#!/bin/bash

# Bring in the variables from SOLUTION file, supporting
# nested substitution
. SOLUTION
. MANIFEST

VARS=($(sed -nE "s,(^[^#][^=]*).*$,\1,pg" SOLUTION))
VARS+=($(sed -nE "s,(^[^#][^=]*).*$,\1,pg" MANIFEST))
for var in ${VARS[@]}; do
  export ${var}
done

[[ -d "templates/${OS_DISTRO}" ]] || {
  echo "Unrecognized OS_DISTRO: '${OS_DISTRO}'"
  exit -1
}


if [[ -e "Dockerfile.solution.${OS_DISTRO}-${OS_RELEASE}" ]]; then
  SOLUTION_SUFFIX=".${OS_DISTRO}-${OS_RELEASE}"
elif [[ -e "Dockerfile.solution.${OS_DISTRO}" ]]; then
  SOLUTION_SUFFIX=".${OS_DISTRO}"
else
  SOLUTION_SUFFIX=""
fi

[[ "${SOLUTION_SUFFIX}" == "" ]] && {
  cat << EOF

The following Dockerfile.solutions were checked, but do not exist:

* Dockerfile.solution.${OS_DISTRO}
* Dockerfile.solution.${OS_DISTRO}-${OS_RELEASE}

Using 'Dockerfile.solution' as default.

EOF
}

export DOCKERFILE="Dockerfile${SOLUTION_SUFFIX}"
export SOLUTION="Dockerfile.solution${SOLUTION_SUFFIX}"
VARS+=("DOCKERFILE")
VARS+=("SOLUTION")

cat << EOF
Using:

  ${SOLUTION}

To generate:

  ${DOCKERFILE}
EOF

# Build a SHELL-FORMAT value to pass to envsubst.
# Only those variables matched in SHELL-FORMAT will
# be escaped by envsubst.
ENV=''
for var in ${VARS[@]}; do
  ENV=${ENV}'$'${var}
done

# Remove the Dockerfile if it exists; should check
# if it is clean first, and abort if not.
#
[ -e ${DOCKERFILE} ] && rm ${DOCKERFILE}

cat << EOM > ${DOCKERFILE}
#
# DO NOT EDIT THIS DOCKERFILE
#
# This file is auto-generated via scripts/build-dockerfile
# by using environment substitution while concatenating the
# contents of templates/*, and then adding the contents
# of ${SOLUTION}
#
# Most solution specific changes should be isolated in
# ${SOLUTION}. After making changes, you can then re-run
# scripts/build-dockerfile
#
EOM



SNIPPETS=()

# Create a list of all the templates for this distro
for snippet in templates/${OS_DISTRO}/??-*.in; do
  SNIPPETS+=($snippet)
done

# Add in the list of templates from the release sub-directory
# removing from the base distro if a name conflict
[[ -d templates/${OS_DISTRO}/${OS_RELEASE} ]] && {
  for snippet in templates/${OS_DISTRO}/${OS_RELEASE}/??-*.in; do
    SNIPPETS=(${SNIPPETS[@]%%*$(basename ${snippet})})
    SNIPPETS+=($snippet)
  done
}

# Sort the entries by the filename by rewriting
# the entries as FILENAME DIRNAME
# Then read the sorted information back out and
# re-create the filepath, storing the results in
# the TEMPLATES array
TEMPLATES=($(for snippet in ${SNIPPETS[@]}; do
  echo $(basename $snippet) $(dirname $snippet)
done | sort | while read base dir; do
  echo ${dir}/${base}
done))

for snippet in ${TEMPLATES[@]}; do
  cat << EOM >> ${DOCKERFILE}

#
# Template from ${snippet}
#
EOM
  envsubst ${ENV} < $snippet >> ${DOCKERFILE}
done

cat << EOM >> ${DOCKERFILE}

#
# Solution begins here (from ${SOLUTION})
#
EOM

envsubst ${ENV} < ${SOLUTION} >> ${DOCKERFILE}

cat << EOM >> ${DOCKERFILE}

#
# Standard ending begins here (from templates/ending.in)
#
EOM

envsubst ${ENV} < templates/ending.in >> ${DOCKERFILE}

cat << EOM

${DOCKERFILE} has been updated.

To build the image, you can run:

  OS_DISTRO=${OS_DISTRO} OS_RELEASE=${OS_RELEASE} scripts/build-image.sh

EOM