<?php
require_once __DIR__ . '/../helpers.php';
require_once __DIR__ . '/_cartPayload.php';
runAuth();

/**
 * Set Line Item (add/update/remove items in cart)
 * POST: { OrderID, ItemID, IsSelected, Quantity?, Remark?, ParentOrderLineItemID?, OrderLineItemID?, ForceNew? }
 */

function nextId(string $table, string $idField): int {
    $q = queryOne("SELECT IFNULL(MAX({$idField}),0) + 1 AS NextID FROM {$table}", []);
    return (int) $q['NextID'];
}

function attachDefaultChildren(int $OrderID, int $ParentLineItemID, int $ParentItemID): void {
    // Direct children
    $qAllKids = queryTimed(
        "SELECT ID, Price, IsCheckedByDefault FROM Items WHERE ParentItemID = ? AND IsActive = 1 ORDER BY SortOrder, ID",
        [$ParentItemID]
    );

    // Template-linked children
    $qTemplateKids = queryTimed(
        "SELECT i.ID, i.Price, i.IsCheckedByDefault
         FROM lt_ItemID_TemplateItemID tl
         INNER JOIN Items i ON i.ParentItemID = tl.TemplateItemID
         WHERE tl.ItemID = ? AND i.IsActive = 1
         ORDER BY i.SortOrder, i.ID",
        [$ParentItemID]
    );

    $allKids = array_merge($qAllKids, $qTemplateKids);

    foreach ($allKids as $kid) {
        if ((int) $kid['IsCheckedByDefault'] === 1) {
            processDefaultChild($OrderID, $ParentLineItemID, (int) $kid['ID'], (float) $kid['Price']);
        } else {
            attachDefaultChildren($OrderID, $ParentLineItemID, (int) $kid['ID']);
        }
    }
}

function processDefaultChild(int $OrderID, int $ParentLineItemID, int $ItemID, float $Price): void {
    $qExisting = queryOne(
        "SELECT ID FROM OrderLineItems WHERE OrderID = ? AND ParentOrderLineItemID = ? AND ItemID = ? LIMIT 1",
        [$OrderID, $ParentLineItemID, $ItemID]
    );

    if ($qExisting) {
        queryTimed("UPDATE OrderLineItems SET IsDeleted = 0 WHERE ID = ?", [(int) $qExisting['ID']]);
        attachDefaultChildren($OrderID, (int) $qExisting['ID'], $ItemID);
    } else {
        $NewLIID = nextId('OrderLineItems', 'ID');
        queryTimed(
            "INSERT INTO OrderLineItems (ID, ParentOrderLineItemID, OrderID, ItemID, StatusID, Price, Quantity, Remark, IsDeleted, AddedOn)
             VALUES (?, ?, ?, ?, 0, ?, 1, NULL, 0, NOW())",
            [$NewLIID, $ParentLineItemID, $OrderID, $ItemID, $Price]
        );
        attachDefaultChildren($OrderID, $NewLIID, $ItemID);
    }
}

// --- Main logic ---

$data = readJsonBody();
$OrderID = (int) ($data['OrderID'] ?? 0);
$ParentLineItemID = (int) ($data['ParentOrderLineItemID'] ?? 0);
$OrderLineItemID = (int) ($data['OrderLineItemID'] ?? 0);
$OriginalItemID = $data['ItemID'] ?? 0;
$ItemID = (int) $OriginalItemID;

// Decode virtual IDs (format: menuItemID * 100000 + realItemID)
$WasDecoded = false;
if ($ItemID > 100000) {
    $WasDecoded = true;
    $ItemID = $ItemID % 100000;
}

$IsSelected = false;
if (isset($data['IsSelected'])) {
    $v = $data['IsSelected'];
    $IsSelected = ($v === true || $v === 1 || (is_string($v) && strtolower($v) === 'true'));
}
$Quantity = (int) ($data['Quantity'] ?? 0);
$Remark = (string) ($data['Remark'] ?? '');
$ForceNew = false;
if (isset($data['ForceNew'])) {
    $v = $data['ForceNew'];
    $ForceNew = ($v === true || $v === 1 || (is_string($v) && strtolower($v) === 'true'));
}

if ($OrderID <= 0 || $ItemID <= 0) {
    apiAbort(['OK' => false, 'ERROR' => 'missing_params', 'MESSAGE' => 'OrderID and ItemID are required.']);
}

try {
    // Load item
    $qItem = queryOne("SELECT ID, Price, ParentItemID, IsActive FROM Items WHERE ID = ? LIMIT 1", [$ItemID]);
    if (!$qItem || (int) $qItem['IsActive'] !== 1) {
        apiAbort(['OK' => false, 'ERROR' => 'bad_item', 'MESSAGE' => "Item not found or inactive. Original={$OriginalItemID} Decoded={$ItemID} WasDecoded=" . ($WasDecoded ? 'true' : 'false')]);
    }

    // Root vs modifier rules
    if ($ParentLineItemID === 0) {
        if ($IsSelected && $Quantity <= 0) {
            apiAbort(['OK' => false, 'ERROR' => 'bad_quantity', 'MESSAGE' => 'Root line items require Quantity > 0.']);
        }
    } else {
        $Quantity = $IsSelected ? 1 : 0;

        // Exclusive selection group handling
        if ($IsSelected) {
            $qParentLI = queryOne("SELECT ItemID FROM OrderLineItems WHERE ID = ? LIMIT 1", [$ParentLineItemID]);
            if ($qParentLI) {
                $qParentItem = queryOne("SELECT MaxNumSelectionReq FROM Items WHERE ID = ? LIMIT 1", [(int) $qParentLI['ItemID']]);
                if ($qParentItem && (int) $qParentItem['MaxNumSelectionReq'] === 1) {
                    queryTimed(
                        "UPDATE OrderLineItems SET IsDeleted = 1 WHERE OrderID = ? AND ParentOrderLineItemID = ? AND ItemID != ? AND IsDeleted = 0",
                        [$OrderID, $ParentLineItemID, $ItemID]
                    );
                }
            }
        }
    }

    // Find existing line item
    if ($ForceNew) {
        $qExisting = null;
    } elseif ($OrderLineItemID > 0) {
        $qExisting = queryOne(
            "SELECT ID FROM OrderLineItems WHERE ID = ? AND OrderID = ? AND IsDeleted = 0 LIMIT 1",
            [$OrderLineItemID, $OrderID]
        );
    } else {
        $qExisting = queryOne(
            "SELECT ID FROM OrderLineItems WHERE OrderID = ? AND ParentOrderLineItemID = ? AND ItemID = ? AND IsDeleted = 0 LIMIT 1",
            [$OrderID, $ParentLineItemID, $ItemID]
        );
    }

    if ($qExisting) {
        // Update existing
        if ($IsSelected) {
            queryTimed(
                "UPDATE OrderLineItems SET IsDeleted = 0, Quantity = ?, Price = ?, Remark = ?, StatusID = 0 WHERE ID = ?",
                [$Quantity, (float) $qItem['Price'], trim($Remark) !== '' ? $Remark : null, (int) $qExisting['ID']]
            );
            attachDefaultChildren($OrderID, (int) $qExisting['ID'], $ItemID);
        } else {
            // Deselecting
            if ($ParentLineItemID > 0) {
                $qItemCheck = queryOne("SELECT IsCheckedByDefault FROM Items WHERE ID = ? LIMIT 1", [$ItemID]);
                if ($qItemCheck && (int) $qItemCheck['IsCheckedByDefault'] === 1) {
                    // Default modifier: keep with Quantity=0
                    queryTimed("UPDATE OrderLineItems SET Quantity = 0 WHERE ID = ?", [(int) $qExisting['ID']]);
                } else {
                    queryTimed("UPDATE OrderLineItems SET IsDeleted = 1 WHERE ID = ?", [(int) $qExisting['ID']]);
                }
            } else {
                // Root item: always delete
                queryTimed("UPDATE OrderLineItems SET IsDeleted = 1 WHERE ID = ?", [(int) $qExisting['ID']]);
            }
        }
    } else {
        // Insert new if selecting
        if ($IsSelected) {
            $NewLIID = nextId('OrderLineItems', 'ID');
            queryTimed(
                "INSERT INTO OrderLineItems (ID, ParentOrderLineItemID, OrderID, ItemID, StatusID, Price, Quantity, Remark, IsDeleted, AddedOn)
                 VALUES (?, ?, ?, ?, 0, ?, ?, ?, 0, NOW())",
                [
                    $NewLIID,
                    $ParentLineItemID,
                    $OrderID,
                    $ItemID,
                    (float) $qItem['Price'],
                    ($ParentLineItemID === 0 ? $Quantity : 1),
                    trim($Remark) !== '' ? $Remark : null,
                ]
            );
            attachDefaultChildren($OrderID, $NewLIID, $ItemID);
        }
    }

    // Touch order last edited
    queryTimed("UPDATE Orders SET LastEditedOn = NOW() WHERE ID = ?", [$OrderID]);

    $payload = loadCartPayload($OrderID);
    jsonResponse($payload);

} catch (Exception $e) {
    jsonResponse([
        'OK'      => false,
        'ERROR'   => 'server_error',
        'MESSAGE' => 'DB error setting line item: ' . $e->getMessage(),
    ]);
}