#!/bin/bash
set -o errexit

# for use with git-remote-hg:
#   http://felipec.wordpress.com/2012/11/13/git-remote-hg-bzr-2/

# Uncomment to have verbose debug output
debug=1

print_usage()
{
    echo "$(basename $0) -- HG subrepository importer for git-remote-hg"
    echo "Usage: $(basename $0) [OPTIONS...]"
}

# git-remote-hg doesn't work with Mercurial subpaths extension,
# so use it manually
hg_subpaths_config() {
    subpaths=$(hg showconfig | grep "subpaths" | grep "HG_REPO")

    echo "subpaths = ${subpaths}"

    if [ -n ${subpaths} ]; then
        sp_src=${subpaths//subpaths./}
        sp_src=${sp_src//=*/}
        sp_src=${sp_src//\\/} # Remove windows separator (LSI)
        sp_dst=${subpaths//*=/}

        if [ -n "${debug}" ]; then
            echo "sp_src = $sp_src"
            echo "sp_dst = $sp_dst"
        fi
    fi
}

# git-remote-hg doesn't work with Mercurial projrc extension,
# so use it manually.
# We parse the projrc file in the assembly (on the server), to check
# for any projrc substitutions.
#
# Arg 1: subproject (path and name)
#
# Return the new substitution name if found, and original subrepo name if not
# (with the path stripped)
hg_check_projrc_config() {
    if [ ${#} -lt 1 ]; then
        echo "Missing subrepos name"
    fi

    # Repo name can have spaces in it, hence the use of ${*}
    local subrepo_orig="${*}"
    local subrepo="${*}"

    # Quote spaces
    subrepo=${subrepo// /\\\\ }

    asm=$(cat .git/config | grep "hg::" | sed "s/.*url = hg::\(.*\)/\1/")

    local baserepo=$(basename "${subrepo}")

    if cat "${asm}/.hg/projrc" | grep -q "${baserepo}" ; then
        projrc=$(cat "${asm}/.hg/projrc" | grep "${baserepo}" | sed "s/.*= \(.*\)/\1/")
    else
        # No substitution, return same name as original
        projrc=$(basename "${subrepo_orig}")
    fi

    echo "${projrc}"
}

# Map a revision to a branch name in HG subrepository
# Use hg log (in original repo) to get branch name corresponding to that
# revision.
#
# Arg 1: subrepository URL
# Arg 2: id
# Arg 3: revision
subrepo_find_branch() {
    local src="${1}"
    local id="${2}"
    local rev="${3}"

    pushd "${src}" 1> /dev/null

    branch=$(hg log -r ${rev} | grep "branch:" | sed "s/branch:\ *//")

    if [ -z "${branch}" ]; then
        # If "branch:" is null, this indicate we are on the default branch
        branch=default
    fi

    num=$(hg log --branch "${branch}" --template '{node}\n' | \
        grep -n ${rev} | awk -F ':' '{print $1}')

    if [ -n "${debug}" ]; then
        echo "  branch: ${branch}"
        echo "  num:    ${num}"
    fi

    popd 1> /dev/null
}

if [ "x${1}" = "x--help" ]; then
    print_usage
    exit 1
fi

if [ ! -f .hgsub ]; then
    echo "No Mercurial subrepositories found"
    exit 1
fi

if [ ! -f .gitignore ]; then
    # We do not want to track .gitignore itself
    echo ".gitignore" > .gitignore
fi

hg_subpaths_config

# Read lines from .hgsub
while read sub; do
    # Remove CR (DOS)
    sub="${sub//$'\r'/}"

    if [ "${sub}" != "" ]; then
        # Get subrepository URL
        src="${sub//*= /}"

        # Replace using subpaths extension content
        src=${src/${sp_src}/${sp_dst}}

        # Get subrepository local alias or label
        dest="${sub// =*}"

        # Get project ID (example: S0289)
        id=$(echo ${sub} | sed "s/.*\(S[0-9][0-9][0-9][0-9]\).*/\1/")

        # Get revision of subrepository (remove CR from .hgsubstate)
        rev=$(cat .hgsubstate | tr -d '\r' | grep "${id}" | sed "s/ .*//")

        # Original name
        repo=$(basename "${src}")
        srcpath=$(dirname "${src}")

        projrc_sub=$(hg_check_projrc_config "${src}")
        src="${srcpath}/${projrc_sub}"

        if [ -n "${debug}" ]; then
            echo "repo: ${repo}"
            echo "  path:   ${srcpath}"
            echo "  id:     ${id}"
            echo "  src:    ${projrc_sub}"
            echo "  dest:   ${dest}"
            echo "  rev:    ${rev}"
        fi

        if [ ! -d "${dest}" ]; then
            subrepo_find_branch "${src}" ${id} ${rev}

            # git-remote-hg seems to replace
            #   "BRANCH - NAME"
            # with
            #   "BRANCH___-___NAME"
            branch="${branch// /___}"

            if [ -n "${debug}" ]; then
                echo "branch: ${branch}"
            fi

            git clone "hg::${src}" "${dest}"

            cd "${dest}"

            if [ -x ${HOME}/scripts/git-set-local-author.sh ]; then
                # Make sure commits have correct author for LSI
                ${HOME}/scripts/git-set-local-author.sh
            fi

            if [ "x${branch}" != "xdefault" ]; then
                # Make tracking branch
                git checkout -f "branches/${branch}"

                # Adjusting git tree to specific commit specified in
                # .hgsubstate:
                # The SHA from hg and git are not the same, therefore, we must
                # find the commit sequence in hg and map this
                # to a hash in git using the ${num} variable:
                git_rev=$(git log --oneline | sed -n "${num}p" | awk '{print $1}')
                git reset --hard ${git_rev}
            fi

            cd ..

            if ! grep -q "${dest}" .gitignore ; then
                # Ignore subrepo in top-level git repository
                echo "${dest}" >> .gitignore
            fi
        fi
    fi
done < .hgsub