extern crate lalrpop;

use std::env;
use std::fs::{self, File};
use std::io::Write;
use std::path::{Path, PathBuf};

fn main() {
    lalrpop::process_root().unwrap();
    if let Err(e) = generate_example_tests() {
        eprintln!("Failure building example tests: {}", e);
        std::process::exit(3);
    }
}

fn generate_example_tests() -> std::io::Result<()> {
    let out_dir = env::var_os("OUT_DIR").expect("OUT_DIR");
    let dest_path = Path::new(&out_dir).join("examples.rs");
    let mut output = File::create(dest_path)?;

    generate_tests(&mut output, PathBuf::from("examples"))?;

    println!("cargo:rerun-if-changed=build.rs");
    println!("cargo:rerun-if-changed=example.rs");
    Ok(())
}

fn generate_tests(f: &mut File, path_so_far: PathBuf) -> std::io::Result<()> {
    for entry in fs::read_dir(path_so_far)? {
        let entry = entry?;
        let file_name = entry
            .file_name()
            .into_string()
            .expect("reasonable file name");
        let name = file_name.trim_end_matches(".ngr");

        if entry.file_type()?.is_dir() {
            writeln!(f, "mod {} {{", name)?;
            writeln!(f, "  use super::*;")?;
            generate_tests(f, entry.path())?;
            writeln!(f, "}}")?;
        } else {
            writeln!(f, "#[test]")?;
            writeln!(f, "fn {}() {{", name)?;
            writeln!(f, "  let mut file_database = SimpleFiles::new();")?;
            writeln!(
                f,
                "  let syntax = Syntax::parse_file(&mut file_database, {:?});",
                entry.path().display()
            )?;
            if entry.path().to_string_lossy().contains("broken") {
                writeln!(f, "  if syntax.is_err() {{")?;
                writeln!(f, "     return;")?;
                writeln!(f, "  }}")?;
                writeln!(f, "  let (errors, _) = syntax.unwrap().validate();")?;
                writeln!(
                    f,
                    "  assert_ne!(errors.len(), 0, \"should have seen an error\");"
                )?;
            } else {
                writeln!(
                    f,
                    "  let syntax = syntax.expect(\"file should have parsed\");"
                )?;
                writeln!(f, "  let (errors, _) = syntax.validate();")?;
                writeln!(
                    f,
                    "  assert_eq!(errors.len(), 0, \"file should have no validation errors\");"
                )?;
                writeln!(f, "  let syntax_result = syntax.eval();")?;
                writeln!(f, "  let ir = IR::from(syntax);")?;
                writeln!(
                    f,
                    "  assert_eq!(syntax_result, ir.eval(), \"syntax equivalent to IR\");"
                )?;
                writeln!(f, "  let compiled_result = Backend::<JITModule>::eval(ir);")?;
                writeln!(f, "  assert_eq!(syntax_result, compiled_result);")?;
            }
            writeln!(f, "}}")?;
        }
    }

    Ok(())
}