module sessions

import json
import orm
import time

// DBStoreSessions is the table that is created in your database and represents a session data record.
pub struct DBStoreSessions {
pub mut:
    session_id string @[primary]
    created_at time.Time
    data       string
}

// DBStore stores sessions in a database.
@[noinit]
pub struct DBStore[T] {
pub mut:
    db orm.Connection @[required]
}

// create a new Database store with a connection to a database.
pub fn DBStore.create[T](db orm.Connection) !DBStore[T] {
    sql db {
        create table DBStoreSessions
    }!

    return DBStore[T]{
        db: db
    }
}

// all gets the data from all sessions.
pub fn (mut store DBStore[T]) all() ![]T {
    rows := sql store.db {
        select from DBStoreSessions
    }!

    // decode should never fail
    return rows.map(json.decode(T, it.data)!)
}

// get session for session id `sid`. The session can be `max_age` old.
// `max_age` will be ignored when set to `0`
pub fn (mut store DBStore[T]) get(sid string, max_age time.Duration) !T {
    rows := sql store.db {
        select from DBStoreSessions where session_id == sid
    }!

    if rows.len == 1 {
        record := rows[0]
        // session is expired
        if max_age != 0 && record.created_at.add(max_age) < time.now() {
            store.destroy(sid)!
            return error('session is expired')
        }

        return json.decode(T, record.data)!
    } else {
        return error('session does not exist')
    }
}

// destroy data for session id `sid`.
pub fn (mut store DBStore[T]) destroy(sid string) ! {
    sql store.db {
        delete from DBStoreSessions where session_id == sid
    }!
}

// clear all sessions.
pub fn (mut store DBStore[T]) clear() ! {
    sql store.db {
        delete from DBStoreSessions where session_id != ''
    }!
}

// set session data for session id `sid`.
pub fn (mut store DBStore[T]) set(sid string, val T) ! {
    count := sql store.db {
        select count from DBStoreSessions where session_id == sid
    }!

    if count == 1 {
        stringified := json.encode(val)
        sql store.db {
            update DBStoreSessions set data = stringified where session_id == sid
        }!
    } else {
        record := DBStoreSessions{
            session_id: sid
            created_at: time.now()
            data:       json.encode(val)
        }

        sql store.db {
            insert record into DBStoreSessions
        }!
    }
}