#include "snote_thread.hpp"

#include "irc_parse_thread.hpp"
#include "ircmsg.hpp"
#include "connection.hpp"
#include "c_callback.hpp"

#include <hs.h>

#include <cstdlib>
#include <cstring>
#include <regex>
#include <stdexcept>
#include <utility>

namespace {

struct SnotePattern
{
    SnotePattern(SnoteTag tag, char const* expression, unsigned flags = 0)
    : tag{tag}
    , expression{expression}
    , regex{expression, std::regex_constants::ECMAScript | std::regex_constants::optimize}
    {
    }

    SnoteTag tag;
    char const* expression;
    std::regex regex;
};

SnotePattern const patterns[] =
{
    {SnoteTag::ClientConnecting,
     R"(^Client connecting: ([^ ]+) \(([^@ ]+)@([^) ]+)\) \[(.*)\] \{([^ ]*)\} <([^ ]*)> \[(.*)\]$)"},

    {SnoteTag::ClientExiting,
     R"(^Client exiting: ([^ ]+) \(([^@ ]+)@([^) ]+)\) \[(.*)\] \[(.*)\]$)"},

    {SnoteTag::RejectingKlined,
     R"(^Rejecting K-Lined user ([^ ]+)\[([^@]+)@([^\]]+)\] \[([^\] ]+)\] \((.*)\)$)"},

    {SnoteTag::NickChange,
     R"(^Nick change: From ([^ ]+) to ([^ ]+) \[([^@]+)@([^ ]+)\]$)"},

    {SnoteTag::CreateChannel,
     R"(^([^ ]+) is creating new channel ([^ ]+)$)"},

    {SnoteTag::TemporaryKlineExpired,
     R"(^Temporary K-line for \[([^ ]+)\] expired$)"},

    {SnoteTag::PropagatedBanExpired,
     R"(^Propagated ban for \[([^ ]+)\] expired$)"},

    {SnoteTag::DisconnectingKlined,
     R"(^Disconnecting K-Lined user ([^ ]+)\[([^@]+)@([^ ]+)\] \((.*)\)$)"},

    {SnoteTag::NewPropagatedKline,
     R"(^([^ ]+)!([^ ]+)@([^ ]+)\{([^ ]+)\} added global ([^ ]+) min\. K-Line for \[([^ ]+)\] \[(.*)\]$)"},

    {SnoteTag::NewTemporaryKline,
     R"(^([^ ]+)!([^ ]+)@([^ ]+)\{([^ ]+)\} added temporary ([^ ]+) min\. K-Line for \[([^ ]+)\] \[(.*)\]$)"},

    {SnoteTag::LoginAttempts,
     "^Warning: \x02([^ ]+)\x02 failed login attempts to \x02([^ ]+)\x02\\. Last attempt received from \x02(.+)\x02.*$"},

    {SnoteTag::PossibleFlooder,
     R"(^Possible Flooder ([^ ]+)\[([^ ]+)@[^ ]+\] on ([^ ]+) target: ([^ ]+)$)"},

    {SnoteTag::Killed,
     R"(^Received KILL message for ([^ ]+)!([^ ]+)@([^ ]+)\. From ([^ ]+) Path: ([^ ]+) \((.*)\)$)"},
};

auto setup_database() -> hs_database_t*
{
    auto const n = std::size(patterns);
    std::vector<char const*> expressions;
    std::vector<unsigned> flags(n, HS_FLAG_SINGLEMATCH);
    std::vector<unsigned> ids;

    expressions.reserve(n);
    ids.reserve(n);

    for (std::size_t i = 0; i < n; i++)
    {
        expressions.push_back(patterns[i].expression);
        ids.push_back(i);
    }

    hs_database_t* db;
    hs_compile_error *error;
    hs_platform_info_t *platform = nullptr; // target current platform
    switch (hs_compile_multi(expressions.data(), flags.data(), ids.data(), expressions.size(), HS_MODE_BLOCK, platform, &db, &error))
    {
        case HS_COMPILER_ERROR:
        {
            std::string msg = error->message;
            hs_free_compile_error(error);
            throw std::runtime_error{std::move(msg)};
        }
        case HS_SUCCESS:
            break;
        default:
            abort();
    }
    return db;
}

} // namespace

auto SnoteThread::start(Connection& connection) -> std::shared_ptr<SnoteThread>
{
    auto thread = std::make_shared<SnoteThread>();

    thread->db_.reset(setup_database());

    hs_scratch_t* scratch = nullptr;
    if (HS_SUCCESS != hs_alloc_scratch(thread->db_.get(), &scratch))
    {
        abort();
    }
    thread->scratch_.reset(scratch);

    static char const* const prefix = "*** Notice -- ";
    connection.add_listener<IrcMsgEvent>([&connection, thread](IrcMsgEvent& event)
    {
        auto& args = event.irc.args;
        if (IrcCommand::NOTICE == event.command && "*" == args[0] && args[1].starts_with(prefix))
        {
            event.handled_ = true;
            auto const message = args[1].substr(strlen(prefix));
            
            unsigned match_id;
            auto cb = [&match_id](unsigned id, unsigned long long, unsigned long long, unsigned) -> int
            {
                match_id = id;
                return 1; // stop scanning
            };

            auto const scan_result =
                hs_scan(
                    thread->db_.get(),
                    message.data(), message.size(),
                    0, // no flags
                    thread->scratch_.get(),
                    CCallback<decltype(cb)>::invoke, &cb
                );

            switch (scan_result)
            {
            case HS_SUCCESS:
                std::cout << "Unknown snote: " << message << std::endl;
                break;
            
            case HS_SCAN_TERMINATED:
            {
                auto& pattern = patterns[match_id];
                std::match_results<std::string_view::const_iterator> results;
                if (not std::regex_match(message.begin(), message.end(), results, pattern.regex))
                {
                    // something went wrong - hyperscan disagrees with std::regex
                    abort();
                }

                std::vector<std::string_view> parts;
                for (auto const sub : results)
                {
                    parts.push_back(std::string_view{sub.first, sub.second});
                }
                connection.make_event<SnoteEvent>(pattern.tag, std::move(parts));
                break;
            }

            default:
                abort();
            }
        }
    });

    return thread;
}

auto SnoteThread::DbDeleter::operator()(hs_database_t * db) const -> void
{
    if (HS_SUCCESS != hs_free_database(db))
    {
        abort();
    }
}

auto SnoteThread::ScratchDeleter::operator()(hs_scratch_t * scratch) const -> void
{
    if (HS_SUCCESS != hs_free_scratch(scratch))
    {
        abort();
    }
}