git-subtree-merge-with-branches.sh

#!/bin/bash

# git subtree merge one repo into another, copying all branches in the source
# repo to the destination repo, with the source repo's name added as a prefix
# to the branch name in the destination repo

# with handling of weird edge cases in subtree merge

# See http://git-scm.com/book/ch6-7.html for an overview of git subtree merge

PARENT_NAME=commcare-hq
CHILD_NAME=core-hq
PARENT_REPO=git@github.com:dimagi/commcare-hq.git
CHILD_REPO=git@github.com:dimagi/core-hq.git

SUBMODULE_DIR=submodules
SUBMODULE=core-hq-src
CHILD_PATH=$SUBMODULE_DIR/$SUBMODULE

PARENT_TARGET_REPO=git@github.com:mwhite/commcare-hq-merge-testing.git
CHILD_TEMP_REPO=git@github.com:mwhite/core-hq-merge-testing.git

ALREADY_FILTERED=true

if [[ ! $CHILD_TEMP_REPO ]]; then
    exit 1
fi

# see http://stackoverflow.com/a/4042965/373514
if [[ $ALREADY_FILTERED != 'true' ]]; then
    rm -rf $CHILD_NAME
    git clone $CHILD_REPO $CHILD_NAME
    cd $CHILD_NAME
    git fetch

    # make sure we do it to all the branches
    child_branches=$(git branch -r | grep -v -e "\->" -e "master" | grep origin | cut -d/ -f 2)
    for branch in $child_branches; do
        git checkout -b $branch origin/$branch
    done

    git filter-branch --tree-filter "
    mkdir -p $CHILD_PATH
    git ls-tree --name-only \$GIT_COMMIT | xargs -I files mv files $CHILD_PATH" -- --all
    git remote rm origin
    git remote add origin $CHILD_TEMP_REPO
    git push -f --all --dry-run
    cd ..
fi

cd $CHILD_NAME
child_branches=$(git branch -r --no-merged | grep -v "\->" | grep origin | cut -d/ -f 2)
cd ..


rm -rf $PARENT_NAME
git clone $PARENT_REPO $PARENT_NAME
cd $PARENT_NAME

parent_branches=$(git branch -r --no-merged | grep -v "\->" | grep origin | cut -d/ -f 2)
for branch in $parent_branches; do
    git checkout -b $branch origin/$branch
done

git remote add -f $CHILD_NAME $CHILD_TEMP_REPO

for branch in $child_branches; do
    git checkout -b $CHILD_NAME-$branch HEAD

    # See http://stackoverflow.com/a/11400433/373514
    git config -f .gitmodules --remove-section submodule.$CHILD_PATH
    git config -f .git/config --remove-section submodule.$CHILD_PATH
    git rm --cached -r $CHILD_PATH
    git add .gitmodules
    git commit -m "remove $CHILD_NAME submodule in preparation for subtree merge"
    rm -rf $CHILD_PATH
    rm -rf .git/modules/$CHILD_PATH
    
    # See http://stackoverflow.com/a/6442034/373514
    git read-tree -m --aggressive -u $CHILD_NAME/$branch
    #git mv TEMP/$SUBMODULE_DIR/$SUBMODULE $SUBMODULE_DIR/
    git commit -m "subtree merge $branch from $CHILD_NAME into $CHILD_PATH (branch $CHILD_NAME-$branch)"

done

git remote rm $CHILD_NAME

# merge core-hq-master into master, leave the rest alone
git checkout master
git merge core-hq-master

if [[ $PARENT_TARGET_REPO ]]; then
    git remote rm origin
    git remote add origin $PARENT_TARGET_REPO
    git push --dry-run -f --all
fi