from __future__ import annotations

import fnmatch
import json
from datetime import datetime
from pathlib import Path
from typing import Any, Optional

from fastmcp import FastMCP


def validate_token(value: str, field: str, allow_colon: bool = False) -> str:
    value = value.strip()
    if not value:
        raise ValueError(f"{field} must not be empty")

    forbidden = ["..", "/", "\\"]
    if not allow_colon:
        forbidden.append(":")

    for marker in forbidden:
        if marker in value:
            raise ValueError(f"{field} contains forbidden sequence: {marker}")
    return value


class MemoryServer:
    def __init__(self, storage_path: Path | None = None):
        self.mcp = FastMCP("Memory-Server")
        self.storage_path = storage_path or Path("./memory_data.json")
        self._register_tools()

    def _load_memory(self) -> dict:
        if not self.storage_path.exists():
            return {}
        with open(self.storage_path, "r", encoding="utf-8") as f:
            return json.load(f)

    def _save_memory(self, data: dict):
        self.storage_path.parent.mkdir(parents=True, exist_ok=True)
        with open(self.storage_path, "w", encoding="utf-8") as f:
            json.dump(data, f, indent=2, ensure_ascii=False)

    def _make_record(self, value: Any) -> dict[str, Any]:
        return {
            "value": value,
            "timestamp": datetime.now().isoformat(timespec="seconds"),
        }

    def _save_entry(self, key: str, value: Any) -> bool:
        key = validate_token(key, "key", allow_colon=True)
        data = self._load_memory()
        data[key] = self._make_record(value)
        self._save_memory(data)
        return True

    def _get_entry(self, key: str) -> Optional[dict]:
        key = validate_token(key, "key", allow_colon=True)
        data = self._load_memory()
        record = data.get(key)
        if record is None:
            return None
        return {"key": key, **record}

    def _delete_entry(self, key: str) -> bool:
        key = validate_token(key, "key", allow_colon=True)
        data = self._load_memory()
        if key not in data:
            return False
        del data[key]
        self._save_memory(data)
        return True

    def _list_entry_keys(self, pattern: str = "*") -> list[str]:
        data = self._load_memory()
        return sorted(key for key in data if fnmatch.fnmatch(key, pattern))

    def _save_namespaced(self, key: str, value: Any, namespace: str = "default") -> bool:
        namespace = validate_token(namespace, "namespace")
        key = validate_token(key, "key")
        return self._save_entry(f"{namespace}:{key}", value)

    def _get_namespace_entries(self, namespace: str = "default") -> list[dict]:
        namespace = validate_token(namespace, "namespace")
        prefix = f"{namespace}:"
        data = self._load_memory()
        result = []
        for key in sorted(data):
            if key.startswith(prefix):
                result.append({"key": key, **data[key]})
        return result

    def _register_tools(self) -> None:
        @self.mcp.tool()
        def save(key: str, value: Any) -> bool:
            """Save a serializable value under a key."""

            return self._save_entry(key, value)

        @self.mcp.tool()
        def get(key: str) -> Optional[dict]:
            """Return a saved value with its metadata or None."""

            return self._get_entry(key)

        @self.mcp.tool()
        def delete(key: str) -> bool:
            """Delete a key from memory if it exists."""

            return self._delete_entry(key)

        @self.mcp.tool()
        def list_keys(pattern: str = "*") -> list[str]:
            """List saved keys filtered by a wildcard pattern."""

            return self._list_entry_keys(pattern)

        @self.mcp.tool()
        def save_with_namespace(key: str, value: Any, namespace: str = "default") -> bool:
            """Save a value inside a namespace using namespace:key format."""

            return self._save_namespaced(key, value, namespace)

        @self.mcp.tool()
        def get_by_namespace(namespace: str = "default") -> list[dict]:
            """Return all records that belong to the namespace."""

            return self._get_namespace_entries(namespace)


if __name__ == "__main__":
    server = MemoryServer()
    server.mcp.run(
        transport="stdio",
        show_banner=False,
        log_level="ERROR",
    )