//! # `msg` — message-layer codecs and callsign hash table
//!
//! Message-layer codecs for WSJT-family digital modes.
//!
//! | Module       | Payload bits | Used by                   |
//! |--------------|--------------|---------------------------|
//! | [`wsjt77`]   | 77           | FT8, FT4, FT2, FST4       |
//! | [`wspr`]     | 50           | WSPR                      |
//! | [`jt72`]     | 72           | JT65, JT9                 |
//!
//! [`hash_table::CallsignHashTable`] tracks hashed callsigns across decodes;
//! typically a single instance lives in the decoder's side-channel state and
//! is shared by every message unpack invocation.

pub mod ap;
pub mod hash_table;
pub mod jt72;
#[cfg(feature = "packet-bytes")]
pub mod packet_bytes;
// Decoder helper that wires `core::pipeline` (FFT-trait); gated on
// the FFT meta-feature so embedded-rx (alloc + microfft) gets it.
#[cfg(any(feature = "fft-rustfft", feature = "fft-extern"))]
pub mod pipeline_ap;
#[cfg(feature = "q65")]
pub mod q65;
pub mod wsjt77;
pub mod wspr;

pub use ap::ApHint;
pub use hash_table::CallsignHashTable;
pub use jt72::{Jt72Codec, Jt72Message};
#[cfg(feature = "packet-bytes")]
pub use packet_bytes::PacketBytesMessage;
#[cfg(feature = "q65")]
pub use q65::Q65Message;
pub use wspr::{Wspr50Message, WsprMessage};

use alloc::format;
use alloc::string::String;
use alloc::vec::Vec;

use crate::core::{DecodeContext, MessageCodec, MessageFields};

/// WSJT 77-bit message codec used by FT8, FT4, FT2 and FST4.
///
/// Pure wrapper around the free functions in [`wsjt77`], implementing the
/// generic [`crate::MessageCodec`] trait so pipeline code can
/// consume messages without knowing which concrete protocol produced them.
#[derive(Copy, Clone, Debug, Default)]
pub struct Wsjt77Message;

impl MessageCodec for Wsjt77Message {
    type Unpacked = String;
    const PAYLOAD_BITS: u32 = 77;
    const CRC_BITS: u32 = 14;

    fn pack(&self, fields: &MessageFields) -> Option<Vec<u8>> {
        // Free text wins if set; otherwise fall back to the standard three-
        // field call/call/report packing used by the overwhelming majority of
        // FT8/FT4 QSOs.
        if let Some(txt) = &fields.free_text {
            return wsjt77::pack77_free_text(txt).map(|a| a.to_vec());
        }
        let call1 = fields.call1.as_deref()?;
        let call2 = fields.call2.as_deref()?;
        // Prefer grid; if the caller supplied a numeric report, format it
        // WSJT-X-style (sign-padded two-digit dB string).
        let report = if let Some(g) = &fields.grid {
            g.clone()
        } else if let Some(r) = fields.report {
            if r >= 0 {
                format!("+{:02}", r)
            } else {
                format!("{:03}", r)
            }
        } else {
            return None;
        };
        wsjt77::pack77(call1, call2, &report).map(|a| a.to_vec())
    }

    fn unpack(&self, payload: &[u8], ctx: &DecodeContext) -> Option<Self::Unpacked> {
        if payload.len() != 77 {
            return None;
        }
        let mut buf = [0u8; 77];
        buf.copy_from_slice(payload);

        // Prefer the hash-aware path when the caller threaded a table through
        // `DecodeContext`; fall back to the placeholder-emitting variant.
        if let Some(any) = ctx.callsign_hash_table.as_ref()
            && let Some(ht) = any.downcast_ref::<CallsignHashTable>()
        {
            return wsjt77::unpack77_with_hash(&buf, ht);
        }
        wsjt77::unpack77(&buf)
    }

    /// Wsjt77 reserves the trailing K-77 info bits for a CRC. Two
    /// flavours coexist in the WSJT-X family: FT8 / FT4 / FT2 use
    /// LDPC(174, 91) with a 14-bit CRC at bits 77..91, while FST4
    /// uses LDPC(240, 101) with a 24-bit CRC at bits 77..101.
    /// Both share the same Wsjt77 77-bit message field; only the
    /// CRC width differs by FEC pairing. We length-dispatch on the
    /// `info` slice the FEC layer passes through here:
    ///
    /// - 91 → [`crate::fec::ldpc::check_crc14`]
    /// - 101 → [`crate::fec::ldpc240_101::check_crc24`]
    /// - other → reject (no Wsjt77-compatible CRC for that K)
    fn verify_info(info: &[u8]) -> bool {
        match info.len() {
            91 => crate::fec::ldpc::check_crc14(info),
            101 => crate::fec::ldpc240_101::check_crc24(info),
            _ => false,
        }
    }
}
