//! Типы сообщений SoC↔MCU (B08, спека v0.4 §6.1). seq — поле кадра (codec), не сообщения.

pub mod wire {
    pub const HEARTBEAT: u8 = 0x01;
    pub const SHUTDOWN_IMMINENT: u8 = 0x02;
    pub const SAFE_TO_CUT: u8 = 0x03;
    pub const ACK: u8 = 0x81;
    pub const ACC: u8 = 0x82;
    pub const VOLTAGE: u8 = 0x83;
    pub const CUT_WARNING: u8 = 0x84;
}

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum SocToMcu {
    Heartbeat,
    ShutdownImminent { budget: u8 },
    SafeToCut,
}

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum McuToSoc {
    Ack,
    Acc { on: bool },
    Voltage { mv: u16 },
    CutWarning,
}

impl SocToMcu {
    pub fn wire_type(&self) -> u8 {
        match self {
            SocToMcu::Heartbeat => wire::HEARTBEAT,
            SocToMcu::ShutdownImminent { .. } => wire::SHUTDOWN_IMMINENT,
            SocToMcu::SafeToCut => wire::SAFE_TO_CUT,
        }
    }
    pub fn payload(&self) -> Vec<u8> {
        match self {
            SocToMcu::ShutdownImminent { budget } => vec![*budget],
            _ => vec![],
        }
    }
    pub fn from_wire(t: u8, p: &[u8]) -> Option<Self> {
        match t {
            wire::HEARTBEAT => Some(SocToMcu::Heartbeat),
            wire::SHUTDOWN_IMMINENT => Some(SocToMcu::ShutdownImminent {
                budget: *p.first()?,
            }),
            wire::SAFE_TO_CUT => Some(SocToMcu::SafeToCut),
            _ => None,
        }
    }
}

impl McuToSoc {
    pub fn wire_type(&self) -> u8 {
        match self {
            McuToSoc::Ack => wire::ACK,
            McuToSoc::Acc { .. } => wire::ACC,
            McuToSoc::Voltage { .. } => wire::VOLTAGE,
            McuToSoc::CutWarning => wire::CUT_WARNING,
        }
    }
    pub fn payload(&self) -> Vec<u8> {
        match self {
            McuToSoc::Acc { on } => vec![*on as u8],
            McuToSoc::Voltage { mv } => mv.to_be_bytes().to_vec(),
            _ => vec![],
        }
    }
    pub fn from_wire(t: u8, p: &[u8]) -> Option<Self> {
        match t {
            wire::ACK => Some(McuToSoc::Ack),
            wire::ACC => Some(McuToSoc::Acc {
                on: *p.first()? != 0,
            }),
            wire::VOLTAGE => Some(McuToSoc::Voltage {
                mv: u16::from_be_bytes([*p.first()?, *p.get(1)?]),
            }),
            wire::CUT_WARNING => Some(McuToSoc::CutWarning),
            _ => None,
        }
    }
}