#!/usr/bin/env bash

### TODO: ensure files deleted in the maintainer repository are
### also deleted in the students repository

### WARN: this script will not work unless the remote name is `origin` (default).

### WARN: this script expects you to connect to github via ssh.
### ensure you registered your public key.

# constant definitions

# WARN: make sure you understand the implications before
# you change the value (or name) of a constant!

required_tools=(
    "cat"
    "dirname"
    "find"
    "git"
    "grep"
    "pandoc"
    "realpath"
    "sed"
    "tar"
    "tput"
)
common_dir="../common"
laboratory_dir="./laboratories"
student_repo_name="student-repository"
student_repo_url="git@github.zhaw.ch:CT/ct1-students.git"
code_start="STUDENTS: To be programmed"
code_end="END: To be programmed"
make_start="solution[s]*=start"
make_end="solution[s]*=end"
md_solution_start="solution[s]*=start"
md_solution_end="solution[s]*=end"
md_student_start="student[s]*=start"
md_student_end="student[s]*=end"
keili_dir_name="keil"
archive_name="release.tar"
exclude_file_name=".release-ignore"

# sanity checks for variables
if [[ "${laboratory_dir}" =~ ".." ]]; then
    echo "'laboratory_dir' has to be a child directory of the one containing this script"
fi
if [[ "." != "$(dirname "${student_repo_name}")" ]]; then
    echo "'student_repo_name' may not contain directories!"
    exit 0
fi
if [[ "." != "$(dirname "${keili_dir_name}")" ]]; then
    echo "'keili_dir_name' may not contain directories!"
    exit 0
fi
if [[ "." != "$(dirname "${exclude_file_name}")" ]]; then
    echo "'exclude_file_name' may not contain directories!"
    exit 0
fi

# helper function declarations

## print highlighted text
##
## used the same as `echo`
function print_highlighted {
    if ! $(which tput &>/dev/null) || [[ -z "$(tput smso)" ]]; then
        echo "$*"
        return 0
    fi

    tput smso
    echo "$*"
    tput sgr0
}

## print yellow text
##
## used the same as `echo`
function print_warning {
    if ! $(which tput &>/dev/null); then
        echo "$*"
        return 0
    fi

    tput setaf 3
    echo "$*"
    tput sgr0
}

## print red text
##
## used the same as `echo`
function print_error {
    if ! $(which tput &>/dev/null); then
        echo "$*"
        return 0
    fi

    tput setaf 1
    echo "$*"
    tput sgr0
}

# main logic

# ensure the required tools are available
unset error_message
for tool in "${required_tools}"; do
    if ! $(which "${tool}" &>/dev/null); then
        error_message+="${tool}"
    fi
done
if [[ -n "${error_message}" ]]; then
    print_error "missing the following tools: [ ${error_message} ]"
    exit 1
fi

# ensure commands are executed in the directory where the
# script is located
root_dir="$(realpath "${BASH_SOURCE}" | dirname -)"
cd "${root_dir}"

# check that there are no paths with spaces
illegal_paths="$(find . -type d -name ".git" -prune -o -name "*" -print |
    sort | grep ' ')"
if [[ -n "${illegal_paths}" ]]; then
    print_error "no spaces in paths allowed!"
    print_error "the following paths are illegal:"
    echo ""
    echo "${illegal_paths}"
    exit 1
fi

# ensure the working tree of the maintainer repository is not behind
# no need to check the students repository, as it is derived from the
# maintainer repository
git fetch &>/dev/null
if [[ -n "$(git diff origin/HEAD)" ]]; then
    print_warning "working tree of the maintainer repository differs from the remotes head."
    print_warning "pull and/or commit/push first to resolve the differences."
    exit 1
fi

# remove trailing whitespace and convert to unix file format
bash "${common_dir}/trailing-whitespace.sh" -u .

# ensure the students repository is checked out
if [[ ! -d "${student_repo_name}" ]]; then
    print_highlighted "cloning students repository"
    git clone "${student_repo_url}" "${student_repo_name}"
fi

# ensure the students repository is ignored
if [[ -z "$(cat "./.gitignore" | grep "${student_repo_name}")" ]]; then
    echo "${student_repo_name}/" >>"./.gitignore"
fi

# remove solutions from source code
code_files=($(
    find "${laboratory_dir}" \
        -type f \
        -name "*.[chs]"
))

for file in "${code_files[@]}"; do
    sed -i "
    /${code_start}/,/${code_end}/ {
        /${code_start}/n
        /${code_end}/!d
    }" ${file}

    # add blank lines to show where code goes
    sed -i "/${code_start}/a\\\\" ${file}
    sed -i "/${code_start}/a\\\\" ${file}
    sed -i "/${code_start}/a\\\\" ${file}
done

echo "> removed solutions from source files."

# removing solutions from makefiles
make_files=($(
    find "${laboratory_dir}" \
        -type f \
        -name "Makefile" \
        -or \
        -name "*.mk"
))

for file in "${make_files[@]}"; do
    sed -i "/${make_start}/,/${make_end}/d" ${file}
done

# remove solutions from lab instructions
md_files=($(
    find "${laboratory_dir}" \
        -type f \
        -name "*.md"
))

for file in "${md_files[@]}"; do
    sed -i "/${md_solution_start}/,/${md_solution_end}/d" ${file}
    sed -i "/${md_student_start}/d" ${file}
    sed -i "/${md_student_end}/d" ${file}
done

echo "> removed solutions from lab instructions."

# convert readmes from `pandoc markdown` to `github flavoured markdown` and pdf
echo "converting markdown files to pdfs"
echo "(this may take a while)"

template="$(realpath "${common_dir}/template.tex")"
unset pdf_files
for file in "${md_files[@]}"; do
    filename="${file##*/}"
    pushd "${file%/*}" &>/dev/null
    pandoc \
        -f markdown \
        -t pdf \
        --pdf-engine pdflatex \
        --listings \
        --template "${template}" \
        "${filename}" \
        -o "${filename/%md/pdf}"
    pandoc \
        -f markdown \
        -t gfm \
        "${filename}" \
        -o "${filename}"
    popd &>/dev/null
    pdf_files+=("${file/%md/pdf}")
done
unset template

echo "> converted readme files to github flavoured markdown."

# generate zip archives of keili projects
keili_dirs=($(find . -type d -name "${keili_dir_name}"))
for item in "${keili_dirs[@]}"; do
    pushd "$(dirname "${item}")" &>/dev/null
    zip -r "${keili_dir_name}.zip" "${keili_dir_name}" &>/dev/null
    popd &>/dev/null
done
unset keili_dirs

keili_archives=($(find "${laboratory_dir}" -name "${keili_dir_name}.zip"))

# copy modified contents to students repository
exclude_patterns=("${exclude_file_name}")
exclude_patterns+=("${keili_dir_name}")
exclude_patterns+=("*.pptx")
exclude_patterns+=("*.docx")

# collect exclude globs
ignore_files=($(find . -type f -iname "${exclude_file_name}"))
for file in "${ignore_files[@]}"; do
    temp_path="$(dirname ${file})/"
    temp_patterns=($(cat "${file}"))
    exclude_patterns+=(${temp_patterns[@]/#/${temp_path}})
done

# remove contents of the student repository to avoid
# orphaned files/directories
find "${student_repo_name}" \
    -mindepth 1 \
    -maxdepth 1 \
    -not -name ".git" \
    -exec rm -rf {} \;

# create release using `tar`
tar -cf "${archive_name}" \
    -h \
    --exclude-vcs \
    --exclude-vcs-ignore \
    --exclude="${archive_name}" \
    "${exclude_patterns[@]/#/--exclude=}" \
    "${keili_archives[@]/#/--add-file=}" \
    "${pdf_files[@]/#/--add-file=}" \
    .
tar -xf "${archive_name}" \
    -C "${student_repo_name}/"

# reset repository after release creation
git reset --hard &>/dev/null
git clean -fd &>/dev/null
rm "${keili_archives[@]}" "${pdf_files[@]}"

# print message to report success and a reminder to commit and
# push the students repository
relative_path="$(dirname "${BASH_SOURCE}")/${student_repo_name}"

echo ""
echo "successfully prepared the release for the students repository."
echo "generated release is found at \`${relative_path}\`."
echo ""

print_highlighted "remember to commit and push the generated release!"

echo ""