#!/usr/bin/env bash

# file      : load/load-with-metadata.in
# license   : MIT; see accompanying LICENSE file

# The wrapper around brep-load, which pulls the package metadata from a git
# repository and runs brep-load, passing the metadata directory to it.
#
# Specifically, pull a pre-cloned (read-only) git repository with the contents
# of an archive-based bpkg repository. Run brep-load with the `--metadata
# <dir>/owners` option, the --metadata-changed option, if the current snapshot
# of the repository has not yet been processed by brep-load, and forward any
# further arguments to brep-load.
#
# --timeout <seconds>
#
#   Git operation timeout. Specifically, the operation will be aborted if
#   there is no network activity for the specified time. Default is 60
#   seconds. Note that currently the git timeout is only supported for the
#   http(s) transport.
#
# --brep-load <path>
#
#   The brep-load program to be used. This should be the path to the brep-load
#   executable.
#
# Note also that this script maintains the <dir>.load file which contains the
# last successfully processed commit.
#
usage="usage: $0 [<options>] <dir> [<brep-load-args>]"

owd="$(pwd)"
trap "{ cd '$owd'; exit 1; }" ERR
set -o errtrace   # Trap in functions and subshells.
set -o pipefail   # Fail if any pipeline command fails.
shopt -s lastpipe # Execute last pipeline command in the current shell.
shopt -s nullglob # Expand no-match globs to nothing rather than themselves.

@import bpkg-util/utility@ # check_git_connectivity()

# The script's own options.
#
timeout=60
brep_load=

while [[ "$#" -gt 0 ]]; do
  case "$1" in
    --timeout)
      shift
      timeout="$1"
      shift || true
      ;;
    --brep-load)
      shift
      brep_load="$1"
      shift || true
      ;;
    *)
      break
      ;;
  esac
done

# The repository directory.
#
repo_dir="${1%/}"

# Validate options and arguments.
#
if [[ -z "$repo_dir" ]]; then
  error "$usage"
fi

if [[ ! -d "$repo_dir" ]]; then
  error "'$repo_dir' does not exist or is not a directory"
fi

shift # repo_dir

# If brep-load path is not specified, then use the brep-load program from the
# script directory, if present. Otherwise, use the 'brep-load' path.
#
if [[ -z "$brep_load" ]]; then
  brep_load="$(dirname "$(realpath "${BASH_SOURCE[0]}")")/brep-load"

  if [[ ! -x "$brep_load" ]]; then
    brep_load=brep-load
  fi
fi

# Make sure the commit file is present.
#
load_commit="$repo_dir.load"
touch "$load_commit"

# Pull the repository shallowly.
#
if ! remote_url="$(git -C "$repo_dir" config --get remote.origin.url)"; then
  error "'$repo_dir' is not a git repository"
fi

# Save the repository name and branch of where the current commit has been
# fetched from, separated by space. For example 'origin master'.
#
# Note that if the commit belongs to multiple repositories/branches, then we
# extract the first their pair from the git-log output.
#
refs=$(git -C "$repo_dir" log -1 --format=%D)
repo_branch="$(sed -n -E 's%^[^/]+ ([^/ ]+)/([^/ ,]+).*$%\1 \2%p' <<<"$refs")"

if [[ -z "$repo_branch" ]]; then
  error "unable to extract repository and branch from '$refs'"
fi

# Git doesn't support the connection timeout option. The options we use are
# just an approximation of the former, that, in particular, don't cover the
# connection establishing. To work around this problem, before running a git
# command that assumes the remote repository communication we manually check
# connectivity with the remote repository.
#
check_git_connectivity "$remote_url" "$timeout"

# Fail if no network activity happens during the time specified.
#
# Note: keep $repo_branch expansion unquoted.
#
git -c http.lowSpeedLimit=1 -c "http.lowSpeedTime=$timeout" \
  -C "$repo_dir" fetch -q --depth=1 $repo_branch

git -C "$repo_dir" reset -q --hard FETCH_HEAD

# Match the HEAD commit id to the one stored in the file. If it matches, then
# nothing changed in the repository since it has been processed by brep-load
# last time and we should not pass the --metadata-changed option to brep-load.
#
commit="$(git -C "$repo_dir" rev-parse HEAD)"
pc="$(cat "$load_commit")"

loader_options=(--metadata "$repo_dir/owners")

if [[ "$commit" != "$pc" ]]; then
  loader_options+=(--metadata-changed)
fi

"$brep_load" "${loader_options[@]}" "$@"

echo "$commit" >"$load_commit"