From ca79b4a20dd63a94e0b7237f662b5693ca70c090 Mon Sep 17 00:00:00 2001
From: Julien Oculi <xdrz.jot.sr@gmail.com>
Date: Thu, 13 Jun 2024 12:03:07 +0200
Subject: [PATCH] feat: :sparkles: add server sessions

---
 src/session/mod.ts | 142 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 142 insertions(+)
 create mode 100644 src/session/mod.ts

diff --git a/src/session/mod.ts b/src/session/mod.ts
new file mode 100644
index 0000000..28748b4
--- /dev/null
+++ b/src/session/mod.ts
@@ -0,0 +1,142 @@
+import { getCookies } from '@std/http/cookie'
+
+type SessionEntry<T extends unknown = unknown> = {
+	accessCount: number
+	flash: boolean
+	value: T
+}
+
+export class SessionStore {
+	static #store = new Map<string, Session>()
+	static createSession(): Session {
+		return new Session(this.#store)
+	}
+
+	static getSession(uuid: string): Session | undefined {
+		// Check session validity
+		const halfHour = 30 * 60 * 1_000
+		const maxAge = Date.now() - halfHour
+		const session = this.#store.get(uuid)
+
+		if (session === undefined) {
+			return undefined
+		}
+
+		if (session.timestamp < maxAge) {
+			session.destroy()
+			return undefined
+		}
+
+		return session
+	}
+
+	static getFromRequest(request: Request): Session | undefined {
+		const sessionId = getCookies(request.headers)['_SESSION'] ?? ''
+		return this.getSession(sessionId)
+	}
+
+	private constructor() {}
+}
+
+class Session {
+	#db = new Map<string, SessionEntry>()
+	#timestamp = Date.now()
+	#uuid = crypto.randomUUID()
+	#store: Map<string, Session>
+
+	constructor(store: Map<string, Session>) {
+		this.#store = store
+		store.set(this.#uuid, this)
+
+		//cleanup old sessions
+		const halfHour = 30 * 60 * 1_000
+		const maxAge = this.#timestamp - halfHour
+
+		for (const [uuid, session] of store.entries()) {
+			if (session.#timestamp < maxAge) {
+				store.delete(uuid)
+			}
+		}
+	}
+
+	#updateTimestamp() {
+		this.#timestamp = Date.now()
+	}
+
+	get uuid() {
+		return this.#uuid
+	}
+
+	get timestamp() {
+		return this.#timestamp
+	}
+
+	get<T extends unknown = unknown>(key: string): T | undefined {
+		this.#updateTimestamp()
+
+		const entry = this.#db.get(key)
+
+		// no entry
+		if (entry === undefined) return
+
+		// flash entry
+		if (entry.flash) {
+			this.#db.delete(key)
+			return entry.value as T
+		}
+
+		// normal entry
+		entry.accessCount++
+		this.#db.set(key, entry)
+		return entry.value as T
+	}
+	set<T extends unknown = unknown>(key: string, value: T): void {
+		this.#updateTimestamp()
+
+		const entry = this.#db.get(key) as SessionEntry<T> | undefined
+
+		// update or create
+		const newEntry: SessionEntry<T> = {
+			accessCount: entry?.accessCount ? entry.accessCount++ : 0,
+			flash: entry?.flash ?? false,
+			value,
+		}
+		this.#db.set(key, newEntry)
+	}
+	delete(key: string): boolean {
+		this.#updateTimestamp()
+
+		return this.#db.delete(key)
+	}
+	has(key: string): boolean {
+		this.#updateTimestamp()
+
+		return this.#db.has(key)
+	}
+	list(): [key: string, value: unknown][] {
+		this.#updateTimestamp()
+
+		const keys = [...this.#db.keys()]
+		return keys.map((key) => ([key, this.get(key)] as [string, unknown]))
+	}
+	flash<T extends unknown = unknown>(key: string, value: T) {
+		this.#updateTimestamp()
+
+		const entry = this.#db.get(key) as SessionEntry<T> | undefined
+
+		// update or create
+		const newEntry: SessionEntry<T> = {
+			accessCount: entry?.accessCount ? entry.accessCount++ : 0,
+			flash: true,
+			value,
+		}
+		this.#db.set(key, newEntry)
+	}
+
+	destroy() {
+		this.#db.clear()
+		this.#store.delete(this.uuid)
+	}
+}
+
+export type { Session }