#!/usr/bin/env bash

# Synopsis:
# Scaffold the files for a new practice exercise.
# After creating the exercise, follow the instructions in the output.

# Example:
# bin/add-practice-exercise two-fer

# Example with difficulty:
# bin/add-practice-exercise -d 5 two-fer

# Example with author and difficulty:
# bin/add-practice-exercise -a foo -d 3 two-fer

set -euo pipefail
scriptname=$0

help_and_exit() {
    echo >&2 "Scaffold the files for a new practice exercise."
    echo >&2 "Usage: ${scriptname} [-h] [-a author] [-d difficulty] <exercise-slug>"
    echo >&2 "Where: author is the GitHub username of the exercise creator."
    echo >&2 "Where: difficulty is between 1 (easiest) to 10 (hardest)."
    exit 1
}

die() { echo >&2 "$*"; exit 1; }

required_tool() {
    command -v "${1}" >/dev/null 2>&1 ||
        die "${1} is required but not installed. Please install it and make sure it's in your PATH."
}

require_files_template() {
    jq -e --arg key "${1}" '.files[$key] | length > 0' config.json > /dev/null ||
        die "The '.files.${1}' array in the 'config.json' file is empty. Please add at least one file. See https://exercism.org/docs/building/tracks/config-json#h-files for more information."
}

required_tool jq

require_files_template "solution"
require_files_template "test"
require_files_template "example"

[[ -f ./bin/fetch-configlet ]] || die "Run this script from the repo's root directory."

author=''
difficulty='1'
while getopts :ha:d: opt; do
    case $opt in
        h) help_and_exit ;;
        a) author=$OPTARG ;;
        d) difficulty=$OPTARG ;;
        ?) echo >&2 "Unknown option: -$OPTARG"; help_and_exit ;;
    esac
done
shift "$((OPTIND - 1))"

(( $# >= 1 )) || help_and_exit

slug="${1}"

if [[ -z "${author}" ]]; then
    read -rp 'Your GitHub username: ' author
fi

./bin/fetch-configlet
./bin/configlet create --practice-exercise "${slug}" --author "${author}" --difficulty "${difficulty}"

exercise_dir="exercises/practice/${slug}"
files=$(jq -r --arg dir "${exercise_dir}" '.files | to_entries | map({key: .key, value: (.value | map("'"'"'" + $dir + "/" + . + "'"'"'") | join(" and "))}) | from_entries' "${exercise_dir}/.meta/config.json")

cp ./libs/exercism/test "exercises/practice/${slug}/libs/exercism/test"

cat << END_TEST > "exercises/practice/${slug}/test.8th"
"${slug}.8th" f:include
needs exercism/test
with: test
N tests

$(curl --silent "https://raw.githubusercontent.com/exercism/problem-specifications/main/exercises/${slug}/canonical-data.json")

end-of-tests
;with
END_TEST

cat << NEXT_STEPS

Your next steps are:
- Create the test suite in $(jq -r '.test' <<< "${files}")
  - The tests should be based on the canonical data at 'https://github.com/exercism/problem-specifications/blob/main/exercises/${slug}/canonical-data.json'
  - Any test cases you don't implement, mark them in 'exercises/practice/${slug}/.meta/tests.toml' with "include = false"
- Create the example solution in $(jq -r '.example' <<< "${files}")
- Verify the example solution passes the tests by running 'bin/verify-exercises ${slug}'
- Create the stub solution in $(jq -r '.solution' <<< "${files}")
- Update the 'difficulty' value for the exercise's entry in the 'config.json' file in the repo's root
- Validate CI using 'bin/configlet lint' and 'bin/configlet fmt'
NEXT_STEPS