use std::sync::{Arc, Mutex};
use std::process;
use std::collections::HashMap;
use std::thread;
use std::time::{Duration, Instant};
use crate::config::{AppConfig, ModbusValueMaps};
use crate::modbus;
use rumqttc::{Event, MqttOptions, Packet, Client, QoS, RecvTimeoutError};

pub fn start_mqtt_thread(config: Arc<Mutex<AppConfig>>, values: Arc<Mutex<ModbusValueMaps>>) {
    let mqtt_config = {
        let cfg = config.lock().unwrap();
        cfg.mqtt.clone()
    };
    let broker = if mqtt_config.broker.is_empty() { "localhost".to_string() } else { mqtt_config.broker.clone() };
    let port = if mqtt_config.port == 0 { 1883 } else { mqtt_config.port };
    let path = if let Some(ref p) = mqtt_config.path { p.clone() } else { "paramod/values".to_string() };
    let leitsystem_path = mqtt_config
        .leitsystem_path
        .clone()
        .unwrap_or_else(|| format!("{}/leitsystem", path));
    let set_write_interval = Duration::from_millis(mqtt_config.set_write_interval_ms.unwrap_or(2000).max(100));
    let user = mqtt_config.user.clone().unwrap_or_default();
    let password = mqtt_config.password.clone().unwrap_or_default();
    let user_is_empty = user.is_empty();

    thread::spawn(move || {
        let client_id = format!("paramod-client-{}", process::id());
        let mut mqttoptions = MqttOptions::new(client_id, broker, port);
        mqttoptions.set_keep_alive(Duration::from_secs(5));
        if !user_is_empty {
            mqttoptions.set_credentials(user, password);
        }
        let (mut client, mut connection) = Client::new(mqttoptions, 10);

        let set_topic = format!("{}/+/set", path);
        if let Err(e) = client.subscribe(set_topic, QoS::AtLeastOnce) {
            eprintln!("MQTT Subscribe fehlgeschlagen: {}", e);
        }
        let leitsystem_state_topic = format!("{}/active", leitsystem_path.trim_end_matches('/'));
        if let Err(e) = client.subscribe(leitsystem_state_topic.clone(), QoS::AtLeastOnce) {
            eprintln!("MQTT Subscribe Leitsystem fehlgeschlagen: {}", e);
        }

        let publish_interval = Duration::from_secs(5);
        let mut last_publish = Instant::now() - publish_interval;
        let mut last_set_write = Instant::now() - set_write_interval;
        let mut pending_set_values: HashMap<String, String> = HashMap::new();
        let mut leitsystem_enabled = false;

        loop {
            if last_publish.elapsed() >= publish_interval {
                {
                    let values = values.lock().unwrap();
                    // Input Register
                    for (name, val) in &values.modbus_input_register_values {
                        if let Some(v) = val {
                            if should_publish(&config, name, "input_register") {
                                let topic = format!("{}/{}/state", path, name);
                                let payload = format!("{}", v);
                                let _ = client.publish(topic, QoS::AtLeastOnce, false, payload);
                            }
                        }
                    }
                    // Holding Register
                    for (name, val) in &values.modbus_holding_register_values {
                        if let Some(v) = val {
                            if should_publish(&config, name, "holding_register") {
                                let topic = format!("{}/{}/state", path, name);
                                let payload = format!("{}", v);
                                let _ = client.publish(topic, QoS::AtLeastOnce, false, payload);
                            }
                        }
                    }
                    // Coils
                    for (name, val) in &values.modbus_coils_values {
                        if let Some(v) = val {
                            if should_publish(&config, name, "coils") {
                                let topic = format!("{}/{}/state", path, name);
                                let payload = format!("{}", v);
                                let _ = client.publish(topic, QoS::AtLeastOnce, false, payload);
                            }
                        }
                    }
                }

                let state_payload = if leitsystem_enabled { "ON" } else { "OFF" };
                let _ = client.publish(
                    leitsystem_state_topic.clone(),
                    QoS::AtLeastOnce,
                    true,
                    state_payload,
                );
                last_publish = Instant::now();
            }

            if last_set_write.elapsed() >= set_write_interval {
                let cfg = {
                    let lock = config.lock().unwrap();
                    lock.clone()
                };

                if leitsystem_enabled {
                    for (name, payload) in &pending_set_values {
                        if let Err(e) = modbus::write_value_by_name(&cfg, name, payload) {
                            eprintln!("MQTT set -> Modbus Fehler ({}): {}", name, e);
                        } else {
                            mirror_set_value(&values, &cfg, name, payload);
                        }
                    }
                }

                last_set_write = Instant::now();
            }

            match connection.recv_timeout(Duration::from_millis(200)) {
                Ok(Ok(Event::Incoming(Packet::Publish(publish)))) => {
                    if publish.topic == leitsystem_state_topic {
                        let payload = String::from_utf8_lossy(&publish.payload).trim().to_string();
                        match parse_boolish(&payload) {
                            Some(v) => leitsystem_enabled = v,
                            None => eprintln!("Ungültiger Leitsystem state '{}', erwartet ON/OFF", payload),
                        }
                        continue;
                    }

                    if let Ok(name) = extract_name_from_set_topic(&path, &publish.topic) {
                        let payload = String::from_utf8_lossy(&publish.payload).trim().to_string();
                        pending_set_values.insert(name.clone(), payload.clone());
                    }
                }
                Ok(Ok(_)) => {}
                Ok(Err(e)) => {
                    eprintln!("MQTT Connection Fehler: {}", e);
                    eprintln!("Hinweis: Häufige Ursache ist eine zweite MQTT-Session mit derselben Client-ID.");
                }
                Err(RecvTimeoutError::Timeout) => {}
                Err(RecvTimeoutError::Disconnected) => {
                    eprintln!("MQTT Verbindung getrennt (request channel geschlossen)");
                    thread::sleep(Duration::from_millis(500));
                }
            }
        }
    });
}

fn parse_boolish(payload: &str) -> Option<bool> {
    match payload.trim().to_ascii_lowercase().as_str() {
        "1" | "true" | "on" => Some(true),
        "0" | "false" | "off" => Some(false),
        _ => None,
    }
}

fn mirror_set_value(values: &Arc<Mutex<ModbusValueMaps>>, cfg: &AppConfig, name: &str, payload: &str) {
    if let Ok(mut maps) = values.lock() {
        if let Some(ref coils) = cfg.modbus_coils {
            for map in coils {
                if map.contains_key(name) {
                    if let Some(v) = parse_boolish(payload) {
                        maps.modbus_coils_values.insert(name.to_string(), Some(if v { 1.0 } else { 0.0 }));
                    }
                    return;
                }
            }
        }

        if let Some(ref holding) = cfg.modbus_holding_register {
            for map in holding {
                if map.contains_key(name) {
                    if let Ok(v) = payload.parse::<f64>() {
                        maps.modbus_holding_register_values.insert(name.to_string(), Some(v));
                    }
                    return;
                }
            }
        }
    }
}

fn extract_name_from_set_topic(base_path: &str, topic: &str) -> Result<String, String> {
    let prefix = format!("{}/", base_path.trim_end_matches('/'));
    if !topic.starts_with(&prefix) || !topic.ends_with("/set") {
        return Err("Topic passt nicht zum /set-Schema".to_string());
    }
    let without_prefix = &topic[prefix.len()..];
    let name = without_prefix.strip_suffix("/set").unwrap_or_default();
    if name.is_empty() || name.contains('/') {
        return Err("Ungültiger Variablenname im Topic".to_string());
    }
    Ok(name.to_string())
}

fn should_publish(config: &Arc<Mutex<AppConfig>>, name: &str, reg_type: &str) -> bool {
    let cfg = config.lock().unwrap();
    match reg_type {
        "input_register" => {
            if let Some(regs) = &cfg.modbus_input_register {
                for map in regs {
                    if let Some(reg) = map.get(name) {
                        return reg.mqtt.unwrap_or(false);
                    }
                }
            }
        }
        "holding_register" => {
            if let Some(regs) = &cfg.modbus_holding_register {
                for map in regs {
                    if let Some(reg) = map.get(name) {
                        return reg.mqtt.unwrap_or(false);
                    }
                }
            }
        }
        "coils" => {
            if let Some(coils) = &cfg.modbus_coils {
                for map in coils {
                    if let Some(coil) = map.get(name) {
                        return coil.mqtt.unwrap_or(false);
                    }
                }
            }
        }
        _ => {}
    }
    false
}