//! Cargo's WASI test runner: one compiled component, isolated instances, and a small core transport.
use anyhow::{Result, bail};
use sausage::{
    Host,
    runtime::{Exit, InstanceConfig, Runtime},
};
use serde_json::{Value, json};
use std::{
    path::{Path, PathBuf},
    sync::Arc,
};
use wasmtime::component::Component;

/// A temporary world remains alive through the end of its WASI store.
struct TestWorld(PathBuf);
impl Drop for TestWorld {
    fn drop(&mut self) {
        let _ = std::fs::remove_dir_all(&self.0);
    }
}
struct Run {
    exit: Exit,
    output: String,
}
/// Runs one instance and separates JSON-RPC requests from ordinary test output.
async fn instance(
    runtime: Arc<Runtime>,
    component: Component,
    args: Vec<String>,
    package: PathBuf,
) -> Result<Run> {
    let path = std::env::temp_dir().join(format!("sausage-test-{}", uuid::Uuid::now_v7()));
    let world = TestWorld(path);
    let host = Host::test_world(&world.0, runtime.clone()).await?;
    let tracker = sausage_vfs::Process::default();
    let mut filesystem = host.filesystem().await?;
    // Virtual ancestors keep directory entries of the absolute package mount traversable.
    for ancestor in package
        .ancestors()
        .skip(1)
        .filter(|path| *path != Path::new("/"))
    {
        filesystem.mount(
            ancestor.to_str().unwrap(),
            Arc::new(sausage_vfs::Memory::default()),
            false,
        );
    }
    filesystem.mount(
        package.to_str().unwrap(),
        Arc::new(sausage_vfs::Host::new(&package, tracker.clone())?),
        false,
    );
    let mut env: Vec<_> = std::env::vars_os()
        .filter_map(|(key, value)| Some((key.into_string().ok()?, value.into_string().ok()?)))
        .filter(|(key, _)| {
            ["CARGO_", "RUST_", "SAUSAGE_"]
                .iter()
                .any(|prefix| key.starts_with(prefix))
        })
        .collect();
    env.extend([
        ("SAUSAGE_PID".into(), "test".into()),
        ("SAUSAGE_PLUGIN".into(), "test".into()),
        ("SAUSAGE_PARENT".into(), "core".into()),
    ]);
    let timeout_secs = std::env::var("SAUSAGE_TEST_TIMEOUT_SECS")
        .ok()
        .and_then(|value| value.parse::<u64>().ok())
        .filter(|value| *value >= 1)
        .unwrap_or(sausage::cargo::DEFAULT_TEST_TIMEOUT_SECS);
    let deadline = tokio::time::Instant::now()
        .checked_add(std::time::Duration::from_secs(timeout_secs))
        .ok_or_else(|| anyhow::anyhow!("test_timeout_secs is too large"))?;
    let (ended, mut ended_rx) = tokio::sync::watch::channel(true);
    let mut guest = runtime
        .start_with_args(
            &component,
            InstanceConfig {
                filesystem,
                store_ended: ended,
                network: true,
                env,
            },
            &args,
        )
        .await?;
    let mut pending = std::collections::VecDeque::new();
    let mut stderr = std::mem::replace(&mut guest.stderr, tokio::sync::mpsc::channel(1).1);
    let (errors, mut stderr_lines) = tokio::sync::mpsc::unbounded_channel();
    let stderr_task = tokio::spawn(async move {
        while let Some(line) = stderr.recv().await {
            let _ = errors.send(line);
        }
    });
    let mut output = String::new();
    let mut stdout_open = true;
    let mut stderr_open = true;
    let mut handlers = tokio::task::JoinSet::new();
    let result = tokio::time::timeout_at(deadline, async {
    while stdout_open || stderr_open || !pending.is_empty() {
        tokio::select! {
            line=async { if let Some(line) = pending.pop_front() { Some(line) } else { guest.stdout.recv().await } }, if stdout_open || !pending.is_empty()=>match line {
                Some(line)=> {
                    // Libtest can prefix its status line before SDK output. The SDK starts JSON on a fresh line.
                    if let Ok(request)=serde_json::from_str::<Value>(&line) && request["jsonrpc"]=="2.0" && request["method"].is_string() {
                        let method = request["method"].as_str().unwrap();
                        if !matches!(method, "core.lock" | "core.log") {
                            let params = request.get("params").cloned().unwrap_or(json!({}));
                            let result = match method {
                                "core.unlock" => host.call(method, params).await,
                                "core.notify" => Ok(Value::Null),
                                _ => Err(json!({"code":-32601,"message":"a test has no other plugins"})),
                            };
                            if let Some(id) = request.get("id") {
                                let response = match result { Ok(result)=>json!({"jsonrpc":"2.0","id":id,"result":result}), Err(error)=>json!({"jsonrpc":"2.0","id":id,"error":error}) };
                                if guest.send_line(&response.to_string(), |line| pending.push_back(line)).await.is_err() { guest.stdin.take(); }
                            }
                            continue;
                        }
                        let host = host.clone();
                        handlers.spawn(async move {
                            let method=request["method"].as_str().unwrap();
                            let params=request.get("params").cloned().unwrap_or(json!({}));
                            let result=match method {
                                "core.lock"|"core.unlock"|"core.log"=>host.call(method,params).await,
                                "core.notify"=>Ok(Value::Null),
                                _=>Err(json!({"code":-32601,"message":"a test has no other plugins"})),
                            };
                            request.get("id").map(|id|match result {Ok(result)=>json!({"jsonrpc":"2.0","id":id,"result":result}),Err(error)=>json!({"jsonrpc":"2.0","id":id,"error":error})})
                        });
                    } else {output.push_str(line.trim_end_matches(['\r', '\n']));output.push('\n');}
                },None=>stdout_open=false,
            },
            line=stderr_lines.recv(), if stderr_open=>match line {Some(line)=>{output.push_str(&line);output.push('\n');},None=>stderr_open=false},
            response=handlers.join_next(), if !handlers.is_empty()=> {
                if let Some(response) = response.transpose()?.flatten()
                    && guest.send_line(&response.to_string(), |line| pending.push_back(line)).await.is_err() { guest.stdin.take(); }
            },
        }
    }
    Ok::<_, anyhow::Error>(guest.wait().await)
    }).await;
    handlers.abort_all();
    // Dropping the instance aborts even a CPU-bound WASI loop. Wait for the
    // store and outstanding filesystem work before removing its test world.
    drop(guest);
    let _ = ended_rx.wait_for(|ended| *ended).await;
    let _ = stderr_task.await;
    tracker.idle().await;
    host.stop().await;
    let exit =
        result.map_err(|_| anyhow::anyhow!("timed out after {timeout_secs} s\n{output}"))??;
    Ok(Run { exit, output })
}
/// Extracts libtest names from its stable list format.
fn names(output: &str) -> Vec<String> {
    output
        .lines()
        .filter_map(|line| line.strip_suffix(": test").map(str::to_owned))
        .collect()
}
/// Lists tests, selects libtest filters, and runs each selected test on the core pool.
pub async fn run(wasm: &Path, args: Vec<String>) -> Result<bool> {
    let package = std::env::current_dir()?;
    let cache = std::env::var_os("XDG_CACHE_HOME")
        .map(PathBuf::from)
        .unwrap_or_else(|| {
            PathBuf::from(std::env::var_os("HOME").unwrap_or_default()).join(".cache")
        })
        .join("sausage");
    let compile_path = wasm.to_path_buf();
    let (runtime, component) = tokio::task::spawn_blocking(move || -> Result<_> {
        let runtime = Runtime::new(&cache)?;
        let component = runtime.compile(&std::fs::read(compile_path)?)?;
        Ok((runtime, component))
    })
    .await??;
    let mut listing_args = vec![wasm.display().to_string(), "--list".into()];
    listing_args.extend(args.iter().filter(|arg| arg.as_str() != "--list").cloned());
    let listing = instance(
        runtime.clone(),
        component.clone(),
        listing_args.clone(),
        package.clone(),
    )
    .await?;
    if !matches!(listing.exit, Exit::Clean) {
        bail!(
            "cannot list WASI tests: {}\n{}",
            listing.exit,
            listing.output
        );
    }
    if args.iter().any(|arg| arg == "--list") {
        print!("{}", listing.output);
        return Ok(true);
    }
    let selected = names(&listing.output);
    listing_args.push("--ignored".into());
    let ignored = if args
        .iter()
        .any(|arg| matches!(arg.as_str(), "--ignored" | "--include-ignored"))
    {
        Vec::new()
    } else {
        names(
            &instance(
                runtime.clone(),
                component.clone(),
                listing_args,
                package.clone(),
            )
            .await?
            .output,
        )
    };
    println!("running {} tests", selected.len());
    let cores = std::thread::available_parallelism()
        .map(usize::from)
        .unwrap_or(1);
    let semaphore = Arc::new(tokio::sync::Semaphore::new(cores));
    let mut tasks = tokio::task::JoinSet::new();
    let mut skipped = 0;
    for name in selected {
        if ignored.contains(&name) {
            println!("test {name} ... ignored");
            skipped += 1;
            continue;
        }
        let runtime = runtime.clone();
        let component = component.clone();
        let package = package.clone();
        let semaphore = semaphore.clone();
        let arguments = vec![
            wasm.display().to_string(),
            "--exact".into(),
            name.clone(),
            "--nocapture".into(),
            "--test-threads=1".into(),
            "--include-ignored".into(),
        ];
        tasks.spawn(async move {
            let _permit = semaphore.acquire_owned().await?;
            let result = instance(runtime, component, arguments, package).await;
            Ok::<_, anyhow::Error>((name, result))
        });
    }
    let mut passed = 0;
    let mut failed = 0;
    while let Some(result) = tasks.join_next().await {
        let (name, result) = result??;
        let success = result
            .as_ref()
            .is_ok_and(|run| matches!(run.exit, Exit::Clean));
        if success {
            passed += 1;
        } else {
            failed += 1;
        }
        println!("test {name} ... {}", if success { "ok" } else { "FAILED" });
        match result {
            Ok(run) => {
                for line in run
                    .output
                    .lines()
                    .filter(|line| {
                        !line.trim().is_empty()
                            && !line.starts_with("test result:")
                            && !matches!(*line, "running 1 test" | "running 0 tests")
                            && !matches!(*line, "ok" | "FAILED")
                    })
                    .map(|line| {
                        line.strip_prefix(&format!("test {name} ... "))
                            .unwrap_or(line)
                    })
                    .filter(|line| {
                        !matches!(*line, "ok" | "FAILED" | "ignored") && !line.is_empty()
                    })
                {
                    // Indentation keeps ordinary test output separate from our libtest status and totals.
                    println!("  {line}");
                }
            }
            Err(error) => println!("{error:#}"),
        }
    }
    println!(
        "\ntest result: {}. {passed} passed; {failed} failed; {skipped} ignored; 0 measured; 0 filtered out",
        if failed == 0 { "ok" } else { "FAILED" }
    );
    Ok(failed == 0)
}