from __future__ import annotations

import re
from datetime import date

import dateparser
import spacy
from spacy.language import Language

from models import ParseResponse

# ── Language model registry ──────────────────────────────────────────────────

_MODEL_NAMES: dict[str, str] = {
    "de": "de_core_news_sm",
    "en": "en_core_web_sm",
    "es": "es_core_news_sm",
}

_nlp_cache: dict[str, Language] = {}


def get_nlp(lang: str) -> Language:
    if lang not in _MODEL_NAMES:
        raise ValueError(f"Unsupported language: {lang!r}. Valid: {list(_MODEL_NAMES)}")
    if lang not in _nlp_cache:
        _nlp_cache[lang] = spacy.load(_MODEL_NAMES[lang])
    return _nlp_cache[lang]


def load_all_models() -> None:
    for lang in _MODEL_NAMES:
        get_nlp(lang)


# ── Step 1: Person name extraction ──────────────────────────────────────────

def extract_person_names(doc) -> list[str]:
    """Return PER entity texts in left-to-right span order."""
    return [ent.text for ent in doc.ents if ent.label_ == "PER"]


# ── Step 2: Role detection ───────────────────────────────────────────────────

_SENDER_PREPS: dict[str, frozenset[str]] = {
    "de": frozenset({"von", "vom"}),
    "en": frozenset({"from", "by"}),
    "es": frozenset({"de", "por"}),
}

_RECEIVER_PREPS: dict[str, frozenset[str]] = {
    "de": frozenset({"an", "nach", "für"}),
    "en": frozenset({"to", "for"}),
    "es": frozenset({"para", "a"}),
}


def detect_person_role(doc, per_spans: list, lang: str) -> str:
    """Return 'sender', 'receiver', or 'any'.

    Only meaningful for single-PER queries — two-person queries always return
    'any' because Java derives direction from list position.
    """
    if len(per_spans) != 1:
        return "any"

    span = per_spans[0]
    root = span.root
    sender = _SENDER_PREPS[lang]
    receiver = _RECEIVER_PREPS[lang]

    # Primary: dependency-tree children of the PER root
    for child in root.children:
        if child.dep_ in ("case", "prep", "mo"):
            if child.lower_ in sender:
                return "sender"
            if child.lower_ in receiver:
                return "receiver"

    # Fallback: token immediately before the span start
    if span.start > 0:
        prev = doc[span.start - 1]
        if prev.lower_ in sender:
            return "sender"
        if prev.lower_ in receiver:
            return "receiver"

    return "any"