#!/usr/bin/env dash
# FAKE_COMPAT

# NOTE: a lot of boilerplate code is pulled from the pure sh bible:
#       https://github.com/dylanaraps/pure-sh-bible

document2() {
    local c=0 # line count
    local d="#""#""#" # marker/delimiter, written this way to avoid self-matching
    # NOTE: since the marker corresponds to a <h3> in markdown, it's used there too.
    local e="${f#sh/}" # function name to expect
    local f="$1" # file
    local o=1 # when one, previous line was a one-liner (@- token).
    [ "$f" != "$e" ] || e="" # only expect function names for stuff in sh/
    while IFS= read -r line; do
        : $((c+=1)) $((o+=1))
        # we only care about lines with our docstring marker in them:
        case "$line" in *"$d"*) :;; *) continue;; esac

        # split by the marker:
        local code="${line%%$d*}" docs="${line#*$d}"
        code="${code#${code%%[! ]*}}" # ltrim
        docs="${docs# }" # ltrim a single space

        local s=' ' n='' # using a space to signify unset

        case "$docs" in
        @-*)
            s="$code"
            n="${s%%[!a-zA-Z0-9_-]*}" # substr first word (might not be one)
            while [ -z "$n" -o "$n" = function -o "$n" = alias ]; do
                [ -n "$s" ] || break
                s="${s#${s%%[!a-zA-Z0-9_-]*}}" # lstrip to end of word
                s="${s#*[!a-zA-Z0-9_-]}" # lstrip to next word
                n="${s%%[!a-zA-Z0-9_-]*}" # substr that word
            done
            s="${docs#@-}" # substr the stuff after the hyphen
            s="${s#${s%%[! ]*}}" # ltrim

            [ -z "$s" ] || o=0
            ;;

        @*-*)
            # split by the hyphen:
            n="${docs%%-*}"
            s="${docs#*-}"

            n="${n#@}" # substr the stuff after the at
            n="${n#${n%%[! ]*}}" # ltrim
            n="${n%${n##*[! ]}}" # rtrim

            s="${s#${s%%[! ]*}}" # ltrim

            [ -z "$s" ] || o=0
            ;;

        @*)
            n="${docs#@}" # substr the stuff after the at
            n="${n#${n%%[! ]*}}" # ltrim
            ;;

        *)
            s="$docs" # leave whitespace intact
            ;;
        esac

        if [ -n "$n" ]; then
            local url=
            # different subdirs need to be handled differently:
            [ "$f" != "${f#sh/}" ] && url="/sh/${f#sh/}#L$c" || url="/home/${f#.}#L$c"
            if [ "$n" = "$e" ]; then
                # function name matches the filename.
                printf '\n%s [%s](%s)\n\n' "$d" "$n" "$url" || return 5
            else
                # this file contains some other function, so include the filename.
                printf '\n%s [%s](%s)\n\n' "$d" "$n (${f#.})" "$url" || return 5
                #printf '\n%s %s\n\n* defined in [%s](%s)\n\n' "%d" "$n" "$f" "$url" || return 5
            fi
        fi

        if [ "$s" != ' ' ]; then # don't bother unless it was set to something
            if [ -z "$n" -o -n "$s" ]; then # might only be a name, check that
                # just pass the remaining comment through:
                if [ $o = 1 ]; then
                    # ensure one-liners are their in their own paragraph.
                    printf '\n' || return 5
                fi
                printf '%s\n' "$s" || return 5
            fi
        fi
    done < "$f" || return 4
}

document1() {
    # NOTE: in the future, it'd be nice to support arbitary files through arguments.

    local in_='rc/README.md'
    local out='rc/README.md~'
    if [ $# -eq 0 ]; then
        cd || return 2
        [ -d rc ] || return 3 # sanity check
    elif [ $# -eq 1 ]; then
        in_='README.md'
        out='README.md~'
        cd "$1" || return 2
    else
        return 1
    fi

    # sanity check:
    [ -d sh ] && [ -f .zshrc ] && [ -f .shrc ] && [ -f .bashrc ] || return 3

    # create new output file (with a tilde as not to overwrite just yet):
    : > "$out" || return 4

    local line=

    if [ -f "$in_" ]; then
        # copy existing lines up to (and including) the "DOCUMENT" marker:
        while IFS= read -r line; do
            printf '%s\n' "$line" >> "$out" || return 5
            case "$line" in *DOCUMENT*) break;; esac
        done < "$in_" || return 4
    fi

    # first section:
    printf '\n## %s\n' 'shell functions' >> "$out" || return 5
    for f in sh/*; do
        [ -e "$f" ] || continue # make sure glob went through

        local fn="${f##*/}"
        # ignore some stuff:
        [ "$fn" = "${fn#_}" ] || continue # completion files
        [ "$fn" = "${fn%.bak}" ] || continue # backup files

        document2 "$f" >> "$out" || return
    done

    # second section:
    printf '\n## %s\n' 'miscellaneous' >> "$out" || return 5
    document2 .zshrc >> "$out" || return
    document2 .bashrc >> "$out" || return
    document2 .shrc >> "$out" || return
}

document() { ### @-
    ### generate a markdown file out of docstrings in shell scripts.
    ###
    ### **TODO:** describe. i have a rough outline written in my scrap file.

    document1 "$@"
    local ret=$?

    case $ret in
        0)
            return 0;;
        1)
            printf '%s\n' "$0: too many arguments" >&2
            return 1;;
        2)
            printf '%s\n' "$0: failed to change directory" >&2
            return 1;;
        3)
            printf '%s\n' "$0: essential files are missing" >&2
            return 1;;
        4)
            printf '%s\n' "$0: failed to open file" >&2
            return 1;;
        5)
            printf '%s\n' "$0: failed to read line" >&2
            return 1;;
        *)
            printf '%s\n' "$0: unknown error occurred" >&2
            return 1;;
    esac
}

[ -n "${preload+-}" ] || document "$@"