#!/usr/bin/env bash

set -euo pipefail

if [[ ${SKIP_VERSION_UPDATE:-0} == 1 ]]; then
  exit 0
fi

gitRoot=$(git rev-parse --show-toplevel)
cd "$gitRoot"

if [[ -f $(git rev-parse --git-path MERGE_HEAD) ]]; then
  exit 0
fi

versionFile=internal/version/version.go
if ! git cat-file -e ":$versionFile" 2>/dev/null; then
  echo "Error: $versionFile must be present in the index." >&2
  exit 1
fi

if ! branchName=$(git symbolic-ref --quiet --short HEAD); then
  echo "Error: Check out a branch or set SKIP_VERSION_UPDATE=1." >&2
  exit 1
fi

newVersion=$(date +%Y.%m.%d)
escapedChannel=${branchName//\\/\\\\}
escapedChannel=${escapedChannel//\"/\\\"}

if grep -Fxq "const Version = \"$newVersion\"" "$versionFile" &&
    grep -Fxq "const Channel = \"$escapedChannel\"" "$versionFile"; then
  exit 0
fi

if ! git diff --quiet -- "$versionFile"; then
  echo "Error: Stage or save unstaged changes in $versionFile before its version update." >&2
  exit 1
fi

if [[ $(grep -Ec '^const Version = ".*"$' "$versionFile") != 1 ]] ||
    [[ $(grep -Ec '^const Channel = ".*"$' "$versionFile") != 1 ]]; then
  echo "Error: Expected one Version constant and one Channel constant in $versionFile." >&2
  exit 1
fi

sedChannel=${escapedChannel//\\/\\\\}
sedChannel=${sedChannel//&/\\&}
sedChannel=${sedChannel//|/\\|}
sed -i \
  -e "s|^const Version = \".*\"$|const Version = \"$newVersion\"|" \
  -e "s|^const Channel = \".*\"$|const Channel = \"$sedChannel\"|" \
  "$versionFile"
git add -- "$versionFile"
echo "Updated Cthulhu version to $newVersion-$branchName."