from __future__ import annotations
from .models import LearnerState, EvidenceEvent, MasteryRecord, PackData

def get_record(state: LearnerState, concept_id: str, dimension: str = "mastery") -> MasteryRecord | None:
    for rec in state.records:
        if rec.concept_id == concept_id and rec.dimension == dimension:
            return rec
    return None

def apply_evidence(state: LearnerState, event: EvidenceEvent, decay: float = 0.05, reinforcement: float = 0.25) -> LearnerState:
    rec = get_record(state, event.concept_id, event.dimension)
    if rec is None:
        rec = MasteryRecord(concept_id=event.concept_id, dimension=event.dimension, score=0.0, confidence=0.0, evidence_count=0, last_updated=event.timestamp)
        state.records.append(rec)
    weight = max(0.05, min(1.0, event.confidence_hint))
    rec.score = ((rec.score * rec.evidence_count) + (event.score * weight)) / max(1, rec.evidence_count + 1)
    rec.confidence = min(1.0, max(0.0, rec.confidence * (1.0 - decay) + reinforcement * weight + 0.10 * max(0.0, min(1.0, event.score))))
    rec.evidence_count += 1
    rec.last_updated = event.timestamp
    state.history.append(event)
    return state

def prereqs_satisfied(state: LearnerState, concept, min_score: float = 0.65, min_confidence: float = 0.45) -> bool:
    for pid in concept.prerequisites:
        rec = get_record(state, pid, concept.masteryDimension)
        if rec is None or rec.score < min_score or rec.confidence < min_confidence:
            return False
    return True

def concept_status(state: LearnerState, concept, min_score: float = 0.65, min_confidence: float = 0.45) -> str:
    rec = get_record(state, concept.id, concept.masteryDimension)
    if rec and rec.score >= min_score and rec.confidence >= min_confidence:
        return "mastered"
    if prereqs_satisfied(state, concept, min_score, min_confidence):
        return "active" if rec else "available"
    return "locked"

def recommend_next(state: LearnerState, pack: PackData) -> list[dict]:
    cards = []
    for concept in pack.concepts:
        status = concept_status(state, concept)
        rec = get_record(state, concept.id, concept.masteryDimension)
        if status in {"available", "active"}:
            cards.append({
                "id": concept.id,
                "title": f"Work on {concept.title}",
                "minutes": 15 if status == "available" else 10,
                "reason": "Prerequisites are satisfied, so this is the best next unlock." if status == "available" else "You have started this concept, but mastery is not yet secure.",
                "why": [
                    "Prerequisite check passed",
                    f"Current score: {rec.score:.2f}" if rec else "No evidence recorded yet",
                    f"Current confidence: {rec.confidence:.2f}" if rec else "Confidence starts after your first exercise",
                ],
                "reward": concept.exerciseReward or f"{concept.title} progress recorded",
                "conceptId": concept.id,
                "scoreHint": 0.82 if status == "available" else 0.76,
                "confidenceHint": 0.72 if status == "available" else 0.55,
            })
    return cards[:4]