#include "irc_service.h"

#include <Arduino.h>

#include <cstdio>

#include "storage_paths.h"

namespace roro {

namespace {
constexpr uint32_t kQuietPingMs = 240000;  // no traffic for 4 min: ping the server
constexpr uint32_t kDeadMs = 330000;       // and give up if it still says nothing

std::string hex(const uint8_t* bytes, size_t n) {
    std::string out;
    char buf[3];
    for (size_t i = 0; i < n; i++) {
        std::snprintf(buf, sizeof(buf), "%02x", bytes[i]);
        out += buf;
    }
    return out;
}
}  // namespace

IrcService::IrcService(KeyValueStore& store, const std::string& defaultNick, WifiService& wifi, StorageService& storage,
                       ClockService& clock, EventBus& bus)
    : config_(store), wifi_(wifi), storage_(storage), clock_(clock), bus_(bus) {
    config_.load(defaultNick);
    session_.reset(new IrcSession(config_));
}

void IrcService::start() {
    if (task_) return;
    lock_ = xSemaphoreCreateMutex();
    xTaskCreate(taskEntry, "irc", 6144, this, 1, &task_);  // peak 4.0 KB (TLS handshake, M2)
}

void IrcService::connect() {
    stoppedByUser_ = false;
    if (wanted_) return;
    retryAtMs_ = millis();
    backoff_.reset();
    wanted_ = true;
}

void IrcService::disconnect() {
    stoppedByUser_ = true;
    stopRequested_ = true;  // the IRC task says QUIT and closes; nothing to do if it never started
    if (!task_) wanted_ = false;
}

int IrcService::totalUnread() {
    Lock l(lock_);
    return session_->totalUnread();
}

IrcConfig IrcService::draftConfig() {
    Lock l(lock_);
    return config_;
}

std::string IrcService::applyConfig(const IrcConfig& draft) {
    std::string error = draft.validate();
    if (!error.empty()) return error;
    Lock l(lock_);
    config_.copySettingsFrom(draft);
    config_.save();
    if (wanted_) restart_ = true;  // the task reconnects with a fresh session
    else session_.reset(new IrcSession(config_));
    return "";
}

void IrcService::taskEntry(void* self) { static_cast<IrcService*>(self)->loop(); }

void IrcService::scheduleRetry(const std::string& why) {
    uint32_t delay = backoff_.nextDelayMs();
    retryAtMs_ = millis() + delay;
    status_ = Status::Retrying;
    Lock l(lock_);
    session_->disconnected(clock_.utcNow(), why + ", retrying in " + std::to_string(delay / 1000) + " s");
}

bool IrcService::open() {
    status_ = Status::Connecting;
    IrcConfig settings = draftConfig();  // a snapshot: the UI may apply new settings meanwhile
    bool pinning = settings.tls && settings.allowSelfSigned;
    conn_ = settings.tls ? static_cast<NetworkClient*>(&tlsClient_) : &plainClient_;
    if (settings.tls) {
        tlsClient_.setTimeout(15);  // seconds, for the handshake
        if (pinning) tlsClient_.setInsecure();
        else tlsClient_.useBuiltinCACertBundle();
    }
    if (!conn_->connect(settings.host.c_str(), settings.port)) return false;

    if (pinning) {
        uint8_t sha[32];
        if (!tlsClient_.getFingerprintSHA256(sha)) {
            tlsClient_.stop();
            return false;
        }
        std::string fingerprint = hex(sha, sizeof(sha));
        if (settings.pinnedSha256.empty()) {
            Lock l(lock_);
            config_.pinnedSha256 = fingerprint;  // trust on first use
            config_.save();
        } else if (settings.pinnedSha256 != fingerprint) {
            tlsClient_.stop();
            Lock l(lock_);
            session_->disconnected(clock_.utcNow(), "server certificate changed: not connecting");
            return false;
        }
    }
    open_ = true;
    partial_.clear();
    lastRxMs_ = millis();
    pingSent_ = false;
    status_ = Status::Registering;
    Lock l(lock_);
    session_->connected(clock_.utcNow());
    return true;
}

void IrcService::close(const std::string& reason) {
    if (open_) conn_->stop();
    open_ = false;
    if (!reason.empty()) {
        Lock l(lock_);
        session_->disconnected(clock_.utcNow(), reason);
    }
}

void IrcService::readLines() {
    while (conn_->available()) {
        char c = static_cast<char>(conn_->read());
        if (c == '\n') {
            lastRxMs_ = millis();
            pingSent_ = false;
            Lock l(lock_);
            session_->receive(partial_, clock_.utcNow());
            partial_.clear();
        } else if (c != '\r' && partial_.size() < 1024) {
            partial_ += c;
        }
    }
}

void IrcService::flushEffects() {
    IrcEffects fx;
    bool registered, quit;
    {
        Lock l(lock_);
        fx = session_->takeEffects();
        registered = session_->registered();
        quit = session_->quitRequested();
    }
    for (auto& line : fx.send)
        if (open_) conn_->print((line + "\r\n").c_str());

    std::string date = clock_.localDate();
    std::string host;
    {
        Lock l(lock_);
        host = config_.host;
    }
    for (auto& entry : fx.logs) {
        const IrcLine& l = entry.line;
        std::string when = l.utc >= 0 ? ClockModel::formatLocalTime(l.utc) : "--:--";
        std::string text;
        switch (l.kind) {
            case IrcLine::Kind::Action:
            case IrcLine::Kind::OwnAction: text = "* " + l.nick + " " + l.text; break;
            case IrcLine::Kind::Notice: text = "-" + l.nick + "- " + l.text; break;
            case IrcLine::Kind::Info: text = l.text; break;
            default: text = "<" + l.nick + "> " + l.text; break;
        }
        storage_.appendLine(storage::dailyLogPath({"irc", host, entry.buffer}, date), when + " " + text);
    }
    for (auto& n : fx.notifications)
        bus_.publish(Event::withText(EventType::Notification, n.c_str(), static_cast<int32_t>(NotificationLevel::Message)));

    if (registered && status_ == Status::Registering) {
        status_ = Status::Online;
        backoff_.reset();
    }
    if (quit) {  // /quit: QUIT is already on its way if connected; stop in any state
        stoppedByUser_ = true;
        stopRequested_ = true;
        quitSent_ = true;
    }
}

void IrcService::loop() {
    for (;;) {
        uint32_t now = millis();
        bool wifiUp = wifi_.state() == WifiController::State::Connected;
        bool monitoring = wifi_.state() == WifiController::State::Monitoring;

        if (stopRequested_) {
            stopRequested_ = false;
            if (open_) {
                if (!quitSent_) conn_->print("QUIT :roro9stack\r\n");
                vTaskDelay(pdMS_TO_TICKS(300));  // let QUIT reach the server
                close("");
            }
            quitSent_ = false;
            wanted_ = false;
            status_ = Status::Stopped;
            Lock l(lock_);
            session_->disconnected(clock_.utcNow(), "disconnected (Enter reconnects)");
        }
        if (restart_) {
            restart_ = false;
            if (open_) {
                conn_->print("QUIT :reconfiguring\r\n");
                vTaskDelay(pdMS_TO_TICKS(300));
                close("");
            }
            Lock l(lock_);
            session_.reset(new IrcSession(config_));
            retryAtMs_ = now;
            backoff_.reset();
        }
        if (!wanted_) {
            if (open_) close("disconnected");
            status_ = Status::Stopped;
        } else if (held_) {
            if (open_) {
                conn_->print("QUIT :updating\r\n");
                vTaskDelay(pdMS_TO_TICKS(300));
                close("paused while the device updates");
            }
            status_ = Status::Paused;
            retryAtMs_ = now;  // back at once when released
        } else if (!wifiUp) {
            if (open_) close(monitoring ? "paused for Wi-Fi monitoring" : "Wi-Fi lost");
            status_ = monitoring ? Status::Paused : Status::WaitingForWifi;
            retryAtMs_ = now;  // reconnect as soon as Wi-Fi is back
        } else if (!open_) {
            if (static_cast<int32_t>(now - retryAtMs_) >= 0) {
                if (!open()) scheduleRetry("could not connect to " + draftConfig().host);
            }
        } else if (!conn_->connected()) {
            close("");
            scheduleRetry("connection lost");
        } else {
            readLines();
            uint32_t quiet = millis() - lastRxMs_;
            if (quiet > kDeadMs) {
                close("");
                scheduleRetry("server stopped answering");
            } else if (quiet > kQuietPingMs && !pingSent_) {
                conn_->print("PING :roro9stack\r\n");
                pingSent_ = true;
            }
        }
        {
            Lock l(lock_);
            session_->tick(millis());
        }
        flushEffects();
        vTaskDelay(pdMS_TO_TICKS(open_ ? 30 : 250));
    }
}

}  // namespace roro