"""Namespace construction and access checks for Memory Gateway."""
from __future__ import annotations

from datetime import datetime, timezone

from .schemas import AccessContext, MemoryRecord, NamespaceInfo, Visibility


def user_profile_namespace(user_id: str) -> str:
    return f"user/{user_id}/profile"


def user_preferences_namespace(user_id: str) -> str:
    return f"user/{user_id}/preferences"


def user_long_term_namespace(user_id: str) -> str:
    return f"user/{user_id}/long_term"


def agent_memory_namespace(agent_id: str) -> str:
    return f"agent/{agent_id}/memory"


def workspace_shared_namespace(workspace_id: str) -> str:
    return f"workspace/{workspace_id}/shared"


def session_episodic_namespace(session_id: str) -> str:
    return f"session/{session_id}/episodic"


def global_public_namespace() -> str:
    return "global/public"


def default_namespace_for_context(ctx: AccessContext, visibility: Visibility) -> str:
    if visibility == Visibility.AGENT_ONLY and ctx.agent_id:
        return agent_memory_namespace(ctx.agent_id)
    if visibility == Visibility.WORKSPACE_SHARED and ctx.workspace_id:
        return workspace_shared_namespace(ctx.workspace_id)
    if ctx.session_id:
        return session_episodic_namespace(ctx.session_id)
    return user_long_term_namespace(ctx.user_id)


def can_access_memory(ctx: AccessContext, memory: MemoryRecord) -> bool:
    if memory.expires_at and memory.expires_at <= datetime.now(timezone.utc):
        return False
    if memory.visibility == Visibility.GLOBAL:
        return True
    if memory.visibility == Visibility.PRIVATE:
        return memory.user_id == ctx.user_id
    if memory.visibility == Visibility.AGENT_ONLY:
        return memory.user_id == ctx.user_id and memory.agent_id == ctx.agent_id
    if memory.visibility == Visibility.WORKSPACE_SHARED:
        return memory.workspace_id is not None and memory.workspace_id == ctx.workspace_id
    return False


def visible_namespaces(ctx: AccessContext) -> list[NamespaceInfo]:
    namespaces = [
        NamespaceInfo(
            namespace=user_profile_namespace(ctx.user_id),
            owner_user_id=ctx.user_id,
            visibility=Visibility.PRIVATE,
            description="用户 profile 与稳定偏好",
        ),
        NamespaceInfo(
            namespace=user_preferences_namespace(ctx.user_id),
            owner_user_id=ctx.user_id,
            visibility=Visibility.PRIVATE,
            description="用户显式偏好",
        ),
        NamespaceInfo(
            namespace=user_long_term_namespace(ctx.user_id),
            owner_user_id=ctx.user_id,
            visibility=Visibility.PRIVATE,
            description="用户长期记忆",
        ),
        NamespaceInfo(
            namespace=global_public_namespace(),
            visibility=Visibility.GLOBAL,
            description="全局公开知识",
        ),
    ]
    if ctx.agent_id:
        namespaces.append(
            NamespaceInfo(
                namespace=agent_memory_namespace(ctx.agent_id),
                owner_user_id=ctx.user_id,
                visibility=Visibility.AGENT_ONLY,
                description="指定 agent 私有经验",
            )
        )
    if ctx.workspace_id:
        namespaces.append(
            NamespaceInfo(
                namespace=workspace_shared_namespace(ctx.workspace_id),
                owner_user_id=ctx.user_id,
                visibility=Visibility.WORKSPACE_SHARED,
                description="workspace / project 共享记忆",
            )
        )
    if ctx.session_id:
        namespaces.append(
            NamespaceInfo(
                namespace=session_episodic_namespace(ctx.session_id),
                owner_user_id=ctx.user_id,
                visibility=Visibility.PRIVATE,
                description="session 临时 episodic memory",
            )
        )
    return namespaces