#! /bin/bash

declare -A opts=(
    ['--fun']=''
    ['--out']='report' # report | edges | graph
)

while :
do
    case "$1" in
        --)
            shift
            break
            ;;
        --*)
            key="$1"
            val="$2"
            if [ -v opts["$key"] ]
            then
                if [ "$val" != "" ]
                then
                    opts["$key"]="$val"
                    shift
                    shift
                else
                    echo "Option $key requires an argument" >&2
                    exit 1
                fi
            else
                echo "Unknown option: $key" >&2
                exit 1
            fi
            ;;
        *)
            break
    esac
done

target_module="$1"
shift
target_fun_regex="${opts['--fun']}"
output_type="${opts['--out']}"
dirs=$@

printf '[DEBUG] target_module    : "%s"\n' "$target_module" >&2
printf '[DEBUG] target_fun_regex : "%s"\n' "$target_fun_regex" >&2
printf '[DEBUG] dirs             : "%s"\n' "$dirs" >&2
printf '[DEBUG] output_type      : "%s"\n' "$output_type" >&2

find $dirs -type f -name '*.erl' -exec grep -Hn "\<$target_module\>:" '{}' \; \
| sed 's/%.*$//g' \
| awk \
    -F "${target_module}:" \
    -v target_module="$target_module" \
    -v output_type="$output_type" \
    -v target_fun_regex="$target_fun_regex" '
    $1 && $2 {
        caller_module_file = $1
        sub(":.*$", "", caller_module_file)

        called_function = $2
        sub("\\(.*$", "", called_function)

        if (called_function ~ /^[a-z][a-zA-Z_0-9]+$/) {
            if (called_function ~ target_fun_regex) {
                Calls[called_function]++
                Calls_from[caller_module_file, called_function]++
                Caller_modules[caller_module_file]++
            }
        } else {
            printf \
                "[WARN] skipped an invalid erlang function name. File: \"%s\", function: \"%s\", original line: \"%s\"\n", \
                caller_module_file, called_function, $0 \
                > "/dev/stderr"
        }
    }

    END {
        if (output_type == "report") {
            report()
        } else if (output_type == "edges") {
            edges()
        } else if (output_type == "graph") {
            printf "digraph {\n"
            vertices() # Vertices must be printed before edges, else records arent recognized.
            edges()
            printf "}\n"
        } else {
            printf "[ERROR] Unknown output type: \"%s\"\n", output_type > "/dev/stderr"
        }
    }

    function vertices() {
        printf "node [shape=record];\n"
        printf "%s [label=\"", target_module;
        sep = ""
        for (called_fun in Calls) {
            printf "%s<%s> %s", sep, called_fun, called_fun
            sep = " | "
        }
        printf "\"];\n"
    }

    function edges() {
        for (cf in Calls_from) {
            split(cf, call, SUBSEP)
            caller_mod = call[1]
            called_mod = target_module
            called_fun = call[2]
            printf("\"%s\" -> %s:%s\n",  caller_mod, called_mod, called_fun)
        }
    }

    function report() {
        indent = "    "
        print "group-by-caller"
        for (caller_module_file in Caller_modules) {
            printf "%s%s\n", indent, caller_module_file;
            sort = "sort -n -k 2 -r | column -t | sed \"s/^/" indent indent "/\""
            for (cf in Calls_from) {
                split(cf, call, SUBSEP);
                if (call[1] == caller_module_file)
                    printf "%s %d\n",  call[2], Calls_from[cf] | sort;
            }
            close(sort)
        }

        print "all"
        sort = "sort -n -k 2 -r | column -t | sed \"s/^/" indent "/\""
        for (called_function in Calls)
            printf "%s %d\n", called_function, Calls[called_function] | sort
        close(sort)
    }'