use std::{convert::AsRef, fmt::Debug, sync::Arc};

use conduwuit::Result;
use futures::{Stream, StreamExt, TryStreamExt, future};
use serde::{Deserialize, Serialize};

use crate::keyval::{KeyVal, result_deserialize, serialize_key};

impl super::Map {
	/// Iterate key-value entries in the map where the key matches a prefix.
	///
	/// - Query is serialized
	/// - Result is deserialized
	pub fn stream_prefix<'a, K, V, P>(
		self: &'a Arc<Self>,
		prefix: &P,
	) -> impl Stream<Item = Result<KeyVal<'a, K, V>>> + Send + use<'a, K, V, P>
	where
		P: Serialize + ?Sized + Debug,
		K: Deserialize<'a> + Send,
		V: Deserialize<'a> + Send,
	{
		self.stream_prefix_raw(prefix)
			.map(result_deserialize::<K, V>)
	}

	/// Iterate key-value entries in the map where the key matches a prefix.
	///
	/// - Query is serialized
	/// - Result is raw
	#[tracing::instrument(skip(self), level = "trace")]
	pub fn stream_prefix_raw<P>(
		self: &Arc<Self>,
		prefix: &P,
	) -> impl Stream<Item = Result<KeyVal<'_>>> + Send + use<'_, P>
	where
		P: Serialize + ?Sized + Debug,
	{
		let key = serialize_key(prefix).expect("failed to serialize query key");
		self.raw_stream_from(&key)
			.try_take_while(move |(k, _): &KeyVal<'_>| future::ok(k.starts_with(&key)))
	}

	/// Iterate key-value entries in the map where the key matches a prefix.
	///
	/// - Query is raw
	/// - Result is deserialized
	pub fn stream_raw_prefix<'a, K, V, P>(
		self: &'a Arc<Self>,
		prefix: &'a P,
	) -> impl Stream<Item = Result<KeyVal<'a, K, V>>> + Send + 'a
	where
		P: AsRef<[u8]> + ?Sized + Debug + Sync + 'a,
		K: Deserialize<'a> + Send + 'a,
		V: Deserialize<'a> + Send + 'a,
	{
		self.raw_stream_prefix(prefix)
			.map(result_deserialize::<K, V>)
	}

	/// Iterate key-value entries in the map where the key matches a prefix.
	///
	/// - Query is raw
	/// - Result is raw
	pub fn raw_stream_prefix<'a, P>(
		self: &'a Arc<Self>,
		prefix: &'a P,
	) -> impl Stream<Item = Result<KeyVal<'a>>> + Send + 'a
	where
		P: AsRef<[u8]> + ?Sized + Debug + Sync + 'a,
	{
		self.raw_stream_from(prefix)
			.try_take_while(|(k, _): &KeyVal<'_>| future::ok(k.starts_with(prefix.as_ref())))
	}
}
