"""Project Templates API endpoints.

Provides CRUD operations for project templates and
the ability to create projects from templates.
"""
import uuid
from typing import List, Optional
from fastapi import APIRouter, Depends, HTTPException, status, Request, Query
from sqlalchemy.orm import Session

from app.core.database import get_db
from app.models import (
    User, Space, Project, TaskStatus, CustomField, ProjectTemplate, AuditAction
)
from app.schemas.project_template import (
    ProjectTemplateCreate,
    ProjectTemplateUpdate,
    ProjectTemplateResponse,
    ProjectTemplateWithOwner,
    ProjectTemplateListResponse,
    CreateProjectFromTemplateRequest,
    CreateProjectFromTemplateResponse,
)
from app.middleware.auth import get_current_user, check_space_access
from app.middleware.audit import get_audit_metadata
from app.services.audit_service import AuditService

router = APIRouter(prefix="/api/templates", tags=["Project Templates"])


def can_view_template(user: User, template: ProjectTemplate) -> bool:
    """Check if a user can view a template."""
    if template.is_public:
        return True
    if template.owner_id == user.id:
        return True
    if user.is_system_admin:
        return True
    return False


def can_edit_template(user: User, template: ProjectTemplate) -> bool:
    """Check if a user can edit a template."""
    if template.owner_id == user.id:
        return True
    if user.is_system_admin:
        return True
    return False


@router.get("", response_model=ProjectTemplateListResponse)
async def list_templates(
    include_private: bool = Query(False, description="Include user's private templates"),
    db: Session = Depends(get_db),
    current_user: User = Depends(get_current_user),
):
    """
    List available project templates.

    By default, only returns public templates.
    Set include_private=true to also include the user's private templates.
    """
    query = db.query(ProjectTemplate).filter(ProjectTemplate.is_active == True)

    if include_private:
        # Public templates OR user's own templates
        query = query.filter(
            (ProjectTemplate.is_public == True) |
            (ProjectTemplate.owner_id == current_user.id)
        )
    else:
        # Only public templates
        query = query.filter(ProjectTemplate.is_public == True)

    templates = query.order_by(ProjectTemplate.name).all()

    result = []
    for template in templates:
        result.append(ProjectTemplateWithOwner(
            id=template.id,
            name=template.name,
            description=template.description,
            is_public=template.is_public,
            task_statuses=template.task_statuses,
            custom_fields=template.custom_fields,
            default_security_level=template.default_security_level,
            owner_id=template.owner_id,
            is_active=template.is_active,
            created_at=template.created_at,
            updated_at=template.updated_at,
            owner_name=template.owner.name if template.owner else None,
        ))

    return ProjectTemplateListResponse(
        templates=result,
        total=len(result),
    )


@router.post("", response_model=ProjectTemplateResponse, status_code=status.HTTP_201_CREATED)
async def create_template(
    template_data: ProjectTemplateCreate,
    request: Request,
    db: Session = Depends(get_db),
    current_user: User = Depends(get_current_user),
):
    """
    Create a new project template.

    The template can include predefined task statuses and custom fields
    that will be copied when creating a project from this template.
    """
    # Convert Pydantic models to dict for JSON storage
    task_statuses_json = None
    if template_data.task_statuses:
        task_statuses_json = [ts.model_dump() for ts in template_data.task_statuses]

    custom_fields_json = None
    if template_data.custom_fields:
        custom_fields_json = [cf.model_dump() for cf in template_data.custom_fields]

    template = ProjectTemplate(
        id=str(uuid.uuid4()),
        name=template_data.name,
        description=template_data.description,
        owner_id=current_user.id,
        is_public=template_data.is_public,
        task_statuses=task_statuses_json,
        custom_fields=custom_fields_json,
        default_security_level=template_data.default_security_level,
    )

    db.add(template)

    # Audit log
    AuditService.log_event(
        db=db,
        event_type="template.create",
        resource_type="project_template",
        action=AuditAction.CREATE,
        user_id=current_user.id,
        resource_id=template.id,
        changes=[{"field": "name", "old_value": None, "new_value": template.name}],
        request_metadata=get_audit_metadata(request),
    )

    db.commit()
    db.refresh(template)

    return template


@router.get("/{template_id}", response_model=ProjectTemplateWithOwner)
async def get_template(
    template_id: str,
    db: Session = Depends(get_db),
    current_user: User = Depends(get_current_user),
):
    """
    Get a project template by ID.
    """
    template = db.query(ProjectTemplate).filter(
        ProjectTemplate.id == template_id,
        ProjectTemplate.is_active == True
    ).first()

    if not template:
        raise HTTPException(
            status_code=status.HTTP_404_NOT_FOUND,
            detail="Template not found",
        )

    if not can_view_template(current_user, template):
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail="Access denied",
        )

    return ProjectTemplateWithOwner(
        id=template.id,
        name=template.name,
        description=template.description,
        is_public=template.is_public,
        task_statuses=template.task_statuses,
        custom_fields=template.custom_fields,
        default_security_level=template.default_security_level,
        owner_id=template.owner_id,
        is_active=template.is_active,
        created_at=template.created_at,
        updated_at=template.updated_at,
        owner_name=template.owner.name if template.owner else None,
    )


@router.patch("/{template_id}", response_model=ProjectTemplateResponse)
async def update_template(
    template_id: str,
    template_data: ProjectTemplateUpdate,
    request: Request,
    db: Session = Depends(get_db),
    current_user: User = Depends(get_current_user),
):
    """
    Update a project template.

    Only the template owner or system admin can update a template.
    """
    template = db.query(ProjectTemplate).filter(
        ProjectTemplate.id == template_id,
        ProjectTemplate.is_active == True
    ).first()

    if not template:
        raise HTTPException(
            status_code=status.HTTP_404_NOT_FOUND,
            detail="Template not found",
        )

    if not can_edit_template(current_user, template):
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail="Only template owner can update",
        )

    # Capture old values for audit
    old_values = {
        "name": template.name,
        "description": template.description,
        "is_public": template.is_public,
    }

    # Update fields
    update_data = template_data.model_dump(exclude_unset=True)

    # Convert Pydantic models to dict for JSON storage
    if "task_statuses" in update_data and update_data["task_statuses"]:
        update_data["task_statuses"] = [ts.model_dump() if hasattr(ts, 'model_dump') else ts for ts in update_data["task_statuses"]]

    if "custom_fields" in update_data and update_data["custom_fields"]:
        update_data["custom_fields"] = [cf.model_dump() if hasattr(cf, 'model_dump') else cf for cf in update_data["custom_fields"]]

    for field, value in update_data.items():
        setattr(template, field, value)

    # Log changes
    new_values = {
        "name": template.name,
        "description": template.description,
        "is_public": template.is_public,
    }

    changes = AuditService.detect_changes(old_values, new_values)
    if changes:
        AuditService.log_event(
            db=db,
            event_type="template.update",
            resource_type="project_template",
            action=AuditAction.UPDATE,
            user_id=current_user.id,
            resource_id=template.id,
            changes=changes,
            request_metadata=get_audit_metadata(request),
        )

    db.commit()
    db.refresh(template)

    return template


@router.delete("/{template_id}", status_code=status.HTTP_204_NO_CONTENT)
async def delete_template(
    template_id: str,
    request: Request,
    db: Session = Depends(get_db),
    current_user: User = Depends(get_current_user),
):
    """
    Delete a project template (soft delete).

    Only the template owner or system admin can delete a template.
    """
    template = db.query(ProjectTemplate).filter(
        ProjectTemplate.id == template_id,
        ProjectTemplate.is_active == True
    ).first()

    if not template:
        raise HTTPException(
            status_code=status.HTTP_404_NOT_FOUND,
            detail="Template not found",
        )

    if not can_edit_template(current_user, template):
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail="Only template owner can delete",
        )

    # Audit log
    AuditService.log_event(
        db=db,
        event_type="template.delete",
        resource_type="project_template",
        action=AuditAction.DELETE,
        user_id=current_user.id,
        resource_id=template.id,
        changes=[{"field": "is_active", "old_value": True, "new_value": False}],
        request_metadata=get_audit_metadata(request),
    )

    # Soft delete
    template.is_active = False
    db.commit()

    return None


@router.post("/create-project", response_model=CreateProjectFromTemplateResponse, status_code=status.HTTP_201_CREATED)
async def create_project_from_template(
    data: CreateProjectFromTemplateRequest,
    request: Request,
    db: Session = Depends(get_db),
    current_user: User = Depends(get_current_user),
):
    """
    Create a new project from a template.

    This will:
    1. Create a new project with the specified title and description
    2. Copy all task statuses from the template
    3. Copy all custom field definitions from the template
    """
    # Get the template
    template = db.query(ProjectTemplate).filter(
        ProjectTemplate.id == data.template_id,
        ProjectTemplate.is_active == True
    ).first()

    if not template:
        raise HTTPException(
            status_code=status.HTTP_404_NOT_FOUND,
            detail="Template not found",
        )

    if not can_view_template(current_user, template):
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail="Access denied to template",
        )

    # Check space access
    space = db.query(Space).filter(
        Space.id == data.space_id,
        Space.is_active == True
    ).first()

    if not space:
        raise HTTPException(
            status_code=status.HTTP_404_NOT_FOUND,
            detail="Space not found",
        )

    if not check_space_access(current_user, space):
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail="Access denied to space",
        )

    # Create the project
    project = Project(
        id=str(uuid.uuid4()),
        space_id=data.space_id,
        title=data.title,
        description=data.description,
        owner_id=current_user.id,
        security_level=template.default_security_level or "department",
        department_id=data.department_id or current_user.department_id,
    )

    db.add(project)
    db.flush()  # Get project ID

    # Copy task statuses from template
    task_statuses_created = 0
    if template.task_statuses:
        for status_data in template.task_statuses:
            task_status = TaskStatus(
                id=str(uuid.uuid4()),
                project_id=project.id,
                name=status_data.get("name", "Unnamed"),
                color=status_data.get("color", "#808080"),
                position=status_data.get("position", 0),
                is_done=status_data.get("is_done", False),
            )
            db.add(task_status)
            task_statuses_created += 1

    # Copy custom fields from template
    custom_fields_created = 0
    if template.custom_fields:
        for field_data in template.custom_fields:
            custom_field = CustomField(
                id=str(uuid.uuid4()),
                project_id=project.id,
                name=field_data.get("name", "Unnamed"),
                field_type=field_data.get("field_type", "text"),
                options=field_data.get("options"),
                formula=field_data.get("formula"),
                is_required=field_data.get("is_required", False),
                position=field_data.get("position", 0),
            )
            db.add(custom_field)
            custom_fields_created += 1

    # Audit log
    AuditService.log_event(
        db=db,
        event_type="project.create_from_template",
        resource_type="project",
        action=AuditAction.CREATE,
        user_id=current_user.id,
        resource_id=project.id,
        changes=[
            {"field": "title", "old_value": None, "new_value": project.title},
            {"field": "template_id", "old_value": None, "new_value": template.id},
        ],
        request_metadata=get_audit_metadata(request),
    )

    db.commit()

    return CreateProjectFromTemplateResponse(
        id=project.id,
        title=project.title,
        template_id=template.id,
        template_name=template.name,
        task_statuses_created=task_statuses_created,
        custom_fields_created=custom_fields_created,
    )