<?php

namespace App\Models;

use Illuminate\Database\Eloquent\Model;
use Illuminate\Database\Eloquent\Builder;

/**
 * RateEntry
 * --------
 * Stores one rate cell from the rate matrix:
 *   direction + service_type + weight + zone + currency + effective_at → rate
 *
 * The latest effective rate for a given (direction, service_type, weight, zone)
 * is used by PriceCalculatorService. Old rates are kept for history.
 */
class RateEntry extends Model
{
    protected $table = 'rate_entries';

    protected $fillable = [
        'direction', 'service_type', 'weight', 'zone',
        'rate', 'currency', 'effective_at',
    ];

    protected $casts = [
        'weight'      => 'float',
        'rate'        => 'float',
        'zone'        => 'integer',
        'effective_at' => 'datetime',
    ];

    /**
     * Scope: get the latest rates effective on or before a given date.
     */
    public function scopeLatestEffective(Builder $q, ?\DateTimeInterface $at = null): Builder
    {
        $at ??= now();
        return $q->where('effective_at', '<=', $at)
                 ->orderByDesc('effective_at');
    }

    /**
     * Look up the applicable rate for a given weight/zone.
     * Rounds UP to the next available weight tier if exact match not found.
     *
     * @return static|null
     */
    public static function lookup(
        string $direction,
        string $serviceType,
        float $weight,
        int $zone,
        string $currency = 'AED',
        ?\DateTimeInterface $at = null
    ): ?self {
        $at ??= now();

        // Try exact weight first
        $entry = self::where('direction',    $direction)
            ->where('service_type', $serviceType)
            ->where('weight',       $weight)
            ->where('zone',          $zone)
            ->where('currency',      $currency)
            ->where('effective_at', '<=', $at)
            ->orderByDesc('effective_at')
            ->first();
        if ($entry) return $entry;

        // Otherwise: round UP to the next available weight tier
        // (this is correct for shipping — a 2.3 kg parcel pays the 2.5 kg rate)
        return self::where('direction',    $direction)
            ->where('service_type', $serviceType)
            ->where('weight',       '>=', $weight)
            ->where('zone',          $zone)
            ->where('currency',      $currency)
            ->where('effective_at', '<=', $at)
            ->orderBy('weight')
            ->orderByDesc('effective_at')
            ->first();
    }
}