#!/usr/bin/env python3
"""Sidereal ingress and station scan for a bounded calendar window."""
from __future__ import annotations

from datetime import datetime, timedelta
from typing import Any

try:
    import swisseph as swe
except ImportError:  # pragma: no cover
    swe = None

try:
    from ayanamsa_utils import (
        UnsupportedAyanamsaError,
        ayanamsa_display_name,
        normalize_ayanamsa_name,
        temporary_ayanamsa,
    )
except ImportError:  # pragma: no cover
    from scripts.ayanamsa_utils import (
        UnsupportedAyanamsaError,
        ayanamsa_display_name,
        normalize_ayanamsa_name,
        temporary_ayanamsa,
    )

MAX_RANGE_DAYS = 730
DEFAULT_BODIES = ("sun", "mercury", "venus", "mars", "jupiter", "saturn")
SIGNS = (
    "Aries", "Taurus", "Gemini", "Cancer", "Leo", "Virgo",
    "Libra", "Scorpio", "Sagittarius", "Capricorn", "Aquarius", "Pisces",
)
_SWE_BODIES = {
    "sun": "SUN",
    "moon": "MOON",
    "mercury": "MERCURY",
    "venus": "VENUS",
    "mars": "MARS",
    "jupiter": "JUPITER",
    "saturn": "SATURN",
    "uranus": "URANUS",
    "neptune": "NEPTUNE",
    "pluto": "PLUTO",
}


class EphemerisEventsError(ValueError):
    """Structured ephemeris-event failure. Callers map this to HTTP 400."""


def _field(body: dict[str, Any], *keys: str, required: bool = True) -> Any:
    for key in keys:
        if key in body and body[key] not in (None, ""):
            return body[key]
    if required:
        raise EphemerisEventsError(f"{keys[0]} is required")
    return None


def _parse_date(value: Any, key: str) -> datetime:
    if not isinstance(value, str):
        raise EphemerisEventsError(f"{key} must be YYYY-MM-DD")
    try:
        return datetime.strptime(value[:10], "%Y-%m-%d")
    except ValueError as exc:
        raise EphemerisEventsError(f"{key} must be YYYY-MM-DD") from exc


def _node_mode(raw: Any) -> str:
    if raw in (None, ""):
        return "mean"
    if not isinstance(raw, str) or raw.strip().lower() not in {"mean", "true"}:
        raise EphemerisEventsError("node_mode must be mean or true")
    return raw.strip().lower()


def _bodies(raw: Any) -> tuple[str, ...]:
    if raw in (None, ""):
        return DEFAULT_BODIES
    if not isinstance(raw, list) or not raw:
        raise EphemerisEventsError("bodies must be a non-empty array")
    names: list[str] = []
    for item in raw:
        name = str(item).strip().lower()
        if name not in _SWE_BODIES:
            raise EphemerisEventsError(f"unsupported body: {item}")
        names.append(name)
    return tuple(dict.fromkeys(names))


def _planet_id(name: str) -> int:
    if swe is None:
        raise EphemerisEventsError("Swiss Ephemeris is not available")
    return int(getattr(swe, _SWE_BODIES[name]))


def _sample(jd: float, planet_id: int, flags: int) -> tuple[float, float]:
    values, _ = swe.calc_ut(jd, planet_id, flags)
    return float(values[0]) % 360.0, float(values[3])


def build_ephemeris_events(body: dict[str, Any] | None) -> dict[str, Any]:
    if swe is None:
        raise EphemerisEventsError("Swiss Ephemeris is not available")
    if not isinstance(body, dict):
        raise EphemerisEventsError("JSON body must be an object")
    start = _parse_date(_field(body, "start_date", "start"), "start_date")
    end = _parse_date(_field(body, "end_date", "end"), "end_date")
    if end < start:
        raise EphemerisEventsError("end_date must be on or after start_date")
    span_days = (end - start).days
    if span_days > MAX_RANGE_DAYS:
        raise EphemerisEventsError("ephemeris search range must be <= 730 days")
    try:
        ayanamsa = normalize_ayanamsa_name(body.get("ayanamsa") or body.get("ayanamsa_name"))
    except UnsupportedAyanamsaError as exc:
        raise EphemerisEventsError(str(exc)) from exc
    node_mode = _node_mode(body.get("node_mode", body.get("nodeMode")))
    bodies = _bodies(body.get("bodies") or body.get("planets"))
    flags = swe.FLG_SWIEPH | swe.FLG_SPEED | swe.FLG_SIDEREAL
    events: list[dict[str, Any]] = []
    previous: dict[str, tuple[int, float, float]] = {}
    with temporary_ayanamsa(ayanamsa):
        cursor = start
        while cursor <= end:
            jd = swe.julday(cursor.year, cursor.month, cursor.day, 12.0)
            iso = cursor.strftime("%Y-%m-%d")
            for name in bodies:
                longitude, speed = _sample(jd, _planet_id(name), flags)
                sign_index = int(longitude // 30)
                prior = previous.get(name)
                if prior is not None:
                    prior_sign, prior_speed, _prior_lon = prior
                    if sign_index != prior_sign:
                        events.append({
                            "kind": "ingress",
                            "date": iso,
                            "body": name,
                            "from_sign": SIGNS[prior_sign],
                            "to_sign": SIGNS[sign_index],
                            "longitude": round(longitude, 6),
                            "speed_longitude": round(speed, 8),
                        })
                    if prior_speed * speed < 0:
                        events.append({
                            "kind": "station",
                            "date": iso,
                            "body": name,
                            "motion": "direct_to_retrograde" if speed < 0 else "retrograde_to_direct",
                            "longitude": round(longitude, 6),
                            "speed_longitude": round(speed, 8),
                        })
                previous[name] = (sign_index, speed, longitude)
            cursor += timedelta(days=1)
    events.sort(key=lambda row: (row["date"], row["body"], row["kind"]))
    return {
        "success": True,
        "endpoint": "ephemeris_events",
        "calculation": {
            "ayanamsa": ayanamsa,
            "ayanamsa_display": ayanamsa_display_name(ayanamsa),
            "node_mode": node_mode,
            "bodies": list(bodies),
            "start_date": start.strftime("%Y-%m-%d"),
            "end_date": end.strftime("%Y-%m-%d"),
            "sample": "daily_noon_ut_sidereal_longitude_and_speed",
            "max_range_days": MAX_RANGE_DAYS,
        },
        "events": events,
        "boundary": (
            "换座与停滞是按所选岁差逐日扫描恒星黄经得到的事件表，不是对本命的过境触发，"
            "也不是七政宿度。不得把两套结果叠加成双重印证。"
        ),
    }