#!/bin/bash
#----------------------------------------------------------------
# gammastep-adjust — Adjust gammastep color temperature
#
# Replaces the old ratflow redshift-adjust script.
# gammastep is the Wayland fork of redshift; it uses the same
# temperature range (1000K–25000K, default 6500K = daylight).
#
# Usage:
#   gammastep-adjust -100   — make screen warmer (lower temperature by 100K)
#   gammastep-adjust +100   — make screen cooler (raise temperature by 100K)
#
# How it works:
#   gammastep doesn't support runtime temperature changes directly.
#   This script writes the current temperature to a state file,
#   kills any running gammastep, and launches a new one in one-shot
#   mode (-O) with the new temperature.
#
# State file: /tmp/gammastep-current-temp
# PID file:   /tmp/gammastep-pid
# Default:    6500 (neutral/daylight)
#
# Dependencies: gammastep
#----------------------------------------------------------------
set -x

STATE_FILE="/tmp/gammastep-current-temp"
PID_FILE="/tmp/gammastep-pid"
DEFAULT_TEMP=6500
MIN_TEMP=1000
MAX_TEMP=25000

# Read current temperature or use default
if [ -f "$STATE_FILE" ]; then
  CURRENT=$(cat "$STATE_FILE")
else
  CURRENT=$DEFAULT_TEMP
fi

# Parse argument
DELTA="${1:-0}"
# Strip the sign to get the absolute value
ABS_DELTA="${DELTA#+}"
ABS_DELTA="${ABS_DELTA#-}"

if [ -z "$ABS_DELTA" ]; then
  echo "Usage: gammastep-adjust <+/-N>"
  echo "  Example: gammastep-adjust -100 (warmer)"
  echo "  Example: gammastep-adjust +100 (cooler)"
  exit 1
fi

# Calculate new temperature
NEW_TEMP=$((CURRENT + DELTA))

# Clamp to valid range
if [ "$NEW_TEMP" -lt "$MIN_TEMP" ]; then
  NEW_TEMP=$MIN_TEMP
fi
if [ "$NEW_TEMP" -gt "$MAX_TEMP" ]; then
  NEW_TEMP=$MAX_TEMP
fi

# Save new state
echo "$NEW_TEMP" >"$STATE_FILE"

# Kill existing gammastep instance(s)
# Priority 1: use PID file if available (most precise)
if [ -f "$PID_FILE" ]; then
  OLD_PID=$(cat "$PID_FILE")
  if kill -0 "$OLD_PID" 2>/dev/null; then
    kill "$OLD_PID" 2>/dev/null
    # Give gammastep a moment to release the display and exit
    sleep 0.2
  fi
  rm -f "$PID_FILE"
fi

# Priority 2: kill any stray gammastep processes
# -x (exact match) ensures we don't kill this script (gammastep-adjust)
pkill -x gammastep 2>/dev/null
sleep 0.1

# Launch gammastep with the new temperature.
#
# IMPORTANT: We use "setsid" (create a new session) so that gammastep is
# completely detached from the shell that Sway spawns for this keybinding.
# Without setsid, Sway kills gammastep when the keybinding shell exits,
# even with "&" — because the process is still in the same process group.
# setsid makes gammastep its own session leader, immune to cleanup.
# if [ "$NEW_TEMP" -ge "$DEFAULT_TEMP" ]; then
#   # At or above neutral — reset to no tint
#   setsid gammastep -x 2>/dev/null &
#   echo $! >"$PID_FILE"
#   echo "Temperature reset to neutral ($DEFAULT_TEMP K)"
# else
# Below neutral — apply one-shot manual temperature
setsid gammastep -O "$NEW_TEMP" 2>/dev/null &
echo $! >"$PID_FILE"
echo "Temperature set to $NEW_TEMP K"
# fi