disassemble

#!/bin/bash

calc_cache_hash() {
  current_hash=$(find .tmp/ -maxdepth 1 -type f -name "*.apk" -exec sha256sum {} \; |  awk '{print $1}' | sort -d | sha256sum | cut -d ' ' -f 1)
}

create_gitignore() {
    cat << EOF > .gitignore &&
.gitignore
build
dist
lib
assets/bttv_contributors.json
smali*/androidx
smali_classes9/bttv
smali_classes9/com
EOF
    find ../../mod/app/src/main/res -type f | sed "s/..\/..\/mod\/app\/src\/main\///" >> .gitignore &&
    echo "" >> .gitignore
}

#
# gather variables
#

[ -z "$JAVA_PATH" ] && JAVA_PATH=java
[ -z "$APKTOOL_PATH" ] && APKTOOL_PATH=/opt/apktool/apktool.jar
[ -z "$BUILD_COMPANION" ] && BUILD_COMPANION=/opt/build-companion
[ -z "$UBER_APK_SIGNER_PATH" ] && UBER_APK_SIGNER_PATH=/opt/uber-apk-signer/uber-apk-signer-1.2.1.jar

[[ -f "twitch.zip" ]] && FILE=twitch.zip
[[ -f "twitch.apk" ]] && FILE=twitch.apk
[ -z "$FILE" ] && echo "neither twitch.zip or twitch.apk where found" && exit 1

echo "JAVA_PATH: $JAVA_PATH"
echo "APKTOOL_PATH: $APKTOOL_PATH"
echo "FILE: $FILE"
echo "BUILD_COMPANION: $BUILD_COMPANION"
echo "UBER_APK_SIGNER_PATH: $UBER_APK_SIGNER_PATH"

# remove old working space
rm -rf .tmp

#
# gather apk files
#

if [ "${FILE: -4}" = ".zip" ]; then
  unzip $FILE -d .tmp
else
  mkdir .tmp
  cp twitch.apk .tmp/tv.twitch.android.app.apk
fi


#
# check if cache available
#

if [ -d ".bttv-cache" ] && [ -f ".bttv-cache/disass_hash" ] && [ -d ".bttv-cache/disass" ];
then
  echo "found cache"
  disass_cache_hash=$(<.bttv-cache/disass_hash)
  calc_cache_hash
  echo $disass_cache_hash
  echo $current_hash

  if [ $current_hash = $disass_cache_hash ]; then
    cp -R .bttv-cache/disass disass
    rm -rf .tmp
    echo "used cache"
    exit 0
  else
    echo "cache invalid, removing..."
    rm -rf .bttv-cache/disass_hash .bttv-cache/disass
  fi
fi

#
# Verify integrity
#

# compare with https://twitch.tv/.well-known/assetlinks.json
FMT_TWITCH_SHA="13:38:F9:B0:49:89:3C:C7:0B:78:43:2A:17:75:82:F9:0B:D4:BC:62:96:EA:4E:D3:5B:CC:7D:F5:96:87:AC:53"
TWITCH_SHA=$(echo $FMT_TWITCH_SHA | sed 's/\://g') # remove all ':'

echo "~~~ Print signatures ~~~" &&
$JAVA_PATH -jar $UBER_APK_SIGNER_PATH -y --verifySha256 $TWITCH_SHA -a .tmp/*.apk

# exit if verification failed
[ $? -eq 2 ] &&
echo "ERROR: 
ERROR: One or more apk files where not signed by twitch!
ERROR: This most likely means you have downloaded a potentialy malicious zip archive!
ERROR: " &&
exit 1

#
# disassemble apk files
#

for file in .tmp/*.apk; do
  echo $file
  echo ====
  $JAVA_PATH -Xmx256m -jar $APKTOOL_PATH d $file -o .tmp/disass/${file/.tmp\//} $file
done

# move base
[[ -d ".tmp/disass/tv.twitch.android.app.apk" ]] && echo "found tv.twitch.android.app.apk" && mv .tmp/disass/tv.twitch.android.app.apk .tmp/base
[[ -d ".tmp/disass/base.apk" ]] && echo "found base.apk" && mv .tmp/disass/base.apk .tmp/base 
[[ -d ".tmp/base" ]] || (echo "could not identify base please file an issue!" && exit 1)

if [ $(find .tmp/disass | wc -l) != "1" ]; then
  #
  # copy all files to base (don't overwrite)
  #
  for dir in .tmp/disass/*; do
    cp -r -n $dir/* .tmp/base
  done

  # fix public.xml
  $BUILD_COMPANION fix .tmp/base .tmp/disass/*/res/values/public.xml
  $BUILD_COMPANION yml .tmp/base .tmp/disass/*/apktool.yml
fi

# fix apktool's &ltannotation bug
sed -i 's/&lt;annotation/<annotation/g; s/&lt;\/annotation/<\/annotation/g' .tmp/base/res/values*/plurals.xml

# remove android:isSplitRequired="true"
sed -i 's/android:isSplitRequired="true"//' .tmp/base/AndroidManifest.xml

# remove vending data
sed -i '/android:name="com.android.dynamic.apk.fused.modules"/d' .tmp/base/AndroidManifest.xml
sed -i 's/com.android.vending.derived.apk.id" android:value="."/com.android.vending.derived.apk.id" android:value="1"/' .tmp/base/AndroidManifest.xml
sed -i '/android:name="com.android.vending.splits.required"/d' .tmp/base/AndroidManifest.xml
sed -i '/android:name="com.android.vending.splits"/d' .tmp/base/AndroidManifest.xml
sed -i '/android:name="com.android.vending.derived.apk.id"/d' .tmp/base/AndroidManifest.xml

# remove stamp data
sed -i '/android:name="com.android.stamp.source"/d' .tmp/base/AndroidManifest.xml
sed -i '/android:name="com.android.stamp.type"/d' .tmp/base/AndroidManifest.xml

# rename apk
sed -i "s/apkFileName: tv.twitch.android.app.apk/apkFileName: twitch.apk/" .tmp/base/apktool.yml
sed -i "s/apkFileName: base.apk/apkFileName: twitch.apk/" .tmp/base/apktool.yml

# fix full dex-files
mkdir .tmp/base/smali_classes9
# mv .tmp/base/smali_classes8/androidx .tmp/base/smali_classes9/.

#
# Create reference for diffs
#
cd .tmp/base &&
git init &&
create_gitignore &&
git add . &&
git commit --quiet -m "base" &&
git tag base &&
cd .. &&
cd ..

#
# cache
#
mkdir -p .bttv-cache
calc_cache_hash
echo $current_hash > .bttv-cache/disass_hash
cp -R .tmp/base .bttv-cache/disass


#
# clean up
#
mv .tmp/base disass
rm .tmp -rf