        this.header = header;
    }

    protected getHeaderRecord(): ObjectMap<Field> | null {
        if (!this.isObjectHeader) return null;

        return (this.header as ObjectHeaderItem[]).reduce((memo, field) =>
            Object.assign({}, memo, {[field.id]: field.title}), {});
    }

    protected getRecordAsArray(record: ObjectMap<Field>): Field[] {
        return this.fieldIds.map(field => record[field]);
    }

    private get fieldIds(): string[] {
        return this.isObjectHeader ? (this.header as ObjectHeaderItem[]).map(column => column.id) : (this.header as string[]);
    }

    private get isObjectHeader(): boolean {
        return isObject(this.header && this.header[0]);
    }
}