alda-mirror/bin/version-changelog

#!/usr/bin/env bash

version="$1"

if [[ -z "$version" ]]; then
  echo "Usage: $0 VERSION" > /dev/stderr
  exit 1
fi

output="$(mktemp)"

found_version=no

while IFS= read -r line; do
  # Skip all lines before the heading for the version we're looking for.
  if [[ "$found_version" != yes ]]; then
    version_prefix="## $version"
    if [[ "$line" == $version_prefix* ]]; then
      found_version=yes
    fi

    continue
  fi

  # Skip any blank lines between the version heading and the content.
  if ! [[ -s "$output" ]] && [[ -z "$line" ]]; then
    continue
  fi

  # Stop when we've encountered the next version heading below the one that we
  # care about.
  if [[ "$line" =~ ^##\ .* ]]; then
    break
  fi

  echo "$line" >> "$output"
done < "$(dirname "$0")/../CHANGELOG.md"

if ! [[ -s "$output" ]]; then
  echo "No changelog found for version $version." > /dev/stderr
  exit 1
fi

cat "$output"