53 lines
1.0 KiB
JavaScript
53 lines
1.0 KiB
JavaScript
|
'use strict';
|
||
|
|
|
||
|
|
const unique = arr => arr.filter((v, i) => arr.lastIndexOf(v) === i);
|
||
|
|
const compact = arr => unique(arr).filter(Boolean);
|
||
|
|
|
||
|
|
module.exports = (action, data = {}, value = '') => {
|
||
|
|
let { past = [], present = '' } = data;
|
||
|
|
let rest, prev;
|
||
|
|
|
||
|
|
switch (action) {
|
||
|
|
case 'prev':
|
||
|
|
case 'undo':
|
||
|
|
rest = past.slice(0, past.length - 1);
|
||
|
|
prev = past[past.length - 1] || '';
|
||
|
|
return {
|
||
|
|
past: compact([value, ...rest]),
|
||
|
|
present: prev
|
||
|
|
};
|
||
|
|
|
||
|
|
case 'next':
|
||
|
|
case 'redo':
|
||
|
|
rest = past.slice(1);
|
||
|
|
prev = past[0] || '';
|
||
|
|
return {
|
||
|
|
past: compact([...rest, value]),
|
||
|
|
present: prev
|
||
|
|
};
|
||
|
|
|
||
|
|
case 'save':
|
||
|
|
return {
|
||
|
|
past: compact([...past, value]),
|
||
|
|
present: ''
|
||
|
|
};
|
||
|
|
|
||
|
|
case 'remove':
|
||
|
|
prev = compact(past.filter(v => v !== value));
|
||
|
|
present = '';
|
||
|
|
|
||
|
|
if (prev.length) {
|
||
|
|
present = prev.pop();
|
||
|
|
}
|
||
|
|
|
||
|
|
return {
|
||
|
|
past: prev,
|
||
|
|
present
|
||
|
|
};
|
||
|
|
|
||
|
|
default: {
|
||
|
|
throw new Error(`Invalid action: "${action}"`);
|
||
|
|
}
|
||
|
|
}
|
||
|
|
};
|