#

# Copyright (c) 2015-2018, Mahlon E. Smith <mahlon@martini.nu>

# All rights reserved.

# Redistribution and use in source and binary forms, with or without

# modification, are permitted provided that the following conditions are met:

#

#     * Redistributions of source code must retain the above copyright

#       notice, this list of conditions and the following disclaimer.

#

#     * Redistributions in binary form must reproduce the above copyright

#       notice, this list of conditions and the following disclaimer in the

#       documentation and/or other materials provided with the distribution.

#

#     * Neither the name of Mahlon E. Smith nor the names of his

#       contributors may be used to endorse or promote products derived

#       from this software without specific prior written permission.

#

# THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND ANY

# EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED

# WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE

# DISCLAIMED. IN NO EVENT SHALL THE REGENTS AND CONTRIBUTORS BE LIABLE FOR ANY

# DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES

# (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;

# LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND

# ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT

# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS

# SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

## This module is a simple interface to the Mongrel2 webserver

## environment (http://mongrel2.org/).  After a Mongrel2 server has been

## properly configured, you can use this library to easily service client

## requests.

##

## Bare minimal, do-nothing example:

##

## .. code-block:: nim

##

##    newM2Handler( "app-id", "tcp://127.0.0.1:9009", "tcp://127.0.0.1:9008" ).run

##

## Yep, that's it.  Assuming your Mongrel2 server is configured with a

## matching application identifier and request/response communication

## ports, that's enough to see the default output from the handler when

## loaded in browser.

##

## It's likely that you'll want to do something of more substance.  This

## is performed via an `action` hook, which is just a proc() reference.

## It is passed the parsed `M2Request` client request, and it needs to

## return a matching `M2Response` object.  What happens in between is

## entirely up to you.

##

## Here's a "hello world":

##

## .. code-block:: nim

##

##    let handler = newM2Handler( "app-id", "tcp://127.0.0.1:9009", "tcp://127.0.0.1:9008" )

##    

##    proc hello_world( request: M2Request ): M2Response =

##        result = request.response

##        result[ "Content-Type" ] = "text/plain"

##        result.body = "Hello there, world!"

##        result.status = HTTP_OK

##    

##    handler.action = hello_world

##    handler.run

##    

## And finally, a slightly more interesting example:

##

## .. code-block:: nim

##

##   import

##       mongrel2,

##       json,

##       re

##   

##   let handler = newM2Handler( "app-id", "tcp://127.0.0.1:9009", "tcp://127.0.0.1:9008" )

##   var data    = %*[] ## the JSON data to "remember"

##   

##   

##   proc demo( request: M2Request ): M2Response =

##       ## This is a demonstration handler action.

##       ##

##       ## It accepts and stores a JSON data structure

##       ## on POST, and returns it on GET.

##   

##       # Create a response object for the current request.

##       var response = request.response

##   

##       case request.meth

##   

##       # For GET requests, display the current JSON structure.

##       #

##       of "GET":

##           if request[ "Accept" ].match( re(".*text/(html|plain).*") ):

##               response[ "Content-Type" ] = "text/plain"

##               response.body   = "Hi there.  POST some JSON to me and I'll remember it.\n\n" & $( data )

##               response.status = HTTP_OK

##   

##           elif request[ "Accept" ].match( re("application/json") ):

##               response[ "Content-Type" ] = "application/json"

##               response.body   = $( data )

##               response.status = HTTP_OK

##   

##           else:

##               response.status = HTTP_BAD_REQUEST

##   

##       # POST requests overwrite the current JSON structure.

##       #

##       of "POST":

##           if request[ "Content-Type" ].match( re(".*application/json.*") ):

##               try:

##                   data = request.body.parse_json

##                   response.status = HTTP_OK

##                   response[ "Content-Type" ] = "application/json"

##                   response.body = $( data )

##               except:

##                   response.status = HTTP_BAD_REQUEST

##                   response[ "Content-Type" ] = "text/plain"

##                   response.body = request.body

##   

##           else:

##               response.body   = "I only accept valid JSON strings."

##               response.status = HTTP_BAD_REQUEST

##   

##       else:

##           response.status = HTTP_NOT_ACCEPTABLE

##   

##       return response

##   

##   

##   # Attach the proc reference to the handler action.

##   handler.action = demo

##   

##   # Start 'er up!

##   handler.run

##

import

    json,

    strutils,

    tables,

    times,

    tnetstring,

    zmq

type

    M2Handler* = ref object of RootObj

        handler_id:         string

        request_sock:       TConnection

        response_sock:      TConnection

        action*:            proc ( request: M2Request ): M2Response

        disconnect_action*: proc ( request: M2Request )

    M2Request* = ref object of RootObj

        sender_id*:   string  ## Mongrel2 app-id

        conn_id*:     string

        path*:        string

        meth*:        string

        version*:     string

        uri*:         string

        pattern*:     string

        scheme*:      string

        remote_addr*: string

        query*:       string

        headers*:     seq[ tuple[name: string, value: string] ]

        body*:        string 

    M2Response* = ref object of RootObj

        sender_id*: string

        conn_id*:   string

        status*:    int

        headers*:   seq[ tuple[name: string, value: string] ]

        body*:      string 

        extended:   string

        ex_data:    seq[ string ]

const 

    MAX_CLIENT_BROADCAST = 128 ## The maximum number of client to broadcast a response to

    CRLF = "\r\n"              ## Network line ending

    DEFAULT_CONTENT = """

<!DOCTYPE html>

<html lang="en">

    <head>

        <title>It works!</title>

        <link href='http://fonts.googleapis.com/css?family=Play' rel='stylesheet' type='text/css'>

        <style>

        body {

            margin: 50px;

            height: 100%;

            background-color: #ddd;

            font-family: Play, Arial, serif;

            font-weight: 400;

            background: linear-gradient( to bottom, #7db9e8 25%,#fff 100% );

        }

        a, a:hover, a:visited {

            text-decoration: none;

            color: rgb( 66,131,251 );

        }

        .content {

            font-size: 1.2em;

            border-radius: 10px;

            margin: 0 auto 0 auto;

            width: 50%;

            padding: 5px 20px 20px 20px;

            box-shadow: 1px 2px 6px #000;

            background-color: #fff;

            border: 1px;

        }

        .handler {

            font-size: 0.9em;

            padding: 2px 0 0 10px;

            color: rgb( 192,220,255 );

            background-color: rgb( 6,20,85 );

            border: 2px solid rgb( 66,131,251 );

        }

        </style>

    </head>

    <body>

        <div class="content">

            <h1>Almost there...</h1>

            <p>

                This is the default handler output.  While this is

                useful to demonstrate that your <a href="http://mongrel2.org">Mongrel2</a>

                server is indeed speaking to your <a href="http://nim-lang.org">nim</a>

                handler, you're probably going to want to do something else for production use.

            </p>

            <p>

                Here's an example handler:

            </p>

            <div class="handler">

            <pre>

import

    mongrel2,

    json,

    re

let handler = newM2Handler( "app-id", "tcp://127.0.0.1:9009", "tcp://127.0.0.1:9008" )

var data    = %*[] ## the JSON data to "remember"

proc demo( request: M2Request ): M2Response =

    ## This is a demonstration handler action.

    ##

    ## It accepts and stores a JSON data structure

    ## on POST, and returns it on GET.

    # Create a response object for the current request.

    var response = request.response

    case request.meth

    # For GET requests, display the current JSON structure.

    #

    of "GET":

        if request[ "Accept" ].match( re(".*text/(html|plain).*") ):

            response[ "Content-Type" ] = "text/plain"

            response.body   = "Hi there.  POST some JSON to me and I'll remember it.\n\n" & $( data )

            response.status = HTTP_OK

        elif request[ "Accept" ].match( re("application/json") ):

            response[ "Content-Type" ] = "application/json"

            response.body   = $( data )

            response.status = HTTP_OK

        else:

            response.status = HTTP_BAD_REQUEST

    # Overwrite the current JSON structure.

    #

    of "POST":

        if request[ "Content-Type" ].match( re(".*application/json.*") ):

            try:

                data = request.body.parse_json

                response.status = HTTP_OK

                response[ "Content-Type" ] = "application/json"

                response.body = $( data )

            except:

                response.status = HTTP_BAD_REQUEST

                response[ "Content-Type" ] = "text/plain"

                response.body = request.body

        else:

            response.body   = "I only accept valid JSON strings."

            response.status = HTTP_BAD_REQUEST

    else:

        response.status = HTTP_NOT_ACCEPTABLE

    return response

# Attach the proc reference to the handler action.

handler.action = demo

# Start 'er up!

handler.run

            </pre>

            </div>

        </div>

    </body>

</html>

    """

    HTTP_CONTINUE*                      = 100

    HTTP_SWITCHING_PROTOCOLS*           = 101

    HTTP_PROCESSING*                    = 102

    HTTP_OK*                            = 200

    HTTP_CREATED*                       = 201

    HTTP_ACCEPTED*                      = 202

    HTTP_NON_AUTHORITATIVE*             = 203

    HTTP_NO_CONTENT*                    = 204

    HTTP_RESET_CONTENT*                 = 205

    HTTP_PARTIAL_CONTENT*               = 206

    HTTP_MULTI_STATUS*                  = 207

    HTTP_MULTIPLE_CHOICES*              = 300

    HTTP_MOVED_PERMANENTLY*             = 301

    HTTP_MOVED*                         = 301

    HTTP_MOVED_TEMPORARILY*             = 302

    HTTP_REDIRECT*                      = 302

    HTTP_SEE_OTHER*                     = 303

    HTTP_NOT_MODIFIED*                  = 304

    HTTP_USE_PROXY*                     = 305

    HTTP_TEMPORARY_REDIRECT*            = 307

    HTTP_BAD_REQUEST*                   = 400

    HTTP_AUTH_REQUIRED*                 = 401

    HTTP_UNAUTHORIZED*                  = 401

    HTTP_PAYMENT_REQUIRED*              = 402

    HTTP_FORBIDDEN*                     = 403

    HTTP_NOT_FOUND*                     = 404

    HTTP_METHOD_NOT_ALLOWED*            = 405

    HTTP_NOT_ACCEPTABLE*                = 406

    HTTP_PROXY_AUTHENTICATION_REQUIRED* = 407

    HTTP_REQUEST_TIME_OUT*              = 408

    HTTP_CONFLICT*                      = 409

    HTTP_GONE*                          = 410

    HTTP_LENGTH_REQUIRED*               = 411

    HTTP_PRECONDITION_FAILED*           = 412

    HTTP_REQUEST_ENTITY_TOO_LARGE*      = 413

    HTTP_REQUEST_URI_TOO_LARGE*         = 414

    HTTP_UNSUPPORTED_MEDIA_TYPE*        = 415

    HTTP_RANGE_NOT_SATISFIABLE*         = 416

    HTTP_EXPECTATION_FAILED*            = 417

    HTTP_UNPROCESSABLE_ENTITY*          = 422

    HTTP_LOCKED*                        = 423

    HTTP_FAILED_DEPENDENCY*             = 424

    HTTP_UPGRADE_REQUIRED*              = 426

    HTTP_RECONDITION_REQUIRED*          = 428

    HTTP_TOO_MANY_REQUESTS*             = 429

    HTTP_REQUEST_HEADERS_TOO_LARGE*     = 431

    HTTP_SERVER_ERROR*                  = 500

    HTTP_NOT_IMPLEMENTED*               = 501

    HTTP_BAD_GATEWAY*                   = 502

    HTTP_SERVICE_UNAVAILABLE*           = 503

    HTTP_GATEWAY_TIME_OUT*              = 504

    HTTP_VERSION_NOT_SUPPORTED*         = 505

    HTTP_VARIANT_ALSO_VARIES*           = 506

    HTTP_INSUFFICIENT_STORAGE*          = 507

    HTTP_NOT_EXTENDED*                  = 510

    HTTPCODE = {

        HTTP_CONTINUE:                      ( desc: "Continue",                        label: "CONTINUE" ),

        HTTP_SWITCHING_PROTOCOLS:           ( desc: "Switching Protocols",             label: "SWITCHING_PROTOCOLS" ),

        HTTP_PROCESSING:                    ( desc: "Processing",                      label: "PROCESSING" ),

        HTTP_OK:                            ( desc: "OK",                              label: "OK" ),

        HTTP_CREATED:                       ( desc: "Created",                         label: "CREATED" ),

        HTTP_ACCEPTED:                      ( desc: "Accepted",                        label: "ACCEPTED" ),

        HTTP_NON_AUTHORITATIVE:             ( desc: "Non-Authoritative Information",   label: "NON_AUTHORITATIVE" ),

        HTTP_NO_CONTENT:                    ( desc: "No Content",                      label: "NO_CONTENT" ),

        HTTP_RESET_CONTENT:                 ( desc: "Reset Content",                   label: "RESET_CONTENT" ),

        HTTP_PARTIAL_CONTENT:               ( desc: "Partial Content",                 label: "PARTIAL_CONTENT" ),

        HTTP_MULTI_STATUS:                  ( desc: "Multi-Status",                    label: "MULTI_STATUS" ),

        HTTP_MULTIPLE_CHOICES:              ( desc: "Multiple Choices",                label: "MULTIPLE_CHOICES" ),

        HTTP_MOVED_PERMANENTLY:             ( desc: "Moved Permanently",               label: "MOVED_PERMANENTLY" ),

        HTTP_MOVED:                         ( desc: "Moved Permanently",               label: "MOVED" ),

        HTTP_MOVED_TEMPORARILY:             ( desc: "Found",                           label: "MOVED_TEMPORARILY" ),

        HTTP_REDIRECT:                      ( desc: "Found",                           label: "REDIRECT" ),

        HTTP_SEE_OTHER:                     ( desc: "See Other",                       label: "SEE_OTHER" ),

        HTTP_NOT_MODIFIED:                  ( desc: "Not Modified",                    label: "NOT_MODIFIED" ),

        HTTP_USE_PROXY:                     ( desc: "Use Proxy",                       label: "USE_PROXY" ),

        HTTP_TEMPORARY_REDIRECT:            ( desc: "Temporary Redirect",              label: "TEMPORARY_REDIRECT" ),

        HTTP_BAD_REQUEST:                   ( desc: "Bad Request",                     label: "BAD_REQUEST" ),

        HTTP_AUTH_REQUIRED:                 ( desc: "Authorization Required",          label: "AUTH_REQUIRED" ),

        HTTP_UNAUTHORIZED:                  ( desc: "Authorization Required",          label: "UNAUTHORIZED" ),

        HTTP_PAYMENT_REQUIRED:              ( desc: "Payment Required",                label: "PAYMENT_REQUIRED" ),

        HTTP_FORBIDDEN:                     ( desc: "Forbidden",                       label: "FORBIDDEN" ),

        HTTP_NOT_FOUND:                     ( desc: "Not Found",                       label: "NOT_FOUND" ),

        HTTP_METHOD_NOT_ALLOWED:            ( desc: "Method Not Allowed",              label: "METHOD_NOT_ALLOWED" ),

        HTTP_NOT_ACCEPTABLE:                ( desc: "Not Acceptable",                  label: "NOT_ACCEPTABLE" ),

        HTTP_PROXY_AUTHENTICATION_REQUIRED: ( desc: "Proxy Authentication Required",   label: "PROXY_AUTHENTICATION_REQUIRED" ),

        HTTP_REQUEST_TIME_OUT:              ( desc: "Request Time-out",                label: "REQUEST_TIME_OUT" ),

        HTTP_CONFLICT:                      ( desc: "Conflict",                        label: "CONFLICT" ),

        HTTP_GONE:                          ( desc: "Gone",                            label: "GONE" ),

        HTTP_LENGTH_REQUIRED:               ( desc: "Length Required",                 label: "LENGTH_REQUIRED" ),

        HTTP_PRECONDITION_FAILED:           ( desc: "Precondition Failed",             label: "PRECONDITION_FAILED" ),

        HTTP_REQUEST_ENTITY_TOO_LARGE:      ( desc: "Request Entity Too Large",        label: "REQUEST_ENTITY_TOO_LARGE" ),

        HTTP_REQUEST_URI_TOO_LARGE:         ( desc: "Request-URI Too Large",           label: "REQUEST_URI_TOO_LARGE" ),

        HTTP_UNSUPPORTED_MEDIA_TYPE:        ( desc: "Unsupported Media Type",          label: "UNSUPPORTED_MEDIA_TYPE" ),

        HTTP_RANGE_NOT_SATISFIABLE:         ( desc: "Requested Range Not Satisfiable", label: "RANGE_NOT_SATISFIABLE" ),

        HTTP_EXPECTATION_FAILED:            ( desc: "Expectation Failed",              label: "EXPECTATION_FAILED" ),

        HTTP_UNPROCESSABLE_ENTITY:          ( desc: "Unprocessable Entity",            label: "UNPROCESSABLE_ENTITY" ),

        HTTP_LOCKED:                        ( desc: "Locked",                          label: "LOCKED" ),

        HTTP_FAILED_DEPENDENCY:             ( desc: "Failed Dependency",               label: "FAILED_DEPENDENCY" ),

        HTTP_UPGRADE_REQUIRED:              ( desc: "Upgrade Required",                label: "UPGRADE_REQUIRED" ),

        HTTP_RECONDITION_REQUIRED:          ( desc: "Precondition Required",           label: "RECONDITION_REQUIRED" ),

        HTTP_TOO_MANY_REQUESTS:             ( desc: "Too Many Requests",               label: "TOO_MANY_REQUESTS" ),

        HTTP_REQUEST_HEADERS_TOO_LARGE:     ( desc: "Request Headers too Large",       label: "REQUEST_HEADERS_TOO_LARGE" ),

        HTTP_SERVER_ERROR:                  ( desc: "Internal Server Error",           label: "SERVER_ERROR" ),

        HTTP_NOT_IMPLEMENTED:               ( desc: "Method Not Implemented",          label: "NOT_IMPLEMENTED" ),

        HTTP_BAD_GATEWAY:                   ( desc: "Bad Gateway",                     label: "BAD_GATEWAY" ),

        HTTP_SERVICE_UNAVAILABLE:           ( desc: "Service Temporarily Unavailable", label: "SERVICE_UNAVAILABLE" ),

        HTTP_GATEWAY_TIME_OUT:              ( desc: "Gateway Time-out",                label: "GATEWAY_TIME_OUT" ),

        HTTP_VERSION_NOT_SUPPORTED:         ( desc: "HTTP Version Not Supported",      label: "VERSION_NOT_SUPPORTED" ),

        HTTP_VARIANT_ALSO_VARIES:           ( desc: "Variant Also Negotiates",         label: "VARIANT_ALSO_VARIES" ),

        HTTP_INSUFFICIENT_STORAGE:          ( desc: "Insufficient Storage",            label: "INSUFFICIENT_STORAGE" ),

        HTTP_NOT_EXTENDED:                  ( desc: "Not Extended",                    label: "NOT_EXTENDED" )

    }.toTable

proc newM2Handler*( id: string, req_sock: string, res_sock: string ): M2Handler =

    ## Instantiate a new `M2Handler` object.

    ## The `id` should match the app ID in the Mongrel2 config,

    ## `req_sock` is the ZMQ::PULL socket Mongrel2 sends client request

    ## data on, and `res_sock` is the ZMQ::PUB socket Mongrel2 subscribes

    ## to.  Nothing is put into action until the run() method is invoked.

    new( result )

    result.handler_id    = id

    result.request_sock  = zmq.connect( req_sock, PULL )

    result.response_sock = zmq.connect( res_sock, PUB )

proc parse_request( request: string ): M2Request =

    ## Parse a message `request` string received from Mongrel2,

    ## return it as a M2Request object.

    var

        reqstr     = request.split( ' ' )

        rest       = ""

        req_tnstr: TNetstringNode

        headers:   JsonNode

    new( result )

    result.sender_id = reqstr[ 0 ]

    result.conn_id   = reqstr[ 1 ]

    result.path      = reqstr[ 2 ]

    # There must be a better way to join() a seq...

    #

    for i in 3 .. reqstr.high:

        rest = rest & reqstr[ i ]

        if i < reqstr.high: rest = rest & ' '

    reqtnstr    = rest.parse_tnetstring

    result.body = reqtnstr.extra.parse_tnetstring.getStr("")

    # Pull Mongrel2 control headers into the request object.

    #

    headers = reqtnstr.getStr.parse_json

    if headers.has_key( "METHOD" ):

        result.meth = headers[ "METHOD" ].getStr

        headers.delete( "METHOD" )

    if headers.has_key( "PATTERN" ):

        result.pattern = headers[ "PATTERN" ].getStr

        headers.delete( "PATTERN" )

    if headers.has_key( "REMOTE_ADDR" ):

        result.remote_addr = headers[ "REMOTE_ADDR" ].getStr

        headers.delete( "REMOTE_ADDR" )

    if headers.has_key( "URI" ):

        result.uri = headers[ "URI" ].getStr

        headers.delete( "URI" )

    if headers.has_key( "URL_SCHEME" ):

        result.scheme = headers[ "URL_SCHEME" ].getStr

        headers.delete( "URL_SCHEME" )

    if headers.has_key( "VERSION" ):

        result.version = headers[ "VERSION" ].getStr

        headers.delete( "VERSION" )

    if headers.has_key( "QUERY" ):

        result.query = headers[ "QUERY" ].getStr

        headers.delete( "QUERY" )

    # Remaining headers are client supplied.

    #

    result.headers = @[]

    for key, val in headers:

        result.headers.add( ( key, val.getStr ) )

proc response*( request: M2Request ): M2Response =

    ## Instantiate a new `M2Response`, paired from an `M2Request`.

    new( result )

    result.sender_id = request.sender_id

    result.conn_id   = request.conn_id

    result.headers   = @[]

proc `[]`*( request: M2Request, label: string ): string =

    ## Defer to the underlying headers tuple array.  Lookup is case-insensitive.

    for header in request.headers:

        if cmpIgnoreCase( label, header.name ) == 0:

            return header.value

    return ""

proc is_disconnect*( request: M2Request ): bool =

    ## Returns true if this is a Mongrel2 disconnect request.

    if ( request.path == "@*" and request.meth == "JSON") :

        var body = request.body.parseJson

        if ( body.has_key( "type" ) and body[ "type" ].getStr == "disconnect" ):

            return true

    return false

proc `[]`*( response: M2Response, label: string ): string =

    ## Defer to the underlying headers tuple array.  Lookup is case-insensitive.

    for header in response.headers:

        if cmpIgnoreCase( label, header.name ) == 0:

            return header.value

    return ""

proc `[]=`*( response: M2Response, name: string, value: string ) =

    ## Set a header on the response.  Duplicates are replaced.