| 'use strict'; |
| |
| var _ = require('lodash'); |
| var chalk = require('chalk'); |
| |
| /** |
| * The paginator keeps track of a pointer index in a list and returns |
| * a subset of the choices if the list is too long. |
| */ |
| |
| class Paginator { |
| constructor(screen) { |
| this.pointer = 0; |
| this.lastIndex = 0; |
| this.screen = screen; |
| } |
| |
| paginate(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(lineParts => lineParts.length).splice(0, active)); |
| lines = _.flatten(lines); |
| } |
| |
| // Make sure there's enough lines to paginate |
| if (lines.length <= pageSize) { |
| return output; |
| } |
| |
| // Move the pointer only when the user go down and limit it to the middle of the list |
| if ( |
| this.pointer < middleOfList && |
| this.lastIndex < active && |
| active - this.lastIndex < pageSize |
| ) { |
| this.pointer = Math.min(middleOfList, this.pointer + active - this.lastIndex); |
| } |
| |
| this.lastIndex = active; |
| |
| // Duplicate the lines so it give an infinite list look |
| var infinite = _.flatten([lines, lines, lines]); |
| var topIndex = Math.max(0, active + lines.length - this.pointer); |
| |
| var section = infinite.splice(topIndex, pageSize).join('\n'); |
| return section + '\n' + chalk.dim('(Move up and down to reveal more choices)'); |
| } |
| } |
| |
| module.exports = Paginator; |