#!/bin/bash
set -euo pipefail

# -- utils ---------------------------------------------------------
prompt_yn() {
  # usage: prompt_yn "Question (y/N): " N
  local prompt="${1:-Proceed (y/N): }"
  local default="${2:-N}"
  local ans=""
  if [ -t 0 ] && [ -t 1 ]; then
    # interactive: read from the TTY (not stdin)
    read -r -p "$prompt" ans </dev/tty || true
  else
    # non-interactive (e.g., curl|bash): use default
    echo "$prompt$default"
    ans="$default"
  fi
  [[ ${ans:-$default} =~ ^[Yy]$ ]]
}

# -- platform detection --------------------------------------------
detect_platform() {
  if [[ "$OSTYPE" == "darwin"* ]]; then
    OS="macos"; PKG_MGR="brew"
    if ! command -v brew &>/dev/null; then
      if prompt_yn "Homebrew not found. Install it now? (y/N): " N; then
        /bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/HEAD/install.sh)"
        echo 'eval "$(/opt/homebrew/bin/brew shellenv)"' >> ~/.zprofile
        eval "$(/opt/homebrew/bin/brew shellenv)"
      else
        echo "Homebrew is required to install Fish on macOS. Exiting."; exit 1
      fi
    fi
  elif command -v apt &>/dev/null; then
    OS="debian"; PKG_MGR="apt"
  elif command -v dnf &>/dev/null; then
    OS="rhel"; PKG_MGR="dnf"
  elif command -v yum &>/dev/null; then
    OS="rhel"; PKG_MGR="yum"
  elif command -v pacman &>/dev/null; then
    OS="arch"; PKG_MGR="pacman"
  else
    echo "Unsupported platform."; exit 1
  fi
}

# -- debian repo/key -----------------------------------------------
install_gpg_if_needed() {
  if [[ "${OS}" == "debian" ]] && ! command -v gpg &>/dev/null; then
    sudo apt update && sudo apt install -y gnupg
  fi
}

add_fish_repo_debian() {
  echo 'deb http://download.opensuse.org/repositories/shells:/fish:/release:/4/Debian_12/ /' \
  | sudo tee /etc/apt/sources.list.d/fish.list >/dev/null
  curl -fsSL https://download.opensuse.org/repositories/shells:fish:release:4/Debian_12/Release.key \
    | gpg --dearmor | sudo tee /etc/apt/trusted.gpg.d/fish.gpg >/dev/null
  sudo apt update
}

# -- install/update fish -------------------------------------------
install_fish() {
  case "$OS" in
    debian) add_fish_repo_debian; sudo apt install -y fish ;;
    rhel)   sudo "$PKG_MGR" install -y fish ;;
    arch)   sudo pacman -Sy --noconfirm fish ;;
    macos)  brew install fish ;;
  esac
}

update_fish() {
  case "$PKG_MGR" in
    apt)
      sudo apt update
      if apt list --upgradable 2>/dev/null | grep -q "^fish/"; then
        if prompt_yn "Fish update available. Update now? (y/N): " N; then
          sudo apt install -y fish
        fi
      fi
      ;;
    dnf|yum)
      sudo "$PKG_MGR" check-update || true
      if "$PKG_MGR" list updates | grep -q "^fish"; then
        if prompt_yn "Fish update available. Update now? (y/N): " N; then
          sudo "$PKG_MGR" update -y fish
        fi
      fi
      ;;
    pacman)
      sudo pacman -Sy --noconfirm
      if pacman -Qu | grep -q "^fish"; then
        if prompt_yn "Fish update available. Update now? (y/N): " N; then
          sudo pacman -S --noconfirm fish
        fi
      fi
      ;;
    brew)
      brew update
      if brew outdated | grep -q "^fish"; then
        if prompt_yn "Fish update available. Update now? (y/N): " N; then
          brew upgrade fish
        fi
      fi
      ;;
  esac
}

# -- fisher & plugins ----------------------------------------------
install_fisher() {
  curl -fsSL https://git.mycod.in/apt/fish_install/raw/branch/main/install_fisher.fish \
    -o /tmp/install_fisher.fish
  chmod +x /tmp/install_fisher.fish
  # prevent fisher from reading our script via stdin
  fish /tmp/install_fisher.fish </dev/null
}

install_fish_plugins() {
  curl -fsSL https://git.mycod.in/apt/fish_install/raw/branch/main/fish_plugins.fish \
    -o /tmp/fish_plugins.fish
  chmod +x /tmp/fish_plugins.fish
  # QUIET mode: suppress noisy file listing. Remove redirection if you want verbosity.
  fish /tmp/fish_plugins.fish </dev/null >/dev/null 2>&1
}

# -- main -----------------------------------------------------------
detect_platform
install_gpg_if_needed

if command -v fish &>/dev/null; then
  echo "Fish shell is already installed."
  update_fish
else
  install_fish
fi

if prompt_yn "Install Fisher plugin manager and recommended plugins? (y/N): " N; then
  install_fisher
  install_fish_plugins
  echo "Fisher and plugins installed!"
else
  echo "Skipping plugin installation."
fi

echo "✅ Fish shell setup complete on ${OS}!"