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.
+ * The paginator returns a subset of the choices if the list is too long.
*/
class Paginator {
- constructor(screen) {
- this.pointer = 0;
+ constructor(screen, options = {}) {
+ const { isInfinite = true } = options;
this.lastIndex = 0;
this.screen = screen;
+ this.isInfinite = isInfinite;
}
paginate(output, active, pageSize) {
pageSize = pageSize || 7;
- var middleOfList = Math.floor(pageSize / 2);
var lines = output.split('\n');
if (this.screen) {
if (lines.length <= pageSize) {
return output;
}
+ const visibleLines = this.isInfinite
+ ? this.getInfiniteLines(lines, active, pageSize)
+ : this.getFiniteLines(lines, active, pageSize);
+ this.lastIndex = active;
+ return (
+ visibleLines.join('\n') +
+ '\n' +
+ chalk.dim('(Move up and down to reveal more choices)')
+ );
+ }
+ getInfiniteLines(lines, active, pageSize) {
+ if (this.pointer === undefined) {
+ this.pointer = 0;
+ }
+ var middleOfList = Math.floor(pageSize / 2);
// Move the pointer only when the user go down and limit it to the middle of the list
if (
this.pointer < middleOfList &&
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)');
+ return infinite.splice(topIndex, pageSize);
+ }
+
+ getFiniteLines(lines, active, pageSize) {
+ var topIndex = active - pageSize / 2;
+ if (topIndex < 0) {
+ topIndex = 0;
+ } else if (topIndex + pageSize > lines.length) {
+ topIndex = lines.length - pageSize;
+ }
+ return lines.splice(topIndex, pageSize);
}
}