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

INSTALL_DIR="/opt/nvim"
BACKUP_DIR="/opt/nvim.backup"
BIN_DIR="/usr/local/bin"

if [[ $EUID -ne 0 ]]; then
    exec sudo bash "$0" "$@"
fi

case "$(dpkg --print-architecture)" in
    amd64) ARCH="x86_64" ;;
    arm64) ARCH="arm64" ;;
    *)
        echo "Unsupported architecture" >&2
        exit 1
        ;;
esac

echo "==> Installing dependencies"
apt-get update
apt-get install -y curl ca-certificates tar

TMP_DIR="$(mktemp -d)"
trap 'rm -rf "$TMP_DIR"' EXIT

ASSET="nvim-linux-${ARCH}"
URL="https://github.com/neovim/neovim/releases/latest/download/${ASSET}.tar.gz"

echo "==> Downloading latest Neovim"
curl -fL --retry 3 \
    "$URL" \
    -o "$TMP_DIR/nvim.tar.gz"

echo "==> Extracting Neovim"
tar -xzf "$TMP_DIR/nvim.tar.gz" -C "$TMP_DIR"

"$TMP_DIR/$ASSET/bin/nvim" --version | head -n 1

echo "==> Installing to $INSTALL_DIR"

# Remove the previous backup
rm -rf "$BACKUP_DIR"

# Back up the current installation
if [[ -e "$INSTALL_DIR" ]]; then
    mv "$INSTALL_DIR" "$BACKUP_DIR"
fi

# Install the new version
if ! mv "$TMP_DIR/$ASSET" "$INSTALL_DIR"; then
    if [[ -d "$BACKUP_DIR" ]]; then
        mv "$BACKUP_DIR" "$INSTALL_DIR"
    fi
    exit 1
fi

echo "==> Creating command symlinks"
mkdir -p "$BIN_DIR"

for cmd in vi vim nvim; do
    ln -sfn "$INSTALL_DIR/bin/nvim" "$BIN_DIR/$cmd"
done

echo "==> Configuring update-alternatives"

update-alternatives \
    --install /usr/bin/vi vi "$INSTALL_DIR/bin/nvim" 100

update-alternatives \
    --install /usr/bin/vim vim "$INSTALL_DIR/bin/nvim" 100

update-alternatives \
    --install /usr/bin/editor editor "$INSTALL_DIR/bin/nvim" 100

for cmd in vi vim editor; do
    update-alternatives --set "$cmd" "$INSTALL_DIR/bin/nvim"
done

echo "==> Setting EDITOR and VISUAL"

cat > /etc/profile.d/neovim.sh <<'EOF'
export EDITOR=/usr/local/bin/nvim
export VISUAL=/usr/local/bin/nvim
EOF

chmod 644 /etc/profile.d/neovim.sh

echo "==> Verifying installation"

for cmd in vi vim nvim; do
    TARGET="$(readlink -f "$BIN_DIR/$cmd")"

    if [[ "$TARGET" != "$INSTALL_DIR/bin/nvim" ]]; then
        echo "Verification failed: $cmd" >&2
        exit 1
    fi

    printf '%-5s -> %s\n' "$cmd" "$TARGET"
done

echo
"$INSTALL_DIR/bin/nvim" --version | head -n 1

echo
echo "Neovim installation completed."
echo "Please reopen your shell to refresh the environment."