55 lines
1.5 KiB
JavaScript
55 lines
1.5 KiB
JavaScript
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'use strict';
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var _ = require('lodash');
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var chalk = require('chalk');
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/**
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* The paginator keeps track of a pointer index in a list and returns
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* a subset of the choices if the list is too long.
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*/
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class Paginator {
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constructor(screen) {
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this.pointer = 0;
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this.lastIndex = 0;
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this.screen = screen;
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}
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paginate(output, active, pageSize) {
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pageSize = pageSize || 7;
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var middleOfList = Math.floor(pageSize / 2);
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var lines = output.split('\n');
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if (this.screen) {
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lines = this.screen.breakLines(lines);
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active = _.sum(lines.map(lineParts => lineParts.length).splice(0, active));
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lines = _.flatten(lines);
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}
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// Make sure there's enough lines to paginate
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if (lines.length <= pageSize) {
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return output;
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}
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// Move the pointer only when the user go down and limit it to the middle of the list
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if (
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this.pointer < middleOfList &&
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this.lastIndex < active &&
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active - this.lastIndex < pageSize
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) {
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this.pointer = Math.min(middleOfList, this.pointer + active - this.lastIndex);
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}
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this.lastIndex = active;
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// Duplicate the lines so it give an infinite list look
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var infinite = _.flatten([lines, lines, lines]);
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var topIndex = Math.max(0, active + lines.length - this.pointer);
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var section = infinite.splice(topIndex, pageSize).join('\n');
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return section + '\n' + chalk.dim('(Move up and down to reveal more choices)');
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}
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}
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module.exports = Paginator;
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