Add moved folder.

src/camera-manager/range.ts

@@ -0,0 +1,125 @@
+import orderBy from 'lodash-es/orderBy';
+
+interface Range<T extends Date | number> {
+  start: T;
+  end: T;
+}
+
+export type DateRange = Range<Date>;
+
+interface MemoryRangeSetInterface<T> {
+  hasCoverage(range: T): boolean;
+  add(range: T): void;
+  clear(): void;
+}
+
+export class MemoryRangeSet implements MemoryRangeSetInterface<DateRange> {
+  protected _ranges: DateRange[];
+
+  constructor(ranges?: DateRange[]) {
+    this._ranges = ranges ?? [];
+  }
+
+  public hasCoverage(range: DateRange): boolean {
+    return this._ranges.some((cachedRange) =>
+      rangeIsEntirelyContained(cachedRange, range),
+    );
+  }
+
+  public add(range: DateRange): void {
+    this._ranges.push(range);
+    this._ranges = compressRanges(this._ranges);
+  }
+
+  public clear(): void {
+    this._ranges = [];
+  }
+}
+
+interface ExpiringRange<T extends Date | number> extends Range<T> {
+  expires: Date;
+}
+
+export class ExpiringMemoryRangeSet
+  implements MemoryRangeSetInterface<ExpiringRange<Date>>
+{
+  protected _ranges: ExpiringRange<Date>[];
+
+  constructor(ranges?: ExpiringRange<Date>[]) {
+    this._ranges = ranges ?? [];
+  }
+
+  public hasCoverage(range: DateRange): boolean {
+    const now = new Date();
+    return this._ranges.some(
+      (cachedRange) =>
+        now < cachedRange.expires && rangeIsEntirelyContained(cachedRange, range),
+    );
+  }
+
+  public add(range: ExpiringRange<Date>): void {
+    this._expireOldRanges();
+    this._ranges.push(range);
+  }
+
+  protected _expireOldRanges(): void {
+    const now = new Date();
+    this._ranges = this._ranges.filter((range) => now < range.expires);
+  }
+
+  public clear(): void {
+    this._ranges = [];
+  }
+}
+
+const rangeIsEntirelyContained = (bigger: DateRange, smaller: DateRange): boolean => {
+  return smaller.start >= bigger.start && smaller.end <= bigger.end;
+};
+
+export const rangesOverlap = (a: DateRange, b: DateRange): boolean => {
+  return (
+    // a starts within the range of b.
+    (a.start >= b.start && a.start <= b.end) ||
+    // a events within the range of b.
+    (a.end >= b.start && a.end <= b.end) ||
+    // a encompasses the entire range of b.
+    (a.start <= b.start && a.end >= b.end)
+  );
+};
+
+export const compressRanges = <T extends Date | number>(
+  ranges: Range<T>[],
+  toleranceSeconds = 0,
+): Range<T>[] => {
+  const compressedRanges: Range<T>[] = [];
+  ranges = orderBy(ranges, (range) => range.start, 'asc');
+
+  let current: Range<T> | null = null;
+  for (let i = 0; i < ranges.length; ++i) {
+    const item = ranges[i];
+    const itemStartSeconds =
+      item.start instanceof Date ? item.start.getTime() : item.start;
+
+    if (!current) {
+      current = { ...item };
+      continue;
+    }
+
+    const currentEndSeconds =
+      current.end instanceof Date ? current.end.getTime() : (current.end as number);
+
+    if (currentEndSeconds + toleranceSeconds * 1000 >= itemStartSeconds) {
+      if (item.end > current.end) {
+        current.end = item.end;
+      }
+    } else {
+      compressedRanges.push(current);
+      current = { ...item };
+    }
+  }
+  if (current) {
+    compressedRanges.push(current);
+  }
+
+  return compressedRanges;
+};