#!/usr/bin/env bash
set -euo pipefail

CONF="${XDG_CONFIG_HOME:-$HOME/.config}/hyprsunset/config"
STATE_DIR="${XDG_STATE_HOME:-$HOME/.local/state}/hyprsunset"
LOG_DIR="${XDG_STATE_HOME:-$HOME/.local/state}/hyprsunset"
AUTO_FILE="$STATE_DIR/auto"          # "1" = automation ON, "0" = OFF
TEMP_FILE="$STATE_DIR/temp"          # last manual/night temp persisted
MODE_FILE="$STATE_DIR/mode"          # "day" or "night"
mkdir -p "$STATE_DIR" "$LOG_DIR"

# Defaults
LAT="52.5200"; LON="13.4050"
TEMP_DAY=6500; TEMP_NIGHT=3800
RAMP_DOWN_MIN=45; RAMP_UP_MIN=35
STEP_K=100
FALLBACK_SUNSET="20:30"; FALLBACK_SUNRISE="06:30"

# Load config
[ -r "$CONF" ] && source "$CONF"

cmd() { hyprctl dispatch exec "$1" >/dev/null 2>&1 || true; }
start_hyprsunset() {
  local t="$1"
  echo -n "$t" > "$TEMP_FILE"
  cmd "hyprsunset -t $t"
}
stop_hyprsunset() {
  cmd "hyprsunset -x"
  pkill -x hyprsunset >/dev/null 2>&1 || true
}

# Compute ramp steps between a and b over minutes, step size STEP_K
ramp_between() {
  local from="$1" to="$2" minutes="$3"
  local step="${STEP_K}"
  local delta=$(( to - from ))
  local sign=1
  (( delta < 0 )) && sign=-1
  local steps=$(( (delta*sign + step - 1) / step ))  # ceil
  [ "$steps" -lt 1 ] && steps=1
  local sleep_s=$(( (minutes*60) / steps ))
  local t="$from"
  for ((i=1;i<=steps;i++)); do
    t=$(( from + sign*i*step ))
    # clamp
    (( sign == 1 && t > to )) && t="$to"
    (( sign == -1 && t < to )) && t="$to"
    start_hyprsunset "$t"
    sleep "$sleep_s"
  done
}

now_hhmm() { date +%H:%M; }
sec_until() {
  # returns seconds until HH:MM tomorrow/ today
  local target="$1"
  local now_s=$(date +%s)
  local tgt_s=$(date -d "$(date +%F) $target" +%s)
  if (( tgt_s <= now_s )); then
    tgt_s=$(( tgt_s + 86400 ))
  fi
  echo $(( tgt_s - now_s ))
}

have_sunwait() { command -v sunwait >/dev/null 2>&1; }

# Initialize state defaults if missing
[ -r "$AUTO_FILE" ] || echo -n "1" > "$AUTO_FILE"   # default: automation ON
[ -r "$TEMP_FILE" ] || echo -n "$TEMP_NIGHT" > "$TEMP_FILE"
[ -r "$MODE_FILE" ] || echo -n "day" > "$MODE_FILE"

log() { printf "[hyprsunset] %s\n" "$*" >&2; }

while :; do
  # If automation is OFF, just sleep and retry
  if [ "$(cat "$AUTO_FILE" 2>/dev/null || echo 1)" != "1" ]; then
    sleep 30
    continue
  fi

  if have_sunwait; then
    # Use sunwait to block until the next event
    # Decide current solar state quickly
    # sunwait 'day' exits 0 if sun is up; 'night' if down
    if sunwait day "$LAT" "$LON" >/dev/null 2>&1; then
      echo -n "day" > "$MODE_FILE"
      # Wait for sunset, then ramp down
      log "waiting for SUNSET via sunwait…"
      sunwait set "$LAT" "$LON" >/dev/null 2>&1
      [ "$(cat "$AUTO_FILE")" = "1" ] || continue
      log "SUNSET reached → ramp down ${TEMP_DAY}→${TEMP_NIGHT} over ${RAMP_DOWN_MIN}m"
      ramp_between "$TEMP_DAY" "$TEMP_NIGHT" "$RAMP_DOWN_MIN"
      echo -n "night" > "$MODE_FILE"
      # Stay in night until sunrise
      log "waiting for SUNRISE via sunwait…"
      sunwait rise "$LAT" "$LON" >/dev/null 2>&1
      [ "$(cat "$AUTO_FILE")" = "1" ] || continue
      log "SUNRISE reached → ramp up ${TEMP_NIGHT}→${TEMP_DAY} over ${RAMP_UP_MIN}m"
      ramp_between "$TEMP_NIGHT" "$TEMP_DAY" "$RAMP_UP_MIN"
      echo -n "day" > "$MODE_FILE"
    else
      echo -n "night" > "$MODE_FILE"
      # We are in night → ramp to night if not already, then wait sunrise
      log "night now → ensure at night temp, then wait SUNRISE"
      start_hyprsunset "$TEMP_NIGHT"
      sunwait rise "$LAT" "$LON" >/dev/null 2>&1
      [ "$(cat "$AUTO_FILE")" = "1" ] || continue
      log "SUNRISE → ramp up ${TEMP_NIGHT}→${TEMP_DAY} over ${RAMP_UP_MIN}m"
      ramp_between "$TEMP_NIGHT" "$TEMP_DAY" "$RAMP_UP_MIN"
      echo -n "day" > "$MODE_FILE"
    fi
  else
    # Fallback fixed schedule
    cur="$(now_hhmm)"
    # If day now (before fallback sunset), wait sunset
    if [[ "$cur" < "$FALLBACK_SUNSET" && "$cur" > "$FALLBACK_SUNRISE" ]]; then
      echo -n "day" > "$MODE_FILE"
      secs=$(sec_until "$FALLBACK_SUNSET")
      log "fallback: waiting $secs s until sunset ${FALLBACK_SUNSET}"
      sleep "$secs"
      [ "$(cat "$AUTO_FILE")" = "1" ] || continue
      ramp_between "$TEMP_DAY" "$TEMP_NIGHT" "$RAMP_DOWN_MIN"
      echo -n "night" > "$MODE_FILE"
    else
      echo -n "night" > "$MODE_FILE"
      secs=$(sec_until "$FALLBACK_SUNRISE")
      log "fallback: waiting $secs s until sunrise ${FALLBACK_SUNRISE}"
      sleep "$secs"
      [ "$(cat "$AUTO_FILE")" = "1" ] || continue
      ramp_between "$TEMP_NIGHT" "$TEMP_DAY" "$RAMP_UP_MIN"
      echo -n "day" > "$MODE_FILE"
    fi
  fi
done