"""
Trunk Recorder config.json (+ CSVs) from the C2 system config (node-26#45).

Same input as radio_config.build_generate_payload — the SystemConfig C2 pushes —
so a node can switch backends without anyone re-entering its system:

    P25 trunked       -> system type "p25", control_channels, talkgroupsFile
    P25 conventional  -> "conventionalP25", channelFile
    Analog            -> "conventional",    channelFile, squelch

Schema per Trunk Recorder v5.2.1 docs/CONFIGURE.md. Pure functions: the I/O is
in trunk_recorder.py. Unverified against a radio — see the notes inline.

Conventional channels are numbered with conventional.channel_tgid (frequency in
100 Hz units), the same synthetic talkgroup the OP25 path reports, so C2 names
a TR call and an OP25 call on the same channel identically.
"""
import csv
import io
from typing import Any, Dict, List, Optional, Tuple

from app.internal.conventional import channel_tgid
from app.internal.radio_config import (
    ANALOG, CONVENTIONAL, DMR, TRUNKED, analog_frequency, conventional_channels, system_mode, to_hz,
)

# Paths INSIDE the trunk-recorder container (see docker-compose.yml).
TR_APP_DIR = "/app"                         # tr_config_dir is mounted here
TR_UPLOAD_SCRIPT = "/drb/drb-upload.sh"     # ./trunk-recorder, read-only
TR_CAPTURE_DIR = "/recordings/tr-capture"   # ./recordings
TR_TEMP_DIR = "/dev/shm"                    # TR's recommended tmpfs (shm_size in compose)
TALKGROUPS_FILE = "talkgroups.csv"
CHANNELS_FILE = "channels.csv"
SHORT_NAME = "drb"

# TR splits a call longer than this; mirrors call_recorder.MAX_RECORDING_SECONDS.
MAX_DURATION_SECONDS = 600
# Seconds of control-channel silence before TR closes a call (TR's default).
CALL_TIMEOUT_SECONDS = 3

# Of an RTL-SDR's sample rate, the share that is usable passband (anti-alias
# roll-off eats the edges). Channels must sit inside +-(rate * share / 2).
USABLE_BANDWIDTH_SHARE = 0.8
# The RTL-SDR's DC spike sits on the centre frequency; keep channels off it.
DC_SPIKE_GUARD_HZ = 25_000
CENTER_NUDGES_HZ = (0, 150_000, -150_000, 300_000, -300_000)


def _fits(center: int, freqs: List[int], half_band: float) -> bool:
    return all(abs(f - center) <= half_band for f in freqs)


def choose_center(freqs: List[int], rate: int, override: Optional[int] = None) -> int:
    """A centre frequency that puts every channel in the passband and none on
    the DC spike. ValueError if they cannot all fit on one SDR."""
    if not freqs:
        raise ValueError("No frequencies to tune to.")
    half = rate * USABLE_BANDWIDTH_SHARE / 2
    if override:
        if not _fits(override, freqs, half):
            raise ValueError(f"TR_CENTER_HZ {override} leaves a channel outside the SDR's {2 * half / 1e6:.1f} MHz.")
        return int(override)
    lo, hi = min(freqs), max(freqs)
    if hi - lo > 2 * half:
        raise ValueError(
            f"Channels span {(hi - lo) / 1e6:.3f} MHz, more than one SDR at {rate / 1e6:.1f} Msps covers "
            f"({2 * half / 1e6:.2f} MHz). Trim the channel list or raise TR_SAMPLE_RATE."
        )
    mid = int(round((lo + hi) / 2))
    for nudge in CENTER_NUDGES_HZ:
        c = mid + nudge
        if _fits(c, freqs, half) and all(abs(f - c) >= DC_SPIKE_GUARD_HZ for f in freqs):
            return c
    return mid  # channels packed around the middle: accept the spike over not fitting


def _csv(header: List[str], rows: List[List[Any]]) -> str:
    buf = io.StringIO()
    w = csv.writer(buf, lineterminator="\n")
    w.writerow(header)
    w.writerows(rows)
    return buf.getvalue()


def talkgroups_csv(talkgroups: List[Dict[str, Any]]) -> str:
    """TR talkgroupsFile: header row required, "Decimal" first (CONFIGURE.md)."""
    rows = []
    for tg in talkgroups:
        if tg.get("id") is None:
            continue
        name = str(tg.get("name") or "").strip()
        rows.append([int(tg["id"]), "D", name, name, "", ""])
    return _csv(["Decimal", "Mode", "Alpha Tag", "Description", "Tag", "Category"], rows)


def channels_csv(channels: List[Dict[str, Any]], squelch: Optional[float] = None) -> str:
    """TR channelFile: header required, "TG Number" first; Frequency in Hz
    (no decimal point = Hz). Per-channel Squelch overrides the system's."""
    header = ["TG Number", "Frequency", "Alpha Tag", "Description"]
    if squelch is not None:
        header.append("Squelch")
    rows = []
    for ch in channels:
        name = ch.get("name") or f"{ch['frequency'] / 1e6:.4f} MHz"
        row = [channel_tgid(ch["frequency"]), ch["frequency"], name, name]
        if squelch is not None:
            row.append(squelch)
        rows.append(row)
    return _csv(header, rows)


def _analog_channels(config: Dict[str, Any]) -> List[Dict[str, Any]]:
    """Every analog channel the config lists (OP25 only ever used the first)."""
    out = []
    for raw in (config or {}).get("channels") or []:
        if isinstance(raw, dict) and raw.get("freq") not in (None, ""):
            out.append({"frequency": to_hz(raw["freq"]), "name": str(raw.get("name") or "").strip()})
    if not out:
        freq = analog_frequency(config)
        if freq:
            out.append({"frequency": freq, "name": ""})
    return out


def _analog_squelch(config: Dict[str, Any], default_db: float) -> float:
    """TR's squelch is an absolute power level — OP25's "power" mode. Its
    squelch_threshold carries over; noise/voice squelch_db has no TR
    equivalent, so those fall back to the default (which needs site tuning)."""
    value = (config or {}).get("squelch_threshold")
    if value is None or (isinstance(value, str) and not value.strip()):
        return float(default_db)
    try:
        return float(value)
    except (TypeError, ValueError):
        raise ValueError(f"squelch_threshold {value!r} isn't a number.")


def build_tr_config(
    system_type: str,
    name: str,
    config: Dict[str, Any],
    *,
    device_serial: Optional[str],
    ppm: Optional[float],
    sample_rate: int,
    gain: float,
    digital_recorders: int,
    min_duration: float,
    squelch_db: float,
    live_port: int,
    center_override: Optional[int] = None,
) -> Tuple[Dict[str, Any], Dict[str, str]]:
    """SystemConfig fields -> (config.json dict, {filename: contents} to write beside it).

    ValueError when the system can't be expressed (DMR, no channels, too wide).
    """
    config = config or {}
    mode = system_mode(system_type, config)
    files: Dict[str, str] = {}
    # Kept per system, not globally: audioArchive/callLog false makes TR delete
    # the wav/json after uploadScript returns, which is why drb-upload.sh
    # copies them out before it exits.
    system: Dict[str, Any] = {
        "shortName": SHORT_NAME,
        "uploadScript": TR_UPLOAD_SCRIPT,
        "audioArchive": False,
        "callLog": False,
        # WAV, not TR's 32k AAC: the recorder's own rule is one lossless copy
        # for Whisper (call_recorder AUDIO_* notes). 8 kHz mono is ~1 MB/min.
        "compressWav": False,
        "minDuration": float(min_duration),
        "maxDuration": MAX_DURATION_SECONDS,
        "hideEncrypted": False,
    }
    source: Dict[str, Any] = {
        "driver": "osmosdr",
        # By serial, like OP25 (sdr_settings.pin_op25_device): "rtl=0" means
        # whichever dongle enumerated first, which a decoder can take.
        "device": f"rtl={device_serial}" if device_serial else "rtl=0",
        "rate": int(sample_rate),
        "gain": float(gain),
        "ppm": float(ppm or 0.0),
    }

    if mode == DMR:
        raise ValueError("DMR isn't supported by the edge node.")

    if mode == TRUNKED:
        ccs = [to_hz(c) for c in config.get("control_channels") or []]
        if not ccs:
            raise ValueError(f"System {name!r} has no control channels.")
        talkgroups = [tg for tg in config.get("talkgroups") or [] if tg.get("id") is not None]
        system.update({
            "type": "p25",
            "control_channels": ccs,
            # TR's default; "fsk4" is accepted too. Overridable from C2.
            "modulation": str(config.get("modulation") or "qpsk"),
        })
        # Same rule as OP25's whitelist: a talkgroup list means record only
        # those; no list means record everything.
        if talkgroups:
            files[TALKGROUPS_FILE] = talkgroups_csv(talkgroups)
            system["talkgroupsFile"] = f"{TR_APP_DIR}/{TALKGROUPS_FILE}"
            system["recordUnknown"] = False
        else:
            system["recordUnknown"] = True
        # Voice channels are wherever the system grants them; only the control
        # channels are known here, so the SDR is centred on those. A system
        # whose voice channels sit outside that ~2 MHz loses those calls (TR
        # logs "no source covering" for each) — needs a second source.
        freqs = ccs
        source["digitalRecorders"] = int(digital_recorders)
    elif mode == CONVENTIONAL:
        chans = conventional_channels(config)
        if not chans:
            raise ValueError(f"System {name!r} has no conventional channels.")
        # No NAC filter: TR's conventionalP25 records whatever it decodes, so a
        # mistyped NAC can no longer silently drop every call (node-26#33).
        system.update({"type": "conventionalP25", "channelFile": f"{TR_APP_DIR}/{CHANNELS_FILE}",
                       "squelch": float(squelch_db)})
        files[CHANNELS_FILE] = channels_csv(chans)
        freqs = [c["frequency"] for c in chans]
    else:  # ANALOG
        chans = _analog_channels(config)
        if not chans:
            raise ValueError(f"System {name!r} has no analog frequency.")
        squelch = _analog_squelch(config, squelch_db)
        system.update({"type": "conventional", "channelFile": f"{TR_APP_DIR}/{CHANNELS_FILE}",
                       "squelch": squelch})
        files[CHANNELS_FILE] = channels_csv(chans)
        freqs = [c["frequency"] for c in chans]

    source["center"] = choose_center(freqs, int(sample_rate), center_override)

    tr = {
        "ver": 2,
        "sources": [source],
        "systems": [system],
        "tempDir": TR_TEMP_DIR,
        "captureDir": TR_CAPTURE_DIR,
        "callTimeout": CALL_TIMEOUT_SECONDS,
        # File log too (stdout still goes to docker logs): trunk_recorder.py
        # reads the control-channel decode rate from it for the health check.
        "logFile": True,
        "logDir": f"{TR_APP_DIR}/logs",
        "logColor": False,
        # Live audio for Discord: simplestream sends every call's PCM to the
        # edge-node, which follows one talkgroup at a time into PulseAudio.
        "audioStreaming": True,
        "plugins": [{
            "name": "simplestream",
            "library": "libsimplestream.so",
            "streams": [{"TGID": 0, "address": "127.0.0.1", "port": int(live_port), "sendTGID": True}],
        }],
    }
    return tr, files


def live_sample_rate(system_type: str, config: Dict[str, Any]) -> int:
    """simplestream sends analog audio at 16 kHz and digital at 8 kHz (Plugins.md)."""
    return 16000 if system_mode(system_type, config or {}) == ANALOG else 8000