//! The WIT file (extensions/quantum-wasmq.wit) is the interface the modules have: each
//! world's functions lower, by the Component Model's canonical ABI, to exactly the core
//! types the reference modules export and an `extern` of the same shape lowers to (§5.2),
//! and its fault reasons are the ones a receipt names.

use wai_quantum::qasm::{ExternArg, ExternDecl};
use wai_wasmq::{abi, profile};
use wit_parser::abi::{AbiVariant, WasmType};
use wit_parser::{Resolve, WorldItem, WorldKey};

const WIT: &str = include_str!("../../extensions/quantum-wasmq.wit");
const DECODER: &[u8] = include_bytes!("../../quantum-conformance/wasmq/modules/qldpc_decoder.wasm");
const PLANNER: &[u8] = include_bytes!("../../quantum-conformance/wasmq/modules/atom_planner.wasm");

fn val(t: WasmType) -> wasmparser::ValType {
    match t {
        WasmType::I32 | WasmType::Pointer | WasmType::Length => wasmparser::ValType::I32,
        WasmType::I64 | WasmType::PointerOrI64 => wasmparser::ValType::I64,
        WasmType::F32 => wasmparser::ValType::F32,
        WasmType::F64 => wasmparser::ValType::F64,
    }
}

/// A core function type: its parameters and results.
type Core = (Vec<wasmparser::ValType>, Vec<wasmparser::ValType>);

fn exports(resolve: &Resolve, world: &str) -> Vec<(String, Core)> {
    let pkg = resolve.packages.iter().next().unwrap().0;
    let w = resolve.select_world(&[pkg], Some(world)).unwrap();
    let mut out = Vec::new();
    for (k, item) in &resolve.worlds[w].exports {
        if let (WorldKey::Name(name), WorldItem::Function(f)) = (k, item) {
            let s = resolve.wasm_signature(AbiVariant::GuestExport, f);
            out.push((name.clone(), (s.params.into_iter().map(val).collect(), s.results.into_iter().map(val).collect())));
        }
    }
    out
}

fn resolve() -> Resolve {
    let mut r = Resolve::default();
    r.push_str("quantum-wasmq.wit", WIT).unwrap();
    r
}

#[test]
fn the_reference_modules_export_what_their_worlds_lower_to() {
    let r = resolve();
    for (world, module) in [("qldpc-decoder", DECODER), ("atom-planner", PLANNER)] {
        let facts = profile::check(module).unwrap();
        let ex = exports(&r, world);
        assert!(ex.len() >= 3, "{world}");
        for (name, sig) in ex {
            if name == "init" {
                continue; // optional, and neither reference module needs it
            }
            assert_eq!(facts.functions.get(&name), Some(&sig), "{world}: {name}");
        }
    }
}

#[test]
fn an_extern_lowers_as_its_wit_function_does() {
    let r = resolve();
    let ex: std::collections::BTreeMap<_, _> = exports(&r, "qldpc-decoder").into_iter().collect();
    let scalar = ExternDecl { name: "decode64".into(), args: vec![ExternArg::Bit(8)], ret: Some(13) };
    assert_eq!(abi::core_type(&scalar), ex["decode64"]);
    let list = ExternDecl { name: "decode".into(), args: vec![ExternArg::Bit(72)], ret: Some(144) };
    assert_eq!(abi::core_type(&list), ex["decode"]);
    // The lifecycle the runner calls is the one the module world declares.
    let m: std::collections::BTreeMap<_, _> = exports(&r, "module").into_iter().collect();
    assert_eq!(m["wasmq-prior"].0.len(), 3);
    assert_eq!(m["wasmq-seed"], (vec![wasmparser::ValType::I64], vec![]));
}

#[test]
fn an_angle_lowers_as_its_wit_u64_does() {
    // The second version's angle argument (§11.1): one u64, in the scalar form and the list.
    let r = resolve();
    let ex: std::collections::BTreeMap<_, _> = exports(&r, "angle-callout").into_iter().collect();
    let scalar = ExternDecl { name: "f".into(), args: vec![ExternArg::Angle(8), ExternArg::Uint(8)], ret: Some(16) };
    assert_eq!(abi::core_type(&scalar), ex["f"]);
    let list = ExternDecl { name: "f".into(), args: vec![ExternArg::Angle(64), ExternArg::Bit(72)], ret: Some(8) };
    assert_eq!(abi::core_type(&list), (vec![wasmparser::ValType::I64, wasmparser::ValType::I32, wasmparser::ValType::I32], vec![wasmparser::ValType::I32]));
}

#[test]
fn the_fault_reasons_are_the_ones_a_receipt_names() {
    let r = resolve();
    let iface = r.interfaces.iter().find(|(_, i)| i.name.as_deref() == Some("receipt")).unwrap().1;
    let ty = iface.types["fault-reason"];
    let wit_parser::TypeDefKind::Enum(e) = &r.types[ty].kind else { panic!("fault-reason is an enum") };
    let wit: Vec<String> = e.cases.iter().map(|c| c.name.replace('-', "_")).collect();
    use wai_wasmq::engine::Trap::*;
    let mut ours: Vec<String> = [Unreachable, MemoryOutOfBounds, TableOutOfBounds, IndirectCallNull, IndirectCallType, DivideByZero, IntegerOverflow, InvalidConversion, Fuel, Stack].iter().map(|t| t.reason().to_string()).collect();
    ours.push("bad_result".into());
    assert_eq!(wit, ours);
}