#!/bin/bash
#
#  Copyright (C) 2019 The Android Open Source Project
#
#  Licensed under the Apache License, Version 2.0 (the "License");
#  you may not use this file except in compliance with the License.
#  You may obtain a copy of the License at
#
#       http://www.apache.org/licenses/LICENSE-2.0
#
#  Unless required by applicable law or agreed to in writing, software
#  distributed under the License is distributed on an "AS IS" BASIS,
#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
#  See the License for the specific language governing permissions and
#  limitations under the License.
#
set -e

supportRoot="$(cd $(dirname $0)/.. && pwd)"
checkoutRoot="$(cd ${supportRoot}/../.. && pwd)"

function die() {
  echo "$@" >&2
  exit 1
}

function usage() {
  violation="$1"
  die "
  Usage: $0 <git treeish>
         $0 <path>:<git treeish> <path>:<git treeish>

  Validates that libraries built from the given versions are the same as
  the build outputs built at HEAD. This can be used to validate that a refactor
  did not change the outputs. If a git treeish is given with no path, the path is considered to be frameworks/support

  Example: $0 HEAD^
  Example: $0 prebuilts/androidx/external:HEAD^ frameworks/support:work^

  * A git treeish is what you type when you run 'git checkout <git treeish>'
    See also https://git-scm.com/docs/gitglossary#Documentation/gitglossary.txt-aiddeftree-ishatree-ishalsotreeish .
  "
  return 1
}

# Fills in a default repository path of "frameworks/support:" for any args that don't specify
# their repository. Given an input of: "work^ prebuilts/androidx/external:HEAD^", should return
# "frameworks/support:work^ prebuilts/androidx/external:HEAD^".
function expandCommitArgs() {
  inputSpecs="$@"
  outputSpecs=""
  for spec in $inputSpecs; do
    if echo "$spec" | grep -v ":" >/dev/null; then
      spec="frameworks/support:$spec"
    fi
    outputSpecs="$outputSpecs $spec"
  done
  echo $outputSpecs
}

# Given a list of paths like "frameworks/support prebuilts/androidx/external",
# runs `git checkout -` in each
function uncheckout() {
  repositoryPaths="$@"
  for repositoryPath in $repositoryPaths; do
    echoAndDo git -C "$checkoutRoot/$repositoryPath" checkout -
  done
}
# Given a list of version specs like "a/b:c d/e:f", returns just the paths: "a/b d/e"
function getParticipatingProjectPaths() {
  specs="$@"
  result=""
  for arg in $specs; do
    echo parsing $arg >&2
    repositoryPath="$(echo $arg | sed 's|\([^:]*\):\([^:]*\)|\1|')"
    otherVersion="$(echo $arg | sed 's|\([^:]*\):\([^:]*\)|\2|')"
    if [ "$otherVersion" != "HEAD" ]; then
      result="$result $repositoryPath"
    fi
  done
  echo $result
}
# Given a list of paths, returns a string containing the currently checked-out version of each
function getCurrentCommits() {
  repositoryPaths="$@"
  result=""
  for repositoryPath in $repositoryPaths; do
    currentVersion="$(cd $checkoutRoot/$repositoryPath && git log -1 --format=%H)"
    result="$result $repositoryPath:$currentVersion"
  done
  echo $result
}
function echoAndDo() {
  echo "$*"
  eval "$*"
}
# Given a list of version specs like "a/b:c d/e:f", checks out the appropriate version in each
# In this example it would be `cd a/b && git checkout e` and `cd e/e && git checkout f`
function checkout() {
  versionSpecs="$1"
  for versionSpec in $versionSpecs; do
    project="$(echo $versionSpec | sed 's|\([^:]*\):\([^:]*\)|\1|')"
    ref="$(echo     $versionSpec | sed 's|\([^:]*\):\([^:]*\)|\2|')"
    echo "checking out $ref in project $project"
    echoAndDo git -C "$checkoutRoot/$project" checkout "$ref"
  done
}
function doBuild() {
  # build androidx
  echoAndDo ./gradlew createArchive generateDocs --no-daemon --rerun-tasks --offline
  archiveName="top-of-tree-m2repository-all-0.zip"
  echoAndDo unzip -q "${tempOutPath}/dist/${archiveName}" -d "${tempOutPath}/dist/${archiveName}.unzipped"
}

oldCommits="$(expandCommitArgs $@)"
projectPaths="$(getParticipatingProjectPaths $oldCommits)"
if echo $projectPaths | grep external/dokka >/dev/null; then
  if [ "$BUILD_DOKKA" == "" ]; then
    echo "It doesn't make sense to include the external/dokka project without also setting BUILD_DOKKA=true. Did you mean to set BUILD_DOKKA=true?"
    exit 1
  fi
fi
echo old commits: $oldCommits
if [ "$oldCommits" == "" ]; then
  usage
fi
newCommits="$(getCurrentCommits $projectPaths)"
cd "$supportRoot"
echo new commits: $newCommits

oldOutPath="${checkoutRoot}/out-old"
newOutPath="${checkoutRoot}/out-new"
tempOutPath="${checkoutRoot}/out"


rm -rf "$oldOutPath" "$newOutPath" "$tempOutPath"

echo building new commit
doBuild
mv "$tempOutPath" "$newOutPath"

echo building previous commit

checkout "$oldCommits"
if doBuild; then
  echo previous build succeeded
else
  echo previous build failed
  uncheckout "$projectPaths"
  exit 1
fi
uncheckout "$projectPaths"
mv "$tempOutPath" "$oldOutPath"

echo
echo diffing results
# Don't care about maven-metadata files because they have timestamps in them
# We might care to know whether .sha1 or .md5 files have changed, but changes in those files will always be accompanied by more meaningful changes in other files, so we don't need to show changes in .sha1 or .md5 files
# We also don't care about several specific files, either
echoAndDo diff -r -x "*.md5*" -x "*.sha*" -x "*maven-metadata.xml" -x buildSrc.jar -x jetifier-standalone.zip -x jetpad-integration.jar -x "top-of-tree-m2repository-all-0.zip" -x noto-emoji-compat-java.jar -x versionedparcelable-annotation.jar -x dokkaTipOfTreeDocs-0.zip -x fakeannotations.jar -x "doclava*.jar" "$oldOutPath/dist" "$newOutPath/dist"
echo end of difference