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

DRY_RUN=true

usage() {
  echo "Usage: $0 [--commit|-c]"
  echo "  --commit, -c   Apply changes (default is dry-run)"
  exit 0
}

while [[ $# -gt 0 ]]; do
  case "$1" in
    --commit|-c) DRY_RUN=false ;;
    --help|-h) usage ;;
    *) echo "Unknown option: $1"; usage ;;
  esac
  shift
done


confirm() {
  local ans
  read -rp "Apply this change? [y/N] " ans </dev/tty
  case "$ans" in
    [Yy]|[Yy][Ee][Ss]) return 0 ;;  # yes
    *) return 1 ;;                   # anything else = no
  esac
}

show_diff() {
  echo "--------------------------------------------------------------------------------"
  diff -ru "$1" "$2" || true
  echo "--------------------------------------------------------------------------------"
}

print_file_status() {
    echo "- $1: $2"
}

sync_exec() {
    local SRC="$1"
    local DEST="$2"
    local RET="$3"
    if ! $DRY_RUN; then
    confirm || return
    fi

    local opts=(-avu)
    $DRY_RUN && opts+=("--dry-run")

    echo "rsync $SRC $DEST $REL"
    mkdir -p "$DEST/$(dirname "$REL")"

    rsync "${opts[@]}" "$SRC" "$DEST/$(dirname "$REL")"| sed 's/^/[rsync] /'
}

sync_root() {
  # local NAME="$1"
  local DIR_A="$2"
  local DIR_B="$(realpath $(dirname "$0"))"
  local PATHS
  PATHS="$(cat)"

  echo "$DIR_A"

  while IFS= read -r REL; do
    [[ -z "$REL" ]] && continue

    local A="$DIR_A/$REL"
    local B="$DIR_B/$REL"

    if [[ -e "$A" && -e "$B" ]]; then
      if diff -rq "$A" "$B" >/dev/null; then
          print_file_status $REL "up-to-date"
        continue
      fi


      if [[ "$A" -nt "$B" ]]; then
        print_file_status $REL "$A is newer than $B"
        echo "  (old) $B"
        echo "  (new) $A"
        show_diff "$B" "$A"
        FROM="$A"
        TO="$DIR_B"
      else
        print_file_status $REL "$B is newer than $A"
        echo "  (old) $A"
        echo "  (new) $B"
        show_diff "$A" "$B"
        FROM="$B"
        TO="$DIR_A"
      fi

      sync_exec $FROM $TO $REL 

    elif [[ -e "$A" ]]; then
      print_file_status $REL "only found in $DIR_A"
        sync_exec $A $DIR_B $REL
    elif [[ -e "$B" ]]; then
      print_file_status $REL "only found in $DIR_B"
      sync_exec $B $DIR_A $REL
    else
      print_file_status $REL "file doesn't exist anywhere"
    fi

    echo
  done <<< "$PATHS"
}

sync_root xdg_config "${XDG_CONFIG_HOME:-$HOME/.config}" <<'EOF'
nvim/init.lua
nvim/after/plugin/config.lua
emacs/init.el
i3/config
i3status/config
alacritty/catppuccin-mocha.toml
alacritty/alacritty.toml
EOF

sync_root home "$HOME" <<'EOF'
.gdbinit
EOF