#define DOCTEST_CONFIG_IMPLEMENT_WITH_MAIN
#include "doctest.h"

#include <fstream>
#include <sstream>

#include <nlohmann/json.hpp>

#include "webmetal/engine.h"

using nlohmann::json;
using webmetal::Engine;

#ifndef WEBMETAL_CONFORMANCE_PATH
#error "WEBMETAL_CONFORMANCE_PATH must be defined by the build"
#endif

namespace {

json loadVectorFile() {
    std::ifstream in(WEBMETAL_CONFORMANCE_PATH);
    REQUIRE_MESSAGE(in.good(), "cannot open " WEBMETAL_CONFORMANCE_PATH);
    std::stringstream buffer;
    buffer << in.rdbuf();
    json j = json::parse(buffer.str(), nullptr, false);
    REQUIRE_FALSE(j.is_discarded());
    return j;
}

struct Layout {
    std::uint32_t pc = 0;
    std::uint32_t status = 1;
    std::uint32_t flagsOffset = 4;
    std::vector<std::string> flagNames;
    struct Entry {
        std::uint32_t offset = 0;
        std::uint32_t count = 0;
    };
    std::map<std::string, Entry> banks;
    std::map<std::string, Entry> memories;
};

Layout parseLayout(const std::string& text) {
    const json j = json::parse(text, nullptr, false);
    REQUIRE_FALSE(j.is_discarded());
    Layout layout;
    layout.pc = j["pc"].get<std::uint32_t>();
    layout.status = j["status"].get<std::uint32_t>();
    layout.flagsOffset = j["flags"]["offset"].get<std::uint32_t>();
    for (const auto& name : j["flags"]["names"]) {
        layout.flagNames.push_back(name.get<std::string>());
    }
    for (const auto& b : j["banks"]) {
        layout.banks[b["name"].get<std::string>()] = {
            b["offset"].get<std::uint32_t>(), b["count"].get<std::uint32_t>()};
    }
    for (const auto& m : j["memories"]) {
        layout.memories[m["name"].get<std::string>()] = {
            m["offset"].get<std::uint32_t>(), m["size"].get<std::uint32_t>()};
    }
    return layout;
}

int flagIndexOf(const Layout& layout, const std::string& name) {
    for (std::size_t i = 0; i < layout.flagNames.size(); i++) {
        if (layout.flagNames[i] == name) return static_cast<int>(i);
    }
    return -1;
}

void applySetup(Engine& engine, const Layout& layout, const json& setup) {
    auto* state = reinterpret_cast<std::uint32_t*>(engine.stateBufferPtr());
    if (setup.contains("banks")) {
        for (const auto& [name, values] : setup["banks"].items()) {
            REQUIRE(layout.banks.count(name) == 1);
            const auto entry = layout.banks.at(name);
            std::uint32_t i = 0;
            for (const auto& v : values) {
                REQUIRE(i < entry.count);
                state[entry.offset + i++] = v.get<std::uint32_t>();
            }
        }
    }
    if (setup.contains("memories")) {
        for (const auto& [name, cells] : setup["memories"].items()) {
            REQUIRE(layout.memories.count(name) == 1);
            const auto entry = layout.memories.at(name);
            for (const auto& [addr, v] : cells.items()) {
                state[entry.offset + std::stoul(addr)] = v.get<std::uint32_t>();
            }
        }
    }
    if (setup.contains("flags")) {
        for (const auto& [name, v] : setup["flags"].items()) {
            const int index = flagIndexOf(layout, name);
            REQUIRE(index >= 0);
            state[layout.flagsOffset + index] = v.get<bool>() ? 1 : 0;
        }
    }
    if (setup.contains("pc")) {
        state[layout.pc] = setup["pc"].get<std::uint32_t>();
    }
}

std::vector<std::string> compareExpect(const Engine& engine,
                                       const Layout& layout,
                                       const json& expect) {
    std::vector<std::string> problems;
    const auto* state =
        reinterpret_cast<const std::uint32_t*>(engine.stateBufferPtr());
    const auto mismatch = [&](const std::string& what, std::uint32_t got,
                              std::uint32_t want) {
        problems.push_back(what + " = " + std::to_string(got) + ", want " +
                           std::to_string(want));
    };
    if (expect.contains("banks")) {
        for (const auto& [name, values] : expect["banks"].items()) {
            const auto entry = layout.banks.at(name);
            std::uint32_t i = 0;
            for (const auto& v : values) {
                const auto want = v.get<std::uint32_t>();
                const auto got = state[entry.offset + i];
                if (got != want) {
                    mismatch(name + "[" + std::to_string(i) + "]", got, want);
                }
                i++;
            }
        }
    }
    if (expect.contains("memories")) {
        for (const auto& [name, cells] : expect["memories"].items()) {
            const auto entry = layout.memories.at(name);
            for (const auto& [addr, v] : cells.items()) {
                const auto want = v.get<std::uint32_t>();
                const auto got = state[entry.offset + std::stoul(addr)];
                if (got != want) mismatch(name + "[" + addr + "]", got, want);
            }
        }
    }
    if (expect.contains("flags")) {
        for (const auto& [name, v] : expect["flags"].items()) {
            const int index = flagIndexOf(layout, name);
            const bool want = v.get<bool>();
            const bool got = state[layout.flagsOffset + index] != 0;
            if (got != want) {
                problems.push_back("flag " + name + " = " +
                                   (got ? "true" : "false"));
            }
        }
    }
    if (expect.contains("pc")) {
        const auto want = expect["pc"].get<std::uint32_t>();
        if (state[layout.pc] != want) mismatch("pc", state[layout.pc], want);
    }
    if (expect.contains("halted")) {
        const bool want = expect["halted"].get<bool>();
        const bool got = (state[layout.status] & 1u) != 0;
        if (got != want) {
            problems.push_back(std::string("halted = ") +
                               (got ? "true" : "false"));
        }
    }
    return problems;
}

}  // namespace

TEST_CASE("C++ engine passes every shared conformance vector") {
    const json file = loadVectorFile();
    const json defaultModel = file["defaultModel"];

    for (const auto& vector : file["vectors"]) {
        const std::string name = vector["name"].get<std::string>();
        CAPTURE(name);

        Engine engine;
        const json model =
            vector.contains("model") ? vector["model"] : defaultModel;
        REQUIRE_MESSAGE(engine.loadModel(model.dump()), name);
        const Layout layout = parseLayout(engine.stateLayout());

        if (vector.contains("setup")) {
            applySetup(engine, layout, vector["setup"]);
        }

        std::string error;
        for (const auto& step : vector["run"]) {
            const std::string operands =
                step.contains("operands") ? step["operands"].dump() : "{}";
            error = engine.execSequence(step["microOps"].dump(), operands);
            if (!error.empty()) break;
        }

        if (vector.contains("expectError")) {
            const auto substring = vector["expectError"].get<std::string>();
            CHECK_MESSAGE(!error.empty(), name, ": expected an error");
            CHECK_MESSAGE(error.find(substring) != std::string::npos, name,
                          ": error \"", error, "\" lacks \"", substring, "\"");
            continue;
        }

        CHECK_MESSAGE(error.empty(), name, ": unexpected error: ", error);
        if (vector.contains("expect")) {
            const auto problems =
                compareExpect(engine, layout, vector["expect"]);
            for (const auto& problem : problems) {
                FAIL_CHECK(name << ": " << problem);
            }
        }
    }
}