hasard/lib/hasard/array.js

Random variables and random nested objects manipulation in javascript

const AbstractHasard = require('./abstract');

class ArrayHasard extends AbstractHasard {
	check(key, value) {
		if (key === 'values' && value !== null && typeof (value) !== 'undefined') {
			if (!Array.isArray(value)) {
				throw (new TypeError(`${key} ${value} must be an array`));
			}
		}
	}

	resolve(unresolved, runOpts) {
		// Do not resolve "value" here, it will be resolved in generate
		const overrideUnresolved = Object.assign({}, unresolved);
		delete overrideUnresolved.value;

		return Object.assign(super.resolve(overrideUnresolved, runOpts), {value: unresolved.value});
	}

	getOpts(opts) {
		let values = null;
		let size;
		let value;
		let randomOrder;
		if (Array.isArray(opts)) {
			values = opts;
			size = values.length;
			value = null;
			randomOrder = false;
		} else {
			size = opts.size;
			values = opts.values;
			value = opts.value;
			randomOrder = opts.randomOrder;
		}

		return {
			size,
			value,
			values,
			randomOrder
		};
	}

	generate(ctx, runOpts) {
		if (ArrayHasard.isHasard(ctx.value)) {
			return new Array(ctx.size).fill(1).map(() => ctx.value.runOnce(runOpts));
		}

		if (ctx.values) {
			let newValues;

			if (typeof (ctx.size) === 'number' || ctx.randomOrder) {
				const size = typeof (ctx.size) === 'number' ? ctx.size : ctx.values.length;

				if (size > ctx.values.length) {
					throw (new Error(`Cannot pick ${size} elements in ${ctx.values.length}-size array`));
				}

				let selectedObjs = ctx.values
					.map((v, i) => ({strength: this.prng(), value: v, index: i}))
					.sort((a, b) => a.strength - b.strength)
					.slice(0, size);

				if (!ctx.randomOrder) {
					selectedObjs = selectedObjs.sort((a, b) => a.index - b.index);
				}

				newValues = selectedObjs.map(({value}) => value);
			} else {
				newValues = ctx.values;
			}

			return newValues.map(v => {
				if (ArrayHasard.isHasard(v)) {
					const res = v.runOnce(runOpts);
					return res;
				}

				return v;
			});
		}

		return new Array(ctx.size).fill(1).map(() => ctx.value);
	}
}

module.exports = ArrayHasard;