import { ref, computed } from 'vue'

type TimeOfDay =
| 'day'
| 'night'
| 'morning0'
| 'morning1'
| 'morning2'
| 'evening0'
| 'evening1'
| 'evening2'

export function calcTimeOfDay(tick: number): TimeOfDay {
  if (tick >= 900 || tick < 80) return 'night'
  if (tick >= 80 && tick < 120) return 'morning0'
  if (tick >= 120 && tick < 150) return 'morning1'
  if (tick >= 150 && tick < 240) return 'morning2'
  if (tick >= 700 && tick < 800) return 'evening0'
  if (tick >= 800 && tick < 850) return 'evening1'
  if (tick >= 850 && tick < 900) return 'evening2'
  return 'day'
}

export function renderClock(tick: number): string {
  const t = tick * 86.4 // 1000 ticks to 86400 seconds (per day)
  const h = ~~(t / 3600.0)
  const m = ~~((t / 3600.0 - h) * 60.0)
  return `${(h + 2) % 24}:${m < 10 ? '0' : ''}${m}`
}

function calcProgress(tick: number, start: number, end: number, span: number): number {
  return (tick - start) / (end - start) * span
}

// calculates the suns angle from -90 (top, at noon), to 0 (at midnight)
export function calcSunAngle(tick: number): number {
  // night time: -10 degrees fixed
  if (tick >= 900 || tick < 80) return -10
  // sunrise: gradually move from -10 to -90, by mapping 80 -> 240 to -10 -> -90
  if (tick >= 80 && tick < 240) return -10 - calcProgress(tick, 80, 240, 80)
  // sundawn: gradually move from -90 to -10, by mapping 700 -> 900 to -90 -> -10
  if (tick >= 700 && tick < 900) return -90 + calcProgress(tick, 700, 900, 80)
  // day time: -90 degrees fixed
  return -90
}

export default function useTime() {
  // the day is split in 1000 parts, so we start in the morning
  const time = ref(240)

  function updateTime() {
    time.value = (time.value + 0.1) % 1000
  }

  const timeOfDay = computed(() => calcTimeOfDay(time.value))
  const clock = computed(() => renderClock(time.value))

  return { time, updateTime, timeOfDay, clock }
}