"""Active learning — what to ask next.

Goal: pick the HPO term whose answer most reduces uncertainty over the
current differential diagnosis distribution. Inspired by PhenoDP.

Bootstrap (today):
  1. Get the current differential (top-K diseases with probabilities).
  2. For each candidate HPO across these diseases, compute an information-gain
     proxy: I(H) = H(D) - E_h[H(D|h)] where h ∈ {present, absent}.
  3. Estimate P(h|D_i) from KG annotations (`Disease -[:HAS_PHENOTYPE]-> HPO`)
     with a Laplace-smoothed prevalence prior.
  4. Rank by I(H), return top-N with rationale.

Wraps `phenotype_recommender.recommend_phenotypes` if available — that already
implements a discriminative-power score; we add SUS-PCDT awareness on top.
"""
from __future__ import annotations
import logging
import math
from typing import Optional

from .types import NextQuestion

logger = logging.getLogger("gemeo.ask")


async def _safe_query(cypher: str, params: dict = None) -> list:
    """Query the *knowledge* KG (raras-app, ~10k diseases / 11k HPOs).

    This module computes MaxInfoGain over disease/phenotype frequency
    profiles which are stored in the raras-app KG, NOT in the cases
    Neo4j (Aura). Previously this routed through space_graph._safe_query
    → Aura, which has only 20 curated diseases → next-questions always
    returned 0. tools.run_query targets the knowledge KG via NEO4J_URI.
    """
    try:
        from tools import run_query
        return await run_query(cypher, params or {}, timeout=10.0)
    except Exception as e:
        logger.debug(f"tools.run_query failed, falling back to space_graph: {e}")
    try:
        from space_graph import _safe_query as q
        return await q(cypher, params or {}, timeout=10.0)
    except Exception as e:
        logger.debug(f"cypher failed: {e}")
        return []


def _entropy(probs: list[float]) -> float:
    s = sum(p for p in probs if p > 0)
    if s <= 0:
        return 0.0
    norm = [p / s for p in probs]
    return -sum(p * math.log2(p) for p in norm if p > 0)


async def _disease_phenotype_matrix(orpha_codes: list[str]) -> dict:
    """Returns {orpha: {hpo_id: prevalence_score}} from KG."""
    if not orpha_codes:
        return {}
    rows = await _safe_query(
        """
        MATCH (d:Disease)-[r:HAS_PHENOTYPE]->(p:Phenotype)
        WHERE d.orphaCode IN $orphas
        RETURN d.orphaCode AS orpha,
               p.hpoId AS hpo,
               p.name AS hpo_name,
               coalesce(r.frequency, r.prevalence, 0.5) AS freq
        """,
        {"orphas": orpha_codes},
    )
    matrix: dict = {}
    names: dict = {}
    for r in rows:
        orpha = r.get("orpha"); hpo = r.get("hpo"); freq = r.get("freq", 0.5)
        if not orpha or not hpo:
            continue
        try:
            f = float(freq)
        except Exception:
            f = 0.5
        matrix.setdefault(orpha, {})[hpo] = max(0.05, min(0.95, f))
        if r.get("hpo_name"):
            names[hpo] = r["hpo_name"]
    matrix["_names"] = names
    return matrix


async def _is_in_pcdt(hpo_id: str, orpha_candidates: list[str]) -> bool:
    """Check if any candidate disease's PCDT mentions this HPO."""
    try:
        from brazilian_context import get_pcdt
    except ImportError:
        return False
    for orpha in orpha_candidates:
        try:
            pcdt = get_pcdt(orpha)
        except Exception:
            continue
        if not pcdt:
            continue
        text = " ".join(str(v) for v in pcdt.values()).lower()
        if hpo_id.lower() in text:
            return True
    return False


async def _info_gain_path(
    differential: list[dict],
    already_present: set,
    top_n: int,
) -> list[NextQuestion]:
    """Compute info-gain over the differential."""
    orphas = [d["orpha"] for d in differential if d.get("orpha")]
    priors = {d["orpha"]: float(d.get("probability", 1.0)) for d in differential if d.get("orpha")}
    prior_sum = sum(priors.values())
    if prior_sum <= 0:
        return []
    priors = {k: v / prior_sum for k, v in priors.items()}

    matrix = await _disease_phenotype_matrix(orphas)
    names = matrix.pop("_names", {})

    # collect candidate HPOs (not already present)
    candidate_hpos = set()
    for orpha, hpos in matrix.items():
        for h in hpos.keys():
            if h not in already_present:
                candidate_hpos.add(h)

    base_entropy = _entropy(list(priors.values()))
    scored = []
    for hpo in candidate_hpos:
        # P(hpo | D_i) = matrix[D_i].get(hpo, 0.05)
        p_h = sum(priors.get(o, 0) * matrix.get(o, {}).get(hpo, 0.05) for o in orphas)
        p_not_h = 1 - p_h
        if p_h <= 0 or p_not_h <= 0:
            continue

        # posterior given hpo present
        post_present = []
        post_absent = []
        for o in orphas:
            f = matrix.get(o, {}).get(hpo, 0.05)
            post_present.append(priors.get(o, 0) * f)
            post_absent.append(priors.get(o, 0) * (1 - f))
        ent_present = _entropy(post_present)
        ent_absent = _entropy(post_absent)
        expected_post = p_h * ent_present + p_not_h * ent_absent
        gain = base_entropy - expected_post
        if gain <= 0:
            continue

        # which diseases does this HPO discriminate among?
        discriminates = []
        for o in orphas:
            f = matrix.get(o, {}).get(hpo, 0.05)
            if f >= 0.7 or f <= 0.15:
                discriminates.append(o)

        scored.append({
            "hpo": hpo,
            "name": names.get(hpo, hpo),
            "gain": gain,
            "discriminates": discriminates[:5],
        })

    scored.sort(key=lambda x: x["gain"], reverse=True)

    out = []
    for s in scored[:top_n]:
        in_pcdt = await _is_in_pcdt(s["hpo"], orphas)
        rationale = (
            f"Reduces diagnostic entropy by {s['gain']:.2f} bits."
            f" Discriminates among: {', '.join(s['discriminates']) or 'differential'}."
        )
        out.append(NextQuestion(
            hpo_id=s["hpo"],
            name=s["name"],
            rationale=rationale,
            information_gain=round(s["gain"], 4),
            discriminates_between=s["discriminates"],
            asks_in_pcdt=in_pcdt,
        ))
    return out


async def recommend(space, top_n: int = 5) -> list[NextQuestion]:
    """Recommend the next phenotypes/labs/tests to investigate."""

    # 1) try the existing phenotype_recommender (it has its own discriminative score).
    # NOTE: signature is recommend_phenotypes(space, max_recommendations=...).
    # We previously passed top_n=top_n which raised TypeError (silently swallowed)
    # → next-questions always returned []. PhenotypeRecommendation also exposes
    # `discriminative_power` + `reason` + `discriminates`, NOT `score`/`rationale`/
    # `discriminates_between`.
    try:
        from phenotype_recommender import recommend_phenotypes
        result = await recommend_phenotypes(space, max_recommendations=top_n)
        if result is not None:
            recs = result.recommendations if hasattr(result, "recommendations") else (
                result.get("recommendations", []) if isinstance(result, dict) else []
            )
            if recs:
                # adapt + enrich with PCDT awareness
                orphas = []
                for hyp in (getattr(space, "_hypotheses", {}) or {}).values():
                    if getattr(hyp, "orpha_code", None):
                        orphas.append(hyp.orpha_code)
                out = []
                for r in recs[:top_n]:
                    if isinstance(r, dict):
                        hpo = r.get("hpo_id"); name = r.get("name")
                        gain = float(
                            r.get("discriminative_power")
                            or r.get("score")
                            or r.get("information_gain")
                            or 0
                        )
                        rationale = r.get("reason") or r.get("rationale") or ""
                        disc = r.get("discriminates") or r.get("discriminates_between") or []
                    else:
                        hpo = getattr(r, "hpo_id", None); name = getattr(r, "name", None)
                        gain = float(
                            getattr(r, "discriminative_power", 0)
                            or getattr(r, "score", 0)
                            or getattr(r, "information_gain", 0)
                            or 0
                        )
                        rationale = getattr(r, "reason", "") or getattr(r, "rationale", "")
                        disc = getattr(r, "discriminates", []) or getattr(r, "discriminates_between", []) or []
                    if not hpo:
                        continue
                    in_pcdt = await _is_in_pcdt(hpo, orphas)
                    out.append(NextQuestion(
                        hpo_id=hpo, name=name or hpo,
                        rationale=rationale or "Discriminative for current differential.",
                        information_gain=gain,
                        discriminates_between=disc,
                        asks_in_pcdt=in_pcdt,
                    ))
                if out:
                    return out
    except ImportError:
        pass
    except Exception as e:
        logger.debug(f"phenotype_recommender failed: {e}")

    # 2) fallback: in-house info-gain path
    differential = []
    for hyp in (getattr(space, "_hypotheses", {}) or {}).values():
        if getattr(hyp, "orpha_code", None):
            differential.append({
                "orpha": hyp.orpha_code,
                "name": getattr(hyp, "disease_name", "") or getattr(hyp, "name", ""),
                "probability": getattr(hyp, "probability", 0.5),
            })
    if not differential:
        return []

    snap = space.get_current_snapshot() if hasattr(space, "get_current_snapshot") else None
    already_present = set()
    if snap:
        for p in snap.phenotypes:
            if p.get("hpo_id"):
                already_present.add(p["hpo_id"])

    return await _info_gain_path(differential, already_present, top_n)