#! /usr/bin/env bash

# Upgrade remote packages in a bdep-managed build2 toolchain build (default
# configurations), essentially as if by executing:
#
# bdep sync -fur && b
#
# In each project of the toolchain.
#
# Note that we can't just do that because as soon as we drop some dependency
# package, the tools (b, bpkg, etc) become non-runnable (missing shared
# libraries, etc). The script expects the current build of the toolchain
# to be runnable.
#
# This script only upgrades the default configurations (including -libs, if
# present). To upgrade the rest you can use the normal way, for example:
#
# bdep sync -Fur @<cfg>|-a
#
# If the -c option is specified, the configuration is upgraded and configured
# but only the build system is updated. This can be done at a later stage by
# running the build system in the configuration directory:
#
# BDEP_SYNC=0 b builds/gcc7/
#
owd="$(pwd)"
trap "{ cd '$owd'; exit 1; }" ERR
set -o errtrace # Trap in functions.

function info () { echo "$*" 1>&2; }
function error () { info "$*"; exit 1; }

# Run a command with tracing (similar to set -x).
#
# Note that this function will execute a command with arguments that contain
# spaces but it will not print them as quoted (and neither does set -x).
#
function run ()
{
  echo "+ $@" 1>&2
  "$@"
}

function run_no_sync ()
{
  echo "+ BDEP_SYNC=0 $@" 1>&2
  BDEP_SYNC=0 "$@"
}

# Make sure the build2 tools are runnable.
#
b    --version >/dev/null
bpkg --version >/dev/null
bdep --version >/dev/null

configure_only=

while [ $# -gt 0 ]; do
  case $1 in
    -c)
      configure_only=--configure-only
      shift
      ;;
    *)
      error "unexpected $1"
      ;;
  esac
done

# Get the configuration directories.
#
tcfg="$(b info: build2/  | sed -n -re 's/^out_root: (.+)$/\1/p')"
lcfg="$(b info: libbutl/ | sed -n -re 's/^out_root: (.+)$/\1/p')"

if [ -z "$tcfg" -o -z "$lcfg" ]; then
  error "unable to determine build configuration directories"
fi

tcfg="$(dirname "$tcfg")"
lcfg="$(dirname "$lcfg")"

if [ "$tcfg" = "$lcfg" ]; then
  lcfg=
fi

# The plan is as follows:
#
# 0. First, make backup copies of configurations. If something goes wrong,
#    it's likely the tools will be left in a non-runnable state.
#
# 1. Next, setup the environment (PATH, LD_LIBRARY_PATH) so that we use the
#    toolchain from the backup copy. Then upgrade the configurations using
#    that.

# Step 0.
#
if test -e "$tcfg.bak"; then
  error "$tcfg.bak already exist"
fi

if [ -n "$lcfg" ]; then
  if test -e "$lcfg.bak"; then
    error "$lcfg.bak already exist"
  fi
fi

run cp -rp "$tcfg" "$tcfg.bak"

if [ -n "$lcfg" ]; then
  run cp -rp "$lcfg" "$lcfg.bak"
fi

# Step 1.
#
# The main problem with running the toolchain from the backup location is the
# rpaths embedded into the executables. We can make sure the libraries are
# found in the backup location with LD_LIBRARY_PATH (or equivalent). But for
# good measure let's also remove all the libraries from the original location
# to make they don't interfere.
#
if [[ "$OSTYPE" == "darwin"* ]]; then
  so=dylib
else
  so=so
fi

libs=()
for f in $(find "$tcfg" -name "*.$so" -a '(' -type f -o -type l ')'); do
  libs+=("$f")
done

run rm -rf "${libs[@]}"

declare -A lib_dirs
for f in $(find "$tcfg.bak" -name "*.$so" -a '(' -type f -o -type l ')'); do
  lib_dirs["$(dirname "$f")"]=
done

# Note that the order should not matter.
#
ldpath=
for d in "${!lib_dirs[@]}"; do
  ldpath="$d:$ldpath"
done

if [[ "$OSTYPE" == "darwin"* ]]; then
  oldpath="$DYLD_LIBRARY_PATH"
  run export DYLD_LIBRARY_PATH="$ldpath$DYLD_LIBRARY_PATH"
else
  oldpath="$LD_LIBRARY_PATH"
  run export LD_LIBRARY_PATH="$ldpath$LD_LIBRARY_PATH"
fi
opath="$PATH"
run export PATH="$tcfg.bak/build2/build2:$tcfg.bak/bpkg/bpkg:$tcfg.bak/bdep/bdep:$PATH"

# Make sure the backup toolchain is runnable.
#
run which b bpkg bdep
run b --version >/dev/null
run bpkg --version >/dev/null
run bdep --version >/dev/null

# Upgrade.
#
run bpkg fetch -d "$tcfg"
run_no_sync bpkg build -d "$tcfg" --keep-out -ur $configure_only

# In configure-only we update the build system manually.
#
if [ -n "$configure_only" ]; then
  run_no_sync b build2/
fi

if [ -n "$lcfg" ]; then
  run bpkg fetch -d "$lcfg"
  run_no_sync bpkg build -d "$lcfg" --keep-out -ur $configure_only
fi

# Restore the original environment.
#
if [[ "$OSTYPE" == "darwin"* ]]; then
  run export DYLD_LIBRARY_PATH="$oldpath"
else
  run export LD_LIBRARY_PATH="$oldpath"
fi
run export PATH="$opath"

run b --version >/dev/null

if [ -z "$configure_only" ]; then
  run bpkg --version >/dev/null
  run bdep --version >/dev/null
  run b build2/ bpkg/ bdep/ # Should be a noop.
fi

run rm -rf "$tcfg.bak"

if [ -n "$lcfg" ]; then
  run rm -rf "$lcfg.bak"
fi