/*

WEBSOCKET MODULE

Copyright (C) 2016-2019 by Xose Pérez <xose dot perez at gmail dot com>

*/

#if WEB_SUPPORT

#include <ESPAsyncTCP.h>
#include <ESPAsyncWebServer.h>
#include <ArduinoJson.h>
#include <Ticker.h>
#include <vector>
#include "libs/WebSocketIncommingBuffer.h"

AsyncWebSocket _ws("/ws");
Ticker _ws_defer;
uint32_t _ws_last_update = 0;

// -----------------------------------------------------------------------------
// WS callbacks
// -----------------------------------------------------------------------------

ws_callbacks_t& ws_callbacks_t::onVisible(ws_on_send_callback_f cb) {
    on_visible.push_back(cb);
    return *this;
}

ws_callbacks_t& ws_callbacks_t::onConnected(ws_on_send_callback_f cb) {
    on_connected.push_back(cb);
    return *this;
}

ws_callbacks_t& ws_callbacks_t::onData(ws_on_send_callback_f cb) {
    on_data.push_back(cb);
    return *this;
}

ws_callbacks_t& ws_callbacks_t::onAction(ws_on_action_callback_f cb) {
    on_action.push_back(cb);
    return *this;
}

ws_callbacks_t& ws_callbacks_t::onKeyCheck(ws_on_keycheck_callback_f cb) {
    on_keycheck.push_back(cb);
    return *this;
}

ws_callbacks_t _ws_callbacks;

struct ws_counter_t {

    ws_counter_t() : current(0), start(0), stop(0) {}

    ws_counter_t(uint32_t start, uint32_t stop) :
        current(start), start(start), stop(stop) {}

    void reset() {
        current = start;
    }

    void next() {
        if (current < stop) {
            ++current;
        }
    }

    bool done() {
        return (current >= stop);
    }

    uint32_t current;
    uint32_t start;
    uint32_t stop;
};

struct ws_data_t {

    enum mode_t {
        SEQUENCE,
        ALL
    };

    ws_data_t(const ws_on_send_callback_f& cb) :
        storage(new ws_on_send_callback_list_t {cb}),
        client_id(0),
        mode(ALL),
        callbacks(*storage.get()),
        counter(0, 1)
    {}

    ws_data_t(const uint32_t client_id, ws_on_send_callback_list_t&& callbacks, mode_t mode = SEQUENCE) :
        storage(new ws_on_send_callback_list_t(std::move(callbacks))),
        client_id(client_id),
        mode(mode),
        callbacks(*storage.get()),
        counter(0, (storage.get())->size())
    {}

    ws_data_t(const uint32_t client_id, const ws_on_send_callback_list_t& callbacks, mode_t mode = SEQUENCE) :
        client_id(client_id),
        mode(mode),
        callbacks(callbacks),
        counter(0, callbacks.size())
    {}

    bool done() {
        return counter.done();
    }

    void sendAll(JsonObject& root) {
        while (!counter.done()) counter.next();
        for (auto& callback : callbacks) {
            callback(root);
        }
    }

    void sendCurrent(JsonObject& root) {
        callbacks[counter.current](root);
        counter.next();
    }

    void send(JsonObject& root) {
        switch (mode) {
            case SEQUENCE: sendCurrent(root); break;
            case ALL: sendAll(root); break;
        }
    }

    std::unique_ptr<ws_on_send_callback_list_t> storage;

    const uint32_t client_id;
    const mode_t mode;
    const ws_on_send_callback_list_t& callbacks;
    ws_counter_t counter;
};

std::queue<ws_data_t> _ws_client_data;

// -----------------------------------------------------------------------------
// WS authentication
// -----------------------------------------------------------------------------

struct ws_ticket_t {
    IPAddress ip;
    unsigned long timestamp = 0;
};
ws_ticket_t _ws_tickets[WS_BUFFER_SIZE];

void _onAuth(AsyncWebServerRequest *request) {

    webLog(request);
    if (!webAuthenticate(request)) return request->requestAuthentication();

    IPAddress ip = request->client()->remoteIP();
    unsigned long now = millis();
    unsigned short index;
    for (index = 0; index < WS_BUFFER_SIZE; index++) {
        if (_ws_tickets[index].ip == ip) break;
        if (_ws_tickets[index].timestamp == 0) break;
        if (now - _ws_tickets[index].timestamp > WS_TIMEOUT) break;
    }
    if (index == WS_BUFFER_SIZE) {
        request->send(429);
    } else {
        _ws_tickets[index].ip = ip;
        _ws_tickets[index].timestamp = now;
        request->send(200, "text/plain", "OK");
    }

}

bool _wsAuth(AsyncWebSocketClient * client) {

    IPAddress ip = client->remoteIP();
    unsigned long now = millis();
    unsigned short index = 0;

    for (index = 0; index < WS_BUFFER_SIZE; index++) {
        if ((_ws_tickets[index].ip == ip) && (now - _ws_tickets[index].timestamp < WS_TIMEOUT)) break;
    }

    if (index == WS_BUFFER_SIZE) {
        return false;
    }

    return true;

}

// -----------------------------------------------------------------------------
// Debug
// -----------------------------------------------------------------------------

#if DEBUG_WEB_SUPPORT

struct ws_debug_msg_t {
    ws_debug_msg_t(const char* prefix, const char* message) :
        prefix(prefix), message(message)
    {}
    String prefix;
    String message;
};

struct ws_debug_t {

    ws_debug_t(size_t capacity) :
        flush(false),
        current(0),
        capacity(capacity)
    {
        messages.reserve(capacity);
    }

    void clear() {
        messages.clear();
        current = 0;
        flush = false;
    }

    void add(const char* prefix, const char* message) {
        if (current >= capacity) {
            flush = true;
            send(wsConnected());
        }

        messages.emplace(messages.begin() + current, prefix, message);
        flush = true;
        ++current;
    }

    void send(const bool connected) {
        if (!connected && flush) {
            clear();
            return;
        }

        if (!flush) return;
        // ref: http://arduinojson.org/v5/assistant/
        // {"weblog": {"msg":[...],"pre":[...]}}
        DynamicJsonBuffer jsonBuffer(2*JSON_ARRAY_SIZE(messages.size()) + JSON_OBJECT_SIZE(1) + JSON_OBJECT_SIZE(2));

        JsonObject& root = jsonBuffer.createObject();
        JsonObject& weblog = root.createNestedObject("weblog");

        JsonArray& msg = weblog.createNestedArray("msg");
        JsonArray& pre = weblog.createNestedArray("pre");

        for (auto& message : messages) {
            pre.add(message.prefix.c_str());
            msg.add(message.message.c_str());
        }

        wsSend(root);
        clear();
    }

    bool flush;
    size_t current;
    const size_t capacity;
    std::vector<ws_debug_msg_t> messages;

};

// TODO: move to the headers?
constexpr const size_t WS_DEBUG_MSG_BUFFER = 8;
ws_debug_t _ws_debug(WS_DEBUG_MSG_BUFFER);

bool wsDebugSend(const char* prefix, const char* message) {
    if (!wsConnected()) return false;
    _ws_debug.add(prefix, message);
    return true;
}

#endif

// Check the existing setting before saving it
// TODO: this should know of the default values, somehow?
// TODO: move webPort handling somewhere else?
bool _wsStore(const String& key, const String& value) {

    if (key == "webPort") {
        if ((value.toInt() == 0) || (value.toInt() == 80)) {
            return delSetting(key);
        }
    }

    if (value != getSetting(key)) {
        return setSetting(key, value);
    }

    return false;

}

// -----------------------------------------------------------------------------
// Store indexed key (key0, key1, etc.) from array
// -----------------------------------------------------------------------------

bool _wsStore(const String& key, JsonArray& value) {

    bool changed = false;

    unsigned char index = 0;
    for (auto element : value) {
        if (_wsStore(key + index, element.as<String>())) changed = true;
        index++;
    }

    // Delete further values
    for (unsigned char i=index; i<SETTINGS_MAX_LIST_COUNT; i++) {
        if (!delSetting(key, index)) break;
        changed = true;
    }

    return changed;

}

bool _wsCheckKey(const String& key, JsonVariant& value) {
    for (auto& callback : _ws_callbacks.on_keycheck) {
        if (callback(key.c_str(), value)) return true;
        // TODO: remove this to call all OnKeyCheckCallbacks with the
        // current key/value
    }
    return false;
}

void _wsParse(AsyncWebSocketClient *client, uint8_t * payload, size_t length) {

    //DEBUG_MSG_P(PSTR("[WEBSOCKET] Parsing: %s\n"), length ? (char*) payload : "");

    // Get client ID
    uint32_t client_id = client->id();

    // Check early for empty object / nothing
    if ((length == 0) || (length == 1)) {
        return;
    }

    if ((length == 3) && (strcmp((char*) payload, "{}") == 0)) {
        return;
    }

    // Parse JSON input
    // TODO: json buffer should be pretty efficient with the non-const payload,
    // most of the space is taken by the object key references
    DynamicJsonBuffer jsonBuffer(512);
    JsonObject& root = jsonBuffer.parseObject((char *) payload);
    if (!root.success()) {
        DEBUG_MSG_P(PSTR("[WEBSOCKET] JSON parsing error\n"));
        wsSend_P(client_id, PSTR("{\"message\": 3}"));
        return;
    }

    // Check actions -----------------------------------------------------------

    const char* action = root["action"];
    if (action) {

        DEBUG_MSG_P(PSTR("[WEBSOCKET] Requested action: %s\n"), action);

        if (strcmp(action, "reboot") == 0) {
            deferredReset(100, CUSTOM_RESET_WEB);
            return;
        }

        if (strcmp(action, "reconnect") == 0) {
            _ws_defer.once_ms(100, wifiDisconnect);
            return;
        }

        if (strcmp(action, "factory_reset") == 0) {
            DEBUG_MSG_P(PSTR("\n\nFACTORY RESET\n\n"));
            resetSettings();
            deferredReset(100, CUSTOM_RESET_FACTORY);
            return;
        }

        JsonObject& data = root["data"];
        if (data.success()) {

            // Callbacks
            for (auto& callback : _ws_callbacks.on_action) {
                callback(client_id, action, data);
            }

            // Restore configuration via websockets
            if (strcmp(action, "restore") == 0) {
                if (settingsRestoreJson(data)) {
                    wsSend_P(client_id, PSTR("{\"message\": 5}"));
                } else {
                    wsSend_P(client_id, PSTR("{\"message\": 4}"));
                }
            }

            return;

        }

    };

    // Check configuration -----------------------------------------------------

    JsonObject& config = root["config"];
    if (config.success()) {

        DEBUG_MSG_P(PSTR("[WEBSOCKET] Parsing configuration data\n"));

        String adminPass;
        bool save = false;

        for (auto kv: config) {

            bool changed = false;
            String key = kv.key;
            JsonVariant& value = kv.value;

            // Check password
            if (key == "adminPass") {
                if (!value.is<JsonArray&>()) continue;
                JsonArray& values = value.as<JsonArray&>();
                if (values.size() != 2) continue;
                if (values[0].as<String>().equals(values[1].as<String>())) {
                    String password = values[0].as<String>();
                    if (password.length() > 0) {
                        setSetting(key, password);
                        save = true;
                        wsSend_P(client_id, PSTR("{\"action\": \"reload\"}"));
                    }
                } else {
                    wsSend_P(client_id, PSTR("{\"message\": 7}"));
                }
                continue;
            }

            if (!_wsCheckKey(key, value)) {
                delSetting(key);
                continue;
            }

            // Store values
            if (value.is<JsonArray&>()) {
                if (_wsStore(key, value.as<JsonArray&>())) changed = true;
            } else {
                if (_wsStore(key, value.as<String>())) changed = true;
            }

            // Update flags if value has changed
            if (changed) {
                save = true;
            }

        }

        // Save settings
        if (save) {

            // Callbacks
            espurnaReload();

            // Persist settings
            saveSettings();

            wsSend_P(client_id, PSTR("{\"message\": 8}"));

        } else {

            wsSend_P(client_id, PSTR("{\"message\": 9}"));

        }

    }

}

void _wsUpdate(JsonObject& root) {
    root["heap"] = getFreeHeap();
    root["uptime"] = getUptime();
    root["rssi"] = WiFi.RSSI();
    root["loadaverage"] = systemLoadAverage();
    #if ADC_MODE_VALUE == ADC_VCC
        root["vcc"] = ESP.getVcc();
    #endif
    #if NTP_SUPPORT
        if (ntpSynced()) root["now"] = now();
    #endif
}

void _wsResetUpdateTimer() {
    _ws_last_update = millis() + WS_UPDATE_INTERVAL;
}

void _wsDoUpdate(const bool connected) {
    if (!connected) return;
    if (millis() - _ws_last_update > WS_UPDATE_INTERVAL) {
        _ws_last_update = millis();
        wsSend(_wsUpdate);
    }
}

bool _wsOnKeyCheck(const char * key, JsonVariant& value) {
    if (strncmp(key, "ws", 2) == 0) return true;
    if (strncmp(key, "admin", 5) == 0) return true;
    if (strncmp(key, "hostname", 8) == 0) return true;
    if (strncmp(key, "desc", 4) == 0) return true;
    if (strncmp(key, "webPort", 7) == 0) return true;
    return false;
}

void _wsOnConnected(JsonObject& root) {
    char chipid[7];
    snprintf_P(chipid, sizeof(chipid), PSTR("%06X"), ESP.getChipId());

    root["webMode"] = WEB_MODE_NORMAL;

    root["app_name"] = APP_NAME;
    root["app_version"] = APP_VERSION;
    root["app_build"] = buildTime();
    #if defined(APP_REVISION)
        root["app_revision"] = APP_REVISION;
    #endif
    root["manufacturer"] = MANUFACTURER;
    root["chipid"] = String(chipid);
    root["mac"] = WiFi.macAddress();
    root["bssid"] = WiFi.BSSIDstr();
    root["channel"] = WiFi.channel();
    root["device"] = DEVICE;
    root["hostname"] = getSetting("hostname");
    root["desc"] = getSetting("desc");
    root["network"] = getNetwork();
    root["deviceip"] = getIP();
    root["sketch_size"] = ESP.getSketchSize();
    root["free_size"] = ESP.getFreeSketchSpace();
    root["sdk"] = ESP.getSdkVersion();
    root["core"] = getCoreVersion();

    root["btnDelay"] = getSetting("btnDelay", BUTTON_DBLCLICK_DELAY).toInt();
    root["webPort"] = getSetting("webPort", WEB_PORT).toInt();
    root["wsAuth"] = getSetting("wsAuth", WS_AUTHENTICATION).toInt() == 1;
    root["hbMode"] = getSetting("hbMode", HEARTBEAT_MODE).toInt();
    root["hbInterval"] = getSetting("hbInterval", HEARTBEAT_INTERVAL).toInt();
}

void wsSend(JsonObject& root) {
    // TODO: avoid serializing twice?
    size_t len = root.measureLength();
    AsyncWebSocketMessageBuffer* buffer = _ws.makeBuffer(len);

    if (buffer) {
        root.printTo(reinterpret_cast<char*>(buffer->get()), len + 1);
        _ws.textAll(buffer);
    }
}

void wsSend(uint32_t client_id, JsonObject& root) {
    AsyncWebSocketClient* client = _ws.client(client_id);
    if (client == nullptr) return;

    // TODO: avoid serializing twice?
    size_t len = root.measureLength();
    AsyncWebSocketMessageBuffer* buffer = _ws.makeBuffer(len);

    if (buffer) {
        root.printTo(reinterpret_cast<char*>(buffer->get()), len + 1);
        client->text(buffer);
    }
}

void _wsConnected(uint32_t client_id) {

    const bool changePassword = (USE_PASSWORD && WEB_FORCE_PASS_CHANGE)
        ? getAdminPass().equals(ADMIN_PASS)
        : false;

    if (changePassword) {
        StaticJsonBuffer<JSON_OBJECT_SIZE(1)> jsonBuffer;
        JsonObject& root = jsonBuffer.createObject();
        root["webMode"] = WEB_MODE_PASSWORD;
        wsSend(client_id, root);
        return;
    }

    wsPostAll(client_id, _ws_callbacks.on_visible);
    wsPostSequence(client_id, _ws_callbacks.on_connected);
    wsPostSequence(client_id, _ws_callbacks.on_data);

}

void _wsEvent(AsyncWebSocket * server, AsyncWebSocketClient * client, AwsEventType type, void * arg, uint8_t *data, size_t len){

    if (type == WS_EVT_CONNECT) {

        client->_tempObject = nullptr;

        #ifndef NOWSAUTH
            if (!_wsAuth(client)) {
                wsSend_P(client->id(), PSTR("{\"message\": 10}"));
                DEBUG_MSG_P(PSTR("[WEBSOCKET] Validation check failed\n"));
                client->close();
                return;
            }
        #endif

        IPAddress ip = client->remoteIP();
        DEBUG_MSG_P(PSTR("[WEBSOCKET] #%u connected, ip: %d.%d.%d.%d, url: %s\n"), client->id(), ip[0], ip[1], ip[2], ip[3], server->url());
        _wsConnected(client->id());
        _wsResetUpdateTimer();
        wifiReconnectCheck();
        client->_tempObject = new WebSocketIncommingBuffer(_wsParse, true);

    } else if(type == WS_EVT_DISCONNECT) {
        DEBUG_MSG_P(PSTR("[WEBSOCKET] #%u disconnected\n"), client->id());
        if (client->_tempObject) {
            delete (WebSocketIncommingBuffer *) client->_tempObject;
        }
        wifiReconnectCheck();

    } else if(type == WS_EVT_ERROR) {
        DEBUG_MSG_P(PSTR("[WEBSOCKET] #%u error(%u): %s\n"), client->id(), *((uint16_t*)arg), (char*)data);

    } else if(type == WS_EVT_PONG) {
        DEBUG_MSG_P(PSTR("[WEBSOCKET] #%u pong(%u): %s\n"), client->id(), len, len ? (char*) data : "");

    } else if(type == WS_EVT_DATA) {
        //DEBUG_MSG_P(PSTR("[WEBSOCKET] #%u data(%u): %s\n"), client->id(), len, len ? (char*) data : "");
        if (!client->_tempObject) return;
        WebSocketIncommingBuffer *buffer = (WebSocketIncommingBuffer *)client->_tempObject;
        AwsFrameInfo * info = (AwsFrameInfo*)arg;
        buffer->data_event(client, info, data, len);

    }

}

// TODO: make this generic loop method to queue important ws messages?
//       or, if something uses ticker / async ctx to send messages,
//       it needs a retry mechanism built into the callback object
void _wsHandleClientData(const bool connected) {

    if (!connected && !_ws_client_data.empty()) {
        _ws_client_data.pop();
        return;
    }

    if (_ws_client_data.empty()) return;
    auto& data = _ws_client_data.front();

    // client_id == 0 means we need to send the message to every client
    if (data.client_id) {
        AsyncWebSocketClient* ws_client = _ws.client(data.client_id);

        if (!ws_client) {
            _ws_client_data.pop();
            return;
        }

        // wait until we can send the next batch of messages
        // XXX: enforce that callbacks send only one message per iteration
        if (ws_client->queueIsFull()) {
            return;
        }
    }

    // XXX: block allocation will try to create *2 next time,
    // likely failing and causing wsSend to reference empty objects
    // XXX: arduinojson6 will not do this, but we may need to use per-callback buffers
    constexpr const size_t BUFFER_SIZE = 3192;
    DynamicJsonBuffer jsonBuffer(BUFFER_SIZE);
    JsonObject& root = jsonBuffer.createObject();

    data.send(root);
    if (data.client_id) {
        wsSend(data.client_id, root);
    } else {
        wsSend(root);
    }
    yield();

    if (data.done()) {
        _ws_client_data.pop();
    }
}

void _wsLoop() {
    const bool connected = wsConnected();
    _wsDoUpdate(connected);
    _wsHandleClientData(connected);
    #if DEBUG_WEB_SUPPORT
        _ws_debug.send(connected);
    #endif
}

// -----------------------------------------------------------------------------
// Public API
// -----------------------------------------------------------------------------

bool wsConnected() {
    return (_ws.count() > 0);
}

bool wsConnected(uint32_t client_id) {
    return _ws.hasClient(client_id);
}

ws_callbacks_t& wsRegister() {
    return _ws_callbacks;
}

void wsSend(ws_on_send_callback_f callback) {
    if (_ws.count() > 0) {
        DynamicJsonBuffer jsonBuffer(512);
        JsonObject& root = jsonBuffer.createObject();
        callback(root);

        wsSend(root);
    }
}

void wsSend(const char * payload) {
    if (_ws.count() > 0) {
        _ws.textAll(payload);
    }
}

void wsSend_P(PGM_P payload) {
    if (_ws.count() > 0) {
        char buffer[strlen_P(payload)];
        strcpy_P(buffer, payload);
        _ws.textAll(buffer);
    }
}

void wsSend(uint32_t client_id, ws_on_send_callback_f callback) {
    AsyncWebSocketClient* client = _ws.client(client_id);
    if (client == nullptr) return;

    DynamicJsonBuffer jsonBuffer(512);
    JsonObject& root = jsonBuffer.createObject();
    callback(root);
    wsSend(client_id, root);
}

void wsSend(uint32_t client_id, const char * payload) {
    _ws.text(client_id, payload);
}

void wsSend_P(uint32_t client_id, PGM_P payload) {
    char buffer[strlen_P(payload)];
    strcpy_P(buffer, payload);
    _ws.text(client_id, buffer);
}

void wsPost(const ws_on_send_callback_f& cb) {
    _ws_client_data.emplace(cb);
}

void wsPostAll(uint32_t client_id, const ws_on_send_callback_list_t& cbs) {
    _ws_client_data.emplace(client_id, cbs, ws_data_t::ALL);
}

void wsPostAll(const ws_on_send_callback_list_t& cbs) {
    _ws_client_data.emplace(0, cbs, ws_data_t::ALL);
}

void wsPostSequence(uint32_t client_id, const ws_on_send_callback_list_t& cbs) {
    _ws_client_data.emplace(client_id, cbs, ws_data_t::SEQUENCE);
}

void wsPostSequence(uint32_t client_id, ws_on_send_callback_list_t&& cbs) {
    _ws_client_data.emplace(client_id, std::forward<ws_on_send_callback_list_t>(cbs), ws_data_t::SEQUENCE);
}

void wsPostSequence(const ws_on_send_callback_list_t& cbs) {
    _ws_client_data.emplace(0, cbs, ws_data_t::SEQUENCE);
}

void wsSetup() {

    _ws.onEvent(_wsEvent);
    webServer()->addHandler(&_ws);

    // CORS
    const String webDomain = getSetting("webDomain", WEB_REMOTE_DOMAIN);
    DefaultHeaders::Instance().addHeader("Access-Control-Allow-Origin", webDomain);
    if (!webDomain.equals("*")) {
        DefaultHeaders::Instance().addHeader("Access-Control-Allow-Credentials", "true");
    }

    webServer()->on("/auth", HTTP_GET, _onAuth);

    wsRegister()
        .onConnected(_wsOnConnected)
        .onKeyCheck(_wsOnKeyCheck);

    espurnaRegisterLoop(_wsLoop);
}

#endif // WEB_SUPPORT