use arbitrary::{Result, Unstructured};

use std::path::Path;

use wasm_encoder::reencode::{self, Reencode};

use wasm_encoder::{ImportSection, Module};

use wit_component::*;

use wit_parser::{LiftLowerAbi, ManglingAndAbi, PackageId, Resolve};

pub fn run(u: &mut Unstructured<'_>) -> Result<()> {

    let wasm = u.arbitrary().and_then(|config| {

        log::debug!("config: {config:#?}");

        wit_smith::smith(&config, u)

    })?;

    write_file("doc1.wasm", &wasm);

    let (resolve, pkg) = match wit_component::decode(&wasm).unwrap() {

        DecodedWasm::WitPackage(resolve, pkg) => (resolve, pkg),

        DecodedWasm::Component(..) => unreachable!(),

    };

    resolve.assert_valid();

    roundtrip_through_printing("doc1", &resolve, pkg, &wasm);

    let (resolve2, pkg2) = match wit_component::decode(&wasm).unwrap() {

        DecodedWasm::WitPackage(resolve, pkgs) => (resolve, pkgs),

        DecodedWasm::Component(..) => unreachable!(),

    };

    resolve2.assert_valid();

    let wasm2 = wit_component::encode(&resolve2, pkg2).expect("failed to encode WIT document");

    write_file("doc2.wasm", &wasm2);

    roundtrip_through_printing("doc2", &resolve2, pkg2, &wasm2);

    if wasm != wasm2 {

        panic!("roundtrip wasm didn't match");

    }

    // If there's hundreds or thousands of worlds only work with the first few

    // to avoid timing out this fuzzer with asan enabled.

    let mut decoded_bindgens = Vec::new();

    for (id, world) in resolve.worlds.iter().take(20) {

        let mangling = match u.int_in_range(0..=3)? {

            0 => ManglingAndAbi::Legacy(LiftLowerAbi::Sync),

            1 => ManglingAndAbi::Legacy(LiftLowerAbi::AsyncCallback),

            2 => ManglingAndAbi::Legacy(LiftLowerAbi::AsyncStackful),

            3 => ManglingAndAbi::Standard32,

            _ => unreachable!(),

        };

        log::debug!(

            "embedding world {} as in a dummy module with abi {mangling:?}",

            world.name

        );

        let mut dummy = wit_component::dummy_module(&resolve, id, mangling);

        if u.arbitrary()? {

            let mut dst = Module::default();

            let mut reencode = RemoveImports {

                u,

                removed_funcs: 0,

            };

            if reencode

                .parse_core_module(&mut dst, Default::default(), &dummy)

                .is_ok()

            {

                dummy = dst.finish();

            }

        }

        wit_component::embed_component_metadata(&mut dummy, &resolve, id, StringEncoding::UTF8)

            .unwrap();

        write_file("dummy.wasm", &dummy);

        log::debug!("... componentizing the world into a binary component");

        let wasm = wit_component::ComponentEncoder::default()

            .module(&dummy)

            .unwrap()

            .encode()

            .unwrap();

        write_file("dummy.component.wasm", &wasm);

        wasmparser::Validator::new_with_features(wasmparser::WasmFeatures::all())

            .validate_all(&wasm)

            .unwrap();

        // Decode what was just created and record it later for testing merging

        // worlds together.

        let (_, decoded) = wit_component::metadata::decode(&dummy).unwrap();

        decoded_bindgens.push((decoded, dummy, world.name.clone()));

        log::debug!("... decoding the component itself");

        wit_component::decode(&wasm).unwrap();

        // Test out importizing the world and then assert the world is still

        // valid.

        log::debug!("... importizing this world");

        let mut resolve2 = resolve.clone();

        let _ = resolve2.importize(id, None);

    }

    if decoded_bindgens.len() < 2 {

        return Ok(());

    }

    let i = u.choose_index(decoded_bindgens.len())?;

    let (mut b1, wasm1, world1) = decoded_bindgens.swap_remove(i);

    if u.arbitrary()? {

        let i = u.choose_index(decoded_bindgens.len())?;

        let (b2, wasm2, world2) = decoded_bindgens.swap_remove(i);

        log::debug!("merging bindgens world {world1} <- world {world2}");

        write_file("bindgen1.wasm", &wasm1);

        write_file("bindgen2.wasm", &wasm2);

        // Merging worlds may fail but if successful then a `Resolve` is asserted

        // to be valid which is what we're interested in here. Note that failure

        // here can be due to the structure of worlds which aren't reasonable to

        // control in this generator, so it's just done to see what happens and try

        // to trigger panics in `Resolve::assert_valid`.

        let _ = b1.merge(b2);

    } else {

        log::debug!("merging world imports based on semver {world1}");

        write_file("bindgen1.wasm", &wasm1);

        let _ = b1.resolve.merge_world_imports_based_on_semver(b1.world);

    }

    Ok(())

}

fn roundtrip_through_printing(file: &str, resolve: &Resolve, pkg: PackageId, wasm: &[u8]) {

    // Print to a single string, using nested `package ... { .. }` statements,

    // and then parse that in a new `Resolve`.

    let mut new_resolve = Resolve::default();

    new_resolve.all_features = true;

    let package_deps = resolve

        .packages

        .iter()

        .map(|p| p.0)

        .filter(|k| *k != pkg)

        .collect::<Vec<_>>();

    let mut printer = WitPrinter::default();

    printer.print(resolve, pkg, &package_deps).unwrap();

    let doc = printer.output.to_string();

    let new_pkg = new_resolve

        .push_str(&format!("printed-{file}.wit"), &doc)

        .unwrap();

    // Finally encode the `new_resolve` which should be the exact same as

    // before.

    let wasm2 = wit_component::encode(&new_resolve, new_pkg).unwrap();

    write_file(&format!("{file}-reencoded.wasm"), &wasm2);

    if wasm != wasm2 {

        panic!("failed to roundtrip through text printing");

    }

}

fn write_file(path: &str, contents: impl AsRef<[u8]>) {

    if !log::log_enabled!(log::Level::Debug) {

        return;

    }

    log::debug!("writing file {path}");

    let contents = contents.as_ref();

    let path = Path::new(path);

    std::fs::write(path, contents).unwrap();

    if path.extension().and_then(|s| s.to_str()) == Some("wasm") {

        let path = path.with_extension("wat");

        log::debug!("writing file {}", path.display());

        std::fs::write(path, wasmprinter::print_bytes(&contents).unwrap()).unwrap();

    }

}

struct RemoveImports<'a, 'b> {

    u: &'a mut Unstructured<'b>,

    removed_funcs: u32,

}

impl Reencode for RemoveImports<'_, '_> {

    type Error = std::convert::Infallible;

    fn function_index(&mut self, idx: u32) -> Result<u32, reencode::Error<Self::Error>> {

        Ok(idx - self.removed_funcs)

    }

    fn parse_import(

        &mut self,

        imports: &mut ImportSection,

        import: wasmparser::Import<'_>,

    ) -> Result<(), reencode::Error<Self::Error>> {

        if self.u.arbitrary().unwrap_or(false) {

            self.removed_funcs += 1;

            Ok(())

        } else {

            reencode::utils::parse_import(self, imports, import)

        }

    }

}

#[test]

fn smoke() {

    super::test::test_n_times(100, run);

}