use crate::command::Command;
use crate::serial::SerialIO;
use crate::types::*;

use anyhow;
use std::{
    error::Error,
    io::{Read, Write},
    thread,
    time::Duration,
    sync::mpsc::Receiver,
};

use esp_idf_hal::prelude::*;
use esp_idf_hal::serial::{self, Rx, Tx};

use embedded_hal::digital::v2::OutputPin;

use mqtt::packet::{ConnectPacket, PublishPacket, QoSWithPacketIdentifier, VariablePacket};
use mqtt::{Encodable, Decodable, TopicName};

pub type Result<T> = std::result::Result<T, ModemError>;

pub struct Modem<UART: serial::Uart> {
    serial: SerialIO<UART>,
}

#[derive(Debug)]
pub enum ModemError {
    CommandError(String),
    SetupError(String),
    SendDataError(String),
    ReadError(String),
    TimeoutError,
}

impl Error for ModemError {}

impl std::fmt::Display for ModemError {
    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
        write!(f, "{:?}", self)
    }
}

impl<UART: serial::Uart> Modem<UART> {
    pub fn new(tx: Tx<UART>, rx: Rx<UART>) -> Self {
        Self {
            serial: SerialIO::new(tx, rx),
        }
    }

    /// Initialize the modem (sim800l in this case). The initialization process sets all pins in the
    /// required state so that the modem is turned on, then resets it a couple of times (beats me) and
    /// sleeps for 3 seconds, which is enough for the modem to come online.
    ///
    /// Below is an example for sim800l pins on a LilyGo TTGO T-Call.
    ///
    /// # Examples
    ///
    /// ```
    /// let modem_pwrkey = dp.pins.gpio4.into_output().unwrap();
    /// let modem_rst = dp.pins.gpio5.into_output().unwrap();
    /// let modem_power = dp.pins.gpio23.into_output().unwrap();
    ///
    /// modem::init(modem_pwrkey, modem_rst, modem_power);
    /// ```
    pub fn init(&mut self, mut pwrkey: impl OutputPin, mut rst: impl OutputPin, mut power: impl OutputPin) -> Result<()> {
        println!("Turning SIM800L on ...");
        power.set_high().map_err(|_| ModemError::SetupError("Error setting POWER to high.".to_string()))?;
        rst.set_high().map_err(|_| ModemError::SetupError("Error setting RST to high.".to_string()))?;
        // Pull down PWRKEY for more than 1 second according to manual requirements
        pwrkey.set_high().map_err(|_| ModemError::SetupError("Error setting PWRKEY to high.".to_string()))?;
        thread::sleep(Duration::from_millis(100));
        pwrkey.set_low().map_err(|_| ModemError::SetupError("Error setting PWRKEY to low.".to_string()))?;
        thread::sleep(Duration::from_millis(1000));
        pwrkey.set_high().map_err(|_| ModemError::SetupError("Error setting PWRKEY to high.".to_string()))?;
        println!("Waiting for sim module to come online ...");
        thread::sleep(Duration::from_millis(3000));
        loop {
            match self.send_command(Command::probe()) {
                Ok(_) => break,
                _ => {
                    thread::sleep(Duration::from_millis(2000));
                    continue
                },
            }
        }
        Ok(())
    }

    /// Reads the serial RX until the `contains` string is encoutered if `contains` is Some(s), if
    /// None, then the first line is returned. If a timeout is reached. The timeout is provided on
    /// input via the `timeout` argument. The first argument `contains` is checked against every
    /// line in the response.
    fn command_read_response(&mut self, contains: Option<String>) -> Result<String> {
        let mut response = String::new();

        loop {
            let mut buf = vec![0; 1024];
            let num_bytes = self.serial
                .read(buf.as_mut_slice())
                .map_err(|err| ModemError::ReadError(format!("Error in serial.read(buf) ({:?})", err)))?;

            response.push_str(std::str::from_utf8(&buf[0..num_bytes])
                .map_err(|err| ModemError::ReadError(format!("Error in str::from_utf8 ({:?})", err)))?);

            if num_bytes < buf.len() {
                break
            }
        }

        print!("Read {} bytes from serial: {}", response.len(), response);
        if let Some(c) = contains {
            if response.contains(&c) {
                Ok(response)
            } else {
                Err(ModemError::CommandError(format!("Didn't get expected ({}) from modem.", c)))
            }
        } else {
            Ok(response)
        }
    }

    fn send_command(&mut self, cmd: Command) -> Result<String> {
        println!("-----------------------------------------------------------");
        println!("Sending {} ...", cmd.text);

        let _ = self.serial
            .write_bytes(cmd.text.as_bytes())
            .map_err(|_| ModemError::SendDataError(format!("Error in send_command({})", cmd.text)))?;

        let _ = self.serial
            .write(&['\r' as u8])
            .map_err(|_| ModemError::SendDataError(format!("Error in send_command({})", cmd.text)))?;

        self.command_read_response(cmd.contains)
    }

    fn handle_prompt(&mut self) -> Result<()> {
        let mut prompt_buf = vec![0; 256];
        let prompt_len = self.serial.read(&mut prompt_buf)
            .map_err(|err| ModemError::ReadError(format!("Error in handle_prompt() ({:?})", err)))?;

        let prompt = String::from_utf8(prompt_buf[0..prompt_len].to_vec())
            .unwrap_or("".to_string())
            .trim()
            .to_string();

        println!("Prompt is: ({})", prompt);

        if prompt != ">" {
            let msg = format!("Prompt error, expected (>), got ({})", prompt);
            Err(ModemError::SendDataError(msg))
        } else {
            Ok(())
        }
    }

    fn tcp_manual_send_data(&mut self, buf: &[u8]) -> Result<String> {
        println!("Sending AT+CIPSEND to serial TX!");
        let _ = self.serial
            .write("AT+CIPSEND\r".as_bytes())
            .map_err(|_| ModemError::SendDataError("Error in tcp_manual_send_data ... AT_CIPSEND\\r".to_string()))?;

        let _ = self.handle_prompt()?;
        println!("Handled prompt OK!!");

        println!("Writing bytes in serial TX! ({:?})", String::from_utf8(buf.to_vec()));
        self.serial
            .write_bytes(buf)
            .map_err(|err| ModemError::SendDataError(format!("{:?}", err)))?;
        self.serial
            .write(&[26_u8])  // 26_u8 = Ctrl+z - to end sending data
            .map_err(|err| ModemError::SendDataError(format!("{:?}", err)))?;
        println!("DONE Writing bytes in serial TX!");

        thread::sleep(Duration::from_millis(500));

        println!("Reading bytes in serial RX!");
        for _ in 0..3 {
            let res = self.command_read_response(Some("SEND OK".into()));
            if res.is_ok() {
                return res;
            }
            thread::sleep(Duration::from_millis(1000))
        }
        Err(ModemError::ReadError(format!("ReadError: cannot read serial RX!")))
    }

    pub fn gprs_status(&mut self) -> Result<String> {
        self.send_command(Command::gprs_bearer_status())
    }

    pub fn gprs_attach_ap(&mut self, apn: &str, username: &str, password: &str)-> Result<()> {
        println!("init gprs ...");
        let _ = self.send_command(Command::gprs_init())?;

        println!("setting up gprs credentials for apn {}, {}:{})", apn, username, password);

        let _ = self.send_command(Command::gprs_set_apn(apn))?;
        let _ = self.send_command(Command::gprs_set_user(username))?;
        let _ = self.send_command(Command::gprs_set_pwd(password))?;

        Ok(())
    }

    pub fn gprs_connect(&mut self)-> Result<()> {
        println!("open gprs ...");
        self.send_command(Command::gprs_bearer_open())
            .map(|_| ())
    }

    pub fn is_gprs_attached(&mut self)-> Result<bool> {
        let res = self.send_command(Command::is_gprs_attached())?;
        Ok(res.contains("+CGATT: 1"))
    }

    fn try_connect_gprs(&mut self) -> Result<()> {
        let mut retries = 0;
        loop {
            if self.is_gprs_attached()? {
                let _ = self.gprs_connect()?;
                thread::sleep(Duration::from_millis(1000));
                let ip_addr = self.gprs_status()?;
                if ip_addr.contains("0.0.0.0") && retries < 5 {
                    thread::sleep(Duration::from_millis(1000));
                    retries += 1;
                    continue
                } else if retries < 5 {
                    break Ok(())
                } else {
                    break Err(ModemError::SetupError(format!("Cannot connect to GPRS after {} retries ... bailing!", retries)));
                }
            }
        }
    }

    pub fn tcp_is_ssl_enabled(&mut self) -> Result<bool> {
        let res = self.send_command(Command::tcp_ssl_check())?;
        Ok(res.contains("+CIPSSL: (1)"))
    }

    pub fn tcp_ssl_disable(&mut self) -> Result<()> {
        self.send_command(Command::tcp_ssl_set(false))
            .map(|_| ())
    }

    pub fn tcp_ssl_enable(&mut self) -> Result<()> {
        self.send_command(Command::tcp_ssl_set(true))
            .map(|_| ())
    }

    pub fn tcp_connect(&mut self, addr: &str, port: u16) -> Result<()> {
        let _ = self.send_command(Command::tcp_connect(addr, port))?;
        for _ in 0..3 {
            if let Ok(reply) = self.command_read_response(Some("CONNECT_OK".to_string())) {
                println!("TCP connect replied with {}", reply);
                break
            }
            thread::sleep(Duration::from_millis(500));
        }
        Ok(())
    }

    pub fn tcp_set_quick_mode(&mut self, mode: bool) -> Result<()> {
        self.send_command(Command::tcp_set_quick_mode(mode))
            .map(|_| ())
    }

    pub fn tcp_set_manual_receive(&mut self, is_manual: bool) -> Result<()> {
        self.send_command(Command::tcp_set_manual_receive(is_manual))
            .map(|_| ())
    }

    pub fn tcp_manual_send(&mut self, buf: &[u8]) -> Result<()> {
        self.tcp_manual_send_data(buf)
            .map(|_| ())
    }

    fn tcp_parse_response_size(&mut self, reply_line: &str) -> Result<usize> {
        reply_line.split(',')
            .into_iter()
            .last()
            .unwrap_or("x")
            .parse::<usize>()
            .map_err(|_| ModemError::CommandError(format!("response size should be a number, got {}", reply_line)))
    }

    pub fn tcp_receive_reply_len(&mut self) -> Result<usize> {
        let reply = self.send_command(Command::tcp_receive_reply_len())?;
        println!("Receiving TCP reply length!");
        let res = reply.lines()
            .filter(|line| line.contains("+CIPRXGET: 4"))
            .next()
            .ok_or(ModemError::CommandError("reply body missing :/".to_string()))
            .and_then(|line| self.tcp_parse_response_size(line))
            .map_err(|_| ModemError::CommandError(format!("received 0 elements from parsing")));
        println!("Received ({:?})", res);
        res
    }

    pub fn tcp_receive(&mut self, buf: &mut [u8]) -> Result<usize> {
        let mut size = 0;
        loop {
            let reply = self.send_command(Command::tcp_receive(buf.len()))
                .map(|reply| {
                    // TODO: parse the response properly
                    // 1. the first line is \r\n
                    // 2. next is the +CIPRXGET: 2,X,Y where X is the number of bytes read and Y is
                    //    the number of bytes left to be read
                    // 3. immediately after this the payload is returned (with size X)
                    // 4. OK
                    reply
                        .split("\r\n")
                        .filter(|line| line.len() > 2 && !line.contains("+CIPRXGET: 2,"))
                        .next()
                        .map(|line| line.chars().enumerate().map(|(idx, c)| buf[size + idx] = c as u8).count())
                })?;
            match reply {
                Some(0) | None => {
                    break Ok(size)
                },
                Some(x) => {
                    size += x;
                    continue
                },
            }
        }
    }

    pub fn tcp_close_connection(&mut self) -> Result<String> {
        self.send_command(Command::tcp_close())
    }

    pub fn http_post(&mut self, url: &str, token: &str, content: &[u8]) -> Result<String> {
        let _ = self.send_command(Command::http_init());
        let _ = self.send_command(Command::http_set_cid());
        let _ = self.send_command(Command::http_set_url(url));
        let _ = self.send_command(Command::http_set_header("X-Secret", token));
        let _ = self.send_command(Command::http_set_header("X-Topic", "device-dev"));
        let _ = self.send_command(Command::http_set_content("application/json"));
        let _ = self.send_command(Command::http_set_ssl(true));
        let _ = self.send_command(Command::http_post_len(content.len(), 100000));
        let _ = self.serial.write_bytes(content);
        let _ = self.serial.write(&[26_u8]);
        let _ = self.send_command(Command::http_post());
        self.send_command(Command::http_read_response())
    }

    pub fn http_get(&mut self, url: &str) -> Result<String> {
        let _ = self.send_command(Command::http_init());
        let _ = self.send_command(Command::http_set_cid());
        let _ = self.send_command(Command::http_set_url(url));
        let _ = self.send_command(Command::http_set_redirect(true));
        let _ = self.send_command(Command::http_set_ssl(true));
        let _ = self.send_command(Command::http_get());
        self.send_command(Command::http_read_response())
    }

    pub fn http_close(&mut self) -> Result<()> {
        self.send_command(Command::http_close())
            .map(|_| ())
    }

    pub fn chip_info(&mut self) -> Result<()> {
        let _ = self.send_command(Command::manufacturer_id())?;
        thread::sleep(Duration::from_millis(1000));
        let _ = self.send_command(Command::model_id())?;
        thread::sleep(Duration::from_millis(1000));
        let _ = self.send_command(Command::release_id())?;
        Ok(())
    }

    pub fn location(&mut self) -> Result<()> {
        self.send_command(Command::get_location())
            .map(|_| ())
    }

    pub fn ssl_opt(&mut self) -> Result<()> {
        self.send_command(Command::ssl_opt())
            .map(|_| ())
    }

    fn file_write(&mut self, buf: &[u8], path: &str, append: bool, input_time_sec: usize) -> Result<()> {
        let cmd = Command::fs_file_write(path, append, buf.len(), input_time_sec);
        let _ = self.serial
            .write(cmd.text.as_bytes())
            .map_err(|err| ModemError::SendDataError(format!("File write error ({:?})", err)))?;

        let _ = self.handle_prompt()?;

        self.serial
            .write(buf)
            .map_err(|err| ModemError::SendDataError(format!("Error sending bytes via serial ({:?})", err)))?;
        let _ = self.command_read_response(None);

        Ok(())
    }

    pub fn upload_cert(&mut self, path: &str, cert: &[u8]) -> Result<()> {
        let _ = self.send_command(Command::fs_file_create(path))?;
        let _ = self.file_write(cert, path, false, 20000)?;
        Ok(())
    }

    pub fn fs_list(&mut self, path: &str) -> Result<()> {
        self.send_command(Command::fs_list(path))
            .map(|_| ())
    }

    pub fn fs_free_space(&mut self) -> Result<()> {
        self.send_command(Command::fs_free_size())
            .map(|_| ())
    }

    pub fn ssl_set_client_cert(&mut self, path: &str, password: &str) -> Result<()> {
        self.send_command(Command::ssl_set_client_cert(path, password))
            .map(|_| ())
    }

    pub fn ssl_set_root_cert(&mut self, path: &str, filesize: usize) -> Result<()> {
        self.send_command(Command::ssl_set_root_cert(path, filesize))
            .map(|_| ())
    }

    fn mqtt_receive_reply(&mut self)  -> Result<VariablePacket> {
        for _ in 0..3 {
            let size = self.tcp_receive_reply_len()?;
            println!("received reply len({}) ...", size);
            if size == 0 {
                println!("retrying ...");
                continue
            } else {
                let mut reply = vec![0 as u8; size];
                println!("receiving mqtt reply ...");
                let _ = self.tcp_receive(&mut reply);
                let reply = std::str::from_utf8(&reply).unwrap_or("");
                println!("received mqtt reply ({})", reply);
                return VariablePacket::decode(&mut reply.as_bytes())
                    .map_err(|err| ModemError::CommandError(format!("Undecodable MQTT message. ({:?})", err)));
            }
        }
        Err(ModemError::ReadError("TCP server didn't respond!".into()))
    }

    fn mqtt_connect(&mut self, device_id: &str) -> anyhow::Result<()> {
        let mut buf = Vec::new();
        let mut conn = ConnectPacket::new(device_id);
        conn.set_clean_session(true);
        conn.set_keep_alive(100);
        let _ = conn.encode(&mut buf)?;
        self.tcp_manual_send(&mut buf).ok();

        let reply = self.mqtt_receive_reply()?;
        println!("mqtt decoded packet: ({:?})", reply);

        match reply {
            VariablePacket::ConnackPacket(_) => Ok(()),
            _ => Err(anyhow::Error::msg("Invalid MQTT reply ... expected CONNACK!"))
        }
    }

    fn mqtt_publish(&mut self, _device_id: &str, message: &str) -> anyhow::Result<()> {
        println!("entered mqtt publish ...");
        let mut buf = Vec::new();
        let packet = PublishPacket::new(
            TopicName::new(format!("bajsevi/location")).unwrap(),
            QoSWithPacketIdentifier::Level0,
            message.as_bytes(),
        );
        let _ = packet.encode(&mut buf)?;
        println!("created mqtt publish packet ... ({})",
            std::str::from_utf8(buf.as_slice()).unwrap_or(""));
        self.tcp_manual_send(&mut buf).ok();
        Ok(())
    }
}

impl<UART: serial::Uart> std::io::Read for Modem<UART> {
    fn read(&mut self, buf: &mut [u8]) -> std::io::Result<usize> {
        self.tcp_receive(buf).map_err(|_| std::io::Error::from(std::io::ErrorKind::ConnectionAborted))
    }
}

pub fn main<T: Sync + Send>(
    rx: esp_idf_hal::gpio::Gpio26<T>,
    tx: esp_idf_hal::gpio::Gpio27<T>,
    uart: serial::UART1,
    pwrkey: esp_idf_hal::gpio::Gpio4<esp_idf_hal::gpio::Output>,
    rst: esp_idf_hal::gpio::Gpio5<esp_idf_hal::gpio::Output>,
    power: esp_idf_hal::gpio::Gpio23<esp_idf_hal::gpio::Output>,
    receiver: Receiver<Msg>,
) -> std::result::Result<(), anyhow::Error> {
    let serial_pins = serial::Pins {
        tx,
        rx,
        cts: None,
        rts: None,
    };

    let serial: serial::Serial<serial::UART1, _, _> = serial::Serial::new(
        uart,
        serial_pins,
        serial::config::Config::default().baudrate(Hertz(115200)),
    )?;

    let (tx, rx) = serial.split();
    let mut mdm = Modem::new(tx, rx);

    mdm.init(pwrkey, rst, power)?;

    // thread::sleep(Duration::from_millis(500));

    //println!("setting up client TLS cert");
    //let client_cert = include_bytes!("../certs/full-bin.p12");
    //let client_cert_path = "C:\\USER\\fullchain.pem";

    //let _ = mdm.upload_cert(client_cert_path, client_cert)?;
    //let _ = mdm.ssl_set_client_cert(client_cert_path, "t")?;
    //let _ = mdm.fs_list("C:\\USER\\")?;

    loop {
        if !mdm.is_gprs_attached()? {
            let _ = mdm.gprs_attach_ap(
                crate::config::A1_GPRS_AP.apn,
                crate::config::A1_GPRS_AP.username,
                crate::config::A1_GPRS_AP.password,
            )?;
        }
        if let Ok(()) = mdm.try_connect_gprs() {
            let device_id = "c36a72df-5bd6-4f9b-995d-059433bc3267";

            let _ = mdm.tcp_set_quick_mode(false);
            let _ = mdm.tcp_set_manual_receive(true);
            let _ = mdm.tcp_connect("51.158.66.64", 7887)?;

            let _ = mdm.mqtt_connect(device_id)?;

            println!("entering queue receive loop ...");
            let mut err_count = 0;
            let _ = loop {
                match receiver.recv() {
                    Ok(Msg::Gps(solution)) => {
                        println!("received GPS solution {:?} | sending to mqtt ...", solution);
                        let _ = mdm.mqtt_publish(device_id, &format!("{:?}", solution))?;
                        err_count = 0;
                    },
                    Ok(Msg::Accelerometer(acc)) => {
                        println!("received accel {} | sending to mqtt ...", acc);
                        let _ = mdm.mqtt_publish(device_id, &format!("{:?}", acc))?;
                        err_count = 0;
                    }
                    Err(e) => {
                        if err_count < 10 {
                            err_count += 1;
                            println!("received error {} | NOT sending to mqtt ...", e);
                        }
                        else {
                            break
                        }
                    }
                }
            };

            let _ = mdm.tcp_close_connection()?;
        }
    }
}