From abaca6c8ef584e4f252d908831fc020d53b60428 Mon Sep 17 00:00:00 2001
From: Nathan Byrd <techy1@gmail.com>
Date: Mon, 28 Mar 2022 14:18:00 -0500
Subject: [PATCH] Fixed changes from code review

---
 core/ansi_escape_parser.js |  2 +-
 core/config_default.js     |  6 ++++
 core/connect.js            | 57 ++++++++++++++++++++++++++++++++++++++
 core/menu_module.js        |  4 +--
 4 files changed, 66 insertions(+), 3 deletions(-)

diff --git a/core/ansi_escape_parser.js b/core/ansi_escape_parser.js
index c6d1276c..73c4f377 100644
--- a/core/ansi_escape_parser.js
+++ b/core/ansi_escape_parser.js
@@ -24,7 +24,7 @@ function ANSIEscapeParser(options) {
     this.scrollBack         = 0;
     this.graphicRendition   = {};
 
-    if(options.startRow != null) {
+    if(!_.isNil(options.startRow)) {
         this.row = options.startRow;
     }
     else {
diff --git a/core/config_default.js b/core/config_default.js
index d5b71ed7..c51fb6a1 100644
--- a/core/config_default.js
+++ b/core/config_default.js
@@ -23,6 +23,12 @@ module.exports = () => {
             // during the connect process, but provides better autoconfiguration of utf-8
             checkUtf8Encoding : true,
 
+            // Checking the ANSI home position also requires the use of cursor position reports, which are not
+            // supported on all terminals. Using this with a terminal that does not support cursor position reports
+            // results in a 3 second delay during the connect process, but works around positioning problems with
+            // non-standard terminals.
+            checkAnsiHomePosition: true,
+
             // List of terms that should be assumed to use cp437 encoding
             cp437TermList     : ['ansi', 'pcansi', 'pc-ansi', 'ansi-bbs', 'qansi', 'scoansi', 'syncterm', 'ansi-256color', 'ansi-256color-rgb'],
             // List of terms that should be assumed to use utf8 encoding
diff --git a/core/connect.js b/core/connect.js
index d20aae39..9acf002f 100644
--- a/core/connect.js
+++ b/core/connect.js
@@ -12,6 +12,58 @@ const async     = require('async');
 
 exports.connectEntry    = connectEntry;
 
+function ansiDiscoverHomePosition(client, cb) {
+    //
+    //  We want to find the home position. ANSI-BBS and most terminals
+    //  utilize 1,1 as home. However, some terminals such as ConnectBot
+    //  think of home as 0,0. If this is the case, we need to offset
+    //  our positioning to accommodate for such.
+    //
+
+
+    if( !Config().term.checkAnsiHomePosition ) {
+        // Skip (and assume 1,1) if the home position check is disabled.
+        return cb(null);
+    }
+
+    const done = (err) => {
+        client.removeListener('cursor position report', cprListener);
+        clearTimeout(giveUpTimer);
+        return cb(err);
+    };
+
+    const cprListener = function(pos) {
+        const h = pos[0];
+        const w = pos[1];
+
+        //
+        //  We expect either 0,0, or 1,1. Anything else will be filed as bad data
+        //
+        if(h > 1 || w > 1) {
+            client.log.warn( { height : h, width : w }, 'Ignoring ANSI home position CPR due to unexpected values');
+            return done(Errors.UnexpectedState('Home position CPR expected to be 0,0, or 1,1'));
+        }
+
+        if(0 === h & 0 === w) {
+            //
+            //  Store a CPR offset in the client. All CPR's from this point on will offset by this amount
+            //
+            client.log.info('Setting CPR offset to 1');
+            client.cprOffset = 1;
+        }
+
+        return done(null);
+    };
+
+    client.once('cursor position report', cprListener);
+
+    const giveUpTimer = setTimeout( () => {
+        return done(Errors.General('Giving up on home position CPR'));
+    }, 3000);   //  3s
+
+    client.term.write(`${ansi.goHome()}${ansi.queryPos()}`);    //  go home, query pos
+}
+
 function ansiAttemptDetectUTF8(client, cb) {
     //
     //  Trick to attempt and detect UTF-8. While there is a lot more than
@@ -173,6 +225,11 @@ function connectEntry(client, nextMenu) {
                 term.rawWrite(ansi.queryDeviceAttributes(0));
                 return callback(null);
             },
+            function discoverHomePosition(callback) {
+                ansiDiscoverHomePosition(client, () => {
+                    return callback(null);  //  we try to continue anyway
+                });
+            },
             function queryTermSizeByNonStandardAnsi(callback) {
                 ansiQueryTermSizeIfNeeded(client, err => {
                     if(err) {
diff --git a/core/menu_module.js b/core/menu_module.js
index ef6ad831..54bda2c7 100644
--- a/core/menu_module.js
+++ b/core/menu_module.js
@@ -105,7 +105,7 @@ exports.MenuModule = class MenuModule extends PluginModule {
 
                     const options = self.menuConfig.config;
 
-                    if(artData != null && artData.height != null) {
+                    if(!_.isNil(artData) && _.isNumber(artData.height)) {
                         options.startRow = artData.height + 1;
                     }
 
@@ -127,7 +127,7 @@ exports.MenuModule = class MenuModule extends PluginModule {
                 },
                 function displayPauseIfRequested(callback) {
                     if(!self.shouldPause()) {
-                        return callback(null);
+                        return callback(null, null);
                     }
 
                     if(self.client.term.termHeight > 0 && pausePosition.row > self.client.termHeight) {