//! Build program to generate a program which runs all the testsuites.
//!
//! By generating a separate `#[test]` test for each file, we allow cargo test
//! to automatically run the files in parallel.
//!
//! Idea adapted from: https://github.com/bytecodealliance/wasmtime/blob/master/build.rs
//! Thanks @sunfishcode

fn main() {
    #[cfg(feature = "wasm_tests")]
    wasm_tests::build_and_generate_tests();
}

#[cfg(feature = "wasm_tests")]
mod wasm_tests {
    use std::env;
    use std::fs::{read_dir, DirEntry, File};
    use std::io::{self, Write};
    use std::path::{Path, PathBuf};
    use std::process::{Command, Stdio};

    pub(crate) fn build_and_generate_tests() {
        // Validate if any of test sources are present and if they changed
        // This should always work since there is no submodule to init anymore
        let bin_tests = std::fs::read_dir("wasi-misc-tests/src/bin").unwrap();
        for test in bin_tests {
            if let Ok(test_file) = test {
                let test_file_path = test_file
                    .path()
                    .into_os_string()
                    .into_string()
                    .expect("test file path");
                println!("cargo:rerun-if-changed={}", test_file_path);
            }
        }
        // Build tests to OUT_DIR (target/*/build/wasi-common-*/out/wasm32-wasi/release/*.wasm)
        let out_dir = PathBuf::from(
            env::var("OUT_DIR").expect("The OUT_DIR environment variable must be set"),
        );
        let mut out = File::create(out_dir.join("wasi_misc_tests.rs"))
            .expect("error generating test source file");
        build_tests("wasi-misc-tests", &out_dir).expect("building tests");
        test_directory(&mut out, "wasi-misc-tests", &out_dir).expect("generating tests");
    }

    fn build_tests(testsuite: &str, out_dir: &Path) -> io::Result<()> {
        let mut cmd = Command::new("cargo");
        cmd.args(&[
            "build",
            "--release",
            "--target=wasm32-wasi",
            "--target-dir",
            out_dir.to_str().unwrap(),
        ])
        .stdout(Stdio::inherit())
        .stderr(Stdio::inherit())
        .current_dir(testsuite);
        let output = cmd.output()?;

        let status = output.status;
        if !status.success() {
            panic!(
                "Building tests failed: exit code: {}",
                status.code().unwrap()
            );
        }

        Ok(())
    }

    fn test_directory(out: &mut File, testsuite: &str, out_dir: &Path) -> io::Result<()> {
        let mut dir_entries: Vec<_> = read_dir(out_dir.join("wasm32-wasi/release"))
            .expect("reading testsuite directory")
            .map(|r| r.expect("reading testsuite directory entry"))
            .filter(|dir_entry| {
                let p = dir_entry.path();
                if let Some(ext) = p.extension() {
                    // Only look at wast files.
                    if ext == "wasm" {
                        // Ignore files starting with `.`, which could be editor temporary files
                        if let Some(stem) = p.file_stem() {
                            if let Some(stemstr) = stem.to_str() {
                                if !stemstr.starts_with('.') {
                                    return true;
                                }
                            }
                        }
                    }
                }
                false
            })
            .collect();

        dir_entries.sort_by_key(|dir| dir.path());

        writeln!(
            out,
            "mod {} {{",
            Path::new(testsuite)
                .file_stem()
                .expect("testsuite filename should have a stem")
                .to_str()
                .expect("testsuite filename should be representable as a string")
                .replace("-", "_")
        )?;
        writeln!(out, "    use super::{{runtime, utils, setup_log}};")?;
        for dir_entry in dir_entries {
            write_testsuite_tests(out, dir_entry, testsuite)?;
        }
        writeln!(out, "}}")?;
        Ok(())
    }

    fn write_testsuite_tests(
        out: &mut File,
        dir_entry: DirEntry,
        testsuite: &str,
    ) -> io::Result<()> {
        let path = dir_entry.path();
        let stemstr = path
            .file_stem()
            .expect("file_stem")
            .to_str()
            .expect("to_str");

        writeln!(out, "    #[test]")?;
        if ignore(testsuite, stemstr) {
            writeln!(out, "    #[ignore]")?;
        }
        writeln!(
            out,
            "    fn r#{}() -> anyhow::Result<()> {{",
            &stemstr.replace("-", "_")
        )?;
        writeln!(out, "        setup_log();")?;
        write!(
            out,
            "        let path = std::path::Path::new(r#\"{}\"#);",
            path.display()
        )?;
        writeln!(out, "        let data = utils::read_wasm(path)?;")?;
        writeln!(
            out,
            "        let bin_name = utils::extract_exec_name_from_path(path)?;"
        )?;
        let workspace = if no_preopens(testsuite, stemstr) {
            "None"
        } else {
            writeln!(
                out,
                "        let workspace = utils::prepare_workspace(&bin_name)?;"
            )?;
            "Some(workspace.path())"
        };
        writeln!(
            out,
            "        runtime::instantiate(&data, &bin_name, {})",
            workspace
        )?;
        writeln!(out, "    }}")?;
        writeln!(out)?;
        Ok(())
    }

    cfg_if::cfg_if! {
        if #[cfg(not(windows))] {
            /// Ignore tests that aren't supported yet.
            fn ignore(_testsuite: &str, _name: &str) -> bool {
                false
            }
        } else {
            /// Ignore tests that aren't supported yet.
            fn ignore(testsuite: &str, name: &str) -> bool {
                if testsuite == "wasi-misc-tests" {
                    match name {
                        "readlink_no_buffer" => true,
                        "dangling_symlink" => true,
                        "symlink_loop" => true,
                        "truncation_rights" => true,
                        "poll_oneoff" => true,
                        "path_link" => true,
                        _ => false,
                    }
                } else {
                    unreachable!()
                }
            }
        }
    }

    /// Mark tests which do not require preopens
    fn no_preopens(testsuite: &str, name: &str) -> bool {
        if testsuite == "wasi-misc-tests" {
            match name {
                "big_random_buf" => true,
                "clock_time_get" => true,
                "sched_yield" => true,
                _ => false,
            }
        } else {
            unreachable!()
        }
    }
}