RattenheimRechner/src/assets/calculator.js

const MINIMUM_BASE_AREA = 0.5;
const MINIMUM_AREA_THREE_RATS = 1.8;
const AREA_PER_ADDITIONAL_RAT = 0.2;
const MAXIMUM_FALL_HEIGHT = 0.5;
const MINIMUM_LENGTH = 0.8;

const FAILED_BASE_AREA = "base_area";
const FAILED_OVERALL_AREA = "overall_area";
const FAILED_FALL_HEIGHT = "fall_height";
const FAILED_NUM_RATS = "num_rats";
const FAILED_LENGTH = "length";

const FAIL_CRITERIA = {
    [FAILED_BASE_AREA]: `Die Mindestgrundfläche des Käfigs muss ${MINIMUM_BASE_AREA}m² (also z.B. 100x50cm) betragen.`,
    [FAILED_OVERALL_AREA]: "Die Gesamtfläche im Käfig ist zu klein.",
    [FAILED_FALL_HEIGHT]: `Die mögliche Fallhöhe darf nicht mehr als ${(MAXIMUM_FALL_HEIGHT * 100).toFixed(3)}cm betragen.`,
    [FAILED_NUM_RATS]: "Es müssen mindestens 3 Ratten zusammenleben, Paarhaltung ist nicht artgerecht.",
    [FAILED_LENGTH]: `Eine Seite des Käfig muss mindestens ${(MINIMUM_LENGTH * 100).toFixed(3)}cm lang sein um Rennen zu ermöglichen.`,
};

class Dimensions {
    constructor(length, width, height) {
        this.length = length;
        this.width = width;
        this.height = height;
    }

    toString() {
        return `${this.length}x${this.width}x${this.height}`;
    }

    static fromDict(data) {
        const { length, width, height } = data;
        return new Dimensions(length, width, height);
    }
}

function overallAreaNeeded(numOfRats) {
    if (numOfRats < 3 || numOfRats > 15) {
        throw new Error("This formula works only from 3 to 15 rats");
    }
    return MINIMUM_AREA_THREE_RATS + (numOfRats - 3) * AREA_PER_ADDITIONAL_RAT;
}

function cageCheck(dimensions, numRats, numFullFloors) {
    let failedCriteria = {};

    if (numRats < 2 || numRats > 15) {
        failedCriteria[FAILED_NUM_RATS] = FAIL_CRITERIA[FAILED_NUM_RATS];
    }

    const baseArea = dimensions.length * dimensions.width;
    if (baseArea < MINIMUM_BASE_AREA) {
        failedCriteria[FAILED_BASE_AREA] = FAIL_CRITERIA[FAILED_BASE_AREA];
    }

    const areaNeeded = overallAreaNeeded(numRats);
    if (baseArea * numFullFloors < areaNeeded) {
        failedCriteria[FAILED_OVERALL_AREA] = FAIL_CRITERIA[FAILED_OVERALL_AREA];
    }

    if (dimensions.height / numFullFloors > MAXIMUM_FALL_HEIGHT) {
        failedCriteria[FAILED_FALL_HEIGHT] = FAIL_CRITERIA[FAILED_FALL_HEIGHT];
    }

    if (dimensions.width < MINIMUM_LENGTH && dimensions.length < MINIMUM_LENGTH) {
        failedCriteria[FAILED_LENGTH] = FAIL_CRITERIA[FAILED_LENGTH];
    }

    return failedCriteria;
}

const expectedAreaPerNumRats = { 3: 1.8, 4: 2.0 };
for (let numRats in expectedAreaPerNumRats) {
    console.log(`Area needed for ${numRats}: Calculated=${overallAreaNeeded(parseInt(numRats))}`);
}

const exampleCageChecks = [
    [[], new Dimensions(1, 0.50, 1), 4, 4],
    [[FAIL_CRITERIA[FAILED_BASE_AREA]], new Dimensions(0.99, 0.50, 1), 3, 4],
    [[FAIL_CRITERIA[FAILED_OVERALL_AREA]], new Dimensions(0.99, 0.50, 1), 4, 4],
    [[FAIL_CRITERIA[FAILED_OVERALL_AREA]], new Dimensions(0.79, 0.79, 1), 4, 4],
];

for (let idx in exampleCageChecks) {
    let check = exampleCageChecks[idx];
    console.log(`Example ${idx}: ${check[1]} n(rats): ${check[2]}, n(floors): ${check[3]}`);
    console.log(`Result: ${JSON.stringify(cageCheck(check[1], check[2], check[3]))}\n`);
}