#!/usr/bin/env bash
# Regenerates the web-features map after a merge and commits it, together with the
# events that merge produced, as one commit on the current branch. The one entry point
# for keeping docs/web-features-map.json current: bench/land.sh runs it in the primary
# checkout after every unattended landing, and a hand landing runs it the same way.
#
#   bench/web-features-update.sh [--no-commit]
#
# Run from anywhere inside a checkout; it works on that checkout's root. Steps:
#   1. refuse if docs/web-features-map.json or docs/web-features-events.jsonl has
#      uncommitted changes (they are this script's to write)
#   2. node oracle/suites/web-features-map.mjs: rewrites the snapshot unless only the
#      engine commit would change
#   3. if the snapshot's content did not change: print "unchanged" and exit 0, with
#      nothing written and nothing committed
#   4. append node oracle/suites/web-features-diff.mjs <old> <new> to
#      docs/web-features-events.jsonl
#   5. commit exactly those two files ("web-features map: ..."), unless --no-commit
#
# Exit 0 when the map is current afterwards (committed, or unchanged); 1 on any failure,
# with the reason on stderr and both files put back as they were, so a failure never
# leaves the checkout dirty and never touches anything else. It never merges, resets or
# pushes. Format and rules: docs/web-features-map.md.
set -euo pipefail

NO_COMMIT=0
for arg in "$@"; do
  case "$arg" in
    --no-commit) NO_COMMIT=1 ;;
    *) echo "usage: bench/web-features-update.sh [--no-commit]" >&2; exit 1 ;;
  esac
done

ROOT="$(git -C "$(dirname "${BASH_SOURCE[0]}")" rev-parse --show-toplevel)"
cd "$ROOT"
MAP=docs/web-features-map.json
LOG=docs/web-features-events.jsonl

if [ -n "$(git status --porcelain -- "$MAP" "$LOG")" ]; then
  echo "web-features map not updated: $MAP or $LOG has uncommitted changes" >&2
  exit 1
fi

TMP="$(mktemp -d)"
DONE=0
restore() {
  local code=$?
  if [ "$DONE" = 0 ]; then
    git reset -q -- "$MAP" "$LOG" 2>/dev/null || true
    git checkout -q -- "$MAP" "$LOG" 2>/dev/null || true
    # A file the checkout did not track yet is removed rather than left behind.
    for f in "$MAP" "$LOG"; do
      git ls-files --error-unmatch "$f" >/dev/null 2>&1 || rm -f "$f"
    done
  fi
  rm -rf "$TMP"
  exit "$code"
}
trap restore EXIT

if [ -f "$MAP" ]; then cp "$MAP" "$TMP/before.json"; else : >"$TMP/before.json"; fi

if ! node oracle/suites/web-features-map.mjs >&2; then
  echo "web-features map not updated: the generator failed" >&2
  exit 1
fi

if [ -s "$TMP/before.json" ] && cmp -s "$TMP/before.json" "$MAP"; then
  DONE=1
  echo "web-features map unchanged"
  exit 0
fi

if ! node oracle/suites/web-features-diff.mjs "$TMP/before.json" "$MAP" >"$TMP/events"; then
  echo "web-features map not updated: the diff failed" >&2
  exit 1
fi
cat "$TMP/events" >>"$LOG"
N="$(wc -l <"$TMP/events" | tr -d ' ')"

if [ "$NO_COMMIT" = 1 ]; then
  DONE=1
  echo "web-features map regenerated, $N events appended (not committed)"
  exit 0
fi

AT="$(git rev-parse --short HEAD)"
git add -- "$MAP" "$LOG"
if ! git commit -q -m "web-features map: regenerate at $AT ($N events)" -- "$MAP" "$LOG"; then
  echo "web-features map not updated: the commit failed" >&2
  exit 1
fi
DONE=1
echo "web-features map committed at $(git rev-parse --short HEAD), $N events"