pub mod backfill_queue;
pub mod error;
pub mod firehose_cursor;
pub mod preferences;

pub use error::{StorageError, StorageResult};

use std::path::Path;
use std::sync::Arc;

/// Fixed-length 3-byte key prefix per data type.
pub(crate) type KeyPrefix = [u8; 3];

pub(crate) const PREFIX_PREFS: KeyPrefix = *b"prf";
pub(crate) const PREFIX_FH_CURSOR: KeyPrefix = *b"fhc";
pub(crate) const PREFIX_BACKFILL: KeyPrefix = *b"bfq";

/// Shared handle to the fjall database and its keyspaces.
pub struct Db {
    pub(crate) database: fjall::Database,
    /// Durable state: preferences, queue jobs, firehose cursor.
    pub(crate) persistent: fjall::Keyspace,
    /// Ephemeral cache — currently unused; kept as a home for future read-through caches.
    #[allow(dead_code)]
    pub(crate) cache: fjall::Keyspace,
}

pub type DbRef = Arc<Db>;

/// Open (or create) the fjall database at `path` and return a shared handle.
pub fn open(path: &Path) -> StorageResult<DbRef> {
    let database = fjall::Database::builder(path).open()?;
    let persistent = database.keyspace("persistent", fjall::KeyspaceCreateOptions::default)?;
    let cache = database.keyspace("cache", fjall::KeyspaceCreateOptions::default)?;
    Ok(Arc::new(Db {
        database,
        persistent,
        cache,
    }))
}