use anyhow::Context;
use std::path::Path;
use wasi_common::pipe::WritePipe;
use wasmtime::{Engine, Linker, Module, Store};
use wasmtime_wasi::sync::{add_to_linker, WasiCtxBuilder};

pub fn instantiate(data: &[u8], bin_name: &str, workspace: Option<&Path>) -> anyhow::Result<()> {
    run(data, bin_name, workspace, false)
}
pub fn instantiate_inherit_stdio(
    data: &[u8],
    bin_name: &str,
    workspace: Option<&Path>,
) -> anyhow::Result<()> {
    run(data, bin_name, workspace, true)
}

fn run(
    data: &[u8],
    bin_name: &str,
    workspace: Option<&Path>,
    inherit_stdio: bool,
) -> anyhow::Result<()> {
    let stdout = WritePipe::new_in_memory();
    let stderr = WritePipe::new_in_memory();

    let r = {
        let engine = Engine::default();
        let module = Module::new(&engine, &data).context("failed to create wasm module")?;
        let mut linker = Linker::new(&engine);
        add_to_linker(&mut linker, |cx| cx)?;

        // Create our wasi context.
        // Additionally register any preopened directories if we have them.
        let mut builder = WasiCtxBuilder::new();

        if inherit_stdio {
            builder = builder.inherit_stdio();
        } else {
            builder = builder
                .stdout(Box::new(stdout.clone()))
                .stderr(Box::new(stderr.clone()));
        }

        builder = builder.arg(bin_name)?.arg(".")?;

        if let Some(workspace) = workspace {
            println!("preopen: {:?}", workspace);
            let preopen_dir = unsafe { cap_std::fs::Dir::open_ambient_dir(workspace) }?;
            builder = builder.preopened_dir(preopen_dir, ".")?;
        }
        for (var, val) in super::test_suite_environment() {
            builder = builder.env(var, val)?;
        }

        // cap-std-sync does not yet support the sync family of fdflags
        builder = builder.env("NO_FDFLAGS_SYNC_SUPPORT", "1")?;

        let mut store = Store::new(&engine, builder.build());
        let instance = linker.instantiate(&mut store, &module)?;
        let start = instance.get_typed_func::<(), (), _>(&mut store, "_start")?;
        start.call(&mut store, ()).map_err(anyhow::Error::from)
    };

    match r {
        Ok(()) => Ok(()),
        Err(trap) => {
            let stdout = stdout
                .try_into_inner()
                .expect("sole ref to stdout")
                .into_inner();
            if !stdout.is_empty() {
                println!("guest stdout:\n{}\n===", String::from_utf8_lossy(&stdout));
            }
            let stderr = stderr
                .try_into_inner()
                .expect("sole ref to stderr")
                .into_inner();
            if !stderr.is_empty() {
                println!("guest stderr:\n{}\n===", String::from_utf8_lossy(&stderr));
            }
            Err(trap.context(format!("error while testing Wasm module '{}'", bin_name,)))
        }
    }
}