bash_prvm

# -*- mode: shell-script -*-

[[ -n "${debug}" ]] && echo "${BASH_SOURCE}"

#
# File of functions specifically for prvm
#
# prvm is my replacement for rvm.  I found rvm way too heavy and
# invasive.  The directory structure is simple.  I will use
# /usr/local/prvm as the base:
#
# /usr/local/prvm:
#   download-images
#     ruby-1.9.1-p376.tar.gz
#     ruby-1.9.3-p194.tar.gz
#     ... (the original compressed tarballs)
#   ruby-1.9.1-p376
#     bin
#     include
#     lib
#     share
#     src
#       This is your build directory and make
#         --prefix=/usr/local/prvm/ruby-1.9.1-p376
#   ruby-1.9.3-p194
#     bin
#     include
#     lib
#     share
#     src
#       This is your build directory and make
#         --prefix=/usr/local/prvm/ruby-1.9.3-p194
#   ...
#
# The scheme revolves around bundler and putting the gems for a
# particular project into .bundle/gems and their associated executable
# into .bundle/bin.  This idea comes from:
# http://tomafro.net/2012/06/tip-bundler-with-binstubs
#
# GEM_HOME would thus be .bundle/gems/ruby/1.9.1 (except made into an
# absolute path)
# 
# There will be a path for the base of the prvm versions of ruby --
# typically set to /usr/local/prvm.
#
# Thus a single line such as:
#
# prvm_use ruby-1.9.3-p194
#
# would set PATH to start with the absolute path to the project with
# .bundle/bin appeneded followed by
# /usr/local/prvm/ruby-1.9.3-p194/bin
#
# GEM_HOME would be set as mentioned above with GEM_PATH set to
# /usr/local/prvm/ruby-1.9.3-p194/lib/ruby/gems/1.9.1
#
# Some type of options are probably needed to add or alter to these
# defaults but until I need them, I won't define them.

PRVM_BASE=/usr/local/prvm

# $1 is a regular expression of the elements of PATH to delete
function delete-path-elements
{
    typeset OIFS=$IFS
    typeset path
    typeset NPATH
    IFS=:
    for path in $PATH ; do
	if [[ "$path" =~ $1 ]] ; then
	    true
	elif [[ -z "$NPATH" ]] ; then
	    NPATH="$path"
	else
	    NPATH="$NPATH:$path"
	fi
    done
    PATH="$NPATH"
    IFS=$OIFS
}

# $1 is an absolute path to prepend to PATH keeping '.' as the first
# element if it started out that way
function prepend-path
{
    local flag
    if [[ "${PATH%%:*}" == "." ]] ; then
	flag=t
	PATH="${PATH#*:}"
    fi
    delete-path-elements "^${1%/}$"
    PATH="${1%/}:${PATH}"
    if [[ "$flag" ]] ; then
	PATH=".:$PATH"
    fi
}

# $1 specifies which ruby to use and $2 specifies the directory
function prvm_setup
{
    typeset ruby="$1"
    typeset prvmrc_path="$2"
    typeset cwd="${PWD}"
    typeset prvmrc_dir
    typeset temp

    if [[ "$prvmrc_path" =~ ^/.* ]] ; then
	true
    else
	prvmrc_path="${PWD}/${prvmrc_path}"
    fi

    # This is silly but I can't resist...
    # strip out /./ in path.
    prvmrc_path="$( echo "$prvmrc_path" | sed -e 's%/\./%/%g' )"
    # strip out /foo/../ in path
    while : ; do
	typeset temp="$( echo "$prvmrc_path" | sed -e 's%/[^/]*/\.\./%/%' )"
	if [[ "$temp" == "$prvmrc_path" ]] ; then
	    break
	fi
	prvmrc_path="$temp"
    done
    prvmrc_dir=${prvmrc_path%/.*}

    # We want to delete what a previous prvm_use added.  This would be
    # some path to /**/.bundle/bin as well as /usr/local/prvm/**
    delete-path-elements '.*/\.bundle/bin$'
    delete-path-elements "${PRVM_BASE}/.*"

    cd "${prvmrc_dir}"

    # Now add in the new path pieces
    prepend-path "${PRVM_BASE}/${ruby}/bin"

    if type -t bundle > /dev/null && bundle exec true > /dev/null 2>&1 ; then
	temp=$( bundle exec env |
		egrep 'GEM_HOME' |
		sed -e 's%^%export %' -e "s%=%='%" -e "s%$%';%" )
	eval $temp
    fi

    prepend-path "${GEM_HOME}/bin"
    prepend-path "${prvmrc_dir}/.bundle/bin"
    if [[ -d "${prvmrc_dir}/bin" ]] ; then
	prepend-path "${prvmrc_dir}/bin"
    fi
}

# $1 specifies which ruby to use.  e.g. prvm_use ruby-1.9.3-p194
function prvm_use
{
    prvm_setup "$1" "${BASH_SOURCE[1]}"
}

function bundle_install
{
    bundle install --path .bundle/gems --binstubs .bundle/bin
}