"""
Apollo Uplink Command Encoder — formats ground commands for AGC channel 45 (INLINK).

The MSFN ground station sends commands to the spacecraft via the Up-Data Link,
which delivers 15-bit words to AGC I/O channel 045 (octal). Each word triggers
the UPRUPT interrupt in the flight software.

Command encoding follows the DSKY command structure: VERB-NOUN pairs optionally
followed by data words. This module translates high-level command descriptions
into the (channel, value) pairs expected by the AGC socket protocol.

Standalone class:
    UplinkEncoder — encodes command types into (channel, value) tuples

GNU Radio wrapper:
    uplink_encoder — message port block for use in GRC flowgraphs

Reference: IMPLEMENTATION_SPEC.md section 1 (INLINK / UPRUPT)
"""

import logging

from apollo.constants import AGC_CH_INLINK

logger = logging.getLogger(__name__)

# DSKY key codes (5-bit encoding used by the AGC for keyboard input).
# These map to the bit patterns the Up-Data Link sends on channel 045.
# Bits 14-10 carry the key code, bits 9-5 carry additional data for DATA words.
KEYCODE_VERB = 0o21     # 17 decimal — VERB key
KEYCODE_NOUN = 0o37     # 31 decimal — NOUN key
KEYCODE_ENTER = 0o34    # 28 decimal — ENTER / PROCEED
KEYCODE_RESET = 0o22    # 18 decimal — RESET / KEY RELEASE
KEYCODE_CLEAR = 0o36    # 30 decimal — CLEAR

# Digit keycodes 0-9
KEYCODE_DIGITS = {
    0: 0o20,   # 16 decimal
    1: 0o01,
    2: 0o02,
    3: 0o03,
    4: 0o04,
    5: 0o05,
    6: 0o06,
    7: 0o07,
    8: 0o10,   # 8 decimal
    9: 0o11,   # 9 decimal
}

KEYCODE_PLUS = 0o32     # 26 decimal — + sign
KEYCODE_MINUS = 0o33    # 27 decimal — - sign


class UplinkEncoder:
    """Encodes ground commands into AGC INLINK (channel, value) pairs.

    Each method returns a list of (channel, value) tuples representing the
    sequence of words to deliver to AGC channel 045. The AGC processes one
    word per UPRUPT, so multi-word sequences must be sent with appropriate
    timing (the bridge handles pacing).

    Args:
        channel: AGC I/O channel for uplink data. Default is channel 045 (INLINK).
    """

    def __init__(self, channel: int = AGC_CH_INLINK):
        self.channel = channel

    def encode_keycode(self, keycode: int) -> tuple[int, int]:
        """Encode a single DSKY keycode as a (channel, value) pair.

        The keycode occupies bits 14-10 of the 15-bit value.
        Bits 9-0 are zero for simple key presses.
        """
        value = (keycode & 0x1F) << 10
        return (self.channel, value)

    def encode_digit(self, digit: int) -> tuple[int, int]:
        """Encode a single decimal digit (0-9)."""
        if digit not in KEYCODE_DIGITS:
            raise ValueError(f"digit must be 0-9, got {digit}")
        return self.encode_keycode(KEYCODE_DIGITS[digit])

    def encode_verb(self, verb_number: int) -> list[tuple[int, int]]:
        """Encode a VERB command (e.g., V37 → [VERB, 3, 7]).

        Args:
            verb_number: Two-digit verb number (0-99).

        Returns:
            List of (channel, value) pairs: VERB key + two digit keys.
        """
        if not 0 <= verb_number <= 99:
            raise ValueError(f"verb must be 0-99, got {verb_number}")
        d1 = verb_number // 10
        d2 = verb_number % 10
        return [
            self.encode_keycode(KEYCODE_VERB),
            self.encode_digit(d1),
            self.encode_digit(d2),
        ]

    def encode_noun(self, noun_number: int) -> list[tuple[int, int]]:
        """Encode a NOUN selection (e.g., N01 → [NOUN, 0, 1]).

        Args:
            noun_number: Two-digit noun number (0-99).

        Returns:
            List of (channel, value) pairs: NOUN key + two digit keys.
        """
        if not 0 <= noun_number <= 99:
            raise ValueError(f"noun must be 0-99, got {noun_number}")
        d1 = noun_number // 10
        d2 = noun_number % 10
        return [
            self.encode_keycode(KEYCODE_NOUN),
            self.encode_digit(d1),
            self.encode_digit(d2),
        ]

    def encode_data(self, value: int, signed: bool = True) -> list[tuple[int, int]]:
        """Encode a 5-digit data entry (e.g., +12345 → [+, 1, 2, 3, 4, 5]).

        Args:
            value: Integer data value. If signed, range is -99999 to +99999.
                If unsigned, range is 0 to 99999.
            signed: If True, prepend a +/- sign key.

        Returns:
            List of (channel, value) pairs for the digit sequence.
        """
        pairs: list[tuple[int, int]] = []

        if signed:
            if value < 0:
                pairs.append(self.encode_keycode(KEYCODE_MINUS))
                value = abs(value)
            else:
                pairs.append(self.encode_keycode(KEYCODE_PLUS))

        if not 0 <= value <= 99999:
            raise ValueError(f"data magnitude must be 0-99999, got {value}")

        digits = f"{value:05d}"
        for ch in digits:
            pairs.append(self.encode_digit(int(ch)))

        return pairs

    def encode_proceed(self) -> list[tuple[int, int]]:
        """Encode a PROCEED (ENTER) keystroke."""
        return [self.encode_keycode(KEYCODE_ENTER)]

    def encode_command(
        self, command_type: str, data: int | None = None
    ) -> list[tuple[int, int]]:
        """High-level command encoder dispatching by type.

        Args:
            command_type: One of "VERB", "NOUN", "DATA", "PROCEED".
            data: Required for VERB (verb number), NOUN (noun number),
                and DATA (integer value). Ignored for PROCEED.

        Returns:
            List of (channel, value) pairs.

        Raises:
            ValueError: Unknown command type or missing data.
        """
        ct = command_type.upper()

        if ct == "VERB":
            if data is None:
                raise ValueError("VERB requires a verb number")
            return self.encode_verb(data)
        elif ct == "NOUN":
            if data is None:
                raise ValueError("NOUN requires a noun number")
            return self.encode_noun(data)
        elif ct == "DATA":
            if data is None:
                raise ValueError("DATA requires a value")
            return self.encode_data(data)
        elif ct == "PROCEED":
            return self.encode_proceed()
        else:
            raise ValueError(f"unknown command type: {command_type!r}")

    def encode_verb_noun(self, verb: int, noun: int) -> list[tuple[int, int]]:
        """Convenience: encode a full V-N-ENTER sequence.

        Args:
            verb: Verb number (0-99).
            noun: Noun number (0-99).

        Returns:
            Sequence: VERB + digits + NOUN + digits + ENTER.
        """
        pairs = self.encode_verb(verb)
        pairs.extend(self.encode_noun(noun))
        pairs.extend(self.encode_proceed())
        return pairs


# ---------------------------------------------------------------------------
# GNU Radio wrapper
# ---------------------------------------------------------------------------

try:
    import pmt
    from gnuradio import gr

    class uplink_encoder(gr.basic_block):
        """GNU Radio block encoding DSKY commands for AGC uplink.

        Message ports:
            command (input) — PDU with metadata dict containing:
                "type": string ("VERB", "NOUN", "DATA", "PROCEED")
                "data": long (optional, depends on type)
            uplink_words (output) — sequence of PDUs, each containing a
                single (channel, value) pair for the AGC bridge
        """

        def __init__(self, channel: int = AGC_CH_INLINK):
            gr.basic_block.__init__(
                self, name="apollo_uplink_encoder", in_sig=[], out_sig=[]
            )
            self.message_port_register_in(pmt.intern("command"))
            self.message_port_register_out(pmt.intern("uplink_words"))
            self.set_msg_handler(pmt.intern("command"), self._handle_command)

            self._encoder = UplinkEncoder(channel=channel)

        def _handle_command(self, msg):
            """Parse a command PDU and emit encoded uplink words."""
            if not pmt.is_pair(msg):
                return

            meta = pmt.car(msg)
            if not pmt.is_dict(meta):
                return

            cmd_type_pmt = pmt.dict_ref(
                meta, pmt.intern("type"), pmt.PMT_NIL
            )
            if pmt.is_null(cmd_type_pmt):
                return
            cmd_type = pmt.symbol_to_string(cmd_type_pmt)

            data_pmt = pmt.dict_ref(meta, pmt.intern("data"), pmt.PMT_NIL)
            data = pmt.to_long(data_pmt) if not pmt.is_null(data_pmt) else None

            try:
                pairs = self._encoder.encode_command(cmd_type, data)
            except ValueError as exc:
                logger.warning("encode_command failed: %s", exc)
                return

            for channel, value in pairs:
                out_meta = pmt.make_dict()
                out_meta = pmt.dict_add(
                    out_meta, pmt.intern("channel"), pmt.from_long(channel)
                )
                out_meta = pmt.dict_add(
                    out_meta, pmt.intern("value"), pmt.from_long(value)
                )
                out_data = pmt.cons(pmt.from_long(channel), pmt.from_long(value))
                self.message_port_pub(
                    pmt.intern("uplink_words"), pmt.cons(out_meta, out_data)
                )

except ImportError:
    pass