#include <Poco/DirectoryIterator.h>
#include <DB/Common/ClickHouseRevision.h>
#include <ext/unlock_guard.hpp>

#include <DB/Common/SipHash.h>
#include <DB/Common/ShellCommand.h>
#include <DB/Common/StringUtils.h>

#include <DB/IO/Operators.h>
#include <DB/IO/ReadBufferFromString.h>
#include <DB/IO/ReadBufferFromFileDescriptor.h>
#include <DB/IO/WriteBufferFromFile.h>

#include <DB/Interpreters/Compiler.h>
#include <DB/Interpreters/config_compile.h>


namespace ProfileEvents
{
    extern const Event CompileAttempt;
    extern const Event CompileSuccess;
}

namespace DB
{


Compiler::Compiler(const std::string & path_, size_t threads)
    : path(path_), pool(threads)
{
    Poco::File(path).createDirectory();

    Poco::DirectoryIterator dir_end;
    for (Poco::DirectoryIterator dir_it(path); dir_end != dir_it; ++dir_it)
    {
        std::string name = dir_it.name();
        if (endsWith(name, ".so"))
        {
            files.insert(name.substr(0, name.size() - 3));
        }
    }

    LOG_INFO(log, "Having " << files.size() << " compiled files from previous start.");
}

Compiler::~Compiler()
{
    LOG_DEBUG(log, "Waiting for threads to finish.");
    pool.wait();
}


static Compiler::HashedKey getHash(const std::string & key)
{
    SipHash hash;

    auto revision = ClickHouseRevision::get();
    hash.update(reinterpret_cast<const char *>(&revision), sizeof(revision));
    hash.update(key.data(), key.size());

    Compiler::HashedKey res;
    hash.get128(res.first, res.second);
    return res;
}


/// Без расширения .so.
static std::string hashedKeyToFileName(Compiler::HashedKey hashed_key)
{
    std::string file_name;

    {
        WriteBufferFromString out(file_name);
        out << hashed_key.first << '_' << hashed_key.second;
    }

    return file_name;
}


SharedLibraryPtr Compiler::getOrCount(
    const std::string & key,
    UInt32 min_count_to_compile,
    const std::string & additional_compiler_flags,
    CodeGenerator get_code,
    ReadyCallback on_ready)
{
    HashedKey hashed_key = getHash(key);

    std::lock_guard<std::mutex> lock(mutex);

    UInt32 count = ++counts[hashed_key];

    /// Есть готовая открытая библиотека? Или, если библиотека в процессе компиляции, там будет nullptr.
    Libraries::iterator it = libraries.find(hashed_key);
    if (libraries.end() != it)
    {
        if (!it->second)
            LOG_INFO(log, "Library " << hashedKeyToFileName(hashed_key) << " is already compiling or compilation was failed.");

        /// TODO В этом случае, после окончания компиляции, не будет дёрнут колбэк.

        return it->second;
    }

    /// Есть файл с библиотекой, оставшийся от предыдущего запуска?
    std::string file_name = hashedKeyToFileName(hashed_key);
    if (files.count(file_name))
    {
        std::string so_file_path = path + '/' + file_name + ".so";
        LOG_INFO(log, "Loading existing library " << so_file_path);

        SharedLibraryPtr lib(new SharedLibrary(so_file_path));
        libraries[hashed_key] = lib;
        return lib;
    }

    /// Достигнуто ли min_count_to_compile?
    if (count >= min_count_to_compile)
    {
        /// Значение min_count_to_compile, равное нулю, обозначает необходимость синхронной компиляции.

        /// Есть ли свободные потоки.
        if (min_count_to_compile == 0 || pool.active() < pool.size())
        {
            /// Обозначает, что библиотека в процессе компиляции.
            libraries[hashed_key] = nullptr;

            LOG_INFO(log, "Compiling code " << file_name << ", key: " << key);

            if (min_count_to_compile == 0)
            {
                {
                    ext::unlock_guard<std::mutex> unlock(mutex);
                    compile(hashed_key, file_name, additional_compiler_flags, get_code, on_ready);
                }

                return libraries[hashed_key];
            }
            else
            {
                pool.schedule([=]
                {
                    try
                    {
                        compile(hashed_key, file_name, additional_compiler_flags, get_code, on_ready);
                    }
                    catch (...)
                    {
                        tryLogCurrentException("Compiler");
                    }
                });
            }
        }
        else
            LOG_INFO(log, "All threads are busy.");
    }

    return nullptr;
}


void Compiler::compile(
    HashedKey hashed_key,
    std::string file_name,
    const std::string & additional_compiler_flags,
    CodeGenerator get_code,
    ReadyCallback on_ready)
{
    ProfileEvents::increment(ProfileEvents::CompileAttempt);

    std::string prefix = path + "/" + file_name;
    std::string cpp_file_path = prefix + ".cpp";
    std::string so_file_path = prefix + ".so";
    std::string so_tmp_file_path = prefix + ".so.tmp";

    {
        WriteBufferFromFile out(cpp_file_path);
        out << get_code();
    }

    std::stringstream command;

    /// Слегка неудобно.
    command <<
        "LD_LIBRARY_PATH=" PATH_SHARE "/clickhouse/bin/"
        " " INTERNAL_COMPILER_EXECUTABLE
        " -B " PATH_SHARE "/clickhouse/bin/"
        " " INTERNAL_COMPILER_FLAGS
#if INTERNAL_COMPILER_CUSTOM_ROOT
        " -isystem " INTERNAL_COMPILER_HEADERS_ROOT "/usr/local/include/"
        " -isystem " INTERNAL_COMPILER_HEADERS_ROOT "/usr/include/"
        " -isystem " INTERNAL_COMPILER_HEADERS_ROOT "/usr/include/mysql/"
        " -isystem " INTERNAL_COMPILER_HEADERS_ROOT "/usr/include/c++/*/"
        " -isystem " INTERNAL_COMPILER_HEADERS_ROOT "/usr/include/x86_64-linux-gnu/"
        " -isystem " INTERNAL_COMPILER_HEADERS_ROOT "/usr/include/x86_64-linux-gnu/c++/*/"
        " -isystem " INTERNAL_COMPILER_HEADERS_ROOT "/usr/local/lib/clang/*/include/"
#endif
        " -I " INTERNAL_COMPILER_HEADERS "/dbms/include/"
        " -I " INTERNAL_COMPILER_HEADERS "/contrib/libcityhash/include/"
        " -I " INTERNAL_DOUBLE_CONVERSION_INCLUDE_DIR
        " -I " INTERNAL_Poco_Foundation_INCLUDE_DIR
        " -I " INTERNAL_Poco_Util_INCLUDE_DIR
        " -I " INTERNAL_Boost_INCLUDE_DIRS
        " -I " INTERNAL_COMPILER_HEADERS "/libs/libcommon/include/"
        " -I " INTERNAL_COMPILER_HEADERS "/libs/libmysqlxx/include/"
        " " << additional_compiler_flags <<
        " -o " << so_tmp_file_path << " " << cpp_file_path
        << " 2>&1 || echo Exit code: $?";

    std::string compile_result;

    {
        auto process = ShellCommand::execute(command.str());
        readStringUntilEOF(compile_result, process->out);
        process->wait();
    }

    if (!compile_result.empty())
        throw Exception("Cannot compile code:\n\n" + command.str() + "\n\n" + compile_result);

    /// Если до этого была ошибка, то файл с кодом остаётся для возможности просмотра.
    Poco::File(cpp_file_path).remove();

    Poco::File(so_tmp_file_path).renameTo(so_file_path);
    SharedLibraryPtr lib(new SharedLibrary(so_file_path));

    {
        std::lock_guard<std::mutex> lock(mutex);
        libraries[hashed_key] = lib;
    }

    LOG_INFO(log, "Compiled code " << file_name);
    ProfileEvents::increment(ProfileEvents::CompileSuccess);

    on_ready(lib);
}


}