#!/bin/bash

# omarchy:summary=Show, set, or adjust focused Hyprland monitor scaling
# omarchy:args=[up|down|SCALE]
# omarchy:examples=omarchy hyprland monitor scaling | omarchy hyprland monitor scaling 1.6 | omarchy hyprland monitor scaling up | omarchy hyprland monitor scaling down

SCALES=(1 1.25 1.6 2 3 4)
STATE_DIR="${XDG_STATE_HOME:-$HOME/.local/state}/omarchy"
SCALE_LOG="$STATE_DIR/monitor-scaling.log"

usage() {
  echo "Usage: omarchy-hyprland-monitor-scaling [up|down|SCALE]"
}

focused_monitor_scale() {
  hyprctl monitors -j | jq -er '.[] | select(.focused == true) | .scale'
}

cmdline_for_pid() {
  local pid="$1"

  [[ -r /proc/$pid/cmdline ]] || return 0
  tr '\0\t\n' '   ' <"/proc/$pid/cmdline" | sed -E 's/[[:space:]]+/ /g; s/[[:space:]]+$//'
}

audit_scale_change() {
  local requested="$1"
  local active_monitor="$2"
  local current_scale="$3"
  local new_scale="$4"
  local parent_pid="$PPID"
  local grandparent_pid
  local parent_cmd
  local grandparent_cmd

  mkdir -p "$STATE_DIR" || return 0

  grandparent_pid=$(ps -o ppid= -p "$parent_pid" 2>/dev/null | tr -d ' ')
  parent_cmd=$(cmdline_for_pid "$parent_pid")
  grandparent_cmd=$(cmdline_for_pid "$grandparent_pid")

  printf 'at=%s\trequested=%s\tcurrent=%s\tnew=%s\tmonitor=%s\tpid=%s\tppid=%s\tparent=%s\tgppid=%s\tgrandparent=%s\n' \
    "$(date --iso-8601=seconds)" \
    "$requested" \
    "$current_scale" \
    "$new_scale" \
    "$active_monitor" \
    "$$" \
    "$parent_pid" \
    "$parent_cmd" \
    "$grandparent_pid" \
    "$grandparent_cmd" >>"$SCALE_LOG"
}

# Hyprland only accepts scales where the mode divides into whole logical
# pixels (in 1/120 steps), so clean scales are divisors of gcd(w*120, h*120).
# Round the requested scale up to the nearest clean value.
clean_scale() {
  awk -v scale="$1" -v width="$2" -v height="$3" '
    function gcd(a, b, t) { while (b) { t = a % b; a = b; b = t } return a }
    BEGIN {
      g = gcd(width * 120, height * 120)
      k = int(scale * 120 + 0.5)
      if (k > g) k = g
      while (g % k != 0) k++
      printf "%g\n", k / 120
    }'
}

normalize_scale() {
  awk 'NR == 1 { printf "%g\n", $0 }'
}

set_scale() {
  local requested_scale="$1"
  local requested="${2:-$requested_scale}"
  local monitor_info="$(hyprctl monitors -j | jq -e -c '.[] | select(.focused == true)')"
  local active_monitor="$(echo "$monitor_info" | jq -r '.name')"
  local current_scale="$(echo "$monitor_info" | jq -r '.scale')"
  local width="$(echo "$monitor_info" | jq -r '.width')"
  local height="$(echo "$monitor_info" | jq -r '.height')"
  local refresh_rate="$(echo "$monitor_info" | jq -r '.refreshRate')"
  local new_scale="$(clean_scale "$requested_scale" "$width" "$height")"
  # GTK only honors integer GDK_SCALE values, so persist the nearest whole
  # factor even when the monitor scale itself is fractional.
  local new_gdk_scale="$(awk -v scale="$new_scale" 'BEGIN { printf "%d", int(scale + 0.5) }')"
  local monitor_lua="$HOME/.config/hypr/monitors.lua"

  hyprctl eval "hl.monitor({ output = \"$active_monitor\", mode = \"${width}x${height}@${refresh_rate}\", position = \"auto\", scale = $new_scale })" >/dev/null
  audit_scale_change "$requested" "$active_monitor" "$current_scale" "$new_scale"

  # Persist to monitors.lua if the user still has Omarchy's generic catch-all
  # defaults, so the scale survives reboots.
  if [[ -f $monitor_lua ]] && grep -q '^local omarchy_monitor_scale = ' "$monitor_lua"; then
    sed -i -E \
      -e "s|^local omarchy_monitor_scale = .*|local omarchy_monitor_scale = ${new_scale}|" \
      -e "s|^local omarchy_gdk_scale = .*|local omarchy_gdk_scale = ${new_gdk_scale}|" \
      "$monitor_lua"
  elif [[ -f $monitor_lua ]] && grep -Eq '^hl\.monitor\(\{ output = "", mode = "preferred", position = "auto", scale = ("auto"|[0-9.]+) \}\)' "$monitor_lua"; then
    sed -i -E \
      -e "s|^(hl\.monitor\(\{ output = \"\", mode = \"preferred\", position = \"auto\", scale = )([^ ]+)( \}\))|\\1${new_scale}\\3|" \
      -e 's|^hl\.env\("GDK_SCALE", ".*"\)|hl.env("GDK_SCALE", "'"$new_gdk_scale"'")|' \
      "$monitor_lua"
  fi
}

scale_from_current() {
  local direction="${1:-}"
  local width="${2:-}"
  local height="${3:-}"

  awk -v direction="$direction" -v list="${SCALES[*]}" -v width="$width" -v height="$height" '
    function gcd(a, b, t) { while (b) { t = a % b; a = b; b = t } return a }
    function clean(scale,    g, k) {
      g = gcd(width * 120, height * 120)
      k = int(scale * 120 + 0.5)
      if (k > g) k = g
      while (g % k != 0) k++
      return k / 120
    }
    NR == 1 { scale = $0; found = 1 }
    END {
      if (!found) exit 1

      preset_count = split(list, presets, " ")
      for (i = 1; i <= preset_count; i++) {
        effective = clean(presets[i])
        key = sprintf("%.8f", effective)
        distance = presets[i] - effective
        if (distance < 0) distance = -distance

        # Multiple presets can collapse to the same clean scale. Keep only the
        # closest label so stepping always moves to a distinct effective value.
        if (!(key in effective_index)) {
          effective_index[key] = ++n
          effective_scales[n] = effective
          scales[n] = presets[i]
          distances[n] = distance
        } else {
          idx = effective_index[key]
          if (distance < distances[idx]) {
            scales[idx] = presets[i]
            distances[idx] = distance
          }
        }
      }

      # Snap to the nearest effective scale first. Hyprland reports floating
      # point values, so exact comparisons can otherwise get stuck.
      best = 1; best_diff = 1e9
      for (i = 1; i <= n; i++) {
        diff = scale - effective_scales[i]; if (diff < 0) diff = -diff
        if (diff < best_diff) { best_diff = diff; best = i }
      }

      if (direction == "next") {
        print scales[(best < n ? best + 1 : n)]
      } else if (direction == "previous") {
        print scales[(best > 1 ? best - 1 : 1)]
      } else {
        print scales[best]
      }
    }'
}

case "${1:-}" in
"")
  focused_monitor_scale | normalize_scale
  ;;
-h | --help)
  usage
  ;;
up)
  monitor_info=$(hyprctl monitors -j | jq -e -c '.[] | select(.focused == true)')
  set_scale "$(echo "$monitor_info" | jq -r '.scale' | scale_from_current next \
    "$(echo "$monitor_info" | jq -r '.width')" "$(echo "$monitor_info" | jq -r '.height')")" "up"
  ;;
down)
  monitor_info=$(hyprctl monitors -j | jq -e -c '.[] | select(.focused == true)')
  set_scale "$(echo "$monitor_info" | jq -r '.scale' | scale_from_current previous \
    "$(echo "$monitor_info" | jq -r '.width')" "$(echo "$monitor_info" | jq -r '.height')")" "down"
  ;;
1 | 1.25 | 1.6 | 2 | 3 | 4)
  set_scale "$1" "$1"
  ;;
*)
  if [[ $1 =~ ^[0-9]+([.][0-9]+)?$ ]] &&
    awk -v scale="$1" 'BEGIN { exit !(scale >= 1 && scale <= 4) }'; then
    set_scale "$1" "$1"
  else
    usage >&2
    exit 1
  fi
  ;;
esac