// Copyright 2021 The Dawn Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#ifndef DAWNNODE_UTILS_DEBUG_H_
#define DAWNNODE_UTILS_DEBUG_H_

#include <iostream>
#include <optional>
#include <sstream>
#include <unordered_map>
#include <variant>
#include <vector>

#include "dawn/webgpu_cpp_print.h"

namespace wgpu { namespace utils {

    // Write() is a helper for printing container types to the std::ostream.
    // Write() is used by the LOG() macro below.

    // Forward declarations
    inline std::ostream& Write(std::ostream& out) {
        return out;
    }
    template <typename T>
    inline std::ostream& Write(std::ostream& out, const std::optional<T>& value);
    template <typename T>
    inline std::ostream& Write(std::ostream& out, const std::vector<T>& value);
    template <typename K, typename V>
    inline std::ostream& Write(std::ostream& out, const std::unordered_map<K, V>& value);
    template <typename... TYS>
    inline std::ostream& Write(std::ostream& out, const std::variant<TYS...>& value);
    template <typename VALUE>
    std::ostream& Write(std::ostream& out, VALUE&& value);

    // Write() implementations
    template <typename T>
    std::ostream& Write(std::ostream& out, const std::optional<T>& value) {
        if (value.has_value()) {
            return Write(out, value.value());
        }
        return out << "<undefined>";
    }

    template <typename T>
    std::ostream& Write(std::ostream& out, const std::vector<T>& value) {
        out << "[";
        bool first = true;
        for (const auto& el : value) {
            if (!first) {
                out << ", ";
            }
            first = false;
            Write(out, el);
        }
        return out << "]";
    }

    template <typename K, typename V>
    std::ostream& Write(std::ostream& out, const std::unordered_map<K, V>& value) {
        out << "{";
        bool first = true;
        for (auto& [key, value] : value) {
            if (!first) {
                out << ", ";
            }
            first = false;
            Write(out, key);
            out << ": ";
            Write(out, value);
        }
        return out << "}";
    }

    template <typename... TYS>
    std::ostream& Write(std::ostream& out, const std::variant<TYS...>& value) {
        std::visit([&](auto&& v) { Write(out, v); }, value);
        return out;
    }

    template <typename VALUE>
    std::ostream& Write(std::ostream& out, VALUE&& value) {
        return out << std::forward<VALUE>(value);
    }

    template <typename FIRST, typename... REST>
    inline std::ostream& Write(std::ostream& out, FIRST&& first, REST&&... rest) {
        Write(out, std::forward<FIRST>(first));
        Write(out, std::forward<REST>(rest)...);
        return out;
    }

    // Fatal() prints a message to stdout with the given file, line, function and optional message,
    // then calls abort(). Fatal() is usually not called directly, but by the UNREACHABLE() and
    // UNIMPLEMENTED() macro below.
    template <typename... MSG_ARGS>
    [[noreturn]] inline void Fatal(const char* reason,
                                   const char* file,
                                   int line,
                                   const char* function,
                                   MSG_ARGS&&... msg_args) {
        std::stringstream msg;
        msg << file << ":" << line << ": " << reason << ": " << function << "()";
        if constexpr (sizeof...(msg_args) > 0) {
            msg << " ";
            Write(msg, std::forward<MSG_ARGS>(msg_args)...);
        }
        std::cout << msg.str() << std::endl;
        abort();
    }

// LOG() prints the current file, line and function to stdout, followed by a
// string representation of all the variadic arguments.
#define LOG(...)                                                                                  \
    ::wgpu::utils::Write(std::cout << __FILE__ << ":" << __LINE__ << " " << __FUNCTION__ << ": ", \
                         ##__VA_ARGS__)                                                           \
        << std::endl

// UNIMPLEMENTED() prints 'UNIMPLEMENTED' with the current file, line and
// function to stdout, along with the optional message, then calls abort().
// The macro calls Fatal(), which is annotated with [[noreturn]].
// Used to stub code that has not yet been implemented.
#define UNIMPLEMENTED(...) \
    ::wgpu::utils::Fatal("UNIMPLEMENTED", __FILE__, __LINE__, __FUNCTION__, ##__VA_ARGS__)

// UNREACHABLE() prints 'UNREACHABLE' with the current file, line and
// function to stdout, along with the optional message, then calls abort().
// The macro calls Fatal(), which is annotated with [[noreturn]].
// Used to stub code that has not yet been implemented.
#define UNREACHABLE(...) \
    ::wgpu::utils::Fatal("UNREACHABLE", __FILE__, __LINE__, __FUNCTION__, ##__VA_ARGS__)

}}  // namespace wgpu::utils

#endif  // DAWNNODE_UTILS_DEBUG_H_