"""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 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
        ],
    }