#!/bin/sh
# A wrapper that will invoke node with `--inspect=xxx` if $NODE_DEBUG_PORT
# is set and the script is an application script and not a node_module.
# The assumption is that node_modules are likely things like nodemon or
# other helper scripts.

# output debug logging if DEBUG is set
debug() {
    if [ -n "$DEBUG" ]; then
        echo "node-wrapper: $*" 1>&2
    fi
}

# find the real node executable (not this wrapper)
findNode() {
    (IFS=:; for dir in $PATH; do \
        # if not the same file as this wrapper; `-ef` is not POSIX but widely supported
        if [ -f "$dir/node" -a -x "$dir/node" ] && ! [ "$dir/node" -ef "$0" ]; then \
            debug "found node in $dir/node"
            echo "$dir/node"; \
            return; \
        fi; \
    done)
}

# find the node script that will be executed
# TODO: use readlink to resolve symlinks?
findScript() {
    for arg in "$@"; do
        case "$arg" in
        -*) # skip option
            ;;
        /*) # absolute path
            echo "$arg"
            return
            ;;
        *)
            echo "$(pwd -P)/$arg"
            return
            ;;
        esac
    done
}

# return 0 if appears to be an application script or 1 if a library (node_modules) script
isApplicationScript() {
    case "$1" in
    */node_modules/*)
        return 1
        ;;
    *)
        return 0
        ;;
    esac
}

# check node arguments for an --inspect style argument; return 0 if found and 1 if not
findInspectArg() {
    for arg in "$@"; do
        case "$arg" in
        --inspect|--inspect=*)
            debug "found $arg"
            echo "$arg"
            return 0
            ;;
        --) # end of node options
            debug "no --inspect found (reached -- end of arguments)"
            return 1
            ;;
        -*) # some other option
            continue
            ;;
        *) 
            debug "no --inspect found (reached file name)" 
            return 1
            ;;
        esac
    done
    return 1
}

# rewrite node-nodemon command-line to add $NODE_DEBUG as first arg to nodemon
# TODO: pretty sure this won't properly pass args with spaces
rewriteNodemon() {
    for arg in "$@"; do
        case "$arg" in
        -*) # node option
            echo "$arg"
            ;;
        */nodemon*)
            echo "$arg"
            echo "$NODE_DEBUG"
            ;;
        *)
            echo "$arg"
            ;;
        esac
    done
}

# strip --inspect argument from command-line
# TODO: pretty sure this won't properly pass args with spaces
stripInspectArg() {
    for arg in "$@"; do
        case "$arg" in
        --inspect*)
            continue
            ;;
        *)
            echo "$arg"
            ;;
        esac
    done
}

debug "cwd: $PWD"
debug "args: $*"

realNode=$(findNode)
if [ -z "$realNode" ]; then
    echo "error: cannot find real node" 1>&2
    exit 255
fi

debug "looking for --inspect in command-line"
inspectArg=$(findInspectArg "$@")
if [ -z "$inspectArg" -a -n "$NODE_OPTIONS" ]; then
    debug "looking for --inspect in NODE_OPTIONS"
    inspectArg=$(findInspectArg $NODE_OPTIONS)
    export NODE_OPTIONS=$(stripInspectArg $NODE_OPTIONS)
fi

# script will be an absolute path
script=$(findScript "$@")
debug "script file: $script"

if $(isApplicationScript "$script"); then
    if [ -n "$inspectArg" ]; then
        debug "app script with --inspect: executing '$realNode $*'"
        exec "$realNode" "$@"
    elif [ -n "$NODE_DEBUG" ]; then
        debug "app script with NODE_DEBUG: executing '$realNode $NODE_DEBUG $*'"
        exec "$realNode" "$NODE_DEBUG" "$@"
    else
        debug "app script but no NODE_DEBUG: executing '$realNode $*'"
        exec "$realNode" "$@"
    fi
    #NOTREACHED
fi

# About to execute a node library script (in node_modules)
# If the script is nodemon then propagate to nodemon
# If we have --inspect, stash it in NODE_DEBUG and continue on
if [ -n "$inspectArg" ]; then
    set -- $(stripInspectArg "$@")
    export NODE_DEBUG="$inspectArg"
    debug "script is in node_modules: setting NODE_DEBUG and stripping $inspectArg"
fi

case "$script" in
*/nodemon*)
    debug "script is nodemon: running '$realNode $(rewriteNodemon "$@")'"
    eval exec "$realNode" $(rewriteNodemon "$@")
    ;;

*)
    debug "script is in node_modules: executing '$realNode $*'"
    exec "$realNode" "$@"
    ;;

esac