#!/usr/bin/env bash
# Compare pages on the VM with the same pages on Railway: status code,
# redirect, and <title>, for each path in ~/railway/paths.txt.
# From https://exe.dev/deploy/migrate-railway
#
#   railway/check           ask Railway now, and save its answers
#   railway/check --saved   compare with the saved answers (Railway is stopped)
set -uo pipefail
rw=~/railway
[ -f $rw/paths.txt ] || echo / > $rw/paths.txt
railway=$(cat $rw/railway-url)
host=$(hostname).exe.xyz

answer() {  # URL [curl options]: "status redirect title"
  local url=$1 out title=''; shift
  out=$(curl -sS -o /tmp/check.body -w '%{http_code} %{redirect_url}' --max-time 20 "$@" "$url" 2>/dev/null |
    sed "s#https\?://[^/]*##")
  # Error pages often come from the platform rather than the app, so
  # titles are compared only for pages that answer 2xx.
  case $out in 2*) title=$(grep -o -i '<title[^>]*>[^<]*' /tmp/check.body | head -1 | sed 's/<[^>]*>//') ;; esac
  printf '%s %s\n' "$out" "$title"
}

[ "${1:-}" = --saved ] || : > $rw/answers.txt.new
diffs=0
while read -r path; do
  [ -n "$path" ] || continue
  if [ "${1:-}" = --saved ]; then
    theirs=$(awk -F'\t' -v p="$path" '$1 == p { print $2; exit }' $rw/answers.txt)
  else
    theirs=$(answer "$railway$path")
    printf '%s\t%s\n' "$path" "$theirs" >> $rw/answers.txt.new
  fi
  ours=$(answer "http://localhost:8000$path" -H "Host: $host" -H "X-Forwarded-Proto: https")
  if [ "$theirs" = "$ours" ]; then
    echo "same      $path  ($ours)"
  else
    echo "DIFFERENT $path  Railway: $theirs  VM: $ours"; diffs=$((diffs + 1))
  fi
done < $rw/paths.txt
if [ "${1:-}" != --saved ]; then
  # Keep the last good answers if Railway didn't answer (stopped, at the move).
  if cut -f2 $rw/answers.txt.new | grep -q '^000'; then
    echo "Railway didn't answer every page; kept the answers saved before."
    rm -f $rw/answers.txt.new
  else
    mv $rw/answers.txt.new $rw/answers.txt
  fi
fi
exit $((diffs > 0))