#!/bin/bash
# RX 6750 XT auto fan controller (Gentoo / amdgpu)
# Junction temperature + 3 fan tiers + logging

GPU_CARD="card0"
INTERVAL=5
LOG_FILE="/var/log/gpu-fan-switcher.log"

# Temperature thresholds (junction)
T_QUIET=65
T_BALANCED=75
HYSTERESIS=3

# ---- root check ----
if [[ $EUID -ne 0 ]]; then
    echo "Run as root: sudo $0"
    exit 1
fi

HWMON_BASE="/sys/class/drm/$GPU_CARD/device/hwmon"

# ---- find junction temperature ----
TEMP_FILE=""
for h in "$HWMON_BASE"/hwmon*; do
    for t in "$h"/temp*_label; do
        [[ -f "$t" ]] || continue
        if grep -qi "junction\|hotspot" "$t"; then
            TEMP_FILE="${t%_label}_input"
            break 2
        fi
    done
done

# fallback to any temp if junction label not found
if [[ -z "$TEMP_FILE" ]]; then
    TEMP_FILE=$(find "$HWMON_BASE" -name "temp*_input" | head -n1)
fi

[[ -z "$TEMP_FILE" ]] && { echo "No temperature sensor found"; exit 1; }

# ---- find fan control ----
PWM_FILE=""
PWM_ENABLE=""
PWM_MAX=255

for h in "$HWMON_BASE"/hwmon*; do
    if [[ -f "$h/pwm1" ]]; then
        PWM_FILE="$h/pwm1"
        [[ -f "$h/pwm1_enable" ]] && PWM_ENABLE="$h/pwm1_enable"
        [[ -f "$h/pwm1_max" ]] && PWM_MAX=$(cat "$h/pwm1_max")
        break
    fi
done

[[ -z "$PWM_FILE" ]] && { echo "Fan control not available"; exit 1; }

# ---- fan tiers ----
FAN_QUIET=$((PWM_MAX * 25 / 100))
FAN_BALANCED=$((PWM_MAX * 45 / 100))
FAN_PERF=$((PWM_MAX * 70 / 100))

# ---- enable manual fan control ----
[[ -n "$PWM_ENABLE" ]] && echo 1 > "$PWM_ENABLE"

# ---- helpers ----
get_temp() {
    echo $(( $(cat "$TEMP_FILE") / 1000 ))
}

set_fan() {
    echo "$1" > "$PWM_FILE"
}

log() {
    echo "$(date '+%F %T') | $1" | tee -a "$LOG_FILE"
}

# ---- init ----
PROFILE="quiet"
set_fan "$FAN_QUIET"

log "Started GPU fan controller"
log "Temp source: $TEMP_FILE"
log "Fan control: $PWM_FILE"
log "PWM max: $PWM_MAX"
log "Quiet=$FAN_QUIET Balanced=$FAN_BALANCED Perf=$FAN_PERF"

# ---- main loop ----
while true; do
    TEMP=$(get_temp)

    case "$PROFILE" in
        quiet)
            if (( TEMP >= T_QUIET + HYSTERESIS )); then
                set_fan "$FAN_BALANCED"
                PROFILE="balanced"
                log "→ BALANCED (${TEMP}°C)"
            fi
            ;;
        balanced)
            if (( TEMP >= T_BALANCED + HYSTERESIS )); then
                set_fan "$FAN_PERF"
                PROFILE="perf"
                log "→ PERFORMANCE (${TEMP}°C)"
            elif (( TEMP <= T_QUIET - HYSTERESIS )); then
                set_fan "$FAN_QUIET"
                PROFILE="quiet"
                log "→ QUIET (${TEMP}°C)"
            fi
            ;;
        perf)
            if (( TEMP <= T_BALANCED - HYSTERESIS )); then
                set_fan "$FAN_BALANCED"
                PROFILE="balanced"
                log "→ BALANCED (${TEMP}°C)"
            fi
            ;;
    esac

    sleep "$INTERVAL"
done