#!/usr/bin/env bash

set -e

DEVICE="$1" # eg: /sys/class/drm/card1/device
HWMON=$(echo "$DEVICE"/hwmon/hwmon*)

exit() {
    echo "Setting controll to auto" >&2
    echo 2 > "$HWMON/pwm1_enable"
}

trap exit EXIT INT

bail() {
    echo "Error: $@" >&2
    echo "Exiting..." >&2
    exit 1
}

if ! [ -d "$HWMON" ]; then
    bail "Invalid HWMON"
fi

TEMP_INPUT="$HWMON/temp2_input"

if ! [ -f $TEMP_INPUT ]; then
    bail "Invalid TEMP_INPUT"
fi

TEMP_MIN="$2"
TEMP_MAX="$3"

if [ -z "$TEMP_MIN" ];then
  bail "No minimum temperature provided"
fi

if [ -z "$TEMP_MAX" ];then
  bail "No maximum temperature provided"
fi

PWM_MIN_PCT="$4"
PWM_MAX_PCT="$5"

if [ -z "$PWM_MIN_PCT" ];then
  bail "No minimum fan speed % not provided"
fi

if [ -z "$PWM_MAX_PCT" ];then
  bail "No maximum fan speed % not provided"
fi

PWM_MIN="$(( $PWM_MIN_PCT * 255 / 100))"
PWM_MAX="$(( $PWM_MAX_PCT * 255 / 100))"

echo "Running..." >&2

echo "TEMP_MIN=$TEMP_MIN°C"
echo "TEMP_MAX=$TEMP_MAX°C"
echo "FAN_MIN=$PWM_MIN_PCT%"
echo "FAN_MAX=$PWM_MAX_PCT%"

echo 1 > "$HWMON/pwm1_enable"

PREV=0

while true; do
    TEMPERATURE_RAW=$(cat "$TEMP_INPUT")
    TEMPERATURE="$(( $TEMPERATURE_RAW / 1000 ))"
    # Remap from a number between 60_000..90_000 to 0..255
    PWM=$(( ($TEMPERATURE - $TEMP_MIN) * $PWM_MAX / ($TEMP_MAX - $TEMP_MIN) ))

    if [ "$PWM" -gt $PWM_MAX ]; then
        PWM=$PWM_MAX
    elif [ "$PWM" -lt $PWM_MIN ]; then
        PWM=$PWM_MIN
    fi

    AVG="$(( ($PWM * 20 + $PREV * 80) / 100 ))"

    echo "$AVG"

    echo "$AVG" > "$HWMON/pwm1"
    PREV="$AVG"
    sleep .1s
done