[Question] How might I best model temporal entities with temporal relationships?

**What's your scenario? What do you want to achieve?**
I’m after some guidance given I’m struggling to work out how best to model my authorization requirements using Casbin. My own attempt feels like it falls a bit short because I've pushed a lot of the complexity into the matcher leaving the policies themselves seemingly redundant. Any help would be very much appreciated.

Here’s a summary of the entities:
- I have a User with ID, type (customer or admin) & active time range (defined by a start & finish)
- I also have a Store with ID & active time range
- A StoreUser represents a relationship between a User & a Store. It has a userID, storeID & active time range
- User A is allowed to view Store B if:
- The User A is active & Store B is active & an active StoreUser exists with userID ‘A’ and storeID ‘B’
- Or, User A has type ‘admin’

A few extra points:
- There are a significant number of Users and Stores. Looking at [Casbin docs on performance optimization](https://casbin.org/docs/performance/) I’m guessing we don’t want the number of policies to scale with the number of Users & Stores.
- There may be many StoreUser entries for the same User & Store. Each of these will have non-overlapping active time ranges. e.g
- userID ‘Bob’, storeID ‘BobsBurgers’, active.Start ‘2023-01-01T00:00:00’, active.Finish ‘2023-01-31T23:59:59’
- userID ‘Bob’, storeID ‘BobsBurgers’, active.Start ‘2023-03-04T12:09:00’, active.Finish ‘2023-03-31T23:59:59’

**Your model:**

```ini
[request_definition]
r = sub, obj, act, user, store

[policy_definition]
p = sub, obj, act

[role_definition]
g = _, _

[policy_effect]
e = some(where (p.eft == allow))

[matchers]
m = g(r.sub, p.sub) && r.obj == p.obj && r.act == p.act && isActive(r.user.active) && isActive(r.store.active) && (r.user.type == "admin" || isActiveStoreUser(r.user,r.store))
```

**Your policy:**

```
p, customer, stores, read
p, admin, stores, read

g, alice, admin
g, bob, customer
```

**Your request(s):**

Assuming these request were made at “2023-01-20T00:00:00”....

```
// expected: true (store is active, alice is active & alice is admin)
alice, stores, read, {type: "admin", id: "alice", active: {start: "2023-01-01T00:00:00", finish: "2023-01-31T23:59:59"}}, {id: "AndysApples", users:[], active: {start: "2023-01-01T00:00:00", finish: "2023-01-31T23:59:59"}}

// expected: false (store is not active)
alice, stores, read, {type: "admin", id: "alice", active: {start: "2023-01-01T00:00:00", finish: "2023-01-31T23:59:59"}}, {id: "AndysApples", users:[], active: {start: "2023-01-01T00:00:00", finish: "2023-01-15T23:59:59"}}

// expected: false (bob is not a StoreUser)
bob, stores, read, {type: "customer", id: "bob", active: {start: "2023-01-01T00:00:00", finish: "2023-01-31T23:59:59"}}, {id: "AndysApples", users:[], active: {start: "2023-01-01T00:00:00", finish: "2023-01-31T23:59:59"}}

// expected: false (alice is not active)
alice, stores, read, {type: "admin", id: "alice", active: {start: "2023-01-01T00:00:00", finish: "2023-01-15T23:59:59"}}, {id: "BobsBurgers", users:[{id: "bob", active: {start: "2023-01-01T00:00:00", finish: "2023-01-15T23:59:59"}}], active: {start: "2023-01-01T00:00:00", finish: "2023-01-31T23:59:59"}}

// expected: false (bob is not an active StoreUser)
bob, stores, read, {type: "customer", id: "bob", active: {start: "2023-01-01T00:00:00", finish: "2023-01-31T23:59:59"}}, {id: "BobsBurgers", users:[{id: "bob", active: {start: "2023-01-01T00:00:00", finish: "2023-01-31T23:59:59"}}], active: {start: "2023-01-01T00:00:00", finish: "2023-01-31T23:59:59"}}

// expected: true (store is active, bob is active & bob is an active StoreUser)
bob, stores, read, {type: "customer", id: "bob", active: {start: "2023-01-01T00:00:00", finish: "2023-01-31T23:59:59"}}, {id: "BobsBurgers", users:[{id: "bob", active: {start: "2023-01-01T00:00:00", finish: "2023-01-15T23:59:59"}}], active: {start: "2023-01-01T00:00:00", finish: "2023-01-31T23:59:59"}}
```