"""
Tiny stand-in for the Tawhiri prediction service. Responds to Tawhiri v2's
GET query-string endpoint with a synthetic trajectory so stratoflights has
something to forward back to leaflet_svelte during e2e tests.

Start:
    python3 /tmp/fake_tawhiri.py

Then tell stratoflights to use it:
    TAWHIRI_BASE_URL=http://localhost:8001/api/v2/ ... python3 manage.py runserver
"""
from http.server import BaseHTTPRequestHandler, HTTPServer
from urllib.parse import parse_qs, urlparse
from datetime import datetime, timedelta, timezone
import copy
import json
import os
import sys

# Optional: serve a canned prediction (stratoflights Prediction dump / Tawhiri
# JSON) instead of synthesizing one. Point datetimes are shifted so the
# trajectory starts at the requested launch_datetime.
TRAJ_FILE = os.environ.get("FAKE_TAWHIRI_TRAJECTORY")


def _iso(dt: datetime) -> str:
    return dt.isoformat().replace("+00:00", "Z")


def _parse(dt: str) -> datetime:
    return datetime.fromisoformat(dt.replace("Z", "+00:00"))


def build_from_file(params):
    d = json.load(open(TRAJ_FILE))
    res = d.get("result") or d
    stages = copy.deepcopy(res["prediction"])
    try:
        launch_dt = _parse(params.get("launch_datetime"))
    except Exception:
        launch_dt = datetime.now(timezone.utc)
    t0 = _parse(stages[0]["trajectory"][0]["datetime"])
    delta = launch_dt - t0
    last = None
    for stage in stages:
        for p in stage["trajectory"]:
            p["datetime"] = _iso(_parse(p["datetime"]) + delta)
            last = p
    return {
        "metadata": {
            "start_datetime": _iso(launch_dt - timedelta(hours=1)),
            "complete_datetime": last["datetime"],
        },
        "prediction": stages,
        "request": res.get("request", {}),
    }


def build_prediction(params):
    try:
        launch_dt = datetime.fromisoformat(
            params.get("launch_datetime", "2026-05-01T12:00:00Z").replace("Z", "+00:00"),
        )
    except Exception:
        launch_dt = datetime.now(timezone.utc)

    launch_lat = float(params.get("launch_latitude", 62.0))
    launch_lng = float(params.get("launch_longitude", 129.0))
    launch_alt = float(params.get("launch_altitude", 0.0))
    burst_alt = float(params.get("burst_altitude", 30000.0))
    ascent_rate = float(params.get("ascent_rate", 5.0))
    descent_rate = float(params.get("descent_rate", 5.0))

    ascent_duration_s = int((burst_alt - launch_alt) / max(0.1, ascent_rate))
    descent_duration_s = int(burst_alt / max(0.1, descent_rate))
    step = 30

    ascent = []
    for t in range(0, ascent_duration_s + 1, step):
        ascent.append({
            "altitude": launch_alt + t * ascent_rate,
            "datetime": _iso(launch_dt + timedelta(seconds=t)),
            "latitude": launch_lat + t * 0.00002,
            "longitude": launch_lng + t * 0.00005,
        })

    descent = []
    burst_dt = launch_dt + timedelta(seconds=ascent_duration_s)
    burst_lat = launch_lat + ascent_duration_s * 0.00002
    burst_lng = launch_lng + ascent_duration_s * 0.00005
    for t in range(0, descent_duration_s + 1, step):
        alt = max(0.0, burst_alt - t * descent_rate)
        descent.append({
            "altitude": alt,
            "datetime": _iso(burst_dt + timedelta(seconds=t)),
            "latitude": burst_lat + t * 0.00001,
            "longitude": burst_lng + t * 0.00003,
        })

    return {
        "metadata": {
            "start_datetime": _iso(launch_dt - timedelta(hours=1)),
            "complete_datetime": _iso(burst_dt + timedelta(seconds=descent_duration_s)),
        },
        "prediction": [
            {"stage": "ascent", "trajectory": ascent},
            {"stage": "descent", "trajectory": descent},
        ],
        "request": {
            "dataset": "fake",
            "launch_latitude": launch_lat,
            "launch_longitude": launch_lng,
            "launch_altitude": launch_alt,
        },
    }


class Handler(BaseHTTPRequestHandler):
    def do_GET(self):
        parsed = urlparse(self.path)
        path = parsed.path.rstrip("/")
        # /api/v2 — legacy e2e endpoint; /api/v1/prediction — what
        # stratoflights' TawhiriClient (Go predictor URL) actually calls.
        if not (path.endswith("/api/v2") or path.endswith("/api/v1/prediction")):
            self.send_error(404)
            return
        params = {k: v[0] for k, v in parse_qs(parsed.query).items()}
        builder = build_from_file if TRAJ_FILE else build_prediction
        body = json.dumps(builder(params)).encode()
        self.send_response(200)
        self.send_header("Content-Type", "application/json")
        self.send_header("Access-Control-Allow-Origin", "*")
        self.end_headers()
        self.wfile.write(body)

    def log_message(self, format, *args):
        # Quiet default access log; keep stderr clean.
        pass


if __name__ == "__main__":
    port = int(sys.argv[1]) if len(sys.argv) > 1 else 8001
    server = HTTPServer(("127.0.0.1", port), Handler)
    src = f"file {TRAJ_FILE}" if TRAJ_FILE else "synthetic"
    print(f"fake-tawhiri listening on http://127.0.0.1:{port}/ ({src})")
    server.serve_forever()