#!/bin/bash

#

# produces two repositories with different common and missing subsets

#

#   $ discovery-helper.sh REPO NBHEADS DEPT

#

# The Goal is to produce two repositories with some common part and some

# exclusive part on each side. Provide a source repository REPO, it will

# produce two repositories REPO-left and REPO-right.

#

# Each repository will be missing some revisions exclusive to NBHEADS of the

# repo topological heads. These heads and revisions exclusive to them (up to

# DEPTH depth) are stripped.

#

# The "left" repository will use the NBHEADS first heads (sorted by

# description). The "right" use the last NBHEADS one.

#

# To find out how many topological heads a repo has, use:

#

#   $ hg heads -t -T '{rev}\n' | wc -l

#

# Example:

#

#  The `pypy-2018-09-01` repository has 192 heads. To produce two repositories

#  with 92 common heads and ~50 exclusive heads on each side.

#

#    $ ./discovery-helper.sh pypy-2018-08-01 50 10

set -euo pipefail

if [ $# -lt 3 ]; then

     echo "usage: `basename $0` REPO NBHEADS DEPTH"

     exit 64

fi

repo="$1"

shift

nbheads="$1"

shift

depth="$1"

shift

leftrepo="${repo}-left"

rightrepo="${repo}-right"

left="first(sort(heads(all()), 'desc'), $nbheads)"

right="last(sort(heads(all()), 'desc'), $nbheads)"

leftsubset="ancestors($left, $depth) and only($left, heads(all() - $left))"

rightsubset="ancestors($right, $depth) and only($right, heads(all() - $right))"

echo '### building left repository:' $left-repo

echo '# cloning'

hg clone --noupdate "${repo}" "${leftrepo}"

echo '# stripping' '"'${leftsubset}'"'

hg -R "${leftrepo}" --config extensions.strip= strip --rev "$leftsubset" --no-backup

echo '### building right repository:' $right-repo

echo '# cloning'

hg clone --noupdate "${repo}" "${rightrepo}"

echo '# stripping:' '"'${rightsubset}'"'

hg -R "${rightrepo}" --config extensions.strip= strip --rev "$rightsubset" --no-backup