feat: implement Sleepy sleep diary

lib/sleep.ts

@@ -0,0 +1,58 @@
+export type AlarmType = 'alarm' | 'natural' | 'awakened';
+
+export interface SleepEntry {
+  date: string;
+  napped: boolean;
+  napStart: string | null;
+  napDurationMinutes: number | null;
+  bedtime: string;
+  sleepLatencyMinutes: number;
+  awakenings: number;
+  wasoMinutes: number;
+  riseTime: string;
+  alarmType: AlarmType;
+  rating: number;
+  notes: string;
+  createdAt?: string;
+  updatedAt?: string;
+}
+
+export interface SleepMetrics {
+  timeInBedMinutes: number;
+  totalSleepMinutes: number;
+  efficiency: number;
+}
+
+export function calculateMetrics(entry: Pick<SleepEntry, 'bedtime' | 'riseTime' | 'sleepLatencyMinutes' | 'wasoMinutes'>): SleepMetrics {
+  const [bedHours, bedMinutes] = entry.bedtime.split(':').map(Number);
+  const [riseHours, riseMinutes] = entry.riseTime.split(':').map(Number);
+  let timeInBedMinutes = riseHours * 60 + riseMinutes - (bedHours * 60 + bedMinutes);
+
+  if (timeInBedMinutes <= 0) timeInBedMinutes += 24 * 60;
+
+  const totalSleepMinutes = Math.max(0, timeInBedMinutes - entry.sleepLatencyMinutes - entry.wasoMinutes);
+  const efficiency = timeInBedMinutes === 0 ? 0 : Math.round((totalSleepMinutes / timeInBedMinutes) * 100);
+
+  return { timeInBedMinutes, totalSleepMinutes, efficiency };
+}
+
+export function formatDuration(minutes: number): string {
+  const hours = Math.floor(minutes / 60);
+  const remainder = minutes % 60;
+  return hours > 0 ? `${hours} ч ${remainder.toString().padStart(2, '0')} мин` : `${remainder} мин`;
+}
+
+export const defaultEntry = (date: string): SleepEntry => ({
+  date,
+  napped: false,
+  napStart: null,
+  napDurationMinutes: null,
+  bedtime: '23:30',
+  sleepLatencyMinutes: 20,
+  awakenings: 0,
+  wasoMinutes: 0,
+  riseTime: '07:00',
+  alarmType: 'natural',
+  rating: 3,
+  notes: '',
+});