#!/usr/bin/env sh
set -eu

tag="${1:-}"

if [ -z "$tag" ]; then
  echo "Missing release tag argument (expected vX.Y.Z)."
  exit 1
fi

if [ ! -f CHANGELOG.md ]; then
  echo "CHANGELOG.md not found."
  exit 1
fi

version="${tag#v}"

awk -v version="$version" '
BEGIN {
  in_section = 0
  started = 0
}
/^## / {
  if (in_section == 1) {
    exit
  }

  if (index($0, version) > 0) {
    in_section = 1
    started = 1
    print $0
    next
  }
}
{
  if (in_section == 1) {
    print $0
  }
}
END {
  if (started == 0) {
    exit 2
  }
}
' CHANGELOG.md