Reduce code duplication and make evaluation order determinisitic

The Rust compiler doesn't guarantee in which order field initialization
are executed. By extracting them, we can make sure they run in a certain
order. This will be important as we add more validations that can
fail.

swap/src/cli/command.rs

@@ -69,41 +69,34 @@ where
     let arguments = match args.cmd {
         RawCommand::BuyXmr {
             seller: Seller { seller },
-            bitcoin:
+            bitcoin,
-                Bitcoin {
-                    bitcoin_electrum_rpc_url,
-                    bitcoin_target_block,
-                },
             bitcoin_change_address,
-            monero: Monero {
+            monero,
-                monero_daemon_address,
-            },
             monero_receive_address,
             tor: Tor { tor_socks5_port },
-        } => Arguments {
+        } => {
-            env_config: env_config_from(is_testnet),
+            let (bitcoin_electrum_rpc_url, bitcoin_target_block) =
-            debug,
+                bitcoin.apply_defaults(is_testnet)?;
-            json,
+            let monero_daemon_address = monero.apply_defaults(is_testnet);
-            data_dir: data::data_dir_from(data, is_testnet)?,
+            let monero_receive_address =
-            cmd: Command::BuyXmr {
+                validate_monero_address(monero_receive_address, is_testnet)?;
-                seller,
+
-                bitcoin_electrum_rpc_url: bitcoin_electrum_rpc_url_from(
+            Arguments {
+                env_config: env_config_from(is_testnet),
+                debug,
+                json,
+                data_dir: data::data_dir_from(data, is_testnet)?,
+                cmd: Command::BuyXmr {
+                    seller,
                     bitcoin_electrum_rpc_url,
-                    is_testnet,
+                    bitcoin_target_block,
-                )?,
+                    bitcoin_change_address,
-                bitcoin_target_block: bitcoin_target_block_from(bitcoin_target_block, is_testnet),
-                bitcoin_change_address,
-                monero_receive_address: validate_monero_address(
                     monero_receive_address,
-                    is_testnet,
-                )?,
-                monero_daemon_address: monero_daemon_address_from(
                     monero_daemon_address,
-                    is_testnet,
+                    tor_socks5_port,
-                ),
+                },
-                tor_socks5_port,
+            }
-            },
+        }
-        },
         RawCommand::History => Arguments {
             env_config: env_config_from(is_testnet),
             debug,
@@ -113,80 +106,70 @@ where
         },
         RawCommand::Resume {
             swap_id: SwapId { swap_id },
-            bitcoin:
+            bitcoin,
-                Bitcoin {
+            monero,
+            tor: Tor { tor_socks5_port },
+        } => {
+            let (bitcoin_electrum_rpc_url, bitcoin_target_block) =
+                bitcoin.apply_defaults(is_testnet)?;
+            let monero_daemon_address = monero.apply_defaults(is_testnet);
+
+            Arguments {
+                env_config: env_config_from(is_testnet),
+                debug,
+                json,
+                data_dir: data::data_dir_from(data, is_testnet)?,
+                cmd: Command::Resume {
+                    swap_id,
                     bitcoin_electrum_rpc_url,
                     bitcoin_target_block,
-                },
-            monero: Monero {
-                monero_daemon_address,
-            },
-            tor: Tor { tor_socks5_port },
-        } => Arguments {
-            env_config: env_config_from(is_testnet),
-            debug,
-            json,
-            data_dir: data::data_dir_from(data, is_testnet)?,
-            cmd: Command::Resume {
-                swap_id,
-                bitcoin_electrum_rpc_url: bitcoin_electrum_rpc_url_from(
-                    bitcoin_electrum_rpc_url,
-                    is_testnet,
-                )?,
-                bitcoin_target_block: bitcoin_target_block_from(bitcoin_target_block, is_testnet),
-                monero_daemon_address: monero_daemon_address_from(
                     monero_daemon_address,
-                    is_testnet,
+                    tor_socks5_port,
-                ),
+                },
-                tor_socks5_port,
+            }
-            },
+        }
-        },
         RawCommand::Cancel {
             swap_id: SwapId { swap_id },
             force,
-            bitcoin:
+            bitcoin,
-                Bitcoin {
+        } => {
+            let (bitcoin_electrum_rpc_url, bitcoin_target_block) =
+                bitcoin.apply_defaults(is_testnet)?;
+
+            Arguments {
+                env_config: env_config_from(is_testnet),
+                debug,
+                json,
+                data_dir: data::data_dir_from(data, is_testnet)?,
+                cmd: Command::Cancel {
+                    swap_id,
+                    force,
                     bitcoin_electrum_rpc_url,
                     bitcoin_target_block,
                 },
-        } => Arguments {
+            }
-            env_config: env_config_from(is_testnet),
+        }
-            debug,
-            json,
-            data_dir: data::data_dir_from(data, is_testnet)?,
-            cmd: Command::Cancel {
-                swap_id,
-                force,
-                bitcoin_electrum_rpc_url: bitcoin_electrum_rpc_url_from(
-                    bitcoin_electrum_rpc_url,
-                    is_testnet,
-                )?,
-                bitcoin_target_block: bitcoin_target_block_from(bitcoin_target_block, is_testnet),
-            },
-        },
         RawCommand::Refund {
             swap_id: SwapId { swap_id },
             force,
-            bitcoin:
+            bitcoin,
-                Bitcoin {
+        } => {
+            let (bitcoin_electrum_rpc_url, bitcoin_target_block) =
+                bitcoin.apply_defaults(is_testnet)?;
+
+            Arguments {
+                env_config: env_config_from(is_testnet),
+                debug,
+                json,
+                data_dir: data::data_dir_from(data, is_testnet)?,
+                cmd: Command::Refund {
+                    swap_id,
+                    force,
                     bitcoin_electrum_rpc_url,
                     bitcoin_target_block,
                 },
-        } => Arguments {
+            }
-            env_config: env_config_from(is_testnet),
+        }
-            debug,
-            json,
-            data_dir: data::data_dir_from(data, is_testnet)?,
-            cmd: Command::Refund {
-                swap_id,
-                force,
-                bitcoin_electrum_rpc_url: bitcoin_electrum_rpc_url_from(
-                    bitcoin_electrum_rpc_url,
-                    is_testnet,
-                )?,
-                bitcoin_target_block: bitcoin_target_block_from(bitcoin_target_block, is_testnet),
-            },
-        },
         RawCommand::ListSellers {
             rendezvous_point,
             tor: Tor { tor_socks5_port },
@@ -369,6 +352,18 @@ struct Monero {
     monero_daemon_address: Option<String>,
 }
 
+impl Monero {
+    fn apply_defaults(self, testnet: bool) -> String {
+        if let Some(address) = self.monero_daemon_address {
+            address
+        } else if testnet {
+            DEFAULT_MONERO_DAEMON_ADDRESS_STAGENET.to_string()
+        } else {
+            DEFAULT_MONERO_DAEMON_ADDRESS.to_string()
+        }
+    }
+}
+
 #[derive(structopt::StructOpt, Debug)]
 struct Bitcoin {
     #[structopt(long = "electrum-rpc", help = "Provide the Bitcoin Electrum RPC URL")]
@@ -381,6 +376,28 @@ struct Bitcoin {
     bitcoin_target_block: Option<usize>,
 }
 
+impl Bitcoin {
+    fn apply_defaults(self, testnet: bool) -> Result<(Url, usize)> {
+        let bitcoin_electrum_rpc_url = if let Some(url) = self.bitcoin_electrum_rpc_url {
+            url
+        } else if testnet {
+            Url::from_str(DEFAULT_ELECTRUM_RPC_URL_TESTNET)?
+        } else {
+            Url::from_str(DEFAULT_ELECTRUM_RPC_URL)?
+        };
+
+        let bitcoin_target_block = if let Some(target_block) = self.bitcoin_target_block {
+            target_block
+        } else if testnet {
+            DEFAULT_BITCOIN_CONFIRMATION_TARGET_TESTNET
+        } else {
+            DEFAULT_BITCOIN_CONFIRMATION_TARGET
+        };
+
+        Ok((bitcoin_electrum_rpc_url, bitcoin_target_block))
+    }
+}
+
 #[derive(structopt::StructOpt, Debug)]
 struct Tor {
     #[structopt(
@@ -428,16 +445,6 @@ mod data {
     }
 }
 
-fn bitcoin_electrum_rpc_url_from(url: Option<Url>, testnet: bool) -> Result<Url> {
-    if let Some(url) = url {
-        Ok(url)
-    } else if testnet {
-        Ok(Url::from_str(DEFAULT_ELECTRUM_RPC_URL_TESTNET)?)
-    } else {
-        Ok(Url::from_str(DEFAULT_ELECTRUM_RPC_URL)?)
-    }
-}
-
 fn rendezvous_namespace_from(is_testnet: bool) -> XmrBtcNamespace {
     if is_testnet {
         XmrBtcNamespace::Testnet
@@ -446,26 +453,6 @@ fn rendezvous_namespace_from(is_testnet: bool) -> XmrBtcNamespace {
     }
 }
 
-fn bitcoin_target_block_from(target_block: Option<usize>, testnet: bool) -> usize {
-    if let Some(target_block) = target_block {
-        target_block
-    } else if testnet {
-        DEFAULT_BITCOIN_CONFIRMATION_TARGET_TESTNET
-    } else {
-        DEFAULT_BITCOIN_CONFIRMATION_TARGET
-    }
-}
-
-fn monero_daemon_address_from(address: Option<String>, testnet: bool) -> String {
-    if let Some(address) = address {
-        address
-    } else if testnet {
-        DEFAULT_MONERO_DAEMON_ADDRESS_STAGENET.to_string()
-    } else {
-        DEFAULT_MONERO_DAEMON_ADDRESS.to_string()
-    }
-}
-
 fn env_config_from(testnet: bool) -> env::Config {
     if testnet {
         env::Testnet::get_config()