<?php
/**
 * The shop's own sales as a price reference, the pure part. No WordPress here.
 */

if (!defined('ABSPATH')) {
    exit;
}

require_once __DIR__ . '/condition-calc.php';

/**
 * A model key from a title alone: its words, without condition, colour and filler, in
 * sorted order -- the service's plain key (matching.py), for when the service has not
 * placed a product. The service's key is better where it has one: it knows "Alpha 7 III"
 * is an "A7 III".
 */
function usedkit_plain_key($title) {
    static $filler = array(
        'used', 'kaytetty', 'begagnad', 'gebraucht', 'uzywany', 'bazar', 'occasion', 'usato',
        'usado', 'gebruikt', 'brugt', 'second', 'hand', 'secondhand', 'like', 'new', 'mint',
        'excellent', 'good', 'fair', 'condition', 'kunto', 'erinomainen', 'hyva', 'tyydyttava',
        'black', 'silver', 'white', 'musta', 'hopea', 'valkoinen', 'svart', 'schwarz', 'noir',
        'nero', 'negro', 'czarny', 'zwart', 'preto', 'and', 'with', 'the', 'an', 'ja', 'och',
        'und', 'et', 'en');
    preg_match_all('/[a-z0-9][a-z0-9.\/-]*/', usedkit_fold($title), $m);
    $kept = array();
    foreach ($m[0] as $w) {
        $w = trim($w, '.-/');
        if (strlen($w) > 1 && !in_array($w, $filler, true)) {
            $kept[$w] = true;
        }
    }
    $kept = array_keys($kept);
    sort($kept, SORT_STRING);
    return $kept ? 'plain:' . implode(' ', $kept) : '';
}

function usedkit_median($values) {
    $values = array_values($values);
    $n = count($values);
    if (!$n) {
        return null;
    }
    sort($values);
    return $n % 2 ? $values[intdiv($n, 2)] : ($values[$n / 2 - 1] + $values[$n / 2]) / 2;
}

/**
 * What the shop's sales of one model say. `$sales` is a list of
 * ['price' => float, 'days' => int|null, 'at' => unix time, 'grade' => string].
 * Items sold for parts are left out: their price says what the fault cost, not what the
 * model is worth.
 */
function usedkit_reference_stats($sales) {
    $sales = array_values(array_filter($sales, function ($s) {
        return ($s['grade'] ?? '') !== 'parts' && $s['price'] > 0;
    }));
    if (!$sales) {
        return null;
    }
    $prices = array_column($sales, 'price');
    $days = array_filter(array_column($sales, 'days'), function ($d) { return $d !== null; });
    usort($sales, function ($a, $b) { return $b['at'] <=> $a['at']; });
    return array(
        'count'  => count($sales),
        'median' => usedkit_median($prices),
        'low'    => min($prices),
        'high'   => max($prices),
        'days'   => $days ? (int) round(usedkit_median($days)) : null,
        'last'   => $sales[0]['at'],
        'sales'  => array_slice($sales, 0, 5),
    );
}