// Copyright 2019-2025 Parity Technologies (UK) Ltd.
// This file is dual-licensed as Apache-2.0 or GPL-3.0.
// see LICENSE for license details.

//! Types representing extrinsics/transactions that have been submitted to a node.

use std::task::Poll;

use crate::{
	backend::{BlockRef, StreamOfResults, TransactionStatus as BackendTxStatus},
	client::OnlineClientT,
	config::{Config, HashFor},
	error::{
		DispatchError, TransactionEventsError, TransactionFinalizedSuccessError,
		TransactionProgressError, TransactionStatusError,
	},
	events::EventsClient,
	utils::strip_compact_prefix,
};
use derive_where::derive_where;
use futures::{Stream, StreamExt};

/// This struct represents a subscription to the progress of some transaction.
pub struct TxProgress<T: Config, C> {
	sub: Option<StreamOfResults<BackendTxStatus<HashFor<T>>>>,
	ext_hash: HashFor<T>,
	client: C,
}

impl<T: Config, C> std::fmt::Debug for TxProgress<T, C> {
	fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
		f.debug_struct("TxProgress")
			.field("sub", &"<subscription>")
			.field("ext_hash", &self.ext_hash)
			.field("client", &"<client>")
			.finish()
	}
}

// The above type is not `Unpin` by default unless the generic param `T` is,
// so we manually make it clear that Unpin is actually fine regardless of `T`
// (we don't care if this moves around in memory while it's "pinned").
impl<T: Config, C> Unpin for TxProgress<T, C> {}

impl<T: Config, C> TxProgress<T, C> {
	/// Instantiate a new [`TxProgress`] from a custom subscription.
	pub fn new(
		sub: StreamOfResults<BackendTxStatus<HashFor<T>>>,
		client: C,
		ext_hash: HashFor<T>,
	) -> Self {
		Self { sub: Some(sub), client, ext_hash }
	}

	/// Return the hash of the extrinsic.
	pub fn extrinsic_hash(&self) -> HashFor<T> {
		self.ext_hash
	}
}

impl<T, C> TxProgress<T, C>
where
	T: Config,
	C: OnlineClientT<T>,
{
	/// Return the next transaction status when it's emitted. This just delegates to the
	/// [`futures::Stream`] implementation for [`TxProgress`], but allows you to
	/// avoid importing that trait if you don't otherwise need it.
	pub async fn next(&mut self) -> Option<Result<TxStatus<T, C>, TransactionProgressError>> {
		StreamExt::next(self).await
	}

	/// Wait for the transaction to be finalized, and return a [`TxInBlock`]
	/// instance when it is, or an error if there was a problem waiting for finalization.
	///
	/// **Note:** consumes `self`. If you'd like to perform multiple actions as the state of the
	/// transaction progresses, use [`TxProgress::next()`] instead.
	///
	/// **Note:** transaction statuses like `Invalid`/`Usurped`/`Dropped` indicate with some
	/// probability that the transaction will not make it into a block but there is no guarantee
	/// that this is true. In those cases the stream is closed however, so you currently have no way
	/// to find out if they finally made it into a block or not.
	pub async fn wait_for_finalized(mut self) -> Result<TxInBlock<T, C>, TransactionProgressError> {
		while let Some(status) = self.next().await {
			match status? {
				// Finalized! Return.
				TxStatus::InFinalizedBlock(s) => return Ok(s),
				// Error scenarios; return the error.
				TxStatus::Error { message } => {
					return Err(TransactionStatusError::Error(message).into());
				},
				TxStatus::Invalid { message } => {
					return Err(TransactionStatusError::Invalid(message).into());
				},
				TxStatus::Dropped { message } => {
					return Err(TransactionStatusError::Dropped(message).into());
				},
				// Ignore and wait for next status event:
				_ => continue,
			}
		}
		Err(TransactionProgressError::UnexpectedEndOfTransactionStatusStream)
	}

	/// Wait for the transaction to be finalized, and for the transaction events to indicate
	/// that the transaction was successful. Returns the events associated with the transaction,
	/// as well as a couple of other details (block hash and extrinsic hash).
	///
	/// **Note:** consumes self. If you'd like to perform multiple actions as progress is made,
	/// use [`TxProgress::next()`] instead.
	///
	/// **Note:** transaction statuses like `Invalid`/`Usurped`/`Dropped` indicate with some
	/// probability that the transaction will not make it into a block but there is no guarantee
	/// that this is true. In those cases the stream is closed however, so you currently have no way
	/// to find out if they finally made it into a block or not.
	pub async fn wait_for_finalized_success(
		self,
	) -> Result<crate::blocks::ExtrinsicEvents<T>, TransactionFinalizedSuccessError> {
		let evs = self.wait_for_finalized().await?.wait_for_success().await?;
		Ok(evs)
	}
}

impl<T: Config, C: Clone> Stream for TxProgress<T, C> {
	type Item = Result<TxStatus<T, C>, TransactionProgressError>;

	fn poll_next(
		mut self: std::pin::Pin<&mut Self>,
		cx: &mut std::task::Context<'_>,
	) -> std::task::Poll<Option<Self::Item>> {
		let sub = match self.sub.as_mut() {
			Some(sub) => sub,
			None => return Poll::Ready(None),
		};

		sub.poll_next_unpin(cx)
			.map_err(TransactionProgressError::CannotGetNextProgressUpdate)
			.map_ok(|status| {
				match status {
					BackendTxStatus::Validated => TxStatus::Validated,
					BackendTxStatus::Broadcasted => TxStatus::Broadcasted,
					BackendTxStatus::NoLongerInBestBlock => TxStatus::NoLongerInBestBlock,
					BackendTxStatus::InBestBlock { hash } => TxStatus::InBestBlock(TxInBlock::new(
						hash,
						self.ext_hash,
						self.client.clone(),
					)),
					// These stream events mean that nothing further will be sent:
					BackendTxStatus::InFinalizedBlock { hash } => {
						self.sub = None;
						TxStatus::InFinalizedBlock(TxInBlock::new(
							hash,
							self.ext_hash,
							self.client.clone(),
						))
					},
					BackendTxStatus::Error { message } => {
						self.sub = None;
						TxStatus::Error { message }
					},
					BackendTxStatus::Invalid { message } => {
						self.sub = None;
						TxStatus::Invalid { message }
					},
					BackendTxStatus::Dropped { message } => {
						self.sub = None;
						TxStatus::Dropped { message }
					},
				}
			})
	}
}

/// Possible transaction statuses returned from our [`TxProgress::next()`] call.
#[derive_where(Debug; C)]
pub enum TxStatus<T: Config, C> {
	/// Transaction is part of the future queue.
	Validated,
	/// The transaction has been broadcast to other nodes.
	Broadcasted,
	/// Transaction is no longer in a best block.
	NoLongerInBestBlock,
	/// Transaction has been included in block with given hash.
	InBestBlock(TxInBlock<T, C>),
	/// Transaction has been finalized by a finality-gadget, e.g GRANDPA
	InFinalizedBlock(TxInBlock<T, C>),
	/// Something went wrong in the node.
	Error {
		/// Human readable message; what went wrong.
		message: String,
	},
	/// Transaction is invalid (bad nonce, signature etc).
	Invalid {
		/// Human readable message; why was it invalid.
		message: String,
	},
	/// The transaction was dropped.
	Dropped {
		/// Human readable message; why was it dropped.
		message: String,
	},
}

impl<T: Config, C> TxStatus<T, C> {
	/// A convenience method to return the finalized details. Returns
	/// [`None`] if the enum variant is not [`TxStatus::InFinalizedBlock`].
	pub fn as_finalized(&self) -> Option<&TxInBlock<T, C>> {
		match self {
			Self::InFinalizedBlock(val) => Some(val),
			_ => None,
		}
	}

	/// A convenience method to return the best block details. Returns
	/// [`None`] if the enum variant is not [`TxStatus::InBestBlock`].
	pub fn as_in_block(&self) -> Option<&TxInBlock<T, C>> {
		match self {
			Self::InBestBlock(val) => Some(val),
			_ => None,
		}
	}
}

/// This struct represents a transaction that has made it into a block.
#[derive_where(Debug; C)]
pub struct TxInBlock<T: Config, C> {
	block_ref: BlockRef<HashFor<T>>,
	ext_hash: HashFor<T>,
	client: C,
}

impl<T: Config, C> TxInBlock<T, C> {
	pub(crate) fn new(block_ref: BlockRef<HashFor<T>>, ext_hash: HashFor<T>, client: C) -> Self {
		Self { block_ref, ext_hash, client }
	}

	/// Return the hash of the block that the transaction has made it into.
	pub fn block_hash(&self) -> HashFor<T> {
		self.block_ref.hash()
	}

	/// Return the hash of the extrinsic that was submitted.
	pub fn extrinsic_hash(&self) -> HashFor<T> {
		self.ext_hash
	}
}

impl<T: Config, C: OnlineClientT<T>> TxInBlock<T, C> {
	/// Fetch the events associated with this transaction. If the transaction
	/// was successful (ie no `ExtrinsicFailed`) events were found, then we return
	/// the events associated with it. If the transaction was not successful, or
	/// something else went wrong, we return an error.
	///
	/// **Note:** If multiple `ExtrinsicFailed` errors are returned (for instance
	/// because a pallet chooses to emit one as an event, which is considered
	/// abnormal behaviour), it is not specified which of the errors is returned here.
	/// You can use [`TxInBlock::fetch_events`] instead if you'd like to
	/// work with multiple "error" events.
	///
	/// **Note:** This has to download block details from the node and decode events
	/// from them.
	pub async fn wait_for_success(
		&self,
	) -> Result<crate::blocks::ExtrinsicEvents<T>, TransactionEventsError> {
		let events = self.fetch_events().await?;

		// Try to find any errors; return the first one we encounter.
		for (ev_idx, ev) in events.iter().enumerate() {
			let ev = ev.map_err(|e| TransactionEventsError::CannotDecodeEventInBlock {
				event_index: ev_idx,
				block_hash: self.block_hash().into(),
				error: e,
			})?;

			if ev.pallet_name() == "System" && ev.variant_name() == "ExtrinsicFailed" {
				let dispatch_error =
					DispatchError::decode_from(ev.field_bytes(), self.client.metadata()).map_err(
						|e| TransactionEventsError::CannotDecodeDispatchError {
							error: e,
							bytes: ev.field_bytes().to_vec(),
						},
					)?;
				return Err(dispatch_error.into());
			}
		}

		Ok(events)
	}

	/// Fetch all of the events associated with this transaction. This succeeds whether
	/// the transaction was a success or not; it's up to you to handle the error and
	/// success events however you prefer.
	///
	/// **Note:** This has to download block details from the node and decode events
	/// from them.
	pub async fn fetch_events(
		&self,
	) -> Result<crate::blocks::ExtrinsicEvents<T>, TransactionEventsError> {
		let hasher = self.client.hasher();

		let block_body = self
			.client
			.backend()
			.block_body(self.block_ref.hash())
			.await
			.map_err(|e| TransactionEventsError::CannotFetchBlockBody {
				block_hash: self.block_hash().into(),
				error: e,
			})?
			.ok_or_else(|| TransactionEventsError::BlockNotFound {
				block_hash: self.block_hash().into(),
			})?;

		let extrinsic_idx = block_body
			.iter()
			.position(|ext| {
				use crate::config::Hasher;
				let Ok((_, stripped)) = strip_compact_prefix(ext) else {
					return false;
				};
				let hash = hasher.hash_of(&stripped);
				hash == self.ext_hash
			})
			// If we successfully obtain the block hash we think contains our
			// extrinsic, the extrinsic should be in there somewhere..
			.ok_or_else(|| TransactionEventsError::CannotFindTransactionInBlock {
				block_hash: self.block_hash().into(),
				transaction_hash: self.ext_hash.into(),
			})?;

		let events = EventsClient::new(self.client.clone())
			.at(self.block_ref.clone())
			.await
			.map_err(|e| TransactionEventsError::CannotFetchEventsForTransaction {
				block_hash: self.block_hash().into(),
				transaction_hash: self.ext_hash.into(),
				error: e,
			})?;

		Ok(crate::blocks::ExtrinsicEvents::new(self.ext_hash, extrinsic_idx as u32, events))
	}
}

#[cfg(test)]
mod test {
	use super::*;
	use pezkuwi_subxt_core::client::RuntimeVersion;

	use crate::{
		BizinikiwConfig,
		backend::{StreamOfResults, TransactionStatus},
		client::{OfflineClientT, OnlineClientT},
		config::{Config, HashFor},
		tx::TxProgress,
	};

	type MockTxProgress = TxProgress<BizinikiwConfig, MockClient>;
	type MockHash = HashFor<BizinikiwConfig>;
	type MockBizinikiwiTxStatus = TransactionStatus<MockHash>;

	/// a mock client to satisfy trait bounds in tests
	#[derive(Clone, Debug)]
	struct MockClient;

	impl OfflineClientT<BizinikiwConfig> for MockClient {
		fn metadata(&self) -> crate::Metadata {
			unimplemented!("just a mock impl to satisfy trait bounds")
		}

		fn genesis_hash(&self) -> MockHash {
			unimplemented!("just a mock impl to satisfy trait bounds")
		}

		fn runtime_version(&self) -> RuntimeVersion {
			unimplemented!("just a mock impl to satisfy trait bounds")
		}

		fn hasher(&self) -> <BizinikiwConfig as Config>::Hasher {
			unimplemented!("just a mock impl to satisfy trait bounds")
		}

		fn client_state(&self) -> pezkuwi_subxt_core::client::ClientState<BizinikiwConfig> {
			unimplemented!("just a mock impl to satisfy trait bounds")
		}
	}

	impl OnlineClientT<BizinikiwConfig> for MockClient {
		fn backend(&self) -> &dyn crate::backend::Backend<BizinikiwConfig> {
			unimplemented!("just a mock impl to satisfy trait bounds")
		}
	}

	#[tokio::test]
	async fn wait_for_finalized_returns_err_when_error() {
		let tx_progress = mock_tx_progress(vec![
			MockBizinikiwiTxStatus::Broadcasted,
			MockBizinikiwiTxStatus::Error { message: "err".into() },
		]);
		let finalized_result = tx_progress.wait_for_finalized().await;
		assert!(matches!(
			finalized_result,
			Err(TransactionProgressError::TransactionStatusError(TransactionStatusError::Error(e))) if e == "err"
		));
	}

	#[tokio::test]
	async fn wait_for_finalized_returns_err_when_invalid() {
		let tx_progress = mock_tx_progress(vec![
			MockBizinikiwiTxStatus::Broadcasted,
			MockBizinikiwiTxStatus::Invalid { message: "err".into() },
		]);
		let finalized_result = tx_progress.wait_for_finalized().await;
		assert!(matches!(
			finalized_result,
			Err(TransactionProgressError::TransactionStatusError(TransactionStatusError::Invalid(e))) if e == "err"
		));
	}

	#[tokio::test]
	async fn wait_for_finalized_returns_err_when_dropped() {
		let tx_progress = mock_tx_progress(vec![
			MockBizinikiwiTxStatus::Broadcasted,
			MockBizinikiwiTxStatus::Dropped { message: "err".into() },
		]);
		let finalized_result = tx_progress.wait_for_finalized().await;
		assert!(matches!(
			finalized_result,
			Err(TransactionProgressError::TransactionStatusError(TransactionStatusError::Dropped(e))) if e == "err"
		));
	}

	fn mock_tx_progress(statuses: Vec<MockBizinikiwiTxStatus>) -> MockTxProgress {
		let sub = create_bizinikiwi_tx_status_subscription(statuses);
		TxProgress::new(sub, MockClient, Default::default())
	}

	fn create_bizinikiwi_tx_status_subscription(
		elements: Vec<MockBizinikiwiTxStatus>,
	) -> StreamOfResults<MockBizinikiwiTxStatus> {
		let results = elements.into_iter().map(Ok);
		let stream = Box::pin(futures::stream::iter(results));
		let sub: StreamOfResults<MockBizinikiwiTxStatus> = StreamOfResults::new(stream);
		sub
	}
}