<?php 
    session_start();

    require '../../../assets/utils/db_auth.php';
    require '../../../assets/utils/classes/WarehouseManager.php';

    $id = 0;
    $warehouse_id = (int)$data['warehouse'];

    $whMgmt = new WarehouseManager($pdo2, $company_id);
    $warehouse = $whMgmt->getStockContext($warehouse_id, $id);
    $table = $warehouse['table'];

    
    // ── Always last 12 months ────────────────────────────────────────────
    $now   = new DateTime();
    $start = (clone $now)->modify('-12 months')->format('Y-m-d 00:00:00');
    $end   = $now->format('Y-m-d 23:59:59');
    
    // ── Get cumulative balance BEFORE the 12-month window ────────────────
    $sql_prior = "SELECT
                    ROUND(COALESCE(SUM(a.`in`), 0) - COALESCE(SUM(a.`out`), 0), 2) AS `balance`
                FROM `{$table}` a
                WHERE 
                    a.company_id = {$company_id} and
                    a.date       < '{$start}'";
    
    $sth = $pdo2->prepare($sql_prior);
    $sth->execute();
    $prior_balance = (float)$sth->fetchColumn();
    
    // ── Get monthly in/out for the 12-month window ──────────────────────
    $sql = "SELECT
                DATE_FORMAT(a.date, '%Y-%m') AS `sort_key`,
                ROUND(SUM(a.`in`),  2)       AS `stock_in`,
                ROUND(SUM(a.`out`), 2)       AS `stock_out`
            FROM `{$table}` a
            WHERE 
                a.company_id = {$company_id} and
                a.date      >= '{$start}' and 
                a.date      <= '{$end}'
            GROUP BY `sort_key`
            ORDER BY `sort_key` ASC";
    
    $sth = $pdo2->prepare($sql);
    $sth->execute();
    $rows = $sth->fetchAll(PDO::FETCH_ASSOC);
    
    // ── Index DB results by sort_key (YYYY-MM) ──────────────────────────
    $dataByMonth = [];
    foreach ($rows as $row) {
        $dataByMonth[$row['sort_key']] = $row;
    }
    
    // ── Always build 12 months, accumulate running balance ──────────────
    $labels  = [];
    $balance = [];
    $running = $prior_balance;
    
    for ($i = 11; $i >= 0; $i--) {
        $dt    = (clone $now)->modify("-{$i} months");
        $key   = $dt->format('Y-m');
        $label = $dt->format('M');
    
        $month_in  = isset($dataByMonth[$key]) ? (float)$dataByMonth[$key]['stock_in']  : 0;
        $month_out = isset($dataByMonth[$key]) ? (float)$dataByMonth[$key]['stock_out'] : 0;
    
        $running += ($month_in - $month_out);
    
        $labels[]  = $label;
        $balance[] = round($running, 2);
    }
    
    // ── Response ─────────────────────────────────────────────────────────
    $output = [
        'labels'  => $labels,
        'balance' => $balance,
    ];
    
    $answer["output"] = $output;
    $answer["success"] = 1;
    exit(json_encode($answer));

?>