#!/usr/bin/env bash
# Build the leveva docs site and publish it to the root of the `www` branch.
# The `www` branch is an orphan that contains ONLY the built site files.
set -euo pipefail

REMOTE="${1:-origin}"
BRANCH="www"

REPO_ROOT="$(git rev-parse --show-toplevel)"
SITE_DIR="$REPO_ROOT/docs/site"
PUBLIC_DIR="$SITE_DIR/public"

# 1. Build the site fresh.
rm -rf "$PUBLIC_DIR"
(cd "$SITE_DIR" && zola build)
# Disable Jekyll processing on static hosts that run it (keeps _-prefixed paths).
touch "$PUBLIC_DIR/.nojekyll"

# 2. Check out `www` into a throwaway worktree (created as an orphan if absent).
# Drop any worktree admin entries left dangling by a previously-failed run.
git -C "$REPO_ROOT" worktree prune
WORKTREE="$(mktemp -d)"
cleanup() {
	git -C "$REPO_ROOT" worktree remove --force "$WORKTREE" 2>/dev/null || rm -rf "$WORKTREE"
	git -C "$REPO_ROOT" worktree prune
}
trap cleanup EXIT

# Resolve the base for `www`, preferring the REMOTE tip so repeated deploys from a
# dev machine never build on (or try to fast-forward over) a stale local `www`:
#   - remote branch exists  → fetch it and reset local `www` to the remote tip;
#   - only a local branch   → build on it (a first push will create the remote);
#   - neither exists         → start a fresh orphan (first-ever deploy).
if git -C "$REPO_ROOT" ls-remote --exit-code --heads "$REMOTE" "$BRANCH" >/dev/null 2>&1; then
	git -C "$REPO_ROOT" fetch "$REMOTE" "$BRANCH"
	git -C "$REPO_ROOT" worktree add --force -B "$BRANCH" "$WORKTREE" "$REMOTE/$BRANCH"
elif git -C "$REPO_ROOT" show-ref --verify --quiet "refs/heads/$BRANCH"; then
	git -C "$REPO_ROOT" worktree add --force "$WORKTREE" "$BRANCH"
else
	git -C "$REPO_ROOT" worktree add --detach "$WORKTREE"
	git -C "$WORKTREE" checkout --orphan "$BRANCH"
fi

# 3. Replace the worktree's entire contents with the freshly built site.
git -C "$WORKTREE" rm -rf --quiet . >/dev/null 2>&1 || true
find "$WORKTREE" -mindepth 1 -maxdepth 1 -not -name '.git' -exec rm -rf {} +
cp -a "$PUBLIC_DIR/." "$WORKTREE/"

# 4. Commit and push only if something changed.
git -C "$WORKTREE" add -A
if git -C "$WORKTREE" diff --cached --quiet; then
	echo "www: already up to date, nothing to publish."
else
	git -C "$WORKTREE" commit -m "Deploy docs site: $(date -u +%Y-%m-%dT%H:%M:%SZ)"
	git -C "$WORKTREE" push "$REMOTE" "$BRANCH"
	echo "www: published to $REMOTE/$BRANCH."
fi