"""Workspace service — CRUD, module config, user assignment, widgets.

Workspaces are UI/navigation context only. They never affect permissions.
See: docs/security_kernel.md
"""

from __future__ import annotations

import uuid
from typing import Any

from sqlalchemy import select, update, func
from sqlalchemy.ext.asyncio import AsyncSession
from sqlalchemy.orm import selectinload

from app.models.workspace import Workspace, WorkspaceModule, WorkspaceUser, WorkspaceWidget


def _workspace_to_dict(ws: Workspace, modules: list[WorkspaceModule] | None = None, user_count: int = 0) -> dict[str, Any]:
    return {
        "id": str(ws.id),
        "name": ws.name,
        "icon": ws.icon,
        "description": ws.description,
        "is_default": ws.is_default,
        "is_active": ws.is_active,
        "created_by": str(ws.created_by) if ws.created_by else None,
        "created_at": ws.created_at.isoformat() if ws.created_at else None,
        "updated_at": ws.updated_at.isoformat() if ws.updated_at else None,
        "modules": [
            {
                "id": str(m.id),
                "module_key": m.module_key,
                "is_visible": m.is_visible,
                "menu_order": m.menu_order,
                "config": m.config or {},
            }
            for m in (modules or [])
        ],
        "user_count": user_count,
    }


async def list_workspaces(
    db: AsyncSession, tenant_id: uuid.UUID
) -> dict[str, Any]:
    """List all workspaces for a tenant."""
    q = select(Workspace).where(
        Workspace.tenant_id == tenant_id,
        Workspace.is_active == True,  # noqa: E712
    ).order_by(Workspace.name)
    result = await db.execute(q)
    workspaces = result.scalars().all()
    
    items = []
    for ws in workspaces:
        # Count users
        count_q = select(func.count()).select_from(WorkspaceUser).where(
            WorkspaceUser.workspace_id == ws.id,
            WorkspaceUser.tenant_id == tenant_id,
        )
        count_result = await db.execute(count_q)
        user_count = count_result.scalar() or 0
        items.append(_workspace_to_dict(ws, user_count=user_count))
    
    return {"items": items, "total": len(items)}


async def get_workspace(
    db: AsyncSession, tenant_id: uuid.UUID, workspace_id: uuid.UUID
) -> dict[str, Any] | None:
    """Get a single workspace with modules and user count."""
    q = select(Workspace).where(
        Workspace.id == workspace_id,
        Workspace.tenant_id == tenant_id,
    )
    result = await db.execute(q)
    ws = result.scalar_one_or_none()
    if ws is None:
        return None
    
    # Get modules
    mod_q = select(WorkspaceModule).where(
        WorkspaceModule.workspace_id == workspace_id,
        WorkspaceModule.tenant_id == tenant_id,
    ).order_by(WorkspaceModule.menu_order)
    mod_result = await db.execute(mod_q)
    modules = mod_result.scalars().all()
    
    # Count users
    count_q = select(func.count()).select_from(WorkspaceUser).where(
        WorkspaceUser.workspace_id == workspace_id,
        WorkspaceUser.tenant_id == tenant_id,
    )
    count_result = await db.execute(count_q)
    user_count = count_result.scalar() or 0
    
    return _workspace_to_dict(ws, modules=modules, user_count=user_count)


async def create_workspace(
    db: AsyncSession,
    tenant_id: uuid.UUID,
    user_id: uuid.UUID,
    name: str,
    icon: str = "LayoutGrid",
    description: str | None = None,
    is_default: bool = False,
) -> dict[str, Any]:
    """Create a new workspace."""
    ws = Workspace(
        tenant_id=tenant_id,
        name=name,
        icon=icon,
        description=description,
        is_default=is_default,
        is_active=True,
        created_by=user_id,
    )
    db.add(ws)
    await db.flush()
    await db.refresh(ws)
    
    # If this is the default workspace, unset others
    if is_default:
        await db.execute(
            update(Workspace)
            .where(
                Workspace.tenant_id == tenant_id,
                Workspace.id != ws.id,
            )
            .values(is_default=False)
        )
    
    # Auto-assign creator as manager
    wu = WorkspaceUser(
        tenant_id=tenant_id,
        workspace_id=ws.id,
        user_id=user_id,
        role="manager",
        is_default=is_default,
        assigned_by=user_id,
    )
    db.add(wu)
    await db.flush()
    
    return _workspace_to_dict(ws, user_count=1)


async def update_workspace(
    db: AsyncSession,
    tenant_id: uuid.UUID,
    workspace_id: uuid.UUID,
    name: str | None = None,
    icon: str | None = None,
    description: str | None = None,
    is_default: bool | None = None,
    is_active: bool | None = None,
) -> dict[str, Any] | None:
    """Update a workspace."""
    q = select(Workspace).where(
        Workspace.id == workspace_id,
        Workspace.tenant_id == tenant_id,
    )
    result = await db.execute(q)
    ws = result.scalar_one_or_none()
    if ws is None:
        return None
    
    if name is not None:
        ws.name = name
    if icon is not None:
        ws.icon = icon
    if description is not None:
        ws.description = description
    if is_active is not None:
        ws.is_active = is_active
    if is_default is True:
        # Unset other defaults
        await db.execute(
            update(Workspace)
            .where(
                Workspace.tenant_id == tenant_id,
                Workspace.id != ws.id,
            )
            .values(is_default=False)
        )
        ws.is_default = True
    elif is_default is False:
        ws.is_default = False
    
    await db.flush()
    await db.refresh(ws)
    return _workspace_to_dict(ws)


async def delete_workspace(
    db: AsyncSession, tenant_id: uuid.UUID, workspace_id: uuid.UUID
) -> bool:
    """Delete a workspace (soft delete by setting is_active=False)."""
    q = select(Workspace).where(
        Workspace.id == workspace_id,
        Workspace.tenant_id == tenant_id,
    )
    result = await db.execute(q)
    ws = result.scalar_one_or_none()
    if ws is None:
        return False
    ws.is_active = False
    await db.flush()
    return True


async def set_workspace_modules(
    db: AsyncSession,
    tenant_id: uuid.UUID,
    workspace_id: uuid.UUID,
    modules: list[dict[str, Any]],
) -> list[dict[str, Any]]:
    """Set the modules for a workspace. Replaces all existing modules."""
    # Delete existing modules
    existing_q = select(WorkspaceModule).where(
        WorkspaceModule.workspace_id == workspace_id,
        WorkspaceModule.tenant_id == tenant_id,
    )
    existing = await db.execute(existing_q)
    for m in existing.scalars().all():
        await db.delete(m)
    
    # Insert new modules
    result = []
    for mod in modules:
        wm = WorkspaceModule(
            tenant_id=tenant_id,
            workspace_id=workspace_id,
            module_key=mod["module_key"],
            is_visible=mod.get("is_visible", True),
            menu_order=mod.get("menu_order", 0),
            config=mod.get("config", {}),
        )
        db.add(wm)
        await db.flush()
        await db.refresh(wm)
        result.append({
            "id": str(wm.id),
            "module_key": wm.module_key,
            "is_visible": wm.is_visible,
            "menu_order": wm.menu_order,
            "config": wm.config or {},
        })
    
    return result


async def assign_user(
    db: AsyncSession,
    tenant_id: uuid.UUID,
    workspace_id: uuid.UUID,
    user_id: uuid.UUID,
    role: str = "member",
    assigned_by: uuid.UUID | None = None,
) -> dict[str, Any]:
    """Assign a user to a workspace."""
    wu = WorkspaceUser(
        tenant_id=tenant_id,
        workspace_id=workspace_id,
        user_id=user_id,
        role=role,
        is_default=False,
        assigned_by=assigned_by,
    )
    db.add(wu)
    await db.flush()
    await db.refresh(wu)
    return {
        "id": str(wu.id),
        "workspace_id": str(wu.workspace_id),
        "user_id": str(wu.user_id),
        "role": wu.role,
        "is_default": wu.is_default,
        "assigned_at": wu.assigned_at.isoformat() if wu.assigned_at else None,
    }


async def remove_user(
    db: AsyncSession, tenant_id: uuid.UUID, workspace_id: uuid.UUID, user_id: uuid.UUID
) -> bool:
    """Remove a user from a workspace."""
    q = select(WorkspaceUser).where(
        WorkspaceUser.workspace_id == workspace_id,
        WorkspaceUser.user_id == user_id,
        WorkspaceUser.tenant_id == tenant_id,
    )
    result = await db.execute(q)
    wu = result.scalar_one_or_none()
    if wu is None:
        return False
    await db.delete(wu)
    await db.flush()
    return True


async def get_my_workspaces(
    db: AsyncSession, tenant_id: uuid.UUID, user_id: uuid.UUID
) -> dict[str, Any]:
    """Get workspaces assigned to the current user."""
    q = (
        select(Workspace, WorkspaceUser)
        .join(WorkspaceUser, WorkspaceUser.workspace_id == Workspace.id)
        .where(
            WorkspaceUser.user_id == user_id,
            Workspace.tenant_id == tenant_id,
            Workspace.is_active == True,  # noqa: E712
        )
        .order_by(Workspace.name)
    )
    result = await db.execute(q)
    rows = result.all()
    
    items = []
    for ws, wu in rows:
        # Get modules for this workspace
        mod_q = select(WorkspaceModule).where(
            WorkspaceModule.workspace_id == ws.id,
            WorkspaceModule.tenant_id == tenant_id,
            WorkspaceModule.is_visible == True,  # noqa: E712
        ).order_by(WorkspaceModule.menu_order)
        mod_result = await db.execute(mod_q)
        modules = mod_result.scalars().all()
        
        items.append({
            "id": str(ws.id),
            "name": ws.name,
            "icon": ws.icon,
            "description": ws.description,
            "is_default": ws.is_default,
            "role": wu.role,
            "is_user_default": wu.is_default,
            "modules": [
                {
                    "module_key": m.module_key,
                    "menu_order": m.menu_order,
                    "config": m.config or {},
                }
                for m in modules
            ],
        })
    
    return {"items": items, "total": len(items)}


async def get_workspace_context(
    db: AsyncSession, tenant_id: uuid.UUID, user_id: uuid.UUID, workspace_id: uuid.UUID
) -> dict[str, Any] | None:
    """Get workspace context for a user — modules, widgets, config.
    
    Validates:
    - Workspace belongs to tenant
    - User is assigned or is system admin / tenant admin
    - Workspace is active
    """
    # Check workspace exists and is active
    ws_q = select(Workspace).where(
        Workspace.id == workspace_id,
        Workspace.tenant_id == tenant_id,
        Workspace.is_active == True,  # noqa: E712
    )
    ws_result = await db.execute(ws_q)
    ws = ws_result.scalar_one_or_none()
    if ws is None:
        return None
    
    # Check user is assigned
    wu_q = select(WorkspaceUser).where(
        WorkspaceUser.workspace_id == workspace_id,
        WorkspaceUser.user_id == user_id,
        WorkspaceUser.tenant_id == tenant_id,
    )
    wu_result = await db.execute(wu_q)
    wu = wu_result.scalar_one_or_none()
    if wu is None:
        return None  # User not assigned — caller can check is_system_admin
    
    # Get visible modules
    mod_q = select(WorkspaceModule).where(
        WorkspaceModule.workspace_id == workspace_id,
        WorkspaceModule.tenant_id == tenant_id,
        WorkspaceModule.is_visible == True,  # noqa: E712
    ).order_by(WorkspaceModule.menu_order)
    mod_result = await db.execute(mod_q)
    modules = mod_result.scalars().all()
    
    # Get widgets
    widget_q = select(WorkspaceWidget).where(
        WorkspaceWidget.workspace_id == workspace_id,
        WorkspaceWidget.tenant_id == tenant_id,
    ).order_by(WorkspaceWidget.position_y, WorkspaceWidget.position_x)
    widget_result = await db.execute(widget_q)
    widgets = widget_result.scalars().all()
    
    return {
        "workspace_id": str(ws.id),
        "name": ws.name,
        "icon": ws.icon,
        "role": wu.role,
        "modules": [
            {
                "module_key": m.module_key,
                "menu_order": m.menu_order,
                "config": m.config or {},
            }
            for m in modules
        ],
        "widgets": [
            {
                "id": str(w.id),
                "widget_key": w.widget_key,
                "position_x": w.position_x,
                "position_y": w.position_y,
                "width": w.width,
                "height": w.height,
                "config": w.config or {},
            }
            for w in widgets
        ],
    }