use futures::stream::BoxStream;

use crate::common::{
    entities::{DecodedValue, Dict, DictEntry, EncodedValue},
    errors::{CodecError, RepositoryError},
};

pub trait SystemDecoder: Send + Sync {
    fn decode(&self, word: &str) -> Result<DecodedValue, CodecError>;
}

pub trait SystemEncoder: Send + Sync {
    fn initialize(&self) -> Result<(), CodecError>;
    fn encode(&self, word: &str) -> Result<EncodedValue, CodecError>;
}

#[async_trait::async_trait]
pub trait DictRepository: Send + Sync {
    fn use_dict(&mut self, name: &str);
    async fn create_dict(&self) -> Result<(), RepositoryError>;

    /// "Upsert" logic:
    /// - If entry exists (by text), update metadata.
    /// - If not, insert new.
    /// - IDs are handled by the Database.
    async fn save_entries(&self, entries: &[DictEntry]) -> Result<(), RepositoryError>;

    /// Fetch a page of entries.
    async fn fetch_many(&self, limit: usize, offset: usize) -> Result<Dict, RepositoryError>;

    /// Returns a cold stream that fetches strings in chunks.
    /// The stream yields `Result<Vec<String>, RepositoryError>`.
    async fn stream_batches(
        &self,
        batch_size: usize,
    ) -> Result<BoxStream<'_, Result<Vec<String>, RepositoryError>>, RepositoryError>;
}

pub trait DictSource {
    fn next_entry(&mut self) -> Option<Result<DictEntry, anyhow::Error>>;
}