server.py

"""FastAPI app factory for the NIGHTWAVE Space orchestrator.

Exposes the same-origin proxy routes the browser radio calls:
  POST /api/broadcast {stage, meter, topic?}
  POST /api/call      {stage, meter, audio_b64}
  POST /api/seek      {meter}

Every proxy call is wrapped in try/except so a Modal hiccup (or cold-start
timeout) NEVER 500s the radio -- we fall back to a canned, stage-appropriate
line and a short silent WAV. The radio must never go silent.

Also provides radio_iframe_html(): reads space/radio.html from disk and wraps
it in a sandboxed <iframe srcdoc=...> for embedding inside the Gradio Blocks
page (gr.HTML does not execute <script>, so the radio must live in an iframe).
"""

import html
import os
from typing import Any, Dict, Optional

from fastapi import FastAPI, Request
from fastapi.responses import JSONResponse
from pydantic import BaseModel

import arc
import content
import proxy

_HERE = os.path.dirname(os.path.abspath(__file__))
_RADIO_HTML_PATH = os.path.join(_HERE, "radio.html")


# ---------------------------------------------------------------------------
# Request models
# ---------------------------------------------------------------------------
class BroadcastReq(BaseModel):
    stage: str
    meter: int
    topic: Optional[str] = None


class CallReq(BaseModel):
    stage: str
    meter: int
    audio_b64: str


class SeekReq(BaseModel):
    meter: int


class SegmentReq(BaseModel):
    kind: str  # station_id | thought | weather | local_weather | dedication | song_intro | rejoin | caller_intro
    ctx: Optional[Dict[str, Any]] = None


class LocaleReq(BaseModel):
    lat: float
    lon: float


class SongCardReq(BaseModel):
    ctx: Optional[Dict[str, Any]] = None


# ---------------------------------------------------------------------------
# Graceful fallbacks (never let the radio go silent)
# ---------------------------------------------------------------------------
_FALLBACK_LINES = [
    "It's Sam Dusk -- we had a little hiccup on the signal there, but I'm still with "
    "you. Let's let this next one play.",
    "Sam Dusk here. The line crackled for a second, friend; pay it no mind and stay "
    "with me a while.",
    "You're back with Sam Dusk on NIGHTWAVE. A small bump in the broadcast -- nothing "
    "the night can't smooth over.",
]


def _fallback_payload(stage: str = "", include_caller: bool = False) -> Dict[str, Any]:
    import random
    payload: Dict[str, Any] = {
        "text": random.choice(_FALLBACK_LINES),
        "mood": "warm",
        "arc_cue": "none",
        "audio_b64": proxy._silent_wav_b64(),
        "words": [],
        "wtimes": [],
        "wdurations": [],
    }
    if include_caller:
        payload["caller_text"] = ""
        payload["meter_delta"] = 0
        payload["memory_patch"] = None
        payload["queue_dedication"] = False
    return payload


# ---------------------------------------------------------------------------
# Radio iframe embedding (for the Gradio Blocks page)
# ---------------------------------------------------------------------------
def radio_iframe_html() -> str:
    """Read radio.html and return it wrapped in a sandboxed iframe srcdoc."""
    with open(_RADIO_HTML_PATH, "r", encoding="utf-8") as fh:
        doc = fh.read()
    escaped = html.escape(doc, quote=True)
    return (
        '<iframe srcdoc="' + escaped + '" '
        'width="100%" height="860" '
        'allow="microphone; autoplay" '
        'style="border:0;display:block" '
        'referrerpolicy="no-referrer"></iframe>'
    )


def read_radio_html() -> str:
    """Return the raw radio document (used by devserver to serve at top level)."""
    with open(_RADIO_HTML_PATH, "r", encoding="utf-8") as fh:
        return fh.read()


# ---------------------------------------------------------------------------
# App factory
# ---------------------------------------------------------------------------
def create_api() -> FastAPI:
    api = FastAPI(title="NIGHTWAVE", docs_url=None, redoc_url=None)

    @api.post("/api/broadcast")
    def api_broadcast(req: BroadcastReq):
        stage = arc.meter_to_stage(req.meter)
        try:
            return proxy.broadcast_turn(stage, req.meter, req.topic)
        except Exception:
            return JSONResponse(_fallback_payload(stage))

    @api.post("/api/call")
    def api_call(req: CallReq):
        stage = arc.meter_to_stage(req.meter)
        try:
            return proxy.call_turn(stage, req.meter, req.audio_b64)
        except Exception:
            return JSONResponse(_fallback_payload(stage, include_caller=True))

    @api.post("/api/seek")
    def api_seek(req: SeekReq):
        return {"stage": arc.meter_to_stage(req.meter)}

    @api.get("/api/songs")
    def api_songs():
        # The curated song bank: the browser renders the generative music + the
        # now-playing plate from each song's musical params, and song_intro uses
        # the title/artist. Single source of truth (space/content.py).
        return {"songs": content.SONGS}

    @api.post("/api/segment")
    def api_segment(req: SegmentReq):
        # One DJ show segment (text + audio). Never break the show: on any failure
        # return a templated segment with a short silent clip (the bed covers it).
        try:
            return proxy.segment_turn(req.kind, req.ctx)
        except Exception:
            return JSONResponse(proxy.segment_fallback(req.kind, req.ctx))

    @api.post("/api/locale")
    def api_locale(req: LocaleReq):
        # Resolve real local weather/time/city for the listener. On any failure,
        # report unresolved so the client cleanly falls back to fictional weather.
        try:
            return proxy.resolve_locale(req.lat, req.lon)
        except Exception:
            return JSONResponse({"resolved": False})

    @api.post("/api/song_card")
    def api_song_card(req: SongCardReq):
        # AI invents a fictional record (validated musical params). On any failure,
        # return {card: None} so the client simply skips it.
        try:
            return {"card": proxy.make_song_card(req.ctx)}
        except Exception:
            return JSONResponse({"card": None})

    @api.get("/api/stalls")
    def api_stalls():
        # Pre-synthesized filler clips the radio plays instantly while a real
        # call reply generates (so the call never has dead air).
        try:
            return {"stalls": proxy.get_stalls()}
        except Exception:
            return {"stalls": []}

    return api