[blockchain] Add an AnyBlockchain enum to allow switching at runtime

This is related to #43

src/blockchain/any.rs

@@ -0,0 +1,166 @@
+// Magical Bitcoin Library
+// Written in 2020 by
+//     Alekos Filini <alekos.filini@gmail.com>
+//
+// Copyright (c) 2020 Magical Bitcoin
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+
+//! Runtime-checked blockchain types
+//!
+//! This module provides the implementation of [`AnyBlockchain`] which allows switching the
+//! inner [`Blockchain`] type at runtime.
+
+use super::*;
+
+macro_rules! impl_from {
+    ( $from:ty, $to:ty, $variant:ident, $( $cfg:tt )* ) => {
+        $( $cfg )*
+        impl From<$from> for $to {
+            fn from(inner: $from) -> Self {
+                <$to>::$variant(inner)
+            }
+        }
+    };
+}
+
+macro_rules! impl_inner_method {
+    ( $self:expr, $name:ident $(, $args:expr)* ) => {
+        match $self {
+            #[cfg(feature = "electrum")]
+            AnyBlockchain::Electrum(inner) => inner.$name( $($args, )* ),
+            #[cfg(feature = "esplora")]
+            AnyBlockchain::Esplora(inner) => inner.$name( $($args, )* ),
+            #[cfg(feature = "compact_filters")]
+            AnyBlockchain::CompactFilters(inner) => inner.$name( $($args, )* ),
+        }
+    }
+}
+
+/// Type that can contain any of the [`Blockchain`] types defined by the library
+///
+/// It allows switching backend at runtime
+pub enum AnyBlockchain {
+    #[cfg(feature = "electrum")]
+    #[cfg_attr(docsrs, doc(cfg(feature = "electrum")))]
+    Electrum(electrum::ElectrumBlockchain),
+    #[cfg(feature = "esplora")]
+    #[cfg_attr(docsrs, doc(cfg(feature = "esplora")))]
+    Esplora(esplora::EsploraBlockchain),
+    #[cfg(feature = "compact_filters")]
+    #[cfg_attr(docsrs, doc(cfg(feature = "compact_filters")))]
+    CompactFilters(compact_filters::CompactFiltersBlockchain),
+}
+
+#[maybe_async]
+impl Blockchain for AnyBlockchain {
+    fn get_capabilities(&self) -> HashSet<Capability> {
+        maybe_await!(impl_inner_method!(self, get_capabilities))
+    }
+
+    fn setup<D: BatchDatabase, P: 'static + Progress>(
+        &self,
+        stop_gap: Option<usize>,
+        database: &mut D,
+        progress_update: P,
+    ) -> Result<(), Error> {
+        maybe_await!(impl_inner_method!(
+            self,
+            setup,
+            stop_gap,
+            database,
+            progress_update
+        ))
+    }
+    fn sync<D: BatchDatabase, P: 'static + Progress>(
+        &self,
+        stop_gap: Option<usize>,
+        database: &mut D,
+        progress_update: P,
+    ) -> Result<(), Error> {
+        maybe_await!(impl_inner_method!(
+            self,
+            sync,
+            stop_gap,
+            database,
+            progress_update
+        ))
+    }
+
+    fn get_tx(&self, txid: &Txid) -> Result<Option<Transaction>, Error> {
+        maybe_await!(impl_inner_method!(self, get_tx, txid))
+    }
+    fn broadcast(&self, tx: &Transaction) -> Result<(), Error> {
+        maybe_await!(impl_inner_method!(self, broadcast, tx))
+    }
+
+    fn get_height(&self) -> Result<u32, Error> {
+        maybe_await!(impl_inner_method!(self, get_height))
+    }
+    fn estimate_fee(&self, target: usize) -> Result<FeeRate, Error> {
+        maybe_await!(impl_inner_method!(self, estimate_fee, target))
+    }
+}
+
+impl_from!(electrum::ElectrumBlockchain, AnyBlockchain, Electrum, #[cfg(feature = "electrum")]);
+impl_from!(esplora::EsploraBlockchain, AnyBlockchain, Esplora, #[cfg(feature = "esplora")]);
+impl_from!(compact_filters::CompactFiltersBlockchain, AnyBlockchain, CompactFilters, #[cfg(feature = "compact_filters")]);
+
+/// Type that can contain any of the blockchain configurations defined by the library
+///
+/// This allows storing a single configuration that can be loaded into an [`AnyBlockchain`]
+/// instance. Wallets that plan to offer users the ability to switch blockchain backend at runtime
+/// will find this particularly useful.
+#[derive(Debug, serde::Serialize, serde::Deserialize)]
+pub enum AnyBlockchainConfig {
+    #[cfg(feature = "electrum")]
+    #[cfg_attr(docsrs, doc(cfg(feature = "electrum")))]
+    Electrum(electrum::ElectrumBlockchainConfig),
+    #[cfg(feature = "esplora")]
+    #[cfg_attr(docsrs, doc(cfg(feature = "esplora")))]
+    Esplora(esplora::EsploraBlockchainConfig),
+    #[cfg(feature = "compact_filters")]
+    #[cfg_attr(docsrs, doc(cfg(feature = "compact_filters")))]
+    CompactFilters(compact_filters::CompactFiltersBlockchainConfig),
+}
+
+impl ConfigurableBlockchain for AnyBlockchain {
+    type Config = AnyBlockchainConfig;
+
+    fn from_config(config: &Self::Config) -> Result<Self, Error> {
+        Ok(match config {
+            #[cfg(feature = "electrum")]
+            AnyBlockchainConfig::Electrum(inner) => {
+                AnyBlockchain::Electrum(electrum::ElectrumBlockchain::from_config(inner)?)
+            }
+            #[cfg(feature = "esplora")]
+            AnyBlockchainConfig::Esplora(inner) => {
+                AnyBlockchain::Esplora(esplora::EsploraBlockchain::from_config(inner)?)
+            }
+            #[cfg(feature = "compact_filters")]
+            AnyBlockchainConfig::CompactFilters(inner) => AnyBlockchain::CompactFilters(
+                compact_filters::CompactFiltersBlockchain::from_config(inner)?,
+            ),
+        })
+    }
+}
+
+impl_from!(electrum::ElectrumBlockchainConfig, AnyBlockchainConfig, Electrum, #[cfg(feature = "electrum")]);
+impl_from!(esplora::EsploraBlockchainConfig, AnyBlockchainConfig, Esplora, #[cfg(feature = "esplora")]);
+impl_from!(compact_filters::CompactFiltersBlockchainConfig, AnyBlockchainConfig, CompactFilters, #[cfg(feature = "compact_filters")]);

src/blockchain/mod.rs

@@ -42,6 +42,11 @@ use crate::FeeRate;
 
 pub(crate) mod utils;
 
+#[cfg(any(feature = "electrum", feature = "esplora", feature = "compact_filters"))]
+pub mod any;
+#[cfg(any(feature = "electrum", feature = "esplora", feature = "compact_filters"))]
+pub use any::{AnyBlockchain, AnyBlockchainConfig};
+
 #[cfg(feature = "electrum")]
 #[cfg_attr(docsrs, doc(cfg(feature = "electrum")))]
 pub mod electrum;