#!/usr/bin/env nix-shell
#!nix-shell -i bash -p bash -p lr -p pandoc

set -euo pipefail

preludeDir="${1:?dir please}"

# each file (except package.dhall) starts with a multiline-comment with markdown docstrings.
# {- maybe docstring
# docstring
# maybe docstring -}
parseDocstringForFile () {
    local doc=$(sed -n \
                    -e '/^{-/,/-}$/ p' \
                    "$1" \
                    | sed -e '1s/^{-\s*//' \
                    | sed -e '$s/\s*-}$//')
    if [ "$doc" = "" ]; then
        printf 'WARNING: %s has no docstring\n' "$1" >&2
    fi
    printf '%s' "$doc"
}


tmp=$(mktemp -d)

for file in $(lr -t "type = f" -s "$preludeDir" "$preludeDir"); do
    # those are the export files
    if [ "$(basename "$file")" = "package.dhall" ]; then
           continue
    fi
    # printf '%s\n' "$tmp/$file"
    echo "## $file"
    echo
    parseDocstringForFile "$preludeDir/$file"
    echo
    # TODO: build helper dhall executable that can print
    # the type of expressions while caching all imports.
    # (use dhall-flycheck code for that)
    echo
    echo "### Type"
    echo '```'
    (
        # don’t use the cache to preserve variable names
        export XDG_CACHE_HOME=/var/empty
        printf '(./%spackage.dhall).%s\n' "$preludeDir" "${file/\//.}" \
            | dhall resolve \
            | dhall type
    )
    echo '```'
    echo
    echo "<hr>"
done | pandoc --standalone --to=html5