#!/usr/bin/env sh
# Bootstrap a headless dev environment on a fresh Ubuntu 22.04 VM.
# Idempotent: safe to re-run.
#
#   curl -fsSL https://raw.githubusercontent.com/<user>/dotfiles/master/nix/bootstrap.sh | sh
#
# Steps:
#   1. Install Nix (Determinate Systems installer, multi-user).
#   2. Clone (or fast-forward) the dotfiles repo to ~/.local/share/dotfiles.
#   3. Run `home-manager switch --flake .../nix#vm`.
#   4. Install python3.11 via `uv` (needed by Mason pip installs).
#   5. Add Nix-store zsh to /etc/shells and chsh the user.
#
# Environment overrides:
#   DOTFILES_REPO   Git URL (default: https://github.com/ruifm/dotfiles)
#   DOTFILES_REF    Branch/tag/sha (default: master)
#   DOTFILES_DIR    Checkout path (default: $HOME/.local/share/dotfiles)

set -eu

REPO="${DOTFILES_REPO:-https://github.com/sommerfelddev/dotfiles}"
REF="${DOTFILES_REF:-master}"
DIR="${DOTFILES_DIR:-$HOME/.local/share/dotfiles}"

log() { printf '\033[1;32m==>\033[0m %s\n' "$*"; }
err() { printf '\033[1;31m==>\033[0m %s\n' "$*" >&2; }

# ── 1. Nix ────────────────────────────────────────────────────────────────────
if ! command -v nix >/dev/null 2>&1; then
  log "Installing Nix (Determinate Systems installer)…"
  curl --proto '=https' --tlsv1.2 -sSf -L \
    https://install.determinate.systems/nix |
    sh -s -- install linux --no-confirm
else
  log "Nix already installed, skipping installer."
fi

# ── 1b. (moved to step 4 — uv comes from the nix profile, only available
#         after `home-manager switch`) ─────────────────────────────────────────

# Source nix env for the rest of this script (installer writes
# /etc/profile.d/nix.sh but the current shell hasn't sourced it).
if [ -f /nix/var/nix/profiles/default/etc/profile.d/nix-daemon.sh ]; then
  # shellcheck disable=SC1091
  . /nix/var/nix/profiles/default/etc/profile.d/nix-daemon.sh
fi

# ── 2. Repo checkout ─────────────────────────────────────────────────────────
if ! command -v git >/dev/null 2>&1; then
  log "Bootstrapping git via nix profile…"
  nix profile install nixpkgs#git
fi

if [ -d "$DIR/.git" ]; then
  log "Updating existing checkout at $DIR…"
  git -C "$DIR" fetch origin "$REF"
  git -C "$DIR" checkout "$REF"
  git -C "$DIR" pull --ff-only
else
  log "Cloning $REPO ($REF) → $DIR…"
  mkdir -p "$(dirname "$DIR")"
  git clone --branch "$REF" "$REPO" "$DIR"
fi

# ── 3. Home-Manager switch ───────────────────────────────────────────────────
log "Running home-manager switch (this can take a while on first run)…"
nix --extra-experimental-features 'nix-command flakes' \
  run home-manager/master -- \
  switch --impure --flake "$DIR/nix#vm" -b backup

# ── 4. Mason's python interpreter (via uv from the nix profile) ──────────────
# Mason installs some LSPs/linters into per-package pip venvs. We need a
# python3.11 that:
#   (a) meets Mason's >=3.10 version requirement (Ubuntu 20.04 ships
#       /usr/bin/python3 = 3.8 — too old), and
#   (b) accepts manylinux wheels (Nix's python rejects them by design;
#       pip then falls back to compiling `nodejs-wheel-binaries` from
#       source, which fails on the host's gcc 9.4 — needs C++20).
#
# `uv python install 3.11` fetches a portable CPython build (python-build-
# standalone, manylinux-compatible) into ~/.local/share/uv/python/. We
# symlink its `python3.11` into ~/.local/bin/ (already on PATH from
# zprofile) so Mason discovers it. Does NOT shadow /usr/bin/python3 —
# leaf-tools policy intact. Works on any distro/release, no PPA required.
UV_BIN="$HOME/.nix-profile/bin/uv"
if [ -x "$UV_BIN" ]; then
  if [ ! -x "$HOME/.local/bin/python3.11" ]; then
    log "Installing python3.11 via uv (required for Mason pip installs)…"
    "$UV_BIN" python install 3.11
    UV_PY311="$("$UV_BIN" python find 3.11)"
    mkdir -p "$HOME/.local/bin"
    ln -sf "$UV_PY311" "$HOME/.local/bin/python3.11"
  fi
fi

# ── 5. chsh to nix-store zsh ─────────────────────────────────────────────────
NIX_ZSH="$HOME/.nix-profile/bin/zsh"
if [ -x "$NIX_ZSH" ]; then
  if ! grep -qxF "$NIX_ZSH" /etc/shells 2>/dev/null; then
    log "Appending $NIX_ZSH to /etc/shells (requires sudo)…"
    echo "$NIX_ZSH" | sudo tee -a /etc/shells >/dev/null
  fi
  current_shell="$(getent passwd "$USER" | cut -d: -f7)"
  if [ "$current_shell" != "$NIX_ZSH" ]; then
    log "Changing login shell to $NIX_ZSH (requires sudo)…"
    sudo chsh -s "$NIX_ZSH" "$USER"
  fi
fi

log "Done. Log out and back in for the new shell to take effect."
log "Then run 'nvim' once to let it fetch plugins on first launch."