79 lines
2.1 KiB
JavaScript
79 lines
2.1 KiB
JavaScript
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'use strict';
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const _ = {
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sum: require('lodash/sum'),
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flatten: require('lodash/flatten'),
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};
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const chalk = require('chalk');
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/**
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* The paginator returns 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, options = {}) {
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const { isInfinite = true } = options;
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this.lastIndex = 0;
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this.screen = screen;
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this.isInfinite = isInfinite;
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}
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paginate(output, active, pageSize) {
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pageSize = pageSize || 7;
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let 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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const visibleLines = this.isInfinite
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? this.getInfiniteLines(lines, active, pageSize)
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: this.getFiniteLines(lines, active, pageSize);
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this.lastIndex = active;
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return (
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visibleLines.join('\n') +
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'\n' +
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chalk.dim('(Move up and down to reveal more choices)')
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);
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}
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getInfiniteLines(lines, active, pageSize) {
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if (this.pointer === undefined) {
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this.pointer = 0;
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}
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const middleOfList = Math.floor(pageSize / 2);
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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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// Duplicate the lines so it give an infinite list look
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const infinite = _.flatten([lines, lines, lines]);
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const topIndex = Math.max(0, active + lines.length - this.pointer);
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return infinite.splice(topIndex, pageSize);
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}
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getFiniteLines(lines, active, pageSize) {
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let topIndex = active - pageSize / 2;
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if (topIndex < 0) {
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topIndex = 0;
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} else if (topIndex + pageSize > lines.length) {
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topIndex = lines.length - pageSize;
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}
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return lines.splice(topIndex, pageSize);
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}
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}
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module.exports = Paginator;
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