use log::info;

use embedded_hal::blocking::spi::Transfer;
use core::convert::TryInto;
use crate::ClockSource as UrukulClockSource;
use crate::ClockSource::*;
use crate::Urukul;
use crate::Error;

#[derive(Debug)]
pub enum MqttCommandType {
    // Urukul/Control/Clock/Source
    ClockSource(UrukulClockSource),
    // Urukul/Control/Clock/Division
    ClockDivision(u8),
    // Urukul/Control/ChannelX/Switch
    Switch(u8, bool),
    // Urukul/Control/ChannelX/Attenuation
    Attenuation(u8, f32),
    // Urukul/Control/ChannelX/SystemClock
    SystemClock(u8, f64),
    // Urukul/Control/ChannelX/ProfileY/Frequency
    SingleToneFrequency(u8, u8, f64),
    // Urukul/Control/ChannelX/ProfileY/Amplitude
    SingleToneAmplitude(u8, u8, f64),
    // Urukul/Control/ChannelX/ProfileY/Phase
    SingleTonePhase(u8, u8, f64),
}

use crate::mqtt_mux::MqttCommandType::*;

pub struct MqttMux<SPI> {
    urukul: Urukul<SPI>
}

impl<SPI, E> MqttMux<SPI> where SPI: Transfer<u8, Error = E> {
    pub fn new(urukul: Urukul<SPI>) -> Self {
        MqttMux {
            urukul
        }
    }

    pub fn handle_command(&mut self, topic: &str, message: &[u8]) -> Result<(), Error<E>> {
        let command = self.parse(topic, message)?;
        self.execute(command)
    }

    // MQTT command are not case tolerant
    // If the command differs by case, space or delimiter, it is a wrong command
    // A starting forward slash ("/") is acceptable, as per MQTT standard
    // Topic should contain the appropriate command header
    // Message should provide the parameter
    fn parse(&mut self, topic: &str, message: &[u8]) -> Result<MqttCommandType, Error<E>> {
        let mut assigned_channel = false;
        let mut assigned_profile = false;
        let mut channel :u8 = 0;
        let mut profile :u8 = 0;

        // Verify that the topic must start with Urukul/Control/ or /Urukul/Control/
        let mut header = topic.strip_prefix("/Urukul/Control/")
                              .or_else(|| topic.strip_prefix("Urukul/Control/"))
                              .ok_or(Error::MqttCommandError)?;

        loop {
            match header {
                // The topic has a channel subtopic
                _ if header.starts_with("Channel") => {
                    // MQTT command should only mention channel once appropriately
                    // Channel must be referred before profile,
                    // as a channel is broader than a profile
                    if assigned_channel || assigned_profile {
                        return Err(Error::MqttCommandError);
                    }
                    // Remove the "Channel" part of the subtopic
                    header = header.strip_prefix("Channel")
                                   .ok_or(Error::MqttCommandError)?;
                    // Remove the channel number at the end of the subtopic
                    // But store the channel as a char, so it can be removed easily
                    let numeric_char :char = header.chars()
                                                   .next()
                                                   .ok_or(Error::MqttCommandError)?;
                    // Record the channel number
                    channel = numeric_char.to_digit(10)
                                          .ok_or(Error::MqttCommandError)?
                                          .try_into()
                                          .unwrap();
                    assigned_channel = true;
                    header = header.strip_prefix(numeric_char)
                                   .ok_or(Error::MqttCommandError)?;
                    // Remove forward slash ("/")
                    header = header.strip_prefix("/")
                                   .ok_or(Error::MqttCommandError)?;
                },

                _ if header.starts_with("Profile") => {
                    // MQTT command should only mention profile once appropriately
                    if assigned_profile {
                        return Err(Error::MqttCommandError);
                    }
                    // Remove the "Profile" part of the subtopic
                    header = header.strip_prefix("Profile")
                                   .ok_or(Error::MqttCommandError)?;
                    // Remove the profile number at the end of the subtopic
                    // But store the profile as a char, so it can be removed easily
                    let numeric_char :char = header.chars()
                                                   .next()
                                                   .ok_or(Error::MqttCommandError)?;
                    // Record the channel number
                    profile = numeric_char.to_digit(10)
                                          .ok_or(Error::MqttCommandError)?
                                          .try_into()
                                          .unwrap();
                    assigned_profile = true;
                    header = header.strip_prefix(numeric_char)
                                   .ok_or(Error::MqttCommandError)?;
                    // Remove forward slash ("/")
                    header = header.strip_prefix("/")
                                   .ok_or(Error::MqttCommandError)?;
                },

                "Clock/Source" => {
                    // Clock/Source refers to the Urukul clock source
                    // It should be common for all channels and profiles
                    if assigned_channel || assigned_profile {
                        return Err(Error::MqttCommandError);
                    }
                    let source_string = core::str::from_utf8(message).unwrap();

                    return match source_string {
                        _ if source_string.eq_ignore_ascii_case("OSC") => {
                            Ok(ClockSource(OSC))
                        },
                        _ if source_string.eq_ignore_ascii_case("SMA") => {
                            Ok(ClockSource(SMA))
                        },
                        _ if source_string.eq_ignore_ascii_case("MMCX") => {
                            Ok(ClockSource(MMCX))
                        },
                        _ => Err(Error::MqttCommandError),
                    };
                }

                "Clock/Division" => {
                    // Clock/Division refers to the Urukul clock division
                    // It should be common for all channels and profiles
                    if assigned_channel || assigned_profile {
                        return Err(Error::MqttCommandError);
                    }

                    let division = u8::from_str_radix(core::str::from_utf8(message).unwrap(), 10)
                        .map_or_else(
                            |_| Err(Error::MqttCommandError),
                            |div| if (div == 1 || div == 2 || div == 4) {
                                Ok(div)
                            } else {
                                Err(Error::MqttCommandError)
                            })?;
                    return Ok(ClockDivision(division));
                }

                "Switch" => {
                    // Switch is a channel specific topic
                    if !(assigned_channel && !assigned_profile) {
                        return Err(Error::MqttCommandError);
                    }

                    let switch_string = core::str::from_utf8(message).unwrap();

                    return match switch_string {
                        _ if switch_string.eq_ignore_ascii_case("on") => {
                            Ok(Switch(channel, true))
                        },
                        _ if switch_string.eq_ignore_ascii_case("off") => {
                            Ok(Switch(channel, false))
                        },
                        _ => Err(Error::MqttCommandError),
                    };
                },

                // TODO: Cover all commands

                _ => return Err(Error::MqttCommandError),
            };
        }
    }

    // TODO: Implement this
    fn execute(&mut self, command_type: MqttCommandType) -> Result<(), Error<E>> {
        info!("{:?}", command_type);
        match command_type {
            Switch(channel, status) => self.urukul.set_channel_switch(channel as u32, status),
            _ => Ok(())
        }
    }
}