#!/usr/bin/env bash

set -eu

echo "::group::changed-files-diff-sha"

echo "Resolving repository path..."

if [[ -n $INPUT_PATH ]]; then
  REPO_DIR="$GITHUB_WORKSPACE/$INPUT_PATH"
  if [[ ! -d "$REPO_DIR" ]]; then
    echo "::warning::Invalid repository path"
    exit 1
  fi
  cd "$REPO_DIR"
fi

SERVER_URL=$(echo "$GITHUB_SERVER_URL" | awk -F/ '{print $3}')

echo "Setting up 'temp_changed_files' remote..."

git ls-remote --exit-code temp_changed_files 1>/dev/null 2>&1 && exit_status=$? || exit_status=$?

if [[ $exit_status -ne 0 ]]; then
  echo "No 'temp_changed_files' remote found"
  echo "Creating 'temp_changed_files' remote..."
  git remote remove temp_changed_files 2>/dev/null || true
  git remote add temp_changed_files "https://${INPUT_TOKEN}@${SERVER_URL}/${GITHUB_REPOSITORY}"
else
  echo "Found 'temp_changed_files' remote"
fi

echo "Getting HEAD SHA..."

if [[ -z $INPUT_SHA ]]; then
  CURRENT_SHA=$(git rev-list --no-merges -n 1 HEAD 2>&1) && exit_status=$? || exit_status=$?
else
  CURRENT_SHA=$INPUT_SHA && exit_status=$? || exit_status=$?
fi

git rev-parse --quiet --verify "$CURRENT_SHA^{commit}" 1>/dev/null 2>&1 && exit_status=$? || exit_status=$?

if [[ $exit_status -ne 0 ]]; then
  echo "::warning::Unable to locate the current sha: $CURRENT_SHA"
  echo "::warning::You seem to be missing 'fetch-depth: 0' or 'fetch-depth: 2'. See https://github.com/tj-actions/changed-files#usage"
  git remote remove temp_changed_files
  exit 1
fi

if [[ -z $GITHUB_BASE_REF ]]; then
  TARGET_BRANCH=${GITHUB_REF/refs\/heads\//}
  CURRENT_BRANCH=$TARGET_BRANCH

  if [[ -z $INPUT_BASE_SHA ]]; then
    PREVIOUS_SHA=$(git rev-list --no-merges -n 1 HEAD^1 2>&1) && exit_status=$? || exit_status=$?
  else
    PREVIOUS_SHA=$INPUT_BASE_SHA && exit_status=$? || exit_status=$?
    TARGET_BRANCH=$(git name-rev --name-only "$PREVIOUS_SHA" 2>&1) && exit_status=$? || exit_status=$?
  fi

  git rev-parse --quiet --verify "$PREVIOUS_SHA^{commit}" 1>/dev/null 2>&1 && exit_status=$? || exit_status=$?

  if [[ $exit_status -ne 0 ]]; then
    echo "::warning::Unable to locate the previous sha: $PREVIOUS_SHA"
    echo "::warning::You seem to be missing 'fetch-depth: 0' or 'fetch-depth: 2'. See https://github.com/tj-actions/changed-files#usage"
    git remote remove temp_changed_files
    exit 1
  fi
else
  TARGET_BRANCH=$GITHUB_BASE_REF
  CURRENT_BRANCH=$GITHUB_HEAD_REF

  if [[ -z $INPUT_BASE_SHA ]]; then
    if [[ "$INPUT_USE_FORK_POINT" == "true" ]]; then
      echo "Getting fork point..."
      git fetch --no-tags -u --progress temp_changed_files "${TARGET_BRANCH}":"${TARGET_BRANCH}" && exit_status=$? || exit_status=$?
      PREVIOUS_SHA=$(git merge-base --fork-point "temp_changed_files/${TARGET_BRANCH}") && exit_status=$? || exit_status=$?
    else
      git fetch --no-tags -u --progress --depth=1 temp_changed_files "${TARGET_BRANCH}":"${TARGET_BRANCH}" && exit_status=$? || exit_status=$?
      PREVIOUS_SHA=$(git rev-list --no-merges -n 1 "${TARGET_BRANCH}" 2>&1) && exit_status=$? || exit_status=$?
    fi
  else
    git fetch --no-tags -u --progress --depth=1 temp_changed_files "$INPUT_BASE_SHA" && exit_status=$? || exit_status=$?
    PREVIOUS_SHA=$INPUT_BASE_SHA
    TARGET_BRANCH=$(git name-rev --name-only "$PREVIOUS_SHA" 2>&1) && exit_status=$? || exit_status=$?
  fi

  echo "Verifying commit SHA..."
  git rev-parse --quiet --verify "$PREVIOUS_SHA^{commit}" 1>/dev/null 2>&1 && exit_status=$? || exit_status=$?

  if [[ $exit_status -ne 0 ]]; then
    echo "::warning::Unable to locate the previous sha: $PREVIOUS_SHA"
    echo "::warning::You seem to be missing 'fetch-depth: 0' or 'fetch-depth: 2'. See https://github.com/tj-actions/changed-files#usage"
    git remote remove temp_changed_files
    exit 1
  fi
fi

echo "::set-output name=target_branch::$TARGET_BRANCH"
echo "::set-output name=current_branch::$CURRENT_BRANCH"
echo "::set-output name=previous_sha::$PREVIOUS_SHA"
echo "::set-output name=current_sha::$CURRENT_SHA"

echo "::endgroup::"