<?php

namespace App\Services;

use App\Enums\PacePreference;
use App\Enums\PhysicalActivityLevel;
use App\Enums\UserSex;
use App\Enums\WeightGoal;
use Carbon\CarbonInterface;
use InvalidArgumentException;

class NutritionPlanCalculator
{
    public const FORMULA_VERSION = 'mifflin_st_jeor_v1';

    /**
     * @return array{
     *     formula_version: string,
     *     calories: int,
     *     proteins: float,
     *     carbs: float,
     *     fats: float,
     *     resting_metabolism: int,
     *     maintenance_calories: int,
     *     calorie_adjustment_percent: float,
     *     calculation_details: array<string, float|int|string>
     * }
     */
    public function calculate(
        float $weightKg,
        int $heightCm,
        CarbonInterface $dateOfBirth,
        UserSex $sex,
        PhysicalActivityLevel $activityLevel,
        WeightGoal $weightGoal,
        PacePreference $pacePreference,
    ): array {
        $sexCoefficient = match ($sex) {
            UserSex::MAN => 5,
            UserSex::WOMAN => -161,
            default => throw new InvalidArgumentException('A metabolic calculation reference is required.'),
        };
        $age = (int) $dateOfBirth->diffInYears(now());
        $restingMetabolism = (int) round(
            (10 * $weightKg) + (6.25 * $heightCm) - (5 * $age) + $sexCoefficient
        );
        $activityFactor = $this->activityFactor($activityLevel);
        $maintenanceCalories = (int) (round(($restingMetabolism * $activityFactor) / 10) * 10);
        $adjustmentPercent = $this->calorieAdjustmentPercent($weightGoal, $pacePreference);
        $unboundedCalories = (int) (round(($maintenanceCalories * (1 + $adjustmentPercent)) / 10) * 10);
        $minimumCalories = max(1200, (int) (ceil(($restingMetabolism * 0.8) / 10) * 10));
        $calorieTarget = max($minimumCalories, $unboundedCalories);
        $heightMeters = $heightCm / 100;
        $proteinReferenceWeight = min($weightKg, 25 * ($heightMeters ** 2));
        $proteinFactor = $this->proteinFactor($activityLevel, $weightGoal);
        $proteins = max(1, (int) round($proteinReferenceWeight * $proteinFactor));
        $fats = max(1, (int) round(($calorieTarget * 0.25) / 9));
        $carbs = max(0, (int) round(($calorieTarget - ($proteins * 4) - ($fats * 9)) / 4));
        $macroCalories = ($proteins * 4) + ($carbs * 4) + ($fats * 9);

        return [
            'formula_version' => self::FORMULA_VERSION,
            'calories' => $macroCalories,
            'proteins' => $proteins,
            'carbs' => $carbs,
            'fats' => $fats,
            'resting_metabolism' => $restingMetabolism,
            'maintenance_calories' => $maintenanceCalories,
            'calorie_adjustment_percent' => $adjustmentPercent,
            'calculation_details' => [
                'activityFactor' => $activityFactor,
                'ageAtCalculation' => $age,
                'heightCm' => $heightCm,
                'inputWeightKg' => round($weightKg, 2),
                'minimumCalories' => $minimumCalories,
                'pacePreference' => $pacePreference->value,
                'proteinFactor' => $proteinFactor,
                'proteinReferenceWeightKg' => round($proteinReferenceWeight, 2),
                'sexReference' => $sex->value,
                'weightGoal' => $weightGoal->value,
            ],
        ];
    }

    private function activityFactor(PhysicalActivityLevel $activityLevel): float
    {
        return match ($activityLevel) {
            PhysicalActivityLevel::SEDENTARY => 1.2,
            PhysicalActivityLevel::LIGHTLY_ACTIVE => 1.375,
            PhysicalActivityLevel::MODERATELY_ACTIVE => 1.55,
            PhysicalActivityLevel::VERY_ACTIVE => 1.725,
            PhysicalActivityLevel::ATHLETE => 1.9,
        };
    }

    private function calorieAdjustmentPercent(WeightGoal $weightGoal, PacePreference $pacePreference): float
    {
        if ($weightGoal === WeightGoal::MAINTAIN_WEIGHT) {
            return 0;
        }

        $magnitude = match ($pacePreference) {
            PacePreference::SLOW => $weightGoal === WeightGoal::LOSE_WEIGHT ? 0.10 : 0.05,
            PacePreference::NORMAL => $weightGoal === WeightGoal::LOSE_WEIGHT ? 0.15 : 0.10,
            PacePreference::FAST => $weightGoal === WeightGoal::LOSE_WEIGHT ? 0.20 : 0.15,
        };

        return $weightGoal === WeightGoal::LOSE_WEIGHT ? -$magnitude : $magnitude;
    }

    private function proteinFactor(PhysicalActivityLevel $activityLevel, WeightGoal $weightGoal): float
    {
        $factor = match ($activityLevel) {
            PhysicalActivityLevel::SEDENTARY => 1.2,
            PhysicalActivityLevel::LIGHTLY_ACTIVE => 1.4,
            PhysicalActivityLevel::MODERATELY_ACTIVE => 1.6,
            PhysicalActivityLevel::VERY_ACTIVE, PhysicalActivityLevel::ATHLETE => 1.8,
        };

        $factor += match ($weightGoal) {
            WeightGoal::LOSE_WEIGHT => 0.2,
            WeightGoal::GAIN_WEIGHT => 0.1,
            WeightGoal::MAINTAIN_WEIGHT => 0,
        };

        return min($factor, 2.0);
    }
}