input: &str,

output: &str,

imports: &str,

host_dir: &PathBuf,

host_main: &PathBuf,

) -> io::Result<()> {

let mut host_program = imports.to_string();

let contents = fs::read_to_string(host_dir)?;

host_program.push_str(&contents);

// Insert input body

let host_program = host_program.replace(utils::HOST_INPUT, input);

// Insert output body

let host_program = host_program.replace(utils::HOST_OUTPUT, output);

// Extract Variable names from host and add them to the ExecutorEnv::builder()

let values = utils::extract_regex(

host_main,

&format!("{}[(](.*?)[)]", regex::escape(utils::IO_WRITE)),

)?;

// Construct new Environment Builder

let mut new_builder = RISC0_ENV_BUILDER.to_string();

for value in values {

new_builder.push_str(&format!(".write({}).unwrap()", value));

}

new_builder.push_str(".build().unwrap();");

// Replace environment builder in host with new one

let host_program = host_program.replace(

"let env = ExecutorEnv::builder().build().unwrap();",

&new_builder,

);

// replace zkRust::out()

let host_program = host_program.replace(utils::IO_OUT, RISC0_IO_OUT);

let mut file = fs::File::create(host_main)?;

file.write_all(host_program.as_bytes())?;

utils::remove_lines(host_main, "zk_rust_io::write(")?;

Ok(())

Command::new("cargo")

.arg("run")

.arg("--release")

.arg("--")

.arg(current_dir)

.current_dir(guest_path)

.status()