"""
Episodic Memory – Past Tasks & Events
=======================================
Stores discrete events / task completions as Markdown files
under  memory/events/*.md

Each event has a timestamp, outcome, and optional linked entities.
Supports keyword search and time-range queries.
"""

from __future__ import annotations

import os
from datetime import datetime
from pathlib import Path
from typing import Any, Dict, List, Optional

from .models import MemoryEntry, MemoryTier


class EpisodicMemory:
    """File-backed store for task / event memories."""

    def __init__(self, base_dir: str = "memory/events"):
        self.base_dir = Path(base_dir)
        self.base_dir.mkdir(parents=True, exist_ok=True)
        # id → MemoryEntry (in-memory index)
        self._index: Dict[str, MemoryEntry] = {}
        self._load_from_disk()

    # ── CRUD ─────────────────────────────────────────────────

    def create(
        self,
        content: str,
        title: str = "",
        tags: Optional[List[str]] = None,
        importance: float = 0.5,
        metadata: Optional[Dict[str, Any]] = None,
        source: str = "",
    ) -> MemoryEntry:
        entry = MemoryEntry(
            content=content,
            title=title or self._auto_title(content),
            tier=MemoryTier.EPISODIC,
            tags=tags or [],
            importance=importance,
            metadata=metadata or {},
            source=source,
            created_at=datetime.utcnow().isoformat(),
            updated_at=datetime.utcnow().isoformat(),
        )
        self._index[entry.id] = entry
        self._persist(entry)
        return entry

    def read(self, entry_id: str) -> Optional[MemoryEntry]:
        entry = self._index.get(entry_id)
        if entry:
            entry.access_count += 1
            entry.updated_at = datetime.utcnow().isoformat()
            self._persist(entry)
        return entry

    def update(self, entry_id: str, **kwargs) -> Optional[MemoryEntry]:
        entry = self._index.get(entry_id)
        if not entry:
            return None
        for k, v in kwargs.items():
            if hasattr(entry, k) and k not in ("id", "tier", "created_at"):
                setattr(entry, k, v)
        entry.updated_at = datetime.utcnow().isoformat()
        self._persist(entry)
        return entry

    def delete(self, entry_id: str) -> bool:
        if entry_id not in self._index:
            return False
        del self._index[entry_id]
        path = self._entry_path(entry_id)
        if path.exists():
            path.unlink()
        return True

    def list_entries(
        self,
        tag: Optional[str] = None,
        since: Optional[str] = None,
        until: Optional[str] = None,
        limit: int = 50,
    ) -> List[MemoryEntry]:
        """List events, optionally filtered by tag and/or time range."""
        entries = list(self._index.values())

        if tag:
            entries = [e for e in entries if tag in e.tags]
        if since:
            entries = [e for e in entries if e.created_at >= since]
        if until:
            entries = [e for e in entries if e.created_at <= until]

        # newest first
        entries.sort(key=lambda e: e.created_at, reverse=True)
        return entries[:limit]

    def search(self, query: str, limit: int = 10) -> List[MemoryEntry]:
        """Keyword search across episodic memories."""
        q = query.lower()
        scored: List[tuple] = []
        for entry in self._index.values():
            text = f"{entry.title} {entry.content} {' '.join(entry.tags)}".lower()
            if q in text:
                # rudimentary relevance: importance + recency
                scored.append((entry, entry.importance))
        scored.sort(key=lambda x: x[1], reverse=True)
        return [e for e, _ in scored[:limit]]

    def count(self) -> int:
        return len(self._index)

    # ── timeline helpers ─────────────────────────────────────

    def recent(self, n: int = 10) -> List[MemoryEntry]:
        """Get the N most recent events."""
        entries = sorted(self._index.values(), key=lambda e: e.created_at, reverse=True)
        return entries[:n]

    def by_tag(self, tag: str) -> List[MemoryEntry]:
        return [e for e in self._index.values() if tag in e.tags]

    # ── persistence ──────────────────────────────────────────

    def _entry_path(self, entry_id: str) -> Path:
        return self.base_dir / f"{entry_id}.md"

    def _persist(self, entry: MemoryEntry):
        path = self._entry_path(entry.id)
        path.write_text(entry.to_markdown(), encoding="utf-8")

    def _load_from_disk(self):
        for md_file in self.base_dir.glob("*.md"):
            try:
                text = md_file.read_text(encoding="utf-8")
                entry = MemoryEntry.from_markdown(text)
                entry.tier = MemoryTier.EPISODIC
                self._index[entry.id] = entry
            except Exception:
                pass

    @staticmethod
    def _auto_title(content: str) -> str:
        """Generate a short title from content."""
        first_line = content.strip().split("\n")[0][:80]
        return first_line if first_line else "Untitled Event"