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

info() {
  printf '\n==> %s\n' "$1"
}

warn() {
  printf 'WARN: %s\n' "$1" >&2
}

append_if_missing() {
  local line="$1"
  local file="$2"
  touch "$file"
  grep -qxF "$line" "$file" || echo "$line" >>"$file"
}

command_exists() {
  command -v "$1" >/dev/null 2>&1
}

AUTO_INSTALL_DEPS=0

find_ssh_key_in_dir() {
  local ssh_dir="$1"
  local key_file=""

  [[ -d "$ssh_dir" ]] || return 1

  while IFS= read -r key_file; do
    case "$(basename "$key_file")" in
      *.pub|authorized_keys|known_hosts|config)
        continue
        ;;
    esac

    if [[ -f "$key_file.pub" ]]; then
      printf '%s' "$key_file"
      return 0
    fi
  done < <(find "$ssh_dir" -maxdepth 1 -type f | sort)

  return 1
}

wait_for_ssh_key() {
  local preferred_path="$1"
  local ssh_dir="$HOME_DIR/.ssh"
  local detected_key=""

  mkdir -p "$ssh_dir"
  chmod 700 "$ssh_dir"

  if [[ -f "$preferred_path" && -f "$preferred_path.pub" ]]; then
    printf '%s' "$preferred_path"
    return 0
  fi

  if detected_key="$(find_ssh_key_in_dir "$ssh_dir")"; then
    printf '%s' "$detected_key"
    return 0
  fi

  info "Waiting for an SSH key to appear in $ssh_dir"
  printf 'Create the key in another terminal, then press Enter here to continue.\n'
  printf 'Expected path: %s (with matching .pub file)\n' "$preferred_path"
  read -r -p "Press Enter once you have generated the SSH key... "
  printf '%s' "$preferred_path"
}

prompt_yes_no() {
  local prompt="$1"
  local default="${2:-Y}"
  local reply=""

  while true; do
    if [[ "$default" == "Y" ]]; then
      read -r -p "$prompt [Y/n] " reply
      reply="${reply:-Y}"
    else
      read -r -p "$prompt [y/N] " reply
      reply="${reply:-N}"
    fi

    case "${reply,,}" in
      y|yes)
        return 0
        ;;
      n|no)
        return 1
        ;;
    esac
  done
}

prompt_dependency_yes_no() {
  local prompt="$1"
  local default="${2:-Y}"

  if [[ "$AUTO_INSTALL_DEPS" -eq 1 ]]; then
    printf '%s\n' "$prompt [auto-yes]"
    return 0
  fi

  prompt_yes_no "$prompt" "$default"
}

prompt_value() {
  local prompt="$1"
  local default="${2:-}"
  local reply=""

  if [[ -n "$default" ]]; then
    read -r -p "$prompt [$default] " reply
    printf '%s' "${reply:-$default}"
  else
    read -r -p "$prompt " reply
    printf '%s' "$reply"
  fi
}

prompt_required_value() {
  local prompt="$1"
  local default="${2:-}"
  local value=""

  while true; do
    value="$(prompt_value "$prompt" "$default")"
    if [[ -n "$value" ]]; then
      printf '%s' "$value"
      return 0
    fi
  done
}

prompt_passphrase() {
  local pass1=""
  local pass2=""

  while true; do
    IFS= read -r -s -p "Enter SSH key passphrase: " pass1
    printf '\n'
    IFS= read -r -s -p "Confirm SSH key passphrase: " pass2
    printf '\n'

    if [[ "$pass1" == "$pass2" ]]; then
      printf '%s' "$pass1"
      return 0
    fi

    warn "Passphrases did not match. Try again."
  done
}

sanitize_slug() {
  local value="$1"
  value="${value,,}"
  value="${value// /-}"
  value="$(printf '%s' "$value" | tr -cd 'a-z0-9_-')"
  printf '%s' "$value"
}

extract_host_from_git_url() {
  local url="$1"

  if [[ "$url" =~ ^ssh://([^/@]+@)?([^/:]+) ]]; then
    printf '%s' "${BASH_REMATCH[2]}"
    return 0
  fi

  if [[ "$url" =~ ^([^/@]+@)?([^:]+): ]]; then
    printf '%s' "${BASH_REMATCH[2]}"
    return 0
  fi

  if [[ "$url" =~ ^https?://([^/]+) ]]; then
    printf '%s' "${BASH_REMATCH[1]}"
    return 0
  fi

  return 1
}

add_host_to_known_hosts() {
  local host="$1"

  if [[ -z "$host" ]]; then
    return 1
  fi

  if ! command_exists ssh-keyscan; then
    warn "ssh-keyscan is not installed; skipping known_hosts update for $host"
    return 1
  fi

  mkdir -p "$HOME_DIR/.ssh"
  touch "$HOME_DIR/.ssh/known_hosts"

  if ssh-keygen -F "$host" -f "$HOME_DIR/.ssh/known_hosts" >/dev/null 2>&1; then
    return 0
  fi

  ssh-keyscan -H "$host" >>"$HOME_DIR/.ssh/known_hosts" 2>/dev/null || true
}

install_pacman_package() {
  local package="$1"
  sudo pacman -S --needed --noconfirm "$package"
}

install_yay() {
  if command_exists yay; then
    info "yay already installed"
    return 0
  fi

  info "Installing yay"
  git clone https://aur.archlinux.org/yay.git "$TMP_DIR/yay"
  (
    cd "$TMP_DIR/yay"
    makepkg -si --noconfirm
  )
}

write_element_desktop_entry() {
  local desktop_file="$1"
  local display_name="$2"
  local exec_line="$3"

  mkdir -p "$HOME_DIR/.local/share/applications"
  cat >"$desktop_file" <<EOF
[Desktop Entry]
Name=Element ($display_name)
Exec=$exec_line
Icon=io.element.Element
Type=Application
Categories=Network;InstantMessaging;Chat;IRCClient
EOF
}

write_keyd_remap_conf() {
  sudo mkdir -p /etc/keyd
  sudo tee /etc/keyd/remap.conf >/dev/null <<'EOF'
[ids]
0001:0001:09b4e68d
[main]
leftalt = leftmeta
leftmeta = leftalt
EOF
}

HOME_DIR="$HOME"
BASHRC="$HOME_DIR/.bashrc"
TMP_DIR="$(mktemp -d)"

cleanup() {
  rm -rf "$TMP_DIR"
}
trap cleanup EXIT

cd "$HOME_DIR"

info "Interactive Arch post-install"

if prompt_yes_no "Auto-install dependency packages and tooling without per-item prompts?" "N"; then
  AUTO_INSTALL_DEPS=1
fi

if prompt_dependency_yes_no "Update the system first?" "Y"; then
  info "Updating system"
  sudo pacman -Syu --noconfirm
fi

declare -a PACMAN_PACKAGES=(
  git
  which
  base-devel
  ttf-jetbrains-mono-nerd
  cliphist
  wl-clipboard
  neovim
  starship
  lazygit
  openssh
  alacritty
  hyprlock
  hyprpaper
  cava
  waybar
  keyd
  grim
  chromium
  uv
  npm
  rofi
  slurp
  brightnessctl
  playerctl
  nautilus
  network-manager-applet
  pavucontrol
  discord
  fastfetch
  ripgrep
  fd
  xdg-desktop-portal-hyprland
  element-desktop
)

info "Package selection"
for package in "${PACMAN_PACKAGES[@]}"; do
  if prompt_dependency_yes_no "Install package '$package'?" "Y"; then
    install_pacman_package "$package"
  fi
done

if prompt_dependency_yes_no "Install AUR helper 'yay'?" "Y"; then
  install_yay
fi

if command_exists yay && prompt_dependency_yes_no "Install AUR package 'zen-browser-bin'?" "Y"; then
  info "Installing zen-browser-bin"
  yay -S --needed --noconfirm zen-browser-bin
fi

if prompt_dependency_yes_no "Install ble.sh?" "Y"; then
  if [[ ! -f "$HOME_DIR/.local/share/blesh/ble.sh" ]]; then
    info "Installing ble.sh"
    git clone --recursive --depth 1 --shallow-submodules https://github.com/akinomyoga/ble.sh.git "$TMP_DIR/ble.sh"
    make -C "$TMP_DIR/ble.sh" install PREFIX="$HOME_DIR/.local"
  else
    info "ble.sh already installed"
  fi

  append_if_missing 'source -- ~/.local/share/blesh/ble.sh' "$BASHRC"
  touch "$HOME_DIR/.blerc"
  append_if_missing '[ -f "$HOME/.config/blerc" ] && source "$HOME/.config/blerc"' "$HOME_DIR/.blerc"
fi

if prompt_dependency_yes_no "Enable starship in ~/.bashrc?" "Y"; then
  info "Configuring shell"
  append_if_missing 'eval "$(starship init bash)"' "$BASHRC"
fi
stty sane || true

if prompt_yes_no "Configure global git identity?" "Y"; then
  info "Configuring git"
  git_name="$(prompt_required_value "Git user name:")"
  git_email="$(prompt_required_value "Git user email:")"
  git config --global user.name "$git_name"
  git config --global user.email "$git_email"
fi

if prompt_yes_no "Wait for an existing SSH key for git access?" "Y"; then
  info "Waiting for SSH key"
  ssh_key_path="$(prompt_required_value "SSH key path:" "$HOME_DIR/.ssh/id_ed25519")"
  ssh_key_path="$(wait_for_ssh_key "$ssh_key_path")"

  if [[ -f "$ssh_key_path" ]]; then
    chmod 600 "$ssh_key_path"
  else
    warn "Private key '$ssh_key_path' was not found; continuing without changing permissions"
  fi

  if [[ -f "$ssh_key_path.pub" ]]; then
    chmod 644 "$ssh_key_path.pub"
  else
    warn "Public key '$ssh_key_path.pub' was not found; clipboard copy will be skipped"
  fi

  if prompt_yes_no "Add a git host to ~/.ssh/known_hosts?" "Y"; then
    git_host="$(prompt_required_value "Git host (for ssh-keyscan):")"
    add_host_to_known_hosts "$git_host"
  fi

  if prompt_yes_no "Copy the public SSH key to the clipboard?" "Y"; then
    if [[ ! -f "$ssh_key_path.pub" ]]; then
      warn "Public key '$ssh_key_path.pub' is not available yet"
    elif command_exists wl-copy; then
      wl-copy <"$ssh_key_path.pub"
      info "Your public SSH key has been copied to the clipboard"
    else
      warn "wl-copy is not installed; printing the key instead"
      cat "$ssh_key_path.pub"
    fi
  fi

  printf '\nPublic key: %s.pub\n' "$ssh_key_path"
fi

if prompt_yes_no "Enable the keyd system service?" "Y"; then
  if command_exists keyd; then
    info "Enabling keyd"
    sudo systemctl enable --now keyd.service
  else
    warn "keyd is not installed; skipping service enablement"
  fi
fi

if prompt_yes_no "Remap ThinkPad Alt to Super with keyd?" "Y"; then
  if command_exists keyd; then
    info "Writing /etc/keyd/remap.conf"
    write_keyd_remap_conf
    sudo systemctl enable --now keyd.service
    sudo systemctl restart keyd.service
  else
    warn "keyd is not installed; skipping remap configuration"
  fi
fi

if prompt_dependency_yes_no "Set up uv with Python 3.14 and global tools?" "Y"; then
  if command_exists uv; then
    info "Configuring uv"
    uv python install 3.14
    uv python pin --global 3.14
    uv tool install ruff
    uv tool install python-lsp-server
  else
    warn "uv is not installed; skipping Python and tool setup"
  fi
fi

if prompt_yes_no "Clone a dotfiles repository into ~/.config?" "Y"; then
  info "Cloning dotfiles"
  dotfiles_repo="$(prompt_required_value "Dotfiles repository URL:")"
  config_target="$(prompt_required_value "Target config directory:" "$HOME_DIR/.config")"

  if [[ -d "$config_target" ]]; then
    if prompt_yes_no "Back up the existing '$config_target' before replacing it?" "Y"; then
      config_backup="${config_target}.backup.$(date +%Y%m%d-%H%M%S)"
      mv "$config_target" "$config_backup"
      info "Existing config moved to $config_backup"
    elif prompt_yes_no "Delete the existing '$config_target' and replace it?" "N"; then
      rm -rf "$config_target"
    else
      warn "Skipping dotfiles clone because target already exists"
      dotfiles_repo=""
    fi
  fi

  if [[ -n "$dotfiles_repo" ]]; then
    if dotfiles_host="$(extract_host_from_git_url "$dotfiles_repo")"; then
      if prompt_yes_no "Add the dotfiles git host to ~/.ssh/known_hosts before cloning?" "Y"; then
        add_host_to_known_hosts "$dotfiles_host"
      fi
    fi

    git clone "$dotfiles_repo" "$config_target"

    if ! dotfiles_host="$(extract_host_from_git_url "$dotfiles_repo")"; then
      warn "Could not determine a host from '$dotfiles_repo'"
    fi
  fi
fi

if prompt_yes_no "Clone a wallpapers repository?" "Y"; then
  info "Cloning wallpapers"
  wallpapers_repo="$(prompt_required_value "Wallpapers repository URL:")"
  wallpaper_target="$(prompt_required_value "Wallpaper target directory:" "$HOME_DIR/.local/share/wallpapers")"

  mkdir -p "$(dirname "$wallpaper_target")"
  if [[ -d "$wallpaper_target" ]]; then
    if prompt_yes_no "Delete the existing wallpaper directory '$wallpaper_target' first?" "Y"; then
      rm -rf "$wallpaper_target"
    else
      warn "Skipping wallpapers clone because target already exists"
      wallpapers_repo=""
    fi
  fi

  if [[ -n "$wallpapers_repo" ]]; then
    git clone "$wallpapers_repo" "$wallpaper_target"
  fi
fi

if prompt_yes_no "Create two custom Element desktop launchers?" "Y"; then
  info "Creating Element desktop entries"
  element_name_default="$(prompt_required_value "Name for the default Element profile launcher:")"
  element_name_secondary="$(prompt_required_value "Name for the second Element profile launcher:")"
  element_slug_default="$(sanitize_slug "$element_name_default")"
  element_slug_secondary="$(sanitize_slug "$element_name_secondary")"
  element_profile_secondary="$(prompt_required_value "Secondary Element profile id:" "profile1")"

  write_element_desktop_entry \
    "$HOME_DIR/.local/share/applications/element-${element_slug_default}.desktop" \
    "$element_name_default" \
    'element-desktop --ozone-platform=x11'

  write_element_desktop_entry \
    "$HOME_DIR/.local/share/applications/element-${element_slug_secondary}.desktop" \
    "$element_name_secondary" \
    "element-desktop --profile $element_profile_secondary"

  update-desktop-database "$HOME_DIR/.local/share/applications" >/dev/null 2>&1 || true
fi

if prompt_yes_no "Enable the sshd system service?" "Y"; then
  info "Enabling sshd"
  sudo systemctl enable --now sshd.service
fi

if prompt_yes_no "Configure SDDM autologin?" "N"; then
  info "Configuring SDDM autologin"
  autologin_user="$(prompt_required_value "Autologin user:")"
  autologin_session="$(prompt_required_value "Autologin session:" "hyprland-uwsm")"
  sudo mkdir -p /etc/sddm.conf.d
  sudo tee /etc/sddm.conf.d/autologin.conf >/dev/null <<EOF
[Autologin]
User=$autologin_user
Session=$autologin_session
EOF
fi

info "Post-install section completed"
printf 'You may want to restart your shell or run: source %s\n' "$BASHRC"