"""
Engagement Score Calculator.
Fuses face, speech, and text emotion data into a unified engagement metric.
"""


# Source weights for multimodal fusion
SOURCE_WEIGHTS = {
    "face": 0.50,
    "speech": 0.30,
    "text": 0.20,
}


def calculate_engagement(face_result=None, speech_result=None, text_result=None):
    """
    Calculate a fused engagement score from multimodal emotion data.
    Uses weighted combination of available modalities.

    Args:
        face_result: dict with 'engagement_score' from face model
        speech_result: dict with 'engagement_score' from speech model
        text_result: dict with 'engagement_score' from text model

    Returns:
        dict with overall engagement score, breakdown, and insights
    """
    scores = {}
    weights_used = {}
    active_sources = []

    if face_result and "engagement_score" in face_result:
        scores["face"] = face_result["engagement_score"]
        weights_used["face"] = SOURCE_WEIGHTS["face"]
        active_sources.append("face")

    if speech_result and "engagement_score" in speech_result:
        scores["speech"] = speech_result["engagement_score"]
        weights_used["speech"] = SOURCE_WEIGHTS["speech"]
        active_sources.append("speech")

    if text_result and "engagement_score" in text_result:
        scores["text"] = text_result["engagement_score"]
        weights_used["text"] = SOURCE_WEIGHTS["text"]
        active_sources.append("text")

    if not scores:
        return {
            "overall_score": 0,
            "breakdown": {},
            "active_sources": [],
            "level": "Unknown",
            "insights": ["No data sources available"],
        }

    # Normalize weights to sum to 1.0 for active sources
    total_weight = sum(weights_used.values())
    normalized_weights = {k: v / total_weight for k, v in weights_used.items()}

    # Weighted average
    overall = sum(
        scores[source] * normalized_weights[source]
        for source in active_sources
    )

    # Determine engagement level
    level = _get_engagement_level(overall)

    # Generate insights
    insights = _generate_insights(scores, face_result, speech_result, text_result)

    return {
        "overall_score": round(overall, 2),
        "breakdown": {
            source: {
                "score": round(scores[source], 2),
                "weight": round(normalized_weights[source], 2),
                "weighted_contribution": round(scores[source] * normalized_weights[source], 2),
            }
            for source in active_sources
        },
        "active_sources": active_sources,
        "level": level,
        "insights": insights,
    }


def _get_engagement_level(score):
    """Map score to human-readable engagement level."""
    if score >= 85:
        return "Highly Engaged"
    elif score >= 70:
        return "Engaged"
    elif score >= 55:
        return "Moderately Engaged"
    elif score >= 40:
        return "Disengaged"
    else:
        return "Very Disengaged"


def _generate_insights(scores, face_result, speech_result, text_result):
    """Generate actionable insights from the analysis."""
    insights = []

    # Face insights
    if face_result:
        emotion = face_result.get("emotion", "Unknown")
        confidence = face_result.get("confidence", 0)
        if emotion in ("Happy", "Surprise"):
            insights.append(f"Student appears {emotion.lower()} ({confidence}% confidence) — positive engagement signal.")
        elif emotion in ("Sad", "Angry", "Fear", "Disgust"):
            insights.append(f"⚠️ Negative facial expression detected: {emotion} ({confidence}%) — consider changing approach.")
        elif emotion == "Neutral":
            insights.append(f"Student facial expression is neutral ({confidence}%) — may need more stimulation.")

    # Speech insights
    if speech_result:
        s_emotion = speech_result.get("emotion", "Unknown")
        if s_emotion in ("Happy", "Surprise"):
            insights.append(f"Voice tone indicates {s_emotion.lower()} — student is vocally engaged.")
        elif s_emotion in ("Sad", "Angry"):
            insights.append(f"⚠️ Voice indicates {s_emotion.lower()} — student may be frustrated.")

    # Text insights
    if text_result:
        sentiment = text_result.get("sentiment", "NEUTRAL")
        if sentiment == "POSITIVE":
            insights.append("Text sentiment is positive — student is expressing interest.")
        elif sentiment == "NEGATIVE":
            insights.append("⚠️ Negative text sentiment detected — review student comments.")

    # Cross-modal insights
    if len(scores) >= 2:
        values = list(scores.values())
        spread = max(values) - min(values)
        if spread > 40:
            insights.append("⚠️ Large discrepancy between modalities — mixed signals detected.")

    if not insights:
        insights.append("Monitoring active. Collecting data...")

    return insights


def calculate_session_trend(emotion_logs):
    """
    Calculate engagement trend from a list of emotion log entries.
    Returns time-series data for charting.
    """
    if not emotion_logs:
        return {"trend": [], "average": 0, "peak": 0, "low": 0}

    trend = []
    engagement_values = []

    for log in emotion_logs:
        score = log.get("engagement_score", 50)
        engagement_values.append(score)
        trend.append({
            "timestamp": log.get("timestamp", ""),
            "score": score,
            "emotion": log.get("emotion", "neutral"),
            "source": log.get("source", "unknown"),
        })

    return {
        "trend": trend,
        "average": round(sum(engagement_values) / len(engagement_values), 2),
        "peak": round(max(engagement_values), 2),
        "low": round(min(engagement_values), 2),
    }