# Copyright (c) 2025 Patrick Motsch
# All rights reserved.
"""
CommCoach Context Retrieval.
Intent detection, retrieval strategies, and context assembly for intelligent session continuity.
"""

import re
import logging
from datetime import datetime
from typing import Optional, Dict, Any, List, Tuple
from enum import Enum

logger = logging.getLogger(__name__)

# Retrieval config
PREVIOUS_SESSION_SUMMARIES_COUNT = 5
ROLLING_OVERVIEW_SESSION_THRESHOLD = 10
ROLLING_OVERVIEW_EVERY_N_SESSIONS = 10
TOPIC_SEARCH_MAX_RESULTS = 5


class RetrievalIntent(str, Enum):
    NORMAL = "normal"
    SUMMARIZE_ALL = "summarize_all"
    RECALL_SESSION = "recall_session"
    RECALL_TOPIC = "recall_topic"


def detectIntent(userMessage: str) -> RetrievalIntent:
    """
    Lightweight intent detection from user message.
    Uses keyword/regex heuristics.
    """
    text = (userMessage or "").strip().lower()
    if len(text) < 3:
        return RetrievalIntent.NORMAL

    summarizePatterns = [
        r"\b(fasse|zusammenfass|zusammenfassung|ueberblick|gesamte?r?\s*chat|alles\s+zusammen)\b",
        r"\b(summarize|summary\s+of\s+all|complete\s+summary)\b",
        r"zusammenfassung\s+(des\s+)?gesamten",
        r"gesamten\s+chat",
    ]
    for p in summarizePatterns:
        if re.search(p, text, re.IGNORECASE):
            return RetrievalIntent.SUMMARIZE_ALL

    datePatterns = [
        r"\b(session|gespraech|besprechung)\s+(vom|am|vom)\s*(\d{1,2})\.(\d{1,2})\.(\d{2,4})",
        r"\b(am|vom)\s*(\d{1,2})\.(\d{1,2})\.(\d{2,4})",
        r"\b(letzte\s+woche|voriger\s+monat|gestern)\b",
        r"\b(session|gespraech)\s+(vom|from)\s+(\d{4}-\d{2}-\d{2})",
    ]
    for p in datePatterns:
        if re.search(p, text, re.IGNORECASE):
            return RetrievalIntent.RECALL_SESSION

    recallTopicPatterns = [
        r"\b(erinnerst\s+du\s+dich|damals\s+als|thema\s+.*\s+von|ueber\s+was\s+haben\s+wir)\b",
        r"\b(was\s+war\s+.*\s+nochmal|thema\s+.*\s+besprochen)\b",
        r"\b(recall|remember|vor\s+\d+\s+sessions?)\b",
    ]
    for p in recallTopicPatterns:
        if re.search(p, text, re.IGNORECASE):
            return RetrievalIntent.RECALL_TOPIC

    return RetrievalIntent.NORMAL


def _parseDateFromMessage(text: str) -> Optional[datetime]:
    """Extract date from user message. Returns date or None."""
    text = text.strip()
    patterns = [
        (r"(\d{1,2})\.(\d{1,2})\.(\d{2,4})", lambda m: (int(m[1]), int(m[2]), int(m[3]))),
        (r"(\d{4})-(\d{2})-(\d{2})", lambda m: (int(m[3]), int(m[2]), int(m[1]))),
    ]
    for pattern, extractor in patterns:
        match = re.search(pattern, text)
        if match:
            try:
                day, month, year = extractor(match)
                if year < 100:
                    year += 2000
                return datetime(year, month, day)
            except (ValueError, IndexError):
                pass
    return None


def findSessionByDate(
    sessions: List[Dict[str, Any]],
    targetDate: Optional[datetime],
) -> Optional[Dict[str, Any]]:
    """
    Find session closest to targetDate.
    sessions: list of session dicts with startedAt/endedAt.
    """
    if not targetDate or not sessions:
        return None

    targetDateOnly = targetDate.date()
    bestMatch = None
    bestDiff = None

    for s in sessions:
        if s.get("status") != "completed":
            continue
        startedAt = s.get("startedAt") or s.get("endedAt") or s.get("createdAt")
        if not startedAt:
            continue
        try:
            dt = datetime.fromisoformat(startedAt.replace("Z", "+00:00"))
            sessionDate = dt.date()
            diff = abs((sessionDate - targetDateOnly).days)
            if bestDiff is None or diff < bestDiff:
                bestDiff = diff
                bestMatch = s
        except Exception:
            continue

    return bestMatch


def searchSessionsByTopic(
    sessions: List[Dict[str, Any]],
    query: str,
    maxResults: int = TOPIC_SEARCH_MAX_RESULTS,
) -> List[Dict[str, Any]]:
    """
    Topic search over sessions.
    Phase 5: Keyword-based (keyTopics + summary).
    Phase 7: Falls back to embedding search when available; for now uses keyword only.
    """
    if not query or not sessions:
        return []

    queryWords = set(re.findall(r"\w+", query.lower()))
    if not queryWords:
        return []

    scored = []
    for s in sessions:
        if s.get("status") != "completed":
            continue
        score = 0
        summary = (s.get("summary") or "").lower()
        keyTopicsRaw = s.get("keyTopics")
        keyTopics = []
        if keyTopicsRaw:
            try:
                import json
                parsed = json.loads(keyTopicsRaw) if isinstance(keyTopicsRaw, str) else keyTopicsRaw
                keyTopics = [t.lower() if isinstance(t, str) else str(t).lower() for t in parsed] if isinstance(parsed, list) else []
            except Exception:
                pass

        for word in queryWords:
            if len(word) < 3:
                continue
            if word in summary:
                score += 1
            for topic in keyTopics:
                if word in topic:
                    score += 2

        if score > 0:
            scored.append((score, s))

    scored.sort(key=lambda x: -x[0])
    return [s for _, s in scored[:maxResults]]


def searchSessionsByTopicRag(
    sessions: List[Dict[str, Any]],
    query: str,
    maxResults: int = TOPIC_SEARCH_MAX_RESULTS,
    embeddingProvider: Optional[Any] = None,
) -> List[Dict[str, Any]]:
    """
    Phase 7 RAG: Semantic search via embeddings.
    When embeddingProvider is None, falls back to keyword search.
    Future: Pass embeddingProvider that has embed(text) -> vector and similarity search.
    """
    if embeddingProvider is None:
        return searchSessionsByTopic(sessions, query, maxResults)
    # TODO: When embedding API exists: embed query, embed session summaries, cosine similarity
    return searchSessionsByTopic(sessions, query, maxResults)


def buildSessionSummariesForPrompt(
    sessions: List[Dict[str, Any]],
    excludeSessionId: Optional[str] = None,
    limit: int = PREVIOUS_SESSION_SUMMARIES_COUNT,
) -> List[Dict[str, Any]]:
    """
    Build list of session summaries with date for prompt.
    Each item: {summary, date, sessionId, keyTopics}.
    """
    completed = [
        s for s in sessions
        if s.get("status") == "completed"
        and s.get("summary")
        and s.get("id") != excludeSessionId
    ]
    completed.sort(key=lambda x: x.get("startedAt") or x.get("createdAt") or "", reverse=True)
    result = []
    for s in completed[:limit]:
        startedAt = s.get("startedAt") or s.get("createdAt") or ""
        dateStr = ""
        if startedAt:
            try:
                dt = datetime.fromisoformat(startedAt.replace("Z", "+00:00"))
                dateStr = dt.strftime("%d.%m.%Y")
            except Exception:
                pass
        result.append({
            "summary": s.get("summary", ""),
            "date": dateStr,
            "sessionId": s.get("id"),
            "keyTopics": s.get("keyTopics"),
        })
    return result