#!/usr/bin/env bash

set -euo pipefail

repo_root=$(cd -- "$(dirname -- "${BASH_SOURCE[0]}")" && pwd)
backup_root=${XDG_STATE_HOME:-"$HOME/.local/state"}/dotfiles-backups/$(date +%Y%m%d-%H%M%S)

link_path() {
  local source_path=$1
  local target_path=$2

  mkdir -p "$(dirname "$target_path")"

  if [[ -L "$target_path" ]]; then
    local resolved
    resolved=$(readlink -f "$target_path")
    if [[ "$resolved" == "$source_path" ]]; then
      printf 'skip %s\n' "$target_path"
      return 0
    fi
  fi

  if [[ -e "$target_path" && ! -L "$target_path" ]]; then
    local backup_path="$backup_root/${target_path#$HOME/}"
    mkdir -p "$(dirname "$backup_path")"
    mv "$target_path" "$backup_path"
    printf 'backup %s -> %s\n' "$target_path" "$backup_path"
  elif [[ -L "$target_path" ]]; then
    rm "$target_path"
  fi

  ln -s "$source_path" "$target_path"
  printf 'link %s -> %s\n' "$target_path" "$source_path"
}

while IFS= read -r entry; do
  [[ -z "$entry" ]] && continue
  link_path "$repo_root/config/$entry" "$HOME/.config/$entry"
done < <(cd "$repo_root/config" && printf '%s\n' *)

if [[ -d "$repo_root/home" ]]; then
  while IFS= read -r entry; do
    [[ -z "$entry" ]] && continue
    link_path "$repo_root/home/$entry" "$HOME/$entry"
  done < <(cd "$repo_root/home" && printf '%s\n' .[^.]* *)
fi

printf '\nDone. Backups, if any, are in %s\n' "$backup_root"