Ambient Dark Mode

ambient_dark_mode.sh

#!/bin/bash
#
# ambient_adaptive.sh
#
# Reads the ambient light sensor (CurrentLux) and:
#   1. Switches macOS Light/Dark mode based on a lux threshold (with hysteresis)
#   2. Sets display brightness using a custom curve with a guaranteed minimum
#
# Requirements:
#   - Self-compiling brightness helper at ~/.local/bin/brightness
#   - Disable "Automatically adjust brightness" in System Settings > Displays
#     (otherwise macOS will fight this script)

# ---- Configuration ----------------------------------------------------

# Dark mode thresholds (hysteresis: dark below DARK_BELOW, light above LIGHT_ABOVE,
# no change in between — prevents flip-flopping around a single threshold)
DARK_BELOW=300
LIGHT_ABOVE=350

# Brightness curve
MIN_BRIGHTNESS=0.78   # your floor — brightness never goes below this
MAX_BRIGHTNESS=1.00   # brightness at LUX_MAX and above
LUX_MIN=0             # lux value at (or below) which brightness = MIN_BRIGHTNESS
LUX_MAX=500           # lux value at (or above) which brightness = MAX_BRIGHTNESS

# Path to the self-compiled brightness helper
BRIGHTNESS_BIN="$HOME/.local/bin/brightness"

LOG_FILE="$HOME/Library/Logs/ambient_adaptive.log"

# ---- Skip when lid is closed --------------------------------------------
# The ambient light sensor sits in the lid; when closed it reads ~0 lux,
# which would wrongly force dark mode / minimum brightness in clamshell mode.

CLAMSHELL=$(ioreg -r -k AppleClamshellState -d 1 2>/dev/null | grep AppleClamshellState | grep -c "Yes")

if [ "$CLAMSHELL" = "1" ]; then
    echo "$(date): Lid closed (clamshell) -> skipping." >> "$LOG_FILE" 2>/dev/null
    exit 0
fi

# ---- Read the sensor ---------------------------------------------------

LUX=$(ioreg -ark CurrentLux | plutil -extract 0.CurrentLux raw - 2>/dev/null)

if ! [[ "$LUX" =~ ^[0-9]+$ ]]; then
    echo "$(date): Could not read CurrentLux (got: '$LUX')." >> "$LOG_FILE" 2>/dev/null
    exit 1
fi

# ---- Dark / Light mode (with hysteresis) --------------------------------

CURRENT_MODE=$(osascript -e 'tell application "System Events" to tell appearance preferences to get dark mode')

TARGET_MODE=""
if [ "$LUX" -lt "$DARK_BELOW" ]; then
    TARGET_MODE="true"
elif [ "$LUX" -gt "$LIGHT_ABOVE" ]; then
    TARGET_MODE="false"
fi
# If lux is between DARK_BELOW and LIGHT_ABOVE, TARGET_MODE stays empty -> no change

if [ -n "$TARGET_MODE" ] && [ "$CURRENT_MODE" != "$TARGET_MODE" ]; then
    osascript -e "tell application \"System Events\" to tell appearance preferences to set dark mode to $TARGET_MODE"
    echo "$(date): Lux=$LUX -> dark mode set to $TARGET_MODE" >> "$LOG_FILE" 2>/dev/null
fi

# ---- Brightness curve ----------------------------------------------------

if [ ! -x "$BRIGHTNESS_BIN" ]; then
    echo "$(date): set_brightness binary not found at $BRIGHTNESS_BIN (compile set_brightness.m first)" >> "$LOG_FILE" 2>/dev/null
    exit 1
fi

# Linear interpolation between (LUX_MIN, MIN_BRIGHTNESS) and (LUX_MAX, MAX_BRIGHTNESS),
# clamped to [MIN_BRIGHTNESS, MAX_BRIGHTNESS].
TARGET_BRIGHTNESS=$(awk -v lux="$LUX" \
                        -v lmin="$LUX_MIN" -v lmax="$LUX_MAX" \
                        -v bmin="$MIN_BRIGHTNESS" -v bmax="$MAX_BRIGHTNESS" '
    BEGIN {
        if (lux <= lmin)      b = bmin;
        else if (lux >= lmax) b = bmax;
        else                  b = bmin + (bmax - bmin) * (lux - lmin) / (lmax - lmin);
        printf "%.2f", b;
    }')

# Read current brightness; set_brightness prints a bare number like "0.50"
CURRENT_BRIGHTNESS=$("$BRIGHTNESS_BIN" 2>/dev/null)

if ! [[ "$CURRENT_BRIGHTNESS" =~ ^[0-9.]+$ ]]; then
    echo "$(date): Could not read current brightness (got: '$CURRENT_BRIGHTNESS')." >> "$LOG_FILE" 2>/dev/null
    exit 1
fi

# Only adjust if the difference is meaningful (avoids constant tiny writes)
NEEDS_CHANGE=$(awk -v c="$CURRENT_BRIGHTNESS" -v t="$TARGET_BRIGHTNESS" '
    BEGIN { d = c - t; if (d < 0) d = -d; print (d > 0.03) ? 1 : 0 }')

if [ "$NEEDS_CHANGE" = "1" ]; then
    "$BRIGHTNESS_BIN" "$TARGET_BRIGHTNESS" >/dev/null 2>&1
    echo "$(date): Lux=$LUX -> brightness $CURRENT_BRIGHTNESS -> $TARGET_BRIGHTNESS" >> "$LOG_FILE" 2>/dev/null
else
    echo "$(date): Lux=$LUX -> brightness OK ($CURRENT_BRIGHTNESS, target $TARGET_BRIGHTNESS)" >> "$LOG_FILE" 2>/dev/null
fi