Paginator now handles multiple lines (#602)

Prior to this, a list with multi-line items works erratically; the
current selection might be off the screen, or the list height may vary
depending on which items are selected.

As part of this, Paginator now takes an optional ScreenManager instance.
Prompts have been updated accordingly.

lib/prompts/checkbox.js

@@ -42,7 +42,7 @@ function Prompt() {
   // Make sure no default is set (so it won't be printed)
   this.opt.default = null;
 
-  this.paginator = new Paginator();
+  this.paginator = new Paginator(this.screen);
 }
 util.inherits(Prompt, Base);
 

lib/prompts/expand.js

@@ -47,7 +47,7 @@ function Prompt() {
   // Setup the default string (capitalize the default key)
   this.opt.default = this.generateChoicesString(this.opt.choices, this.opt.default);
 
-  this.paginator = new Paginator();
+  this.paginator = new Paginator(this.screen);
 }
 util.inherits(Prompt, Base);
 

lib/prompts/list.js

@@ -45,7 +45,7 @@ function Prompt() {
   // Make sure no default is set (so it won't be printed)
   this.opt.default = null;
 
-  this.paginator = new Paginator();
+  this.paginator = new Paginator(this.screen);
 }
 util.inherits(Prompt, Base);
 

lib/utils/paginator.js

@@ -8,16 +8,25 @@ var chalk = require('chalk');
  * a subset of the choices if the list is too long.
  */
 
-var Paginator = module.exports = function () {
+var Paginator = module.exports = function (screen) {
   this.pointer = 0;
   this.lastIndex = 0;
+  this.screen = screen;
 };
 
 Paginator.prototype.paginate = function (output, active, pageSize) {
   pageSize = pageSize || 7;
   var middleOfList = Math.floor(pageSize / 2);
   var lines = output.split('\n');
 
+  if (this.screen) {
+    lines = this.screen.breakLines(lines);
+    active = _.sum(lines.map(function (lineParts) {
+      return lineParts.length;
+    }).splice(0, active));
+    lines = _.flatten(lines);
+  }
+
   // Make sure there's enough lines to paginate
   if (lines.length <= pageSize) {
     return output;

lib/utils/screen-manager.js

@@ -45,9 +45,9 @@ ScreenManager.prototype.render = function (content, bottomContent) {
   var cursorPos = this.rl._getCursorPos();
   var width = this.normalizedCliWidth();
 
-  content = forceLineReturn(content, width);
+  content = this.forceLineReturn(content, width);
   if (bottomContent) {
-    bottomContent = forceLineReturn(bottomContent, width);
+    bottomContent = this.forceLineReturn(bottomContent, width);
   }
   // Manually insert an extra line if we're at the end of the line.
   // This prevent the cursor from appearing at the beginning of the
@@ -115,9 +115,10 @@ ScreenManager.prototype.normalizedCliWidth = function () {
   return width;
 };
 
-function breakLines(lines, width) {
-  // Break lines who're longuer than the cli width so we can normalize the natural line
-  // returns behavior accross terminals.
+ScreenManager.prototype.breakLines = function (lines, width) {
+  // Break lines who're longer than the cli width so we can normalize the natural line
+  // returns behavior across terminals.
+  width = width || this.normalizedCliWidth();
   var regex = new RegExp(
     '(?:(?:\\033[[0-9;]*m)*.?){1,' + width + '}',
     'g'
@@ -128,8 +129,9 @@ function breakLines(lines, width) {
     chunk.pop();
     return chunk || '';
   });
-}
+};
 
-function forceLineReturn(content, width) {
-  return _.flatten(breakLines(content.split('\n'), width)).join('\n');
-}
+ScreenManager.prototype.forceLineReturn = function (content, width) {
+  width = width || this.normalizedCliWidth();
+  return _.flatten(this.breakLines(content.split('\n'), width)).join('\n');
+};