storage interface

.gitignore

@@ -8,3 +8,5 @@ pnpm-debug.log
 
 package-lock.json
 shrinkwrap.yaml
+
+vbb-telegram.ldb

lib/storage.js

@@ -0,0 +1,62 @@
+'use strict'
+
+const level = require('level')
+const path = require('path')
+const hifo = require('hifo')
+
+const last = '\xff'
+
+const db = level(path.join(__dirname, '..', 'vbb-telegram.ldb'), {
+	valueEncoding: 'json'
+})
+
+const getCommand = (user) => {
+	return db.get(user + ':cmd')
+	.catch((err) => {
+		if (err.notFound) return null
+		else throw err
+	})
+}
+
+const putCommand = (user, cmd) => {
+	return db.put(user + ':cmd', cmd)
+}
+
+// todo: sth more efficient
+const getTopLocations = (user) => {
+	const ns = user + ':locations:'
+	const top = hifo(hifo.highest('count'), 3)
+
+	const onItem = ({key, value}) => {
+		const id = key.slice(ns.length)
+		top.add({id, count: value})
+	}
+
+	const items = db.createReadStream({gt: ns, lt: ns + last})
+	return new Promise((resolve, reject) => {
+		items.once('error', (err) => {
+			reject(err)
+			items.destroy()
+		})
+		items.once('end', () => {
+			resolve(top.data)
+		})
+		items.on('data', onItem)
+	})
+}
+
+const incLocation = async (user, id) => {
+	const key = user + ':locations:' + id
+	try {
+		const count = await db.get(key)
+		await db.put(key, count + 1)
+	} catch (err) {
+		if (err.notFound) await db.put(key, 1)
+		else throw err
+	}
+}
+
+module.exports = {
+	getCommand, putCommand,
+	getTopLocations, incLocation
+}

package.json

@@ -21,5 +21,7 @@
 		"node": ">=8"
 	},
 	"dependencies": {
+		"hifo": "^1.0.0",
+		"level": "^3.0.0"
 	}
 }