1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
|
// Specify types of keys and values (any, in the case of json).
import {Level} from 'level';
import {Account, Bank} from './bank.js';
import {Option, fromNullable} from 'fp-ts/lib/Option.js';
export class LevelBank implements Bank {
db: Level<string, number>;
file: string;
constructor(file: string) {
this.file = file;
this.db = new Level<Account, number>(file, {
valueEncoding: 'json',
});
}
async populateWith(
initialAccounts: Map<Account, number>,
): Promise<LevelBank> {
await this.db.open({createIfMissing: true});
const puts: Promise<void>[] = [];
initialAccounts.forEach((v, k) => {
puts.push(this.db.put(k, v));
});
await Promise.all(puts);
return this;
}
async balance(account: string): Promise<Option<number>> {
const result = await this.db.get(account);
return fromNullable(result);
}
async deposit(account: string, amt: number): Promise<void> {
const current = await this.db.get(account);
if (current) {
await this.db.put(account, current + amt);
}
}
async withdraw(account: string, amt: number): Promise<void> {
const current = await this.db.get(account);
if (current) {
await this.db.put(account, current - amt);
}
}
}
|
