#!/usr/bin/env bash
# Install hyprlogin + greetd config from chezmoi-tracked sources into /etc.
# Run manually after `chezmoi apply` when files under system/ change.
#
# Usage: ~/.local/share/chezmoi/system/install-greeter.sh [--dry-run]

set -euo pipefail

dry_run=0
[[ "${1:-}" == "--dry-run" ]] && dry_run=1

source_dir="${CHEZMOI_SOURCE_DIR:-}"
if [[ -z "$source_dir" ]] && command -v chezmoi >/dev/null 2>&1; then
  source_dir="$(chezmoi source-path 2>/dev/null || true)"
fi
[[ -z "$source_dir" ]] && source_dir="$HOME/.local/share/chezmoi"
sys_dir="$source_dir/system"

if [[ ! -d "$sys_dir" ]]; then
  echo "no system/ tree in $source_dir" >&2
  exit 1
fi

staging="$(mktemp -d -t greeter-staging-XXXXXX)"
trap 'rm -rf "$staging"' EXIT

# Files to install: source.tmpl  →  /etc target  (mode)
files=(
  "etc/greetd/greetd.conf.tmpl           /etc/greetd/greetd.conf            0644"
  "etc/hyprlogin/apex-neon.conf.tmpl     /etc/hyprlogin/apex-neon.conf      0644"
  "etc/hyprlogin/hyprlogin.conf.tmpl     /etc/hyprlogin/hyprlogin.conf      0644"
  "etc/hyprlogin/hyprland-greeter.conf.tmpl  /etc/hyprlogin/hyprland-greeter.conf  0644"
)

render() {
  local src="$1" dst="$2"
  mkdir -p "$(dirname "$dst")"
  chezmoi execute-template --source "$source_dir" < "$src" > "$dst"
}

needs_install=0
declare -a plan
for entry in "${files[@]}"; do
  read -r rel target mode <<<"$entry"
  src="$sys_dir/$rel"
  rendered="$staging/$rel"
  rendered="${rendered%.tmpl}"
  render "$src" "$rendered"
  if [[ ! -f "$target" ]] || ! diff -q "$rendered" "$target" >/dev/null 2>&1; then
    plan+=("$rendered → $target  ($mode)")
    needs_install=1
  fi
done

# Wallpapers: per-monitor, driven by chezmoi data.monitors[].lockscreen-wallpaper
# Renders a "name|path" line per monitor that has a wallpaper set.
wp_tmpl='{{ range .monitors }}{{ $wp := index . "lockscreen-wallpaper" }}{{ if $wp }}{{ .name }}|{{ $wp }}
{{ end }}{{ end }}'
declare -a wp_plan
while IFS='|' read -r mon wp; do
  [[ -z "$mon" || -z "$wp" ]] && continue
  wp="${wp/#\~/$HOME}"
  if [[ ! -f "$wp" ]]; then
    echo "warning: monitor $mon wallpaper missing: $wp" >&2
    continue
  fi
  ext="${wp##*.}"
  target="/etc/hyprlogin/wallpaper-${mon}.${ext}"
  if [[ ! -f "$target" ]] || ! cmp -s "$wp" "$target"; then
    plan+=("$wp → $target  (0644)")
    wp_plan+=("$wp|$target")
    needs_install=1
  fi
done < <(chezmoi execute-template --source "$source_dir" <<<"$wp_tmpl")

if (( ! needs_install )); then
  echo "nothing to do — /etc files already match chezmoi source"
  exit 0
fi

echo "would install:"
printf '  %s\n' "${plan[@]}"

if (( dry_run )); then
  exit 0
fi

# Back up current greetd config once, the first time, for one-step rollback.
if [[ -f /etc/greetd/greetd.conf && ! -f /etc/greetd/greetd.conf.nwg-hello-bak ]]; then
  echo "backing up existing /etc/greetd/greetd.conf → /etc/greetd/greetd.conf.nwg-hello-bak"
  sudo cp -a /etc/greetd/greetd.conf /etc/greetd/greetd.conf.nwg-hello-bak
fi

for entry in "${files[@]}"; do
  read -r rel target mode <<<"$entry"
  rendered="$staging/${rel%.tmpl}"
  sudo install -Dm"$mode" "$rendered" "$target"
done

for pair in "${wp_plan[@]:-}"; do
  [[ -z "$pair" ]] && continue
  IFS='|' read -r src target <<<"$pair"
  sudo install -Dm0644 "$src" "$target"
done

cat <<EOF

done. to apply on the running system (do this from a spare TTY — Ctrl+Alt+F3 — so you don't lock yourself out):
  sudo systemctl restart greetd

rollback:
  sudo cp /etc/greetd/greetd.conf.nwg-hello-bak /etc/greetd/greetd.conf && sudo systemctl restart greetd
EOF