------------------------------------------------
	Description of the jsonEventLoop and JSON schema
	------------------------------------------------

Purpose: JSON-based asynchronous API for signal-cli.

This mode is not intended to be used directly from the command line, but to 
provide an easy use API for other scripting languages.

signal-cli listens for JSON requests on stdin. Each JSON request must be
a single valid JSON object (enclosed in {}), followed by LF. The JSON text
itself hence must not contain linefeeds (only escaped as \n and no pretty
printing enabled).

When incoming messages are received from the signal back-end, they are
in turned JSON encoded and sent out on stdout.

Any error messages or debug information is sent out on stderr as expected.

Start signal-cli with the jsonEventLoop command to start this mode of operation.


JSON Schema Version 2 
=====================


JSON Requests are read line by line from STDIN in "jsonEventLoop" mode and the Reponses are
sent to STDOUT.

Generic Request attributes valid for ALL requests
{
	"reqType": "<request-type>",				// MANDATORY: Name of request type
	"reqID": <integer or string>				// Optional: reqID that will be present in the 
												// response message for async callers to use as transaction id
												// (note: for brevity omitted in the examples below)
}
Generic Response attributes valid for ALL responses
{
	"respType": "<response-type>",				// Name of response type
	"reqID": <object>,							// Request Identifier as present in the request object
	"statusCode": <int>,						// Status of the response. 0=OK, >0 = Error code (see Status code list)
	"errorMessage": <string>					// Text describing error state, only present if statusCode > 0
}


When the jsonEventLoop command is started, it begins with emitting an metadata response
containing some vital information for the "client" application.

Metadata Response (automatically issued on startup)
{
	"respType": "metadata",
	"apiVer": 2,								// Version of the API signal-cli uses
	"attachmentsPath": "<path>"					// Absolute path to the directory where attachments are stored by 
												// signal-cli when downloaded from the server
}



Send Message Request (direct message to another recipient)
{
	"reqType": "send_message",
	"recipient": {
		"number": "<number>"
	},
	"dataMessage": {
		"message": "😋😋😋",
		"attachments": [
			{
				"contentType": "image/jpeg",
				"filename": "signal-2020-02-09-122846.jpeg"
			}
		]
	},
}


Send Message Request (to group chat)
{
	"reqType": "send_message",
	"dataMessage": {
		"message": "😋😋😋",
		"attachments": [
			{
				"contentType": "image/jpeg",
				"filename": "signal-2020-02-09-122846.jpeg"
			},
			{
				"filename": "signal-2020-02-09-122846.jpeg"
			}
		],
		"groupInfo": {
			"groupId": "FRasdb7mSVwGwetQSX8mkjQ=="
		}
	},
}



Message Envelope Received, sent to group chat with some attachements present
{
	"apiVer": 2,
	"respType": "envelope",
	"reqID": null,
	"status": "ok",
	"envelope": {
		"source": "+46123456",
		"sourceDevice": 1,
		"relay": null,
		"timestamp": 1581272926239,
		"isReceipt": false,
		"dataMessage": {
			"timestamp": 1581272926239,
			"message": "😋😋😋",
			"expiresInSeconds": 0,
			"attachments": [
				{
					"contentType": "image/jpeg",
					"filename": "signal-2020-02-09-122846.jpeg",
					"id": "8983570171695764643",
					"size": 569218
				},
				{
					"contentType": "image/jpeg",
					"filename": "signal-2020-02-09-122846.jpeg",
					"id": "119656560176959856",
					"size": 311650
				}
			],
			"groupInfo": {
				"groupId": "FRasdb7mSVwGwetQSX8mkjQ==",
				"members": null,
				"name": null,
				"type": "DELIVER"
			}
		},
		"syncMessage": null,
		"callMessage": null,
		"receiptMessage": null
	}
}


List known groups and their properties
{
	"reqType": "list_groups"
}

List groups response
{
	"respType":"list_groups",
	"reqID":null,
	"statusCode":0,
	"data": [
		{
			"groupId":"+rtjbBy781Tgfpkc9HiNCg==",
			"name":"test-group",
			"members": [
				"+46123445566",
				"+46222222222",
				"+4687345232989874",
			],
			"color":"blue",
			"blocked":false,
			"active":true,
			"inboxPosition":null,
			"archived":false
		}
	]
}



List contacts and their properties
{
	"reqType": "list_contacts"
}

List groups response
{
	"respType":"list_contacts",
	"reqID":null,
	"statusCode":0,
	"data": [
		{
			"name":"Persons A Full Name",
			"number":"+46999999",
			"color":"blue_grey",
			"profileKey":null,
			"blocked":false,
			"inboxPosition":50,
			"archived":true
		},
		{
			"name":"Persons B Full Name",
			"number":"+46999444444",
			"color":"teal",
			"profileKey":null,
			"blocked":false,
			"inboxPosition":0,
			"archived":true
		}
	]
}



Alive Request (Test if signal-cli is still responding)
{
	"reqType": "alive"
}

Alive Response
{
	"respType": "alive",
	"statusCode": 0
}


Exit Request (Request immediate termination of signal-cli client)
{
	"reqType": "exit"
}

Exit Response to an exit request
Indicated the exit was due to an exit request as opposed to an error
{
	"respType": "exit",
	"statusCode": 0
}

Exit Response due to an unrecoverable error
{
	"respType": "exit",
	"statusCode": >0,
	"errorMessage": "<error-message>"
}

Generic Error Response
{
	"respType": "error",
	"statusCode": 1,
	"errorMessage": "<error-message>"
}


Status Code List
================

	statusCode 	description
	----------	-------------------------------------
		0		STATUSCODE_OK 
		1		STATUSCODE_GENERIC_ERROR
		2		STATUSCODE_SEND_ERROR
		3		STATUSCODE_GROUP_ID_FORMAT_ERROR
		4		STATUSCODE_RECIPIENT_FORMAT_ERROR
		5		STATUSCODE_REQUEST_FORMAT_ERROR
		6		STATUSCODE_JSON_PARSE_ERROR
		7		STATUSCODE_USER_NOT_REGISTERED_ERROR