<?php
declare(strict_types=1);

require_once __DIR__ . '/forecast.php';
require_once __DIR__ . '/../../system/audit.php';

function get_default_location_ids(PDO $pdo): array
{
    $row = $pdo->query(
        "SELECT
            (SELECT id FROM location WHERE type = 'storage' ORDER BY id LIMIT 1) AS storage_id,
            (SELECT id FROM location WHERE type = 'dispatch' ORDER BY id LIMIT 1) AS dispatch_id"
    )->fetch();

    if (!is_array($row) || $row['storage_id'] === null || $row['dispatch_id'] === null) {
        throw new RuntimeException('Erforderliche Lagerorte fehlen');
    }

    return [
        'storage' => (int) $row['storage_id'],
        'dispatch' => (int) $row['dispatch_id'],
    ];
}

function get_otc_order_form_products(PDO $pdo): array
{
    $stmt = $pdo->query(
        "SELECT
            p.id,
            p.name,
            p.sku,
            p.uom,
            COALESCE(SUM(v.qty_net), 0) AS available_qty
         FROM product p
         LEFT JOIN stock_lot sl
             ON sl.product_id = p.id
            AND sl.status = 'current'
         LEFT JOIN v_stock_lot_balance v
             ON v.stock_lot_id = sl.id
         WHERE p.status = 'active'
         GROUP BY p.id, p.name, p.sku, p.uom
         ORDER BY p.name ASC, p.id ASC"
    );

    $products = [];
    foreach ($stmt->fetchAll() as $row) {
        $products[] = [
            'id' => (int) $row['id'],
            'name' => (string) $row['name'],
            'sku' => (string) $row['sku'],
            'uom' => (string) $row['uom'],
            'available_qty' => (float) $row['available_qty'],
            'has_sellable_mapping' => false,
        ];
    }

    $mappingStmt = $pdo->query(
        'SELECT DISTINCT product_id
         FROM sellable_item_component'
    );
    $mappedProductIds = array_fill_keys(array_map('intval', $mappingStmt->fetchAll(PDO::FETCH_COLUMN)), true);
    foreach ($products as &$product) {
        $product['has_sellable_mapping'] = isset($mappedProductIds[$product['id']]);
    }
    unset($product);

    return $products;
}

function get_lager_product_overview(PDO $pdo): array
{
    $stmt = $pdo->query(
        "SELECT
            p.id,
            p.name,
            p.sku,
            p.uom,
            COALESCE(SUM(v.qty_net), 0) AS available_qty,
            COALESCE(v.qty_in, 0) AS qty_in,
            sl.lot_number,
            sl.id AS lot_id,
            sl.manufacturer_party_id,
            sl.manufacturer_lot_number,
            mp.name AS manufacturer_name,
            sl.mfg_date,
            sl.expiry_date,
            sl.purchase_date,
            sl.sellout_date,
            sl.sellout_forecast_status,
            COALESCE((
                SELECT SUM(a.qty)
                FROM sales_order_line_lot_allocation a
                INNER JOIN stock_lot virtual_lot ON virtual_lot.id = a.lot_id
                WHERE virtual_lot.product_id = p.id
                  AND virtual_lot.status = 'virtual_shortage'
                  AND a.allocation_status = 'reserved'
            ), 0) AS virtual_shortage_qty,
            (
                SELECT virtual_lot.lot_number
                FROM stock_lot virtual_lot
                WHERE virtual_lot.product_id = p.id
                  AND virtual_lot.status = 'virtual_shortage'
                ORDER BY virtual_lot.id
                LIMIT 1
            ) AS virtual_lot_number
         FROM product p
         LEFT JOIN stock_lot sl
             ON sl.product_id = p.id
            AND sl.status = 'current'
         LEFT JOIN party mp ON mp.id = sl.manufacturer_party_id
         LEFT JOIN v_stock_lot_balance v
             ON v.stock_lot_id = sl.id
         WHERE p.status = 'active'
         GROUP BY p.id, p.name, p.sku, p.uom, sl.id, sl.lot_number, sl.manufacturer_party_id,
                  sl.manufacturer_lot_number, mp.name, sl.mfg_date, sl.expiry_date, sl.purchase_date,
                  sl.sellout_date, sl.sellout_forecast_status, v.qty_in
         ORDER BY p.name ASC, p.id ASC"
    );

    $products = array_map(
        static fn (array $row): array => [
            'id' => (int) $row['id'],
            'name' => (string) $row['name'],
            'sku' => (string) $row['sku'],
            'uom' => (string) $row['uom'],
            'available_qty' => (float) $row['available_qty'],
            'qty_in' => (float) $row['qty_in'],
            'lot_id' => $row['lot_id'] === null ? null : (int) $row['lot_id'],
            'lot_number' => $row['lot_number'],
            'manufacturer_party_id' => $row['manufacturer_party_id'] === null ? null : (int) $row['manufacturer_party_id'],
            'manufacturer_lot_number' => $row['manufacturer_lot_number'],
            'manufacturer_name' => $row['manufacturer_name'],
            'mfg_date' => $row['mfg_date'],
            'expiry_date' => $row['expiry_date'],
            'purchase_date' => $row['purchase_date'],
            'sellout_date' => $row['sellout_date'],
            'sellout_forecast_status' => (string) ($row['sellout_forecast_status'] ?? 'no_demand'),
            'virtual_shortage_qty' => (float) ($row['virtual_shortage_qty'] ?? 0),
            'virtual_lot_number' => $row['virtual_lot_number'],
        ],
        $stmt->fetchAll()
    );

    $historicalStmt = $pdo->query(
        "SELECT
            sl.product_id,
            sl.id AS lot_id,
            sl.lot_number,
            sl.mfg_date,
            sl.expiry_date,
            sl.purchase_date,
            sl.manufacturer_lot_number,
            mp.name AS manufacturer_name,
            COALESCE(v.qty_in, 0) AS qty_in,
            COALESCE(v.qty_out, 0) AS qty_out,
            COALESCE(v.qty_net, 0) AS qty_net,
            MIN(sm.move_date) FILTER (WHERE sm.move_type = 'in') AS first_in_at,
            MAX(sm.move_date) FILTER (WHERE sm.move_type = 'out') AS last_out_at
         FROM stock_lot sl
         LEFT JOIN party mp ON mp.id = sl.manufacturer_party_id
         LEFT JOIN v_stock_lot_balance v ON v.stock_lot_id = sl.id
         LEFT JOIN stock_move sm ON sm.lot_id = sl.id
         WHERE sl.status = 'closed'
           AND sl.lot_number NOT LIKE 'INIT-%'
         GROUP BY sl.product_id, sl.id, sl.lot_number, sl.mfg_date, sl.expiry_date,
                  sl.purchase_date, sl.manufacturer_lot_number, mp.name,
                  v.qty_in, v.qty_out, v.qty_net
         ORDER BY sl.product_id, sl.id DESC"
    );

    $historicalLotsByProduct = [];
    foreach ($historicalStmt->fetchAll() as $row) {
        $historicalLotsByProduct[(int) $row['product_id']][] = [
            'lot_id' => (int) $row['lot_id'],
            'lot_number' => $row['lot_number'],
            'mfg_date' => $row['mfg_date'],
            'expiry_date' => $row['expiry_date'],
            'purchase_date' => $row['purchase_date'],
            'manufacturer_lot_number' => $row['manufacturer_lot_number'],
            'manufacturer_name' => $row['manufacturer_name'],
            'qty_in' => (float) $row['qty_in'],
            'qty_out' => (float) $row['qty_out'],
            'qty_net' => (float) $row['qty_net'],
            'first_in_at' => $row['first_in_at'],
            'last_out_at' => $row['last_out_at'],
        ];
    }

    $openStmt = $pdo->query(
        "SELECT
            sl.product_id,
            sl.id AS lot_id,
            sl.lot_number,
            sl.manufacturer_party_id,
            sl.manufacturer_lot_number,
            mp.name AS manufacturer_name,
            sl.mfg_date,
            sl.expiry_date,
            sl.purchase_date,
            COALESCE(v.qty_in, 0) AS qty_in,
            COALESCE(v.qty_net, 0) AS qty_net
         FROM stock_lot sl
         LEFT JOIN party mp ON mp.id = sl.manufacturer_party_id
         LEFT JOIN v_stock_lot_balance v ON v.stock_lot_id = sl.id
         WHERE sl.status = 'open'
         ORDER BY sl.product_id, sl.id"
    );
    $openLotsByProduct = [];
    foreach ($openStmt->fetchAll() as $openLot) {
        $openLotsByProduct[(int) $openLot['product_id']][] = [
                'lot_id' => (int) $openLot['lot_id'],
                'lot_number' => $openLot['lot_number'],
                'manufacturer_party_id' => $openLot['manufacturer_party_id'] === null ? null : (int) $openLot['manufacturer_party_id'],
                'manufacturer_lot_number' => $openLot['manufacturer_lot_number'],
                'manufacturer_name' => $openLot['manufacturer_name'],
                'mfg_date' => $openLot['mfg_date'],
                'expiry_date' => $openLot['expiry_date'],
                'purchase_date' => $openLot['purchase_date'],
                'qty_in' => (float) $openLot['qty_in'],
                'qty_net' => (float) $openLot['qty_net'],
        ];
    }

    foreach ($products as &$product) {
        $product['historical_lots'] = $historicalLotsByProduct[$product['id']] ?? [];
        $product['open_lots'] = $openLotsByProduct[$product['id']] ?? [];
    }
    unset($product);

    return $products;
}

function update_stock_lot_traceability(
    PDO $pdo,
    int $lotId,
    ?int $manufacturerPartyId,
    ?string $manufacturerLotNumber,
    ?string $mfgDate,
    ?string $expiryDate,
    ?string $purchaseDate,
    string $changedBy,
    float $receiptQty = 0.0,
    float $adjustmentQty = 0.0,
    float $outQty = 0.0,
    ?string $lotNumber = null
): array {
    if ($lotId <= 0) {
        throw new InvalidArgumentException('Chargen-ID fehlt');
    }

    $manufacturerLotNumber = $manufacturerLotNumber !== null ? trim($manufacturerLotNumber) : null;
    if ($manufacturerLotNumber === '') {
        $manufacturerLotNumber = null;
    }
    $lotNumber = $lotNumber !== null ? trim($lotNumber) : null;
    if ($lotNumber === '') {
        throw new InvalidArgumentException('Naurua-Chargennummer fehlt');
    }

    if (!is_finite($receiptQty) || !is_finite($adjustmentQty) || !is_finite($outQty)) {
        throw new InvalidArgumentException('Ungueltige Bewegungsmenge');
    }
    if ($receiptQty < 0 || $outQty < 0) {
        throw new InvalidArgumentException('Zugang und Abgang duerfen nicht negativ sein');
    }
    if (fmod($adjustmentQty, 1.0) !== 0.0) {
        throw new InvalidArgumentException('Bestandskorrekturen muessen ganzzahlig sein');
    }
    if ($adjustmentQty !== 0.0 && abs($adjustmentQty) < 0.0001) {
        $adjustmentQty = 0.0;
    }

    $dates = [
        'mfg_date' => $mfgDate,
        'expiry_date' => $expiryDate,
        'purchase_date' => $purchaseDate,
    ];
    foreach ($dates as $field => $value) {
        if ($value !== null && $value !== '') {
            $parsed = DateTimeImmutable::createFromFormat('!Y-m-d', $value);
            $errors = DateTimeImmutable::getLastErrors();
            if ($parsed === false || (is_array($errors) && (($errors['warning_count'] ?? 0) > 0 || ($errors['error_count'] ?? 0) > 0))) {
                throw new InvalidArgumentException("Ungueltiges Datum fuer {$field}");
            }
        }
        $dates[$field] = $value !== null && $value !== '' ? $value : null;
    }

    $startedTransaction = !$pdo->inTransaction();
    if ($startedTransaction) {
        $pdo->beginTransaction();
    }

    try {
        $lotStmt = $pdo->prepare(
            "SELECT id, product_id, lot_number, manufacturer_party_id, manufacturer_lot_number,
                    mfg_date, expiry_date, purchase_date, status
             FROM stock_lot
             WHERE id = :id
             FOR UPDATE"
        );
        $lotStmt->execute([':id' => $lotId]);
        $before = $lotStmt->fetch();
        if (!is_array($before)) {
            throw new RuntimeException('Charge nicht gefunden');
        }
        if ((string) $before['status'] === 'virtual_shortage') {
            throw new InvalidArgumentException('Virtuelle Fehlbestandschargen koennen nicht gepflegt werden');
        }
        if ($lotNumber !== null && (string) $before['status'] !== 'open') {
            throw new InvalidArgumentException('Nur offene Chargen koennen neu angelegt werden');
        }

        if ($manufacturerPartyId !== null) {
            $manufacturerStmt = $pdo->prepare(
                "SELECT p.id
                 FROM party p
                 INNER JOIN party_role pr ON pr.party_id = p.id AND pr.role_code = 'manufacturer'
                 WHERE p.id = :id AND p.status = 'active'
                 LIMIT 1"
            );
            $manufacturerStmt->execute([':id' => $manufacturerPartyId]);
            if ($manufacturerStmt->fetchColumn() === false) {
                throw new InvalidArgumentException('Hersteller ist nicht aktiv oder nicht als Hersteller gepflegt');
            }
        }

        if ($manufacturerPartyId === null && $manufacturerLotNumber !== null) {
            throw new InvalidArgumentException('Hersteller-Chargennummer benoetigt einen Hersteller');
        }
        if ($manufacturerPartyId !== null && $manufacturerLotNumber === null && (string) $before['status'] !== 'open') {
            throw new InvalidArgumentException('Hersteller-Chargennummer fehlt');
        }
        if (($adjustmentQty !== 0.0 || $outQty > 0) && (string) $before['status'] !== 'current') {
            throw new InvalidArgumentException('Korrekturen und Abgaenge koennen nur auf der aktiven Charge gebucht werden');
        }

        $updateStmt = $pdo->prepare(
            "UPDATE stock_lot
             SET lot_number = COALESCE(:lot_number, lot_number),
                 manufacturer_party_id = :manufacturer_party_id,
                 manufacturer_lot_number = :manufacturer_lot_number,
                 mfg_date = :mfg_date,
                 expiry_date = :expiry_date,
                 purchase_date = :purchase_date,
                 updated_at = NOW()
             WHERE id = :id"
        );
        $updateStmt->execute([
            ':lot_number' => $lotNumber,
            ':manufacturer_party_id' => $manufacturerPartyId,
            ':manufacturer_lot_number' => $manufacturerLotNumber,
            ':mfg_date' => $dates['mfg_date'],
            ':expiry_date' => $dates['expiry_date'],
            ':purchase_date' => $dates['purchase_date'],
            ':id' => $lotId,
        ]);

        $after = $before;
        if ($lotNumber !== null) {
            $after['lot_number'] = $lotNumber;
        }
        $after['manufacturer_party_id'] = $manufacturerPartyId;
        $after['manufacturer_lot_number'] = $manufacturerLotNumber;
        $after['mfg_date'] = $dates['mfg_date'];
        $after['expiry_date'] = $dates['expiry_date'];
        $after['purchase_date'] = $dates['purchase_date'];
        system_write_audit_log($pdo, 'stock_lot', (string) $lotId, 'traceability_updated', $changedBy, $before, $after, [
            'module' => 'erp.lager',
        ]);

        if ($receiptQty > 0 || $adjustmentQty !== 0.0 || $outQty > 0) {
            book_stock_lot_movements($pdo, (int) $before['product_id'], $lotId, $receiptQty, $adjustmentQty, $outQty);
        }

        if ($startedTransaction) {
            $pdo->commit();
        }

        return $after;
    } catch (Throwable $error) {
        if ($startedTransaction && $pdo->inTransaction()) {
            $pdo->rollBack();
        }
        throw $error;
    }
}

function get_current_lot_balance_for_update(PDO $pdo, int $productId): array
{
    $stmt = $pdo->prepare(
        "SELECT
            sl.id AS lot_id,
            COALESCE((
                SELECT v.qty_net
                FROM v_stock_lot_balance v
                WHERE v.stock_lot_id = sl.id
            ), 0) AS qty_net
         FROM stock_lot sl
         WHERE sl.product_id = :product_id
           AND sl.status = 'current'
         LIMIT 1
         FOR UPDATE"
    );
    $stmt->execute([':product_id' => $productId]);
    $row = $stmt->fetch();

    if ($row === false) {
        throw new RuntimeException("Keine aktuelle Charge fuer Produkt {$productId} vorhanden");
    }

    return [
        'lot_id' => (int) $row['lot_id'],
        'qty_net' => (float) $row['qty_net'],
    ];
}

function get_stock_lot_balance(PDO $pdo, int $lotId): array
{
    $stmt = $pdo->prepare(
        "SELECT
            COALESCE(v.qty_net, 0) AS qty_net,
            COALESCE(v.qty_in, 0) AS qty_in,
            COALESCE(v.qty_out, 0) AS qty_out
         FROM stock_lot sl
         LEFT JOIN v_stock_lot_balance v ON v.stock_lot_id = sl.id
         WHERE sl.id = :lot_id"
    );
    $stmt->execute([':lot_id' => $lotId]);
    $row = $stmt->fetch();
    if (!is_array($row)) {
        throw new RuntimeException('Charge nicht gefunden');
    }

    return [
        'qty_net' => (float) $row['qty_net'],
        'qty_in' => (float) $row['qty_in'],
        'qty_out' => (float) $row['qty_out'],
    ];
}

function insert_stock_move_out(
    PDO $pdo,
    int $productId,
    int $lotId,
    float $qty,
    int $fromLocationId,
    int $toLocationId,
    string $note
): int {
    $stmt = $pdo->prepare(
        "INSERT INTO stock_move (
            product_id, lot_id, from_location_id, to_location_id, qty, move_type, move_date, note, created_at, updated_at
         ) VALUES (
            :product_id, :lot_id, :from_location_id, :to_location_id, :qty, 'out', NOW(), :note, NOW(), NOW()
         )
         RETURNING id"
    );
    $stmt->execute([
        ':product_id' => $productId,
        ':lot_id' => $lotId,
        ':from_location_id' => $fromLocationId,
        ':to_location_id' => $toLocationId,
        ':qty' => $qty,
        ':note' => $note,
    ]);

    $id = $stmt->fetchColumn();
    if ($id === false) {
        throw new RuntimeException('Konnte Lagerabgang nicht schreiben');
    }

    return (int) $id;
}

function insert_stock_move_in(
    PDO $pdo,
    int $productId,
    int $lotId,
    float $qty,
    int $fromLocationId,
    int $toLocationId,
    string $note
): int {
    $stmt = $pdo->prepare(
        "INSERT INTO stock_move (
            product_id, lot_id, from_location_id, to_location_id, qty, move_type, move_date, note, created_at, updated_at
         ) VALUES (
            :product_id, :lot_id, :from_location_id, :to_location_id, :qty, 'in', NOW(), :note, NOW(), NOW()
         )
         RETURNING id"
    );
    $stmt->execute([
        ':product_id' => $productId,
        ':lot_id' => $lotId,
        ':from_location_id' => $fromLocationId,
        ':to_location_id' => $toLocationId,
        ':qty' => $qty,
        ':note' => $note,
    ]);

    $id = $stmt->fetchColumn();
    if ($id === false) {
        throw new RuntimeException('Konnte Lagerzugang nicht schreiben');
    }

    return (int) $id;
}

function insert_stock_move_adjustment(
    PDO $pdo,
    int $productId,
    int $lotId,
    float $qty,
    ?int $fromLocationId,
    ?int $toLocationId,
    string $note
): int {
    $stmt = $pdo->prepare(
        "INSERT INTO stock_move (
            product_id, lot_id, from_location_id, to_location_id, qty, move_type, move_date, note, created_at, updated_at
         ) VALUES (
            :product_id, :lot_id, :from_location_id, :to_location_id, :qty, 'adjustment', NOW(), :note, NOW(), NOW()
         )
         RETURNING id"
    );
    $stmt->execute([
        ':product_id' => $productId,
        ':lot_id' => $lotId,
        ':from_location_id' => $fromLocationId,
        ':to_location_id' => $toLocationId,
        ':qty' => $qty,
        ':note' => $note,
    ]);

    $id = $stmt->fetchColumn();
    if ($id === false) {
        throw new RuntimeException('Konnte Bestandskorrektur nicht schreiben');
    }

    return (int) $id;
}

function book_stock_lot_movements(
    PDO $pdo,
    int $productId,
    int $lotId,
    float $receiptQty,
    float $adjustmentQty,
    float $outQty
): void {
    $locations = get_default_location_ids($pdo);
    $balanceStmt = $pdo->prepare(
        "SELECT COALESCE(
            SUM(CASE
                WHEN move_type = 'in' THEN qty
                WHEN move_type = 'out' THEN -qty
                WHEN move_type = 'adjustment' AND to_location_id IS NOT NULL AND from_location_id IS NULL THEN qty
                WHEN move_type = 'adjustment' AND from_location_id IS NOT NULL AND to_location_id IS NULL THEN -qty
                ELSE 0
            END), 0
         )
         FROM stock_move
         WHERE lot_id = :lot_id"
    );
    $balanceStmt->execute([':lot_id' => $lotId]);
    $balance = (float) $balanceStmt->fetchColumn();

    if ($receiptQty > 0) {
        insert_stock_move_in($pdo, $productId, $lotId, $receiptQty, $locations['storage'], $locations['storage'], 'Manueller Lagerzugang via Chargenformular');
        $balance += $receiptQty;
    }

    if ($adjustmentQty !== 0.0) {
        if ($adjustmentQty > 0) {
            insert_stock_move_adjustment($pdo, $productId, $lotId, $adjustmentQty, null, $locations['storage'], 'Manuelle Bestandskorrektur via Chargenformular');
        } else {
            $correctionQty = abs($adjustmentQty);
            if ($correctionQty > $balance) {
                throw new InvalidArgumentException('Bestandskorrektur wuerde den Chargensaldo negativ machen');
            }
            insert_stock_move_adjustment($pdo, $productId, $lotId, $correctionQty, $locations['storage'], null, 'Manuelle Bestandskorrektur via Chargenformular');
        }
        $balance += $adjustmentQty;
    }

    if ($outQty > $balance) {
        throw new InvalidArgumentException('Lagerabgang ist groesser als der aktuelle Chargenbestand');
    }
    if ($outQty > 0) {
        insert_stock_move_out($pdo, $productId, $lotId, $outQty, $locations['storage'], $locations['dispatch'], 'Manueller Lagerabgang via Chargenformular');
    }
}

function switch_current_lot(PDO $pdo, int $productId, int $oldCurrentLotId, int $storageLocationId): int
{
    $closeStmt = $pdo->prepare(
        "UPDATE stock_lot
         SET status = 'closed', updated_at = NOW()
         WHERE id = :id"
    );
    $closeStmt->execute([':id' => $oldCurrentLotId]);

    $openStmt = $pdo->prepare(
        "SELECT id
         FROM stock_lot
         WHERE product_id = :product_id
           AND status = 'open'
           AND lot_number IS NOT NULL
         ORDER BY id
         LIMIT 1
         FOR UPDATE"
    );
    $openStmt->execute([':product_id' => $productId]);
    $newCurrentLotId = $openStmt->fetchColumn();

    if ($newCurrentLotId === false) {
        throw new RuntimeException("Keine offene Platzhalter-Charge fuer Produkt {$productId} vorhanden");
    }

    $promoteStmt = $pdo->prepare(
        "UPDATE stock_lot
         SET status = 'current',
             updated_at = NOW()
         WHERE id = :id"
    );
    $promoteStmt->execute([':id' => (int) $newCurrentLotId]);

    $createOpenStmt = $pdo->prepare(
        "INSERT INTO stock_lot (product_id, status, created_at, updated_at)
         VALUES (:product_id, 'open', NOW(), NOW())
         RETURNING id"
    );
    $createOpenStmt->execute([':product_id' => $productId]);
    $createdOpenLotId = $createOpenStmt->fetchColumn();
    if ($createdOpenLotId === false) {
        throw new RuntimeException("Konnte keine neue offene Platzhalter-Charge fuer Produkt {$productId} anlegen");
    }

    return (int) $newCurrentLotId;
}

function reverse_existing_allocations_for_order(PDO $pdo, int $orderId, int $fallbackStorageLocationId): array
{
    $stmt = $pdo->prepare(
        "SELECT
            a.stock_move_id,
            a.product_id,
            a.lot_id,
            a.qty,
            sm.from_location_id,
            sm.to_location_id
         FROM sales_order_line_lot_allocation a
         LEFT JOIN stock_move sm ON sm.id = a.stock_move_id
         INNER JOIN sales_order_line sol ON sol.id = a.sales_order_line_id
         WHERE sol.sales_order_id = :order_id
         ORDER BY a.id DESC"
    );
    $stmt->execute([':order_id' => $orderId]);
    $rows = $stmt->fetchAll();

    $reverseCount = 0;
    $reverseQty = 0.0;

    foreach ($rows as $row) {
        $productId = (int) $row['product_id'];
        $lotId = (int) $row['lot_id'];
        $qty = (float) $row['qty'];
        $fromLocationId = (int) ($row['from_location_id'] ?? $fallbackStorageLocationId);
        $toLocationId = (int) ($row['to_location_id'] ?? $fallbackStorageLocationId);

        insert_stock_move_in(
            $pdo,
            $productId,
            $lotId,
            $qty,
            $toLocationId,
            $fromLocationId,
            "reverse-order={$orderId}"
        );

        $reverseCount++;
        $reverseQty += $qty;
    }

    return [
        'reversedMoves' => $reverseCount,
        'reversedQty' => $reverseQty,
    ];
}

function has_available_stock_for_product(PDO $pdo, int $productId, float $epsilon = 0.0000001): bool
{
    $stmt = $pdo->prepare(
        "SELECT COALESCE(SUM(v.qty_net), 0) AS qty_net
         FROM v_stock_lot_balance v
         INNER JOIN stock_lot sl ON sl.id = v.stock_lot_id
         WHERE sl.product_id = :product_id
           AND sl.status = 'current'"
    );
    $stmt->execute([':product_id' => $productId]);
    $qty = (float) ($stmt->fetchColumn() ?: 0);
    return $qty > $epsilon;
}

function get_or_create_virtual_shortage_lot(PDO $pdo, int $productId): int
{
    $lotNumber = "VIRT-{$productId}-UNBEKANNT";
    $select = $pdo->prepare(
        "SELECT id
         FROM stock_lot
         WHERE product_id = :product_id
           AND status = 'virtual_shortage'
           AND lot_number = :lot_number
         FOR UPDATE"
    );
    $select->execute([
        ':product_id' => $productId,
        ':lot_number' => $lotNumber,
    ]);
    $lotId = $select->fetchColumn();
    if ($lotId !== false) {
        return (int) $lotId;
    }

    $insert = $pdo->prepare(
        "INSERT INTO stock_lot (product_id, lot_number, status, created_at, updated_at)
         VALUES (:product_id, :lot_number, 'virtual_shortage', NOW(), NOW())
         RETURNING id"
    );
    $insert->execute([
        ':product_id' => $productId,
        ':lot_number' => $lotNumber,
    ]);
    $newLotId = $insert->fetchColumn();
    if ($newLotId === false) {
        throw new RuntimeException("Virtuelle Fehlbestandscharge fuer Produkt {$productId} konnte nicht angelegt werden");
    }

    return (int) $newLotId;
}

function get_or_create_open_lot(PDO $pdo, int $productId): int
{
    $select = $pdo->prepare(
        "SELECT id
         FROM stock_lot
         WHERE product_id = :product_id
           AND status = 'open'
         ORDER BY id
         LIMIT 1
         FOR UPDATE"
    );
    $select->execute([':product_id' => $productId]);
    $lotId = $select->fetchColumn();
    if ($lotId !== false) {
        return (int) $lotId;
    }

    $insert = $pdo->prepare(
        "INSERT INTO stock_lot (product_id, status, created_at, updated_at)
         VALUES (:product_id, 'open', NOW(), NOW())
         RETURNING id"
    );
    $insert->execute([':product_id' => $productId]);
    $newLotId = $insert->fetchColumn();
    if ($newLotId === false) {
        throw new RuntimeException('Offene Charge konnte nicht angelegt werden');
    }

    return (int) $newLotId;
}

function replace_virtual_lot_allocation(
    PDO $pdo,
    int $allocationId,
    int $realLotId,
    float $qty,
    string $changedBy,
    string $reason
): int {
    if ($qty <= 0 || trim($changedBy) === '' || trim($reason) === '') {
        throw new InvalidArgumentException('Menge, Bediener und Grund sind erforderlich');
    }

    $startedTransaction = !$pdo->inTransaction();
    if ($startedTransaction) {
        $pdo->beginTransaction();
    }

    try {
        $allocationStmt = $pdo->prepare(
            "SELECT a.id, a.sales_order_line_id, a.product_id, a.lot_id, a.qty, a.allocation_status,
                    sol.sales_order_id, sol.line_no,
                    source_lot.status AS source_lot_status,
                    target_lot.product_id AS target_product_id,
                    target_lot.status AS target_lot_status
             FROM sales_order_line_lot_allocation a
             INNER JOIN sales_order_line sol ON sol.id = a.sales_order_line_id
             INNER JOIN stock_lot source_lot ON source_lot.id = a.lot_id
             INNER JOIN stock_lot target_lot ON target_lot.id = :target_lot_id
             WHERE a.id = :allocation_id
             FOR UPDATE"
        );
        $allocationStmt->execute([
            ':allocation_id' => $allocationId,
            ':target_lot_id' => $realLotId,
        ]);
        $allocation = $allocationStmt->fetch();
        if (!is_array($allocation)) {
            throw new RuntimeException("Chargenzuordnung {$allocationId} fehlt");
        }

        if (($allocation['allocation_status'] ?? null) !== 'reserved' || $allocation['source_lot_status'] !== 'virtual_shortage') {
            throw new RuntimeException('Nur reservierte virtuelle Chargenzuordnungen koennen ersetzt werden');
        }
        if ((int) $allocation['product_id'] !== (int) $allocation['target_product_id']) {
            throw new RuntimeException('Echte Charge gehoert zu einem anderen Produkt');
        }
        if ($allocation['target_lot_status'] !== 'current') {
            throw new RuntimeException('Echte Zielcharge muss aktuell sein');
        }

        $sourceQty = (float) $allocation['qty'];
        if ($qty > $sourceQty + 0.0000001) {
            throw new RuntimeException('Ersetzungsmenge uebersteigt virtuelle Zuordnung');
        }

        $balanceStmt = $pdo->prepare(
            "SELECT COALESCE(v.qty_net, 0)
             FROM v_stock_lot_balance v
             WHERE v.stock_lot_id = :lot_id
             FOR UPDATE"
        );
        $balanceStmt->execute([':lot_id' => $realLotId]);
        $available = (float) ($balanceStmt->fetchColumn() ?: 0);
        if ($available + 0.0000001 < $qty) {
            throw new RuntimeException('Nicht genuegend Bestand in der echten Zielcharge');
        }

        $locations = get_default_location_ids($pdo);
        $stockMoveId = insert_stock_move_out(
            $pdo,
            (int) $allocation['product_id'],
            $realLotId,
            $qty,
            (int) $locations['storage'],
            (int) $locations['dispatch'],
            "lot-replacement:order={$allocation['sales_order_id']}:line={$allocation['line_no']}:product={$allocation['product_id']}"
        );

        $releaseStmt = $pdo->prepare(
            "UPDATE sales_order_line_lot_allocation
             SET allocation_status = 'released', released_at = NOW(), updated_at = NOW()
             WHERE id = :id"
        );
        $releaseStmt->execute([':id' => $allocationId]);

        $remainingQty = $sourceQty - $qty;
        if ($remainingQty > 0.0000001) {
            $residualStmt = $pdo->prepare(
                "INSERT INTO sales_order_line_lot_allocation (
                    sales_order_line_id, product_id, lot_id, qty, allocation_status, created_at, updated_at
                 ) VALUES (
                    :sales_order_line_id, :product_id, :lot_id, :qty, 'reserved', NOW(), NOW()
                 )"
            );
            $residualStmt->execute([
                ':sales_order_line_id' => (int) $allocation['sales_order_line_id'],
                ':product_id' => (int) $allocation['product_id'],
                ':lot_id' => (int) $allocation['lot_id'],
                ':qty' => $remainingQty,
            ]);
        }

        $newAllocationStmt = $pdo->prepare(
            "INSERT INTO sales_order_line_lot_allocation (
                sales_order_line_id, product_id, lot_id, qty, allocation_status, stock_move_id, created_at, updated_at
             ) VALUES (
                :sales_order_line_id, :product_id, :lot_id, :qty, 'allocated', :stock_move_id, NOW(), NOW()
             ) RETURNING id"
        );
        $newAllocationStmt->execute([
            ':sales_order_line_id' => (int) $allocation['sales_order_line_id'],
            ':product_id' => (int) $allocation['product_id'],
            ':lot_id' => $realLotId,
            ':qty' => $qty,
            ':stock_move_id' => $stockMoveId,
        ]);
        $newAllocationId = $newAllocationStmt->fetchColumn();
        if ($newAllocationId === false) {
            throw new RuntimeException('Neue reale Chargenzuordnung konnte nicht angelegt werden');
        }

        $replacementStmt = $pdo->prepare(
            "INSERT INTO stock_lot_allocation_replacement (
                from_allocation_id, to_allocation_id, from_lot_id, to_lot_id,
                product_id, qty, changed_by, reason, created_at
             ) VALUES (
                :from_allocation_id, :to_allocation_id, :from_lot_id, :to_lot_id,
                :product_id, :qty, :changed_by, :reason, NOW()
             )"
        );
        $replacementStmt->execute([
            ':from_allocation_id' => $allocationId,
            ':to_allocation_id' => (int) $newAllocationId,
            ':from_lot_id' => (int) $allocation['lot_id'],
            ':to_lot_id' => $realLotId,
            ':product_id' => (int) $allocation['product_id'],
            ':qty' => $qty,
            ':changed_by' => trim($changedBy),
            ':reason' => trim($reason),
        ]);

        if ($startedTransaction) {
            $pdo->commit();
        }
        return (int) $newAllocationId;
    } catch (Throwable $exception) {
        if ($startedTransaction && $pdo->inTransaction()) {
            $pdo->rollBack();
        }
        throw $exception;
    }
}

function allocate_components_for_line(
    PDO $pdo,
    int $orderId,
    int $lineId,
    int $lineNo,
    array $components,
    float $lineQty,
    array $locations,
    string $movementSource = 'otc-order'
): array {
    if ($components === []) {
        throw new RuntimeException("Keine Komponenten fuer Verkaufsposition {$lineNo} gefunden");
    }

    $allocationCount = 0;
    $virtualAllocationCount = 0;
    $forecastProductIds = [];
    foreach ($components as $component) {
        $productId = (int) $component['product_id'];
        $forecastProductIds[$productId] = true;
        $remaining = $lineQty * (float) $component['qty_per_item'];
        $guard = 0;

        while ($remaining > 0.0000001) {
            $guard++;
            if ($guard > 100) {
                throw new RuntimeException("Allokationsschutz ausgelost fuer Produkt {$productId}");
            }

            $current = get_current_lot_balance_for_update($pdo, $productId);
            $lotId = $current['lot_id'];
            $available = $current['qty_net'];

            if ($available <= 0.0000001) {
                $take = $remaining;
                $lotId = get_or_create_virtual_shortage_lot($pdo, $productId);
                $stockMoveId = null;
                $allocationStatus = 'reserved';
                $virtualAllocationCount++;
            } else {
                $take = min($remaining, $available);
                $stockMoveId = insert_stock_move_out(
                    $pdo,
                    $productId,
                    $lotId,
                    $take,
                    (int) $locations['storage'],
                    (int) $locations['dispatch'],
                    "{$movementSource}:order={$orderId}:line={$lineNo}:product={$productId}"
                );
                $allocationStatus = 'allocated';
            }

            $allocationInsert = $pdo->prepare(
                "INSERT INTO sales_order_line_lot_allocation (
                    sales_order_line_id, product_id, lot_id, qty, allocation_status, stock_move_id, created_at, updated_at
                 ) VALUES (
                    :sales_order_line_id, :product_id, :lot_id, :qty, :allocation_status, :stock_move_id, NOW(), NOW()
                 )"
            );

            $allocationInsert->execute([
                ':sales_order_line_id' => $lineId,
                ':product_id' => $productId,
                ':lot_id' => $lotId,
                ':qty' => $take,
                ':allocation_status' => $allocationStatus,
                ':stock_move_id' => $stockMoveId,
            ]);
            $allocationCount++;

            $remaining -= $take;
        }
    }

    foreach (array_keys($forecastProductIds) as $productId) {
        refresh_lager_stock_lot_forecast_for_product($pdo, (int) $productId);
    }

    return [
        'allocated' => true,
        'allocationCount' => $allocationCount,
        'virtualAllocationCount' => $virtualAllocationCount,
    ];
}

function allocate_line_inventory(
    PDO $pdo,
    int $orderId,
    int $lineId,
    int $lineNo,
    float $lineQty,
    int $sellableItemId,
    array $locations,
    string $movementSource = 'otc-order'
): array {
    $components = get_item_components($pdo, $sellableItemId);
    return allocate_components_for_line($pdo, $orderId, $lineId, $lineNo, $components, $lineQty, $locations, $movementSource);
}

function allocate_line_inventory_fallback_product(
    PDO $pdo,
    int $orderId,
    int $lineId,
    int $lineNo,
    float $lineQty,
    int $productId,
    array $locations
): array {
    $components = [[
        'product_id' => $productId,
        'qty_per_item' => 1.0,
    ]];
    return allocate_components_for_line($pdo, $orderId, $lineId, $lineNo, $components, $lineQty, $locations);
}