const std = @import("std");
const config = @import("../../config.zig");
const Storage = @import("../root.zig");

pub const Session = @import("session.zig");

const Self = @This();

pub const empty: Self = .{
    .cache = .empty,
};

cache: std.StringHashMapUnmanaged(Session),
rw_lock: std.Thread.RwLock = .{},

pub fn add(self: *Self, storage: *Storage, info: Storage.User.Info) !*Session {
    self.rw_lock.lock();
    defer self.rw_lock.unlock();

    const session = try Session.init(storage.allocator, info);
    errdefer session.deinit(storage.allocator);
    try self.cache.put(storage.allocator, session.fingerprint, session);
    return self.cache.getPtr(session.fingerprint) orelse unreachable;
}

pub fn renew(self: *Self, storage: *Storage, fingerprint: []const u8) !*Session {
    self.rw_lock.lockShared();
    if (self.cache.get(fingerprint)) |s| {
        self.rw_lock.unlockShared();
        self.rw_lock.lock();
        defer self.rw_lock.unlock();

        var session = s;
        try session.reset();

        try self.cache.put(storage.allocator, session.fingerprint, session);

        _ = self.cache.remove(fingerprint);

        return self.cache.getPtr(session.fingerprint) orelse unreachable;
    } else {
        self.rw_lock.unlockShared();
    }
    return error.SessionNotFound;
}

pub fn remove(self: *Self, storage: *Storage, fingerprint: []const u8) void {
    self.rw_lock.lockShared();
    if (self.cache.getPtr(fingerprint)) |session| {
        self.rw_lock.unlockShared();
        self.rw_lock.lock();
        defer self.rw_lock.unlock();

        session.deinit(storage.allocator);
        _ = self.cache.remove(fingerprint);
    } else {
        self.rw_lock.unlockShared();
    }
}

pub fn get(self: *Self, storage: *Storage, fingerprint: []const u8) ?*Session {
    self.rw_lock.lockShared();
    defer self.rw_lock.unlockShared();
    if (self.cache.getPtr(fingerprint)) |session| {
        const now = std.time.Instant.now() catch return null;
        const since = now.since(session.age);

        if (since > storage.config.session_expires_after) {
            session.deinit(storage.allocator);
            _ = self.cache.remove(fingerprint);
            return null;
        }

        return session;
    }

    return null;
}