hg-fast-export 20120921-1 / usr / bin / git-hg

#!/usr/bin/env bash

if which python2 >&/dev/null; then
    PYTHON=python2
    export PYTHON
fi

set -e

# Try to use GNU Coreutils readlink --canonicalize if available,
# falling back to less robust shell script only if not found.
if which greadlink >&/dev/null; then
    canon="greadlink --canonicalize"
elif readlink --canonicalize / >&/dev/null; then
    canon="readlink --canonicalize"
else
    canon=canonicalize
fi

function canonicalize {
    path="$1"
    
    while [[ -L "$path" ]]; do
	dir=$(dirname "$path")
	path=$(ls -l "$path" | sed -e 's/.* -> //')
	cd "$dir"
    done
    
    dir=$(dirname "$path")
    file=$(basename "$path")
    if [[ ! -d "$dir" ]]; then
	echo "canonize: $dir: No such directory" >&2
	exit 1
    fi
    cdir=$(cd "$dir" && pwd -P)
    printf "%s/%s\n" "$cdir" "$file"
}

function get-gitdir {
    if [ -n "${GIT_DIR}" ]; then
	echo "error: environment variable GIT_DIR must not be set"
	exit 1
    fi
    GITDIR="$(git rev-parse --git-dir)"
}

function git-current-branch {
    local ref
    ref=$(git symbolic-ref -q HEAD) && echo "${ref#refs/heads/}"
}

function check-hg-fast-export {
    # Search for hg-fast-export $PATH, use if available, if not fall back
    # to looking around for it in sibling directory of bin directory of
    # the current exeuctable, possibly tracing back along symbolic link.
    if type hg-fast-export > /dev/null 2>&1 ; then
	HG_FAST_EXPORT=hg-fast-export
    else
	GITHG_HOME=$($canon "$(dirname "$($canon "$0")")/..")
	HG_FAST_EXPORT=$GITHG_HOME/fast-export/hg-fast-export.sh
	if ! type "$HG_FAST_EXPORT" > /dev/null 2>&1 ; then
	    echo "error: executable not found, $HG_FAST_EXPORT"
	    echo 'Possible fixes: run "git submodule update --init" in git-hg repo, or'
	    echo 'install hg-fast-export executable in directory on $PATH.'
	    exit 1
	fi
    fi
}

function git-hg-clone {
    check-hg-fast-export
    
    if [[ $1 == "--force" ]]; then
        FORCE="--force"
        shift
    fi
    HG_REMOTE=$1
    
    if [[ $# -lt 2 ]]; then
        CHECKOUT=$(basename "${1%#*}")
    else
        CHECKOUT=$2
    fi
    if [[ -a $CHECKOUT ]]; then
	echo "error: $CHECKOUT exists"
	exit 1
    fi
    git init "$CHECKOUT"
    (
	cd "$CHECKOUT"
	get-gitdir
	hg clone -U "$HG_REMOTE" "${GITDIR}/hgcheckout"
	git init --bare ${GITDIR}/hgremote
	(
	    cd ${GITDIR}/hgremote
	    "$HG_FAST_EXPORT" -r ../hgcheckout $FORCE
	)
	git remote add hg ${GITDIR}/hgremote
	git fetch hg
        if git rev-parse --verify -q remotes/hg/master > /dev/null; then
	    local branch="master"
        else
            local branch=$(cd ${GITDIR}/hgcheckout/ && hg tip | grep branch | awk '{print $2}')
        fi
        git config hg.tracking.master "$branch"
        git pull hg "$branch"
    )
}

function git-hg-fetch {
    check-hg-fast-export
    if [[ $1 == "--force" ]]; then
        FORCE="--force"
        shift
    fi
    get-gitdir
    hg -R ${GITDIR}/hgcheckout pull
    (
	cd ${GITDIR}/hgremote
	"$HG_FAST_EXPORT" $FORCE
    )
    git fetch hg
}

function git-hg-pull {
    while [[ $# -gt 0 ]]; do
        case "$1" in
        --rebase)
            REBASE="--rebase"
            ;;
        --force)
            FORCE="--force"
            ;;
        esac
	shift
    done

    git-hg-fetch $FORCE

    local current_branch remote_branch

    if ! current_branch=$(git-current-branch); then
	    echo "ERROR: You are not currently on a branch."
	    exit 1
    fi

    if [[ $current_branch == "master" ]]; then
        remote_branch=$(git config hg.tracking.master || true)
        
        if [[ -z $remote_branch ]]; then
            if git rev-parse --verify -q remotes/hg/master > /dev/null; then
                remote_branch="master"
                git config hg.tracking.master master
            else
                echo "ERROR: Cannot determine remote branch. There is no remote branch called master, and hg.tracking.master not set. Merge the desired branch manually."
                exit 1
            fi
        fi
    else
        remote_branch=$(git config "hg.tracking.$current_branch" || true)
        if [[ -z $remote_branch ]]; then
             echo "ERROR: Cannot determine the remote branch to pull from. Run git merge manually against the desired remote branch."
             echo "Alternatively, set hg.tracking.$current_branch to the name of the branch in hg the current branch should track"
             exit 1
        fi
    fi

    if [[ "$REBASE" == "--rebase" ]]; then
        git rebase "hg/$remote_branch"
    else
        git merge "hg/$remote_branch"
    fi
}

function git-hg-checkout {
    if [[ $1 == "--force" ]]; then
        FORCE="--force"
        shift
    fi
    git-hg-fetch $FORCE
    git checkout "hg/$1" -b "$1"
}

function git-hg-push {
    HG_REPO=$1
    get-gitdir
    hg --config extensions.convert= convert . ${GITDIR}/hgcheckout
    hg -R ${GITDIR}/hgcheckout push "$HG_REPO"
}

function usage {
    echo "To clone a mercurial repo run:"
    echo "  clone <path/to/mercurial/repo> [local_checkout_path]"
    echo ""
    echo " if that fails (due to unnamed heads) try:"
    echo "  git-hg clone --force <path/to/mercurial/repo> [local_checkout_path]"
    echo ""
    echo "To work with a cloned mercurial repo use: "
    echo "  fetch [ --force ]                   fetch latest branches from mercurial"
    echo "  pull [ --force ] [ --rebase ]       fetch and merge (or rebase) into the"
    echo "                                      current branch"
    echo "  push [destination]                  push latest changes to mercurial"
    echo "  checkout [ --force ] branch_name    checkout a mercurial branch"
}

FORCE=
REBASE=
CMD=$1
shift
case "$CMD" in
    clone|fetch|pull|checkout|push)
	git-hg-$CMD "$@"
	;;
    *)
	usage
	exit 1
	;;
esac