from __future__ import annotations

import json
import logging
from typing import Any

from pydantic import BaseModel

logger = logging.getLogger(__name__)


class MemoryDecision(BaseModel):
    should_store: bool = False
    memory_type: str = "note"
    summary: str = ""
    importance: float = 0.0
    scope: str = "workspace"
    metadata: dict[str, str] = {}


class MemoryPolicy:
    """Decides whether task output should be stored in memory.

    When *model_client* is provided, uses an LLM call to classify the task
    transcript.  Falls back to a safe default (should_store=False) on any
    error so the runtime is never blocked by policy failures.
    """

    _PROMPT_SYSTEM = (
        "You are DuckLM memory policy. Decide whether the given task transcript "
        "contains information worth storing in long-term memory.\n\n"
        "Return ONLY valid JSON with these keys:\n"
        "  should_store: boolean — true if this is worth remembering\n"
        "  memory_type: string — one of: fact, preference, lesson, decision, event, note\n"
        "  summary: string — concise one-sentence summary (max 200 chars)\n"
        "  importance: number — 0.0 to 1.0\n"
        "  scope: string — one of: global, workspace, conversation\n"
        "  metadata: object — optional extra key-value pairs\n\n"
        "Rules:\n"
        "- Store user preferences, important decisions, reusable lessons, key facts.\n"
        "- Do NOT store routine tool calls, temporary state, or trivial observations.\n"
        "- importance >= 0.7 for preferences and lessons, >= 0.4 for facts, < 0.4 for events.\n"
        "- scope='global' for user preferences and system-wide facts.\n"
        "- scope='workspace' for project-specific information.\n"
        "- scope='conversation' for chat-specific context.\n"
    )

    _RESPONSE_SCHEMA = {
        "type": "object",
        "required": ["should_store", "memory_type", "summary", "importance", "scope", "metadata"],
        "additionalProperties": False,
        "properties": {
            "should_store": {"type": "boolean"},
            "memory_type": {
                "type": "string",
                "enum": ["fact", "preference", "lesson", "decision", "event", "note"],
            },
            "summary": {"type": "string", "maxLength": 300},
            "importance": {"type": "number", "minimum": 0.0, "maximum": 1.0},
            "scope": {"type": "string", "enum": ["global", "workspace", "conversation"]},
            "metadata": {"type": "object", "additionalProperties": {"type": "string"}},
        },
    }

    def __init__(
        self,
        model_client: Any | None = None,
        role: str = "memory_policy",
    ):
        self._model_client = model_client
        self._role = role

    async def classify(self, summary: str, task_id: str) -> MemoryDecision:
        """Classify whether *summary* from *task_id* should be stored in memory.

        If no model client is configured, returns the safe default
        (should_store=False) — the old stub behaviour.
        """
        if self._model_client is None:
            return MemoryDecision(
                should_store=False,
                memory_type="event",
                summary=summary,
                importance=0.0,
                metadata={"task_id": task_id, "source": "stub_policy"},
            )

        return await self._classify_with_llm(summary, task_id)

    async def _classify_with_llm(self, summary: str, task_id: str) -> MemoryDecision:
        messages = [
            {
                "role": "user",
                "content": f"Task ID: {task_id}\n\nTranscript:\n{summary}",
            }
        ]

        response_format = {
            "type": "json_schema",
            "json_schema": {
                "name": "memory_decision",
                "schema": self._RESPONSE_SCHEMA,
                "strict": True,
            },
        }

        try:
            response = await self._model_client.chat(
                self._role,
                messages,
                response_format=response_format,
            )
        except Exception as exc:
            logger.warning("MemoryPolicy LLM call failed for %s: %s", task_id, exc)
            return MemoryDecision(
                should_store=False,
                memory_type="event",
                summary=summary,
                importance=0.0,
                metadata={"task_id": task_id, "source": "llm_policy_fallback"},
            )

        return self._parse_response(response.content, summary, task_id)

    def _parse_response(self, content: str, summary: str, task_id: str) -> MemoryDecision:
        try:
            data = json.loads(content)
        except (json.JSONDecodeError, TypeError):
            logger.warning("MemoryPolicy: invalid JSON for %s: %s", task_id, content[:200])
            return MemoryDecision(
                should_store=False,
                memory_type="event",
                summary=summary,
                importance=0.0,
                metadata={"task_id": task_id, "source": "llm_policy_fallback"},
            )

        required = ("should_store", "memory_type", "summary", "importance", "scope")
        if not all(key in data for key in required):
            logger.warning("MemoryPolicy: missing fields for %s: %s", task_id, list(data.keys()))
            return MemoryDecision(
                should_store=False,
                memory_type="event",
                summary=summary,
                importance=0.0,
                metadata={"task_id": task_id, "source": "llm_policy_fallback"},
            )

        return MemoryDecision(
            should_store=bool(data.get("should_store", False)),
            memory_type=str(data.get("memory_type", "note")),
            summary=str(data.get("summary", summary))[:300],
            importance=float(max(0.0, min(data.get("importance", 0.0), 1.0))),
            scope=str(data.get("scope", "workspace")),
            metadata={
                "task_id": task_id,
                "source": "llm_policy",
                **{str(k): str(v) for k, v in data.get("metadata", {}).items()},
            },
        )