use super::{
    ad7172,
    channels::{Channels, CHANNELS},
    command_parser::{
        CenterPoint, Command, Ipv4Config, PidParameter, Polarity, PwmPin, ShParameter, ShowCommand,
    },
    config::ChannelConfig,
    dfu,
    flash_store::FlashStore,
    hw_rev::HWRev,
    net, FanCtrl, CHANNEL_CONFIG_KEY,
};
use core::fmt::Write;
use heapless::{consts::U1024, Vec};
use log::{error, warn};
use smoltcp::socket::TcpSocket;

use uom::si::{
    electric_current::ampere,
    electric_potential::volt,
    electrical_resistance::ohm,
    f64::{ElectricCurrent, ElectricPotential, ElectricalResistance, ThermodynamicTemperature},
    thermodynamic_temperature::degree_celsius,
};

#[derive(Debug, Clone, PartialEq)]
pub enum Handler {
    Handled,
    CloseSocket,
    NewIPV4(Ipv4Config),
    Reset,
}

#[derive(Clone, Debug, PartialEq)]
pub enum Error {
    Report,
    PostFilterRate,
    Flash,
}

pub type JsonBuffer = Vec<u8, U1024>;

fn send_line(socket: &mut TcpSocket, data: &[u8]) -> bool {
    let send_free = socket.send_capacity() - socket.send_queue();
    if data.len() > send_free + 1 {
        // Not enough buffer space, skip report for now,
        // instead of sending incomplete line
        warn!(
            "TCP socket has only {}/{} needed {}",
            send_free + 1,
            socket.send_capacity(),
            data.len(),
        );
    } else {
        match socket.send_slice(data) {
            Ok(sent) if sent == data.len() => {
                let _ = socket.send_slice(b"\n");
                // success
                return true;
            }
            Ok(sent) => warn!("sent only {}/{} bytes", sent, data.len()),
            Err(e) => error!("error sending line: {:?}", e),
        }
    }
    // not success
    false
}

impl Handler {
    fn show_report(socket: &mut TcpSocket, channels: &mut Channels) -> Result<Handler, Error> {
        match channels.reports_json() {
            Ok(buf) => {
                send_line(socket, &buf[..]);
            }
            Err(e) => {
                error!("unable to serialize report: {:?}", e);
                let _ = writeln!(socket, "{{\"error\":\"{:?}\"}}", e);
                return Err(Error::Report);
            }
        }
        Ok(Handler::Handled)
    }

    fn show_pid(socket: &mut TcpSocket, channels: &mut Channels) -> Result<Handler, Error> {
        match channels.pid_summaries_json() {
            Ok(buf) => {
                send_line(socket, &buf);
            }
            Err(e) => {
                error!("unable to serialize pid summary: {:?}", e);
                let _ = writeln!(socket, "{{\"error\":\"{:?}\"}}", e);
                return Err(Error::Report);
            }
        }
        Ok(Handler::Handled)
    }

    fn show_pwm(socket: &mut TcpSocket, channels: &mut Channels) -> Result<Handler, Error> {
        match channels.pwm_summaries_json() {
            Ok(buf) => {
                send_line(socket, &buf);
            }
            Err(e) => {
                error!("unable to serialize pwm summary: {:?}", e);
                let _ = writeln!(socket, "{{\"error\":\"{:?}\"}}", e);
                return Err(Error::Report);
            }
        }
        Ok(Handler::Handled)
    }

    fn show_steinhart_hart(
        socket: &mut TcpSocket,
        channels: &mut Channels,
    ) -> Result<Handler, Error> {
        match channels.steinhart_hart_summaries_json() {
            Ok(buf) => {
                send_line(socket, &buf);
            }
            Err(e) => {
                error!("unable to serialize steinhart-hart summaries: {:?}", e);
                let _ = writeln!(socket, "{{\"error\":\"{:?}\"}}", e);
                return Err(Error::Report);
            }
        }
        Ok(Handler::Handled)
    }

    fn show_post_filter(socket: &mut TcpSocket, channels: &mut Channels) -> Result<Handler, Error> {
        match channels.postfilter_summaries_json() {
            Ok(buf) => {
                send_line(socket, &buf);
            }
            Err(e) => {
                error!("unable to serialize postfilter summary: {:?}", e);
                let _ = writeln!(socket, "{{\"error\":\"{:?}\"}}", e);
                return Err(Error::Report);
            }
        }
        Ok(Handler::Handled)
    }

    fn show_ipv4(socket: &mut TcpSocket, ipv4_config: &mut Ipv4Config) -> Result<Handler, Error> {
        let (cidr, gateway) = net::split_ipv4_config(ipv4_config.clone());
        let _ = write!(socket, "{{\"addr\":\"{}\"", cidr);
        gateway.map(|gateway| write!(socket, ",\"gateway\":\"{}\"", gateway));
        let _ = writeln!(socket, "}}");
        Ok(Handler::Handled)
    }

    fn engage_pid(
        socket: &mut TcpSocket,
        channels: &mut Channels,
        channel: usize,
    ) -> Result<Handler, Error> {
        channels.channel_state(channel).pid_engaged = true;
        send_line(socket, b"{}");
        Ok(Handler::Handled)
    }

    fn set_polarity(
        socket: &mut TcpSocket,
        channels: &mut Channels,
        channel: usize,
        polarity: Polarity,
    ) -> Result<Handler, Error> {
        channels.set_polarity(channel, polarity);
        send_line(socket, b"{}");
        Ok(Handler::Handled)
    }

    fn set_pwm(
        socket: &mut TcpSocket,
        channels: &mut Channels,
        channel: usize,
        pin: PwmPin,
        value: f64,
    ) -> Result<Handler, Error> {
        match pin {
            PwmPin::ISet => {
                channels.channel_state(channel).pid_engaged = false;
                let current = ElectricCurrent::new::<ampere>(value);
                channels.set_i(channel, current);
                channels.power_up(channel);
            }
            PwmPin::MaxV => {
                let voltage = ElectricPotential::new::<volt>(value);
                channels.set_max_v(channel, voltage);
            }
            PwmPin::MaxIPos => {
                let current = ElectricCurrent::new::<ampere>(value);
                channels.set_max_i_pos(channel, current);
            }
            PwmPin::MaxINeg => {
                let current = ElectricCurrent::new::<ampere>(value);
                channels.set_max_i_neg(channel, current);
            }
        }
        send_line(socket, b"{}");
        Ok(Handler::Handled)
    }

    fn set_center_point(
        socket: &mut TcpSocket,
        channels: &mut Channels,
        channel: usize,
        center: CenterPoint,
    ) -> Result<Handler, Error> {
        let i_set = channels.get_i(channel);
        let state = channels.channel_state(channel);
        state.center = center;
        if !state.pid_engaged {
            channels.set_i(channel, i_set);
        }
        send_line(socket, b"{}");
        Ok(Handler::Handled)
    }

    fn set_pid(
        socket: &mut TcpSocket,
        channels: &mut Channels,
        channel: usize,
        parameter: PidParameter,
        value: f64,
    ) -> Result<Handler, Error> {
        let pid = &mut channels.channel_state(channel).pid;
        use super::command_parser::PidParameter::*;
        match parameter {
            Target => pid.target = value,
            KP => pid.parameters.kp = value as f32,
            KI => pid.update_ki(value as f32),
            KD => pid.parameters.kd = value as f32,
            OutputMin => pid.parameters.output_min = value as f32,
            OutputMax => pid.parameters.output_max = value as f32,
        }
        send_line(socket, b"{}");
        Ok(Handler::Handled)
    }

    fn set_steinhart_hart(
        socket: &mut TcpSocket,
        channels: &mut Channels,
        channel: usize,
        parameter: ShParameter,
        value: f64,
    ) -> Result<Handler, Error> {
        let sh = &mut channels.channel_state(channel).sh;
        use super::command_parser::ShParameter::*;
        match parameter {
            T0 => sh.t0 = ThermodynamicTemperature::new::<degree_celsius>(value),
            B => sh.b = value,
            R0 => sh.r0 = ElectricalResistance::new::<ohm>(value),
        }
        send_line(socket, b"{}");
        Ok(Handler::Handled)
    }

    fn reset_post_filter(
        socket: &mut TcpSocket,
        channels: &mut Channels,
        channel: usize,
    ) -> Result<Handler, Error> {
        channels.adc.set_postfilter(channel as u8, None).unwrap();
        send_line(socket, b"{}");
        Ok(Handler::Handled)
    }

    fn set_post_filter(
        socket: &mut TcpSocket,
        channels: &mut Channels,
        channel: usize,
        rate: f32,
    ) -> Result<Handler, Error> {
        let filter = ad7172::PostFilter::closest(rate);
        match filter {
            Some(filter) => {
                channels
                    .adc
                    .set_postfilter(channel as u8, Some(filter))
                    .unwrap();
                send_line(socket, b"{}");
            }
            None => {
                error!("unable to choose postfilter for rate {:.3}", rate);
                send_line(
                    socket,
                    b"{{\"error\": \"unable to choose postfilter rate\"}}",
                );
                return Err(Error::PostFilterRate);
            }
        }
        Ok(Handler::Handled)
    }

    fn load_channel(
        socket: &mut TcpSocket,
        channels: &mut Channels,
        store: &mut FlashStore,
        channel: Option<usize>,
    ) -> Result<Handler, Error> {
        for (c, key) in CHANNEL_CONFIG_KEY.iter().enumerate().take(CHANNELS) {
            if channel.is_none() || channel == Some(c) {
                match store.read_value::<ChannelConfig>(key) {
                    Ok(Some(config)) => {
                        config.apply(channels, c);
                        send_line(socket, b"{}");
                    }
                    Ok(None) => {
                        error!("flash config not found");
                        send_line(socket, b"{{\"error\": \"flash config not found\"}}");
                    }
                    Err(e) => {
                        error!("unable to load config from flash: {:?}", e);
                        let _ = writeln!(socket, "{{\"error\":\"{:?}\"}}", e);
                        return Err(Error::Flash);
                    }
                }
            }
        }
        Ok(Handler::Handled)
    }

    fn save_channel(
        socket: &mut TcpSocket,
        channels: &mut Channels,
        channel: Option<usize>,
        store: &mut FlashStore,
    ) -> Result<Handler, Error> {
        for (c, key) in CHANNEL_CONFIG_KEY.iter().enumerate().take(CHANNELS) {
            let mut store_value_buf = [0u8; 256];
            if channel.is_none() || channel == Some(c) {
                let config = ChannelConfig::new(channels, c);
                match store.write_value(key, &config, &mut store_value_buf) {
                    Ok(()) => {
                        send_line(socket, b"{}");
                    }
                    Err(e) => {
                        error!("unable to save channel {} config to flash: {:?}", c, e);
                        let _ = writeln!(socket, "{{\"error\":\"{:?}\"}}", e);
                        return Err(Error::Flash);
                    }
                }
            }
        }
        Ok(Handler::Handled)
    }

    fn set_ipv4(
        socket: &mut TcpSocket,
        store: &mut FlashStore,
        config: Ipv4Config,
    ) -> Result<Handler, Error> {
        let _ = store
            .write_value("ipv4", &config, [0; 16])
            .map_err(|e| error!("unable to save ipv4 config to flash: {:?}", e));
        let new_ipv4_config = Some(config);
        send_line(socket, b"{}");
        Ok(Handler::NewIPV4(new_ipv4_config.unwrap()))
    }

    fn reset(channels: &mut Channels) -> Result<Handler, Error> {
        for i in 0..CHANNELS {
            channels.power_down(i);
        }
        // should_reset = true;
        Ok(Handler::Reset)
    }

    fn dfu(channels: &mut Channels) -> Result<Handler, Error> {
        for i in 0..CHANNELS {
            channels.power_down(i);
        }
        unsafe {
            dfu::set_dfu_trigger();
        }
        // should_reset = true;
        Ok(Handler::Reset)
    }

    fn set_fan(
        socket: &mut TcpSocket,
        fan_pwm: u32,
        fan_ctrl: &mut FanCtrl,
    ) -> Result<Handler, Error> {
        if !fan_ctrl.fan_available() {
            send_line(
                socket,
                b"{ \"warning\": \"this thermostat doesn't have a fan!\" }",
            );
            return Ok(Handler::Handled);
        }
        fan_ctrl.set_auto_mode(false);
        fan_ctrl.set_pwm(fan_pwm);
        if fan_ctrl.fan_pwm_recommended() {
            send_line(socket, b"{}");
        } else {
            send_line(socket, b"{ \"warning\": \"this fan doesn't have full PWM support. Use it at your own risk!\" }");
        }
        Ok(Handler::Handled)
    }

    fn show_fan(socket: &mut TcpSocket, fan_ctrl: &mut FanCtrl) -> Result<Handler, Error> {
        match fan_ctrl.summary() {
            Ok(buf) => {
                send_line(socket, &buf);
                Ok(Handler::Handled)
            }
            Err(e) => {
                error!("unable to serialize fan summary: {:?}", e);
                let _ = writeln!(socket, "{{\"error\":\"{:?}\"}}", e);
                Err(Error::Report)
            }
        }
    }

    fn fan_auto(socket: &mut TcpSocket, fan_ctrl: &mut FanCtrl) -> Result<Handler, Error> {
        if !fan_ctrl.fan_available() {
            send_line(
                socket,
                b"{ \"warning\": \"this thermostat doesn't have a fan!\" }",
            );
            return Ok(Handler::Handled);
        }
        fan_ctrl.set_auto_mode(true);
        if fan_ctrl.fan_pwm_recommended() {
            send_line(socket, b"{}");
        } else {
            send_line(socket, b"{ \"warning\": \"this fan doesn't have full PWM support. Use it at your own risk!\" }");
        }
        Ok(Handler::Handled)
    }

    fn fan_curve(
        socket: &mut TcpSocket,
        fan_ctrl: &mut FanCtrl,
        k_a: f32,
        k_b: f32,
        k_c: f32,
    ) -> Result<Handler, Error> {
        fan_ctrl.set_curve(k_a, k_b, k_c);
        send_line(socket, b"{}");
        Ok(Handler::Handled)
    }

    fn fan_defaults(socket: &mut TcpSocket, fan_ctrl: &mut FanCtrl) -> Result<Handler, Error> {
        fan_ctrl.restore_defaults();
        send_line(socket, b"{}");
        Ok(Handler::Handled)
    }

    fn show_hwrev(socket: &mut TcpSocket, hwrev: HWRev) -> Result<Handler, Error> {
        match hwrev.summary() {
            Ok(buf) => {
                send_line(socket, &buf);
                Ok(Handler::Handled)
            }
            Err(e) => {
                error!("unable to serialize HWRev summary: {:?}", e);
                let _ = writeln!(socket, "{{\"error\":\"{:?}\"}}", e);
                Err(Error::Report)
            }
        }
    }

    pub fn handle_command(
        command: Command,
        socket: &mut TcpSocket,
        channels: &mut Channels,
        store: &mut FlashStore,
        ipv4_config: &mut Ipv4Config,
        fan_ctrl: &mut FanCtrl,
        hwrev: HWRev,
    ) -> Result<Self, Error> {
        match command {
            Command::Quit => Ok(Handler::CloseSocket),
            Command::Show(ShowCommand::Input) => Handler::show_report(socket, channels),
            Command::Show(ShowCommand::Pid) => Handler::show_pid(socket, channels),
            Command::Show(ShowCommand::Pwm) => Handler::show_pwm(socket, channels),
            Command::Show(ShowCommand::SteinhartHart) => {
                Handler::show_steinhart_hart(socket, channels)
            }
            Command::Show(ShowCommand::PostFilter) => Handler::show_post_filter(socket, channels),
            Command::Show(ShowCommand::Ipv4) => Handler::show_ipv4(socket, ipv4_config),
            Command::PwmPid { channel } => Handler::engage_pid(socket, channels, channel),
            Command::PwmPolarity { channel, polarity } => {
                Handler::set_polarity(socket, channels, channel, polarity)
            }
            Command::Pwm {
                channel,
                pin,
                value,
            } => Handler::set_pwm(socket, channels, channel, pin, value),
            Command::CenterPoint { channel, center } => {
                Handler::set_center_point(socket, channels, channel, center)
            }
            Command::Pid {
                channel,
                parameter,
                value,
            } => Handler::set_pid(socket, channels, channel, parameter, value),
            Command::SteinhartHart {
                channel,
                parameter,
                value,
            } => Handler::set_steinhart_hart(socket, channels, channel, parameter, value),
            Command::PostFilter {
                channel,
                rate: None,
            } => Handler::reset_post_filter(socket, channels, channel),
            Command::PostFilter {
                channel,
                rate: Some(rate),
            } => Handler::set_post_filter(socket, channels, channel, rate),
            Command::Load { channel } => Handler::load_channel(socket, channels, store, channel),
            Command::Save { channel } => Handler::save_channel(socket, channels, channel, store),
            Command::Ipv4(config) => Handler::set_ipv4(socket, store, config),
            Command::Reset => Handler::reset(channels),
            Command::Dfu => Handler::dfu(channels),
            Command::FanSet { fan_pwm } => Handler::set_fan(socket, fan_pwm, fan_ctrl),
            Command::ShowFan => Handler::show_fan(socket, fan_ctrl),
            Command::FanAuto => Handler::fan_auto(socket, fan_ctrl),
            Command::FanCurve { k_a, k_b, k_c } => {
                Handler::fan_curve(socket, fan_ctrl, k_a, k_b, k_c)
            }
            Command::FanCurveDefaults => Handler::fan_defaults(socket, fan_ctrl),
            Command::ShowHWRev => Handler::show_hwrev(socket, hwrev),
        }
    }
}