Compile contracts using solcjs or solc

bridge/build.rs

@@ -1,3 +1,4 @@
+use std::fs;
 use std::process::Command;
 
 fn main() {
@@ -15,14 +16,6 @@ fn main() {
     let git_hash = String::from_utf8(output.stdout).unwrap();
     println!("cargo:rustc-env=GIT_HASH={}", git_hash);
 
-    // make solc version used to compile contracts (`solc --version`)
-    // available via `env!("SOLC_VERSION")` in sources
-    let output = Command::new("solc").args(&["--version"]).output().unwrap();
-    let output_string = String::from_utf8(output.stdout).unwrap();
-    let solc_version = output_string.lines().last().unwrap();
-    println!("cargo:rustc-env=SOLC_VERSION={}", solc_version);
-
-    // compile contracts for inclusion with ethabis `use_contract!`
     match Command::new("solc")
         .arg("--abi")
         .arg("--bin")
@@ -40,14 +33,110 @@ fn main() {
                 } else {
                     panic!("`solc` exited because it was terminated by a signal");
                 }
+            } else {
+                let output = Command::new("solc").args(&["--version"]).output().unwrap();
+                let output_string = String::from_utf8(output.stdout).unwrap();
+                let solc_version = output_string.lines().last().unwrap();
+                println!("cargo:rustc-env=SOLC_VERSION={}", solc_version);
             }
         }
         Err(err) => {
+            // we could have panicked here
             if let std::io::ErrorKind::NotFound = err.kind() {
-                panic!("`solc` executable not found in `$PATH`. `solc` is required to compile the bridge contracts. please install it: https://solidity.readthedocs.io/en/develop/installing-solidity.html");
+                // but let's see if solcjs is available or not
+                compile_using_solcjs();
             } else {
                 panic!("an error occurred when trying to spawn `solc`: {}", err);
             }
         }
     }
 }
+
+fn compile_using_solcjs() {
+    match Command::new("solcjs").arg("--version").output() {
+        Ok(exit_status) => {
+            let output_string = String::from_utf8(exit_status.stdout).unwrap();
+            let solc_version = output_string.lines().last().unwrap();
+            println!("cargo:rustc-env=SOLC_VERSION={}", solc_version);
+            // overwrite option is not available in solcjs
+            // so we better remove old compiled contracts
+            match fs::remove_dir_all("../compiled_contracts") {
+                Ok(()) => {
+                    println!("Removed old files");
+                }
+                Err(err) => {
+                    // do not panic if we are unable to delete files
+                    // this may occur if files do not exist, due to this being the first run
+                    println!("Files not removed: {}", err);
+                }
+            };
+            // compile contracts using `solcjs`
+            match Command::new("solcjs")
+                .arg("--abi")
+                .arg("--bin")
+                .arg("--optimize")
+                .arg("--output-dir")
+                .arg("../compiled_contracts")
+                .arg("../contracts/bridge.sol")
+                .status()
+            {
+                Ok(exit_status) => {
+                    if !exit_status.success() {
+                        if let Some(code) = exit_status.code() {
+                            panic!("`solcjs` exited with error exit status code `{}`", code);
+                        } else {
+                            panic!("`solcjs` exited because it was terminated by a signal");
+                        }
+                    } else {
+                        // make solcjs version used to compile contracts (`solcjs --version`)
+                        // available via `env!("SOLC_VERSION")` in sources
+                        let output = Command::new("solcjs")
+                            .args(&["--version"])
+                            .output()
+                            .unwrap();
+                        let output_string = String::from_utf8(output.stdout).unwrap();
+                        let solc_version = output_string.lines().last().unwrap();
+                        println!("cargo:rustc-env=SOLC_VERSION={}", solc_version);
+                    }
+                }
+                Err(err) => {
+                    panic!("an error occurred when trying to spawn `solcjs`: {}", err);
+                }
+            }
+            // contracts compiled using solcjs are named differently
+            // we need to rename them
+            let prepend = "../compiled_contracts/";
+            let paths = fs::read_dir("../compiled_contracts").unwrap();
+            for path in paths {
+                let _file_name: String = format!(
+                    "{}{}",
+                    prepend,
+                    path.unwrap().file_name().into_string().expect(
+                        "error: the first argument is not a file\
+                         system path representable in UTF-8.",
+                    )
+                );
+                let _replaced_name: String =
+                    str::replace(&_file_name, "___contracts_bridge_sol_", "");
+                match fs::rename(&_file_name, &_replaced_name) {
+                    Ok(_status) => {
+                        println!("Renamed successfully");
+                    }
+                    Err(err) => {
+                        println!("Tried looking for {}", &_file_name);
+                        panic!("Error renaming: {}", err);
+                    }
+                }
+                println!("Old name: {}, New name: {}", _file_name, _replaced_name);
+            }
+        }
+        Err(err) => {
+            // this shows that neither solc is available, nor solcjs
+            if let std::io::ErrorKind::NotFound = err.kind() {
+                panic!("No compiler available for solidity. Try installing `solc` or `solcjs`");
+            } else {
+                panic!("Unable to run solcjs: {}", err);
+            }
+        }
+    }
+}