export const equivalentUnits = {
    'kg': {
        'kgs': 1,
        'kilograms': 1,
        'kilogram': 1,

        'g': 1000,
        'gram': 1000,
        'grams': 1000,

        'lb': 2.20462,
        'lbs': 2.20462,
        'pound': 2.20462,
        'pounds': 2.20462,
    },
    'litres': {
        'l': 1,
        'liter': 1,
        'litre': 1,

        'ml': 1000,
        'milliliters': 1000,
        'milliliter': 1000,

        'fl oz': 33.814,
        'fluid ounce': 33.814,
        'fluid ounces': 33.814,

        'cup': 4.22675,
        'cups': 4.22675,

        'tbsp': 67.628,
        'tablespoon': 67.628,
        'tablespoons': 67.628,

        'tsp': 202.884,
        'teaspoon': 202.884,
        'teaspoons': 202.884,

        'pt': 2.11338,
        'pint': 2.11338,
        'pints': 2.11338,

        'qt': 1.05669,
        'quart': 1.05669,
        'quarts': 1.05669,

        'gal': 0.264172,
        'gallon': 0.264172,
        'gallons': 0.264172,

        'oz': 35.1951,
        'ounce': 35.1951,
    },
    'items': {
        'item': 1,
        'items': 1,
        'pcs': 1,
        'piece': 1,
        'pieces': 1,
        'florets': 8, // Broccoli
        'head': 1, // Broccoli
        'heads': 1, // Broccoli
        'slice': 10, // Bread
        'slices': 10, // Bread
        'loaf': 1, // Bread
        'loaves': 1, // Bread
        'cloves': 8, // Garlic
        'bulb': 1, // Garlic
        'bulbs': 1, // Garlic
        'stalk': 1, // Celery
        'stalks': 1, // Celery
        'bunch': 1, // Cilantro
        'bunches': 1, // Cilantro
        'sprig': 1, // Cilantro
        'sprigs': 1, // Cilantro
        'cans': 1, // Canned goods
        'can': 1, // Canned goods
        'pack': 1, // Packaged goods
        'packs': 1, // Packaged goods
        'package': 1, // Packaged goods
        'packages': 1, // Packaged goods
        'container': 1, // Packaged goods
        'containers': 1, // Packaged goods
    },
}

function getBaseUnit(unit) {
    for (const unitType in equivalentUnits) {
        if (unit in equivalentUnits[unitType]) {
            return unitType;
        }
    }

    return null;
}

export function getConversionFactor(unit) {
    if (unit in equivalentUnits) {
        return { unit, factor: 1 };
    }

    const unitLower = unit.toLowerCase();
    if (unitLower in equivalentUnits) {
        return { unit: unitLower, factor: 1 };
    }
    
    const baseUnit = getBaseUnit(unit);
    if (baseUnit) {
        return {
            unit: baseUnit,
            factor: equivalentUnits[baseUnit][unit],
        };
    }

    const baseUnitLower = getBaseUnit(unitLower);
    if (baseUnitLower) {
        return {
            unit: baseUnitLower,
            factor: equivalentUnits[baseUnitLower][unitLower],
        };
    }

    return null;
}

export function calculateTotals(quantityList) {
    const totals = {};
    for (const quantity of quantityList) {
        const baseUnit = getConversionFactor(quantity.unit) ?? { unit: quantity.unit, factor: 1 };
        const factor = baseUnit.factor;
        const unit = baseUnit.unit;

        if (!totals[unit]) {
            totals[unit] = 0;
        }

        totals[unit] += quantity.quantity / factor;
    }

    return Object.keys(totals).map(unit => ({ unit, quantity: totals[unit] }));
}