#!/usr/bin/env bash
# update-wordpress.sh — bring a new WordPress release into the fork.
#
#   tools/update-wordpress.sh 7.1.2
#
# Two steps, and the second is the one that matters:
#
#   1. Import the pristine release onto the `sirius-press/wordpress-upstream`
#      branch — one commit per version, nothing but upstream, never edited.
#   2. `git subtree merge` that branch into wordpress/, which three-way merges
#      it against the fork's own commits on top of the last import.
#
# That second step is why core is vendored rather than patched at build time.
# A three-way merge understands that upstream changed lines A and B while the
# fork changed line C, and only stops when they overlap. It also leaves a
# conflict you resolve once, in the file, instead of a patch you re-derive
# every release.
#
# The merge happens in a temporary worktree, not in your checkout. git-subtree
# refuses to run at all when anything in the repository is modified, and in a
# monorepo shared with other work that is the normal state — the merge would
# be blocked by uncommitted files it does not touch. A worktree is clean by
# construction, and the result comes back as one ordinary merge commit.
#
# Nothing is pushed. Run it, look at the merge, run the tests, then push.

set -euo pipefail

here="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
repo="$(git -C "$here" rev-parse --show-toplevel)"
# Ask git for the path rather than subtracting strings: on Windows
# --show-toplevel answers "D:/…" while $PWD is "/d/…", and the subtraction
# silently leaves an absolute path, which --prefix then rejects.
prefix="$(cd "$here" && git rev-parse --show-prefix)wordpress"

VERSION="${1:-}"

say()  { printf '\033[1m→\033[0m %s\n' "$*"; }
warn() { printf '\033[33mwarning:\033[0m %s\n' "$*" >&2; }
die()  { printf '\033[31merror:\033[0m %s\n' "$*" >&2; exit 1; }

[ -n "$VERSION" ] || die "usage: tools/update-wordpress.sh <version>"
[[ "$VERSION" =~ ^[0-9]+\.[0-9]+(\.[0-9]+)?$ ]] || die "'$VERSION' does not look like a WordPress version"

# shellcheck source=wordpress.lock
source "$here/tools/wordpress.lock"
CURRENT="$WP_VERSION"
[ "$VERSION" != "$CURRENT" ] || die "the fork is already on WordPress $VERSION"

UPSTREAM_BRANCH="sirius-press/wordpress-upstream"
git -C "$repo" rev-parse --verify --quiet "$UPSTREAM_BRANCH" >/dev/null \
  || die "the branch $UPSTREAM_BRANCH is missing. It holds the pristine upstream
imports that the subtree merges against; without it this fork cannot take an
upstream release. See docs/upstream-merges.md."

# The merge lands on top of whatever is committed, so anything staged or
# modified under the subtree itself would be lost or fought over.
if ! git -C "$repo" diff --quiet -- "$prefix" 2>/dev/null; then
  die "${prefix}/ has uncommitted changes. Commit or stash them first."
fi

CACHE="$here/dist/.cache"
mkdir -p "$CACHE"
URL="https://wordpress.org/wordpress-${VERSION}.tar.gz"
TARBALL="$CACHE/wordpress-${VERSION}.tar.gz"

# ------------------------------------------------------------------- fetch

if [ ! -f "$TARBALL" ]; then
  say "downloading WordPress $VERSION"
  curl -fsSL -o "$TARBALL.part" "$URL" || die "could not download $URL — does that version exist?"
  mv "$TARBALL.part" "$TARBALL"
fi

say "checking it against the SHA-1 wordpress.org publishes"
published="$(curl -fsSL "${URL}.sha1" 2>/dev/null || true)"
actual_sha1="$(sha1sum "$TARBALL" | cut -d' ' -f1)"
if [ -z "$published" ]; then
  warn "wordpress.org served no .sha1 for this release; recording the sha256 below unverified"
elif [ "$published" != "$actual_sha1" ]; then
  rm -f "$TARBALL"
  die "SHA-1 mismatch — the download is not what wordpress.org publishes.
  published $published
  got       $actual_sha1"
fi
NEW_SHA256="$(sha256sum "$TARBALL" | cut -d' ' -f1)"

# ------------------------------------------- import onto the upstream branch

IMPORT_TREE="$here/dist/.vendor-import"
MERGE_TREE="$here/dist/.vendor-merge"
MERGE_BRANCH="sirius-press/_merge-${VERSION}"

drop_worktree() {
  git -C "$repo" worktree remove --force "$1" >/dev/null 2>&1 || true
}

say "importing the pristine tree onto $UPSTREAM_BRANCH"
drop_worktree "$IMPORT_TREE"
rm -rf "$IMPORT_TREE"
git -C "$repo" worktree add --quiet "$IMPORT_TREE" "$UPSTREAM_BRANCH"
trap 'drop_worktree "$IMPORT_TREE"' EXIT

# Replace the tree wholesale: files upstream deleted have to disappear, or the
# subtree merge would keep resurrecting them.
find "$IMPORT_TREE" -mindepth 1 -maxdepth 1 ! -name '.git' -exec rm -rf {} +
tar -xzf "$TARBALL" -C "$IMPORT_TREE" --strip-components=1

git -C "$IMPORT_TREE" add -A
if git -C "$IMPORT_TREE" diff --cached --quiet; then
  # Already imported — a previous run got this far and then stopped. Carry on
  # to the merge rather than refusing, so a failure is retryable.
  say "WordPress $VERSION was already imported; continuing to the merge"
else
  git -C "$IMPORT_TREE" \
    -c user.name="Silent Mode" -c user.email="hephaestus@silentmode.st" \
    commit -q -m "WordPress ${VERSION}

Pristine upstream, unpacked from the official wordpress.org tarball.

  ${URL}
  sha1   ${actual_sha1}  (published by wordpress.org)
  sha256 ${NEW_SHA256}

This branch carries nothing but upstream releases, one commit each, and is
never edited."
  say "imported as $(git -C "$IMPORT_TREE" rev-parse --short HEAD)"
fi

drop_worktree "$IMPORT_TREE"
trap - EXIT

# ------------------------------------------------------------ subtree merge

say "merging into ${prefix}/ (in a scratch worktree)"
drop_worktree "$MERGE_TREE"
rm -rf "$MERGE_TREE"
git -C "$repo" branch -D "$MERGE_BRANCH" >/dev/null 2>&1 || true
git -C "$repo" worktree add --quiet -b "$MERGE_BRANCH" "$MERGE_TREE" HEAD

if git -C "$MERGE_TREE" \
  -c user.name="Silent Mode" -c user.email="hephaestus@silentmode.st" \
  subtree merge --prefix="$prefix" "$UPSTREAM_BRANCH" \
  -m "merge: WordPress ${VERSION} into the vendored subtree"
then
  say "merged cleanly"
else
  cat >&2 <<EOF

$(printf '\033[31mThe merge did not complete.\033[0m')

Usually this means upstream changed code the fork also changes — in practice
wp-admin/install.php, the only file this fork patches. Your own checkout is
untouched and still on WordPress ${CURRENT}; the half-done merge is in a
scratch worktree:

  cd ${MERGE_TREE}
  git status                        # what conflicted
  \$EDITOR ${prefix}/wp-admin/install.php
  git add ${prefix}/wp-admin/install.php
  git commit                        # finish the merge

Then bring it back and finish up:

  cd ${repo}
  git merge --no-ff ${MERGE_BRANCH}
  git worktree remove ${MERGE_TREE}
  git branch -d ${MERGE_BRANCH}
  ${here}/tools/refresh-patches.sh
  # set WP_VERSION / WP_URL / WP_SHA256 / WP_SHA1 in tools/wordpress.lock

EOF
  exit 1
fi

# Bring the merge home. This touches only ${prefix}/, so unrelated modified
# files elsewhere in the repository are not in its way.
say "bringing the merge into the working branch"
git -C "$repo" merge --no-ff -q \
  -m "merge: WordPress ${VERSION} into ${prefix}/" "$MERGE_BRANCH" \
  || die "could not merge ${MERGE_BRANCH} into the working branch. It is still
there, with the subtree merge already done — resolve and merge it by hand."

drop_worktree "$MERGE_TREE"
git -C "$repo" branch -D "$MERGE_BRANCH" >/dev/null 2>&1 || true

# --------------------------------------------------------------- the lock

say "updating tools/wordpress.lock"
python3 - "$VERSION" "$URL" "$NEW_SHA256" "$actual_sha1" "$here/tools/wordpress.lock" <<'PY'
import io, sys
version, url, sha256, sha1, path = sys.argv[1:6]
fields = {
    'WP_VERSION=': version,
    'WP_URL=': url,
    'WP_SHA256=': sha256,
    'WP_SHA1=': sha1,
}
out = []
for line in io.open(path, encoding='utf-8'):
    for key, value in fields.items():
        if line.startswith(key):
            line = f'{key}{value}\n'
            break
    out.append(line)
io.open(path, 'w', encoding='utf-8', newline='').write(''.join(out))
PY

if [ -x "$here/tools/refresh-patches.sh" ]; then
  say "refreshing patches/ so it still describes the fork's core diff"
  "$here/tools/refresh-patches.sh" >/dev/null || warn "could not refresh patches/ — do it by hand"
fi

cat <<EOF

$(printf '\033[32mSirius Press now builds on WordPress %s.\033[0m' "$VERSION")

  ${CURRENT} -> ${VERSION}

The subtree merge is committed. tools/wordpress.lock and patches/ are changed
but not committed — look at them, then commit. Before pushing:

  tests/run.sh
  tools/build.sh
  then walk through wp-admin/install.php once — the setup wizard is the only
  file this fork patches, so it is the only thing this can have broken.

EOF