//! Experimental build tool for cargo

extern crate glob;
extern crate wasm_utils;
extern crate clap;
extern crate parity_wasm;

use std::{fs, io};
use std::io::Write;
use std::path::PathBuf;

use clap::{App, Arg};
use parity_wasm::elements;

use wasm_utils::{CREATE_SYMBOL, CALL_SYMBOL, SET_TEMP_RET_SYMBOL};

#[derive(Debug)]
pub enum Error {
	Io(io::Error),
	NoSuitableFile(String),
	TooManyFiles(String),
	NoEnvVar,
}

impl From<io::Error> for Error {
	fn from(err: io::Error) -> Self {
		Error::Io(err)
	}
}

pub fn wasm_path(target_dir: &str, bin_name: &str) -> String {
	let mut path = PathBuf::from(target_dir);
	path.push(format!("{}.wasm", bin_name));
	path.to_string_lossy().to_string()
}

pub fn process_output(target_dir: &str, bin_name: &str) -> Result<(), Error> {
	let mut cargo_path = PathBuf::from(target_dir);
	let wasm_name = bin_name.to_string().replace("-", "_");
	cargo_path.push("wasm32-unknown-emscripten");
	cargo_path.push("release");
	cargo_path.push(format!("{}.wasm", wasm_name));

	let mut target_path = PathBuf::from(target_dir);
	target_path.push(format!("{}.wasm", bin_name));
	fs::copy(cargo_path, target_path)?;

	Ok(())
}

fn has_ctor(module: &elements::Module) -> bool {
	if let Some(ref section) = module.export_section() {
		section.entries().iter().any(|e| CREATE_SYMBOL == e.field())
	} else {
		false
	}
}

fn main() {
	wasm_utils::init_log();

	let matches = App::new("wasm-build")
		.arg(Arg::with_name("target")
			.index(1)
			.required(true)
			.help("Cargo target directory"))
		.arg(Arg::with_name("wasm")
			.index(2)
			.required(true)
			.help("Wasm binary name"))
		.arg(Arg::with_name("skip_optimization")
			.help("Skip symbol optimization step producing final wasm")
			.long("skip-optimization"))
		.arg(Arg::with_name("skip_externalize")
			.help("Skip externalizer step producing final wasm")
			.long("skip-externalize"))
		.arg(Arg::with_name("runtime_type")
			.help("Injects RUNTIME_TYPE global export")
			.takes_value(true)
			.long("runtime-type"))
		.arg(Arg::with_name("runtime_version")
			.help("Injects RUNTIME_VERSION global export")
			.takes_value(true)
			.long("runtime-version"))
		.get_matches();

    let target_dir = matches.value_of("target").expect("is required; qed");
    let wasm_binary = matches.value_of("wasm").expect("is required; qed");

	process_output(target_dir, wasm_binary).expect("Failed to process cargo target directory");

	let path = wasm_path(target_dir, wasm_binary);

	let mut module = parity_wasm::deserialize_file(&path).unwrap();

	if !matches.is_present("skip_externalize") {
		module = wasm_utils::externalize(
			module,
			vec!["_free", "_malloc", "_memcpy", "_memset", "_memmove"],
		);
	}

	if let Some(runtime_type) = matches.value_of("runtime_type") {
		let runtime_type: &[u8] = runtime_type.as_bytes();
		if runtime_type.len() != 4 {
			panic!("--runtime-type should be equal to 4 bytes");
		}
		let runtime_version: u32 = matches.value_of("runtime_version").unwrap_or("1").parse()
			.expect("--runtime-version should be a positive integer");
		module = wasm_utils::inject_runtime_type(module, &runtime_type, runtime_version);
	}

	let mut ctor_module = module.clone();

	if !matches.is_present("skip_optimization") {
		wasm_utils::optimize(&mut module, vec![CALL_SYMBOL, SET_TEMP_RET_SYMBOL]).expect("Optimizer to finish without errors");
	}

	let raw_module = parity_wasm::serialize(module).expect("Failed to serialize module");

	// If module has an exported function with name=CREATE_SYMBOL
	// build will pack the module (raw_module) into this funciton and export as CALL_SYMBOL.
	// Otherwise it will just save an optimised raw_module
	if has_ctor(&ctor_module) {
		if !matches.is_present("skip_optimization") {
			wasm_utils::optimize(&mut ctor_module, vec![CREATE_SYMBOL, SET_TEMP_RET_SYMBOL]).expect("Optimizer to finish without errors");
		}
		wasm_utils::pack_instance(raw_module, &mut ctor_module);
		parity_wasm::serialize_to_file(&path, ctor_module).expect("Failed to serialize to file");
	} else {
		let mut file = fs::File::create(&path).expect("Failed to create file");
		file.write_all(&raw_module).expect("Failed to write module to file");
	}

}

#[cfg(test)]
mod tests {
	extern crate tempdir;

	use self::tempdir::TempDir;
	use std::fs;

	use super::process_output;

	#[test]
	fn processes_cargo_output() {
    	let tmp_dir = TempDir::new("target").expect("temp dir failed");

		let target_path = tmp_dir.path().join("wasm32-unknown-emscripten").join("release");
		fs::create_dir_all(target_path.clone()).expect("create dir failed");

		{
			use std::io::Write;

			let wasm_path = target_path.join("example_wasm.wasm");
			let mut f = fs::File::create(wasm_path).expect("create fail failed");
			f.write(b"\0asm").expect("write file failed");
		}

		process_output(&tmp_dir.path().to_string_lossy(), "example-wasm").expect("process output failed");

		assert!(
			fs::metadata(tmp_dir.path().join("example-wasm.wasm")).expect("metadata failed").is_file()
		)
	}

}