#!/bin/env sh

SUNRISE_START="$((5 * 60 * 60))"  # When to start turning up temperature
SUNRISE_END="$((7 * 60 * 60))"  # When to reach max temperature

SUNSET_START="$((21 * 60 * 60))"  # When to start turning down temperature
SUNSET_END="$((23 * 60 * 60))"  # When to reach min temperature

DAY_TEMP="6000"  # Display temperature (K) to use in full daylight
NIGHT_TEMP="2400"  # Display temperature (K) to use at night

CURRENT="$(((($(date '+%H') * 60) + $(date '+%M')) * 60 + $(date '+%S')))"  # Time in seconds since start of day

# Performs a calculation using an argument containing an input string
calc() {
  echo "scale=4; $1" | bc
}

# Evaluates a boolean expression on an argument containing an input string
bool() {
  echo "scale=1; $1" | bc
}

# GLSL Smoothstep, takes a single number as an argument
smoothstep() {
  if [ "$(bool "$1 <= 0")" = "1" ]; then
    echo 0
  elif [ "$(bool "$1 >= 1")" = "1" ]; then
    echo 1
  else
    calc "$1 * $1 * (3 - 2 * $1)"
  fi
}

# Interpolates between the 4th and 5th arguments based on the value of the 2nd in relation to the 1st and 3rd
interpolate() {
  LOWER_IN="$1"
  VALUE="$2"
  UPPER_IN="$3"
  LOWER_OUT="$4"
  UPPER_OUT="$5"

  if [ "$((VALUE <= LOWER_IN))" = "1" ]; then
    echo "$LOWER_OUT"
  elif [ "$((VALUE < UPPER_IN))" = "1" ]; then
    calc "$LOWER_OUT + (($UPPER_OUT - $LOWER_OUT) * $(smoothstep "$(calc "($VALUE - $LOWER_IN) / ($UPPER_IN - $LOWER_IN)")"))"
  else
    echo "$UPPER_OUT"
  fi
}

if [ "$((CURRENT <= SUNRISE_START))" = "1" ]; then
  TEMP="$NIGHT_TEMP"
elif [ "$((CURRENT < SUNRISE_END))" = "1" ]; then
  TEMP="$(interpolate "$SUNRISE_START" "$CURRENT" "$SUNRISE_END" "$NIGHT_TEMP" "$DAY_TEMP")"
elif [ "$((CURRENT <= SUNSET_START))" = "1" ]; then
  TEMP="$DAY_TEMP"
elif [ "$((CURRENT < SUNSET_END))" = "1" ]; then
  TEMP="$(interpolate "$SUNSET_START" "$CURRENT" "$SUNSET_END" "$DAY_TEMP" "$NIGHT_TEMP")"
else
  TEMP="$NIGHT_TEMP"
fi

hyprctl hyprsunset temperature "$TEMP"