//! This file will run at build time to autogenerate the Emscripten tests
//! It will compile the files indicated in TESTS, to:executable and .wasm
//! - Compile using cc and get the output from it (expected output)
//! - Compile using emcc and get the .wasm from it (wasm)
//! - Generate the test that will compare the output of running the .wasm file
//!   with wasmer with the expected output
use std::fs;
use std::path::PathBuf;
use std::process::Command;


static BANNER: &str = "// Rust test file autogenerated with cargo build (build/emtests.rs).
// Please do NOT modify it by hand, as it will be reseted on next build.\n";

const TESTS: [&str; 2] = [
    "emtests/puts.c",
    "emtests/printf.c"
];

pub fn compile(file: &str) -> String {
    let mut output_path = PathBuf::from(file);
    output_path.set_extension("out");
    let output_str = output_path.to_str().unwrap();
    
    // Compile to .out
    Command::new("cc")
            .arg(file)
            .arg("-o")
            .arg(output_str)
            .output()
            .expect("failed to execute process");

    // Get the result of .out
    let output = Command::new(output_str)
            .arg(output_str)
            .output()
            .expect("failed to execute process");

    // Remove executable
    fs::remove_file(output_str).unwrap();

    let mut output_path = PathBuf::from(file);
    output_path.set_extension("js");
    let output_str = output_path.to_str().unwrap();

    // Compile to wasm
    let _wasm_compilation = Command::new("emcc")
            .arg(file)
            .arg("-s").arg("WASM=1")
            .arg("-o")
            .arg(output_str)
            .output()
            .expect("failed to execute process");

    // panic!("{:?}", wasm_compilation);
    // if output.stderr {
    //     panic!("{}", output.stderr);
    // }
    // Remove js file
    fs::remove_file(output_str).unwrap();

    let mut output_path = PathBuf::from(file);
    output_path.set_extension("output");
    let module_name = output_path.file_stem().unwrap().to_str().unwrap().to_owned();
    
    let output_str = output_path.to_str().unwrap();

    // Write the output to file
    fs::write(output_str, output.stdout).expect("Unable to write file");

    let rust_test_filepath = format!(
        concat!(env!("CARGO_MANIFEST_DIR"), "/src/emtests/{}.rs"),
        module_name.as_str()
    );

    let contents = format!("#[test]
fn test_{module_name}() {{
    assert_emscripten_output!(\"../../emtests/{module_name}.wasm\", \"{module_name}\", vec![], \"../../emtests/{module_name}.output\");
}}
", module_name=module_name);

    fs::write(&rust_test_filepath, contents.as_bytes()).unwrap();

    module_name
    
    // panic!("OUTPUT: {:?}", output);
}

pub fn build() {
    let rust_test_modpath = concat!(env!("CARGO_MANIFEST_DIR"), "/src/emtests/mod.rs");

    let mut modules: Vec<String> = Vec::new();
    // modules.reserve_exact(TESTS.len());
    for test in TESTS.iter() {
        let moudle_name = compile(test);
        modules.push(format!("mod {};", moudle_name));
    }
    modules.insert(0, BANNER.to_string());
    modules.insert(1, "// The _common module is not autogenerated, as it provides common macros for the emtests\n#[macro_use]\nmod _common;".to_string());
    // We add an empty line
    modules.push("".to_string());

    let modfile: String = modules.join("\n");
    let source = fs::read(&rust_test_modpath).unwrap();
    // We only modify the mod file if has changed
    if source != modfile.as_bytes() {
        fs::write(&rust_test_modpath, modfile.as_bytes()).unwrap();
    }
}