56 lines
1.5 KiB
JavaScript
56 lines
1.5 KiB
JavaScript
export const SORT_INCREMENT = 16384;
|
|
|
|
function midpoint(items, to) {
|
|
const below = items[to - 1];
|
|
const above = items[to];
|
|
|
|
if (!below) {
|
|
return above.sort_order / 2;
|
|
} else if (!above) {
|
|
return below.sort_order + SORT_INCREMENT;
|
|
} else {
|
|
return (below.sort_order + above.sort_order) / 2;
|
|
}
|
|
}
|
|
|
|
export function shoveSortOrders(items, targetId) {
|
|
const to = items.findIndex(item => item.id === targetId);
|
|
const target = items[to];
|
|
const before = items[to - 1];
|
|
let updates = [];
|
|
|
|
// If no target is specified, append at the end
|
|
if (!targetId || to === -1) {
|
|
let order;
|
|
if (items.length > 0) {
|
|
// Add a new increment to whatever is the latest sort order
|
|
order = items[items.length - 1].sort_order + SORT_INCREMENT;
|
|
} else {
|
|
// If no items exist, the default is to use the first increment
|
|
order = SORT_INCREMENT;
|
|
}
|
|
|
|
return { updates, sort_order: order };
|
|
} else {
|
|
if (target.sort_order - (before ? before.sort_order : 0) <= 2) {
|
|
let next = to;
|
|
let order = Math.floor(items[next].sort_order) + SORT_INCREMENT;
|
|
while (next < items.length) {
|
|
// No need to update it if it's already greater than the current
|
|
// order. This can happen because there may already be large
|
|
// gaps
|
|
if (order <= items[next].sort_order) {
|
|
break;
|
|
}
|
|
|
|
updates.push({ id: items[next].id, sort_order: order });
|
|
|
|
next++;
|
|
order += SORT_INCREMENT;
|
|
}
|
|
}
|
|
|
|
return { updates, sort_order: midpoint(items, to) };
|
|
}
|
|
}
|