import csv

from django.contrib.auth import get_user_model
from django.db.models import Q
from django.http import HttpResponse
from django.utils import timezone
from ninja import Router

from apps.accounts.api import require_permission
from apps.audit.models import OperationAuditLog
from apps.tickets.models import Ticket, TicketAttachment, TicketComment, TicketEvent
from apps.tickets.schemas import (
    TicketAttachmentIn,
    TicketAttachmentOut,
    TicketCommentIn,
    TicketCommentOut,
    TicketIn,
    TicketOut,
    TicketStatusIn,
    TicketUpdateIn,
)
from apps.tickets.services import transition_ticket

router = Router(tags=["tickets"])


def next_ticket_no() -> str:
    prefix = timezone.localdate().strftime("TK%Y%m%d")
    count = Ticket.objects.filter(ticket_no__startswith=prefix).count() + 1
    return f"{prefix}{count:04d}"


@router.post("", response=TicketOut)
def create_ticket(request, payload: TicketIn):
    require_permission(request, "ticket.create")
    assignee = None
    if payload.assignee_id:
        assignee = get_user_model().objects.filter(id=payload.assignee_id).first()
    ticket = Ticket.objects.create(
        ticket_no=next_ticket_no(),
        title=payload.title,
        description=payload.description,
        priority=payload.priority,
        impact_scope=payload.impact_scope,
        environment=payload.environment,
        related_system=payload.related_system,
        assignee=assignee,
        created_by=request.user if request.user.is_authenticated else None,
    )
    TicketEvent.objects.create(
        ticket=ticket,
        event_type="created",
        to_value={"status": ticket.status},
    )
    return ticket


@router.get("", response=list[TicketOut])
def list_tickets(request, status: str | None = None, q: str | None = None):
    require_permission(request, "ticket.view")
    queryset = Ticket.objects.all()
    if status:
        queryset = queryset.filter(status=status)
    if q:
        queryset = queryset.filter(Q(ticket_no__icontains=q) | Q(title__icontains=q))
    return queryset[:100]


@router.get("/export")
def export_tickets(request):
    require_permission(request, "ticket.export")
    response = HttpResponse(content_type="text/csv")
    response["Content-Disposition"] = 'attachment; filename="tickets.csv"'
    writer = csv.writer(response)
    writer.writerow(["ticket_no", "title", "status", "priority", "created_at"])
    for ticket in Ticket.objects.all().order_by("ticket_no"):
        writer.writerow(
            [
                ticket.ticket_no,
                ticket.title,
                ticket.status,
                ticket.priority,
                ticket.created_at.isoformat(),
            ]
        )
    OperationAuditLog.objects.create(
        user=request.user if request.user.is_authenticated else None,
        module="tickets",
        action="export",
        target_type="ticket",
        result="success",
        request_snapshot={},
    )
    return response


@router.get("/{ticket_id}", response=TicketOut)
def get_ticket(request, ticket_id: int):
    require_permission(request, "ticket.view")
    return Ticket.objects.get(id=ticket_id)


@router.patch("/{ticket_id}", response=TicketOut)
def update_ticket(request, ticket_id: int, payload: TicketUpdateIn):
    require_permission(request, "ticket.edit")
    ticket = Ticket.objects.get(id=ticket_id)
    before = {
        "title": ticket.title,
        "priority": ticket.priority,
        "impact_scope": ticket.impact_scope,
        "environment": ticket.environment,
        "related_system": ticket.related_system,
    }
    for field, value in payload.dict(exclude_unset=True).items():
        if field == "assignee_id":
            user = get_user_model().objects.filter(id=value).first() if value else None
            ticket.assignee = user
        else:
            setattr(ticket, field, value)
    ticket.save()
    TicketEvent.objects.create(
        ticket=ticket,
        event_type="updated",
        from_value=before,
        to_value=payload.dict(exclude_unset=True),
        operator=request.user if request.user.is_authenticated else None,
    )
    return ticket


@router.post("/{ticket_id}/status", response=TicketOut)
def update_ticket_status(request, ticket_id: int, payload: TicketStatusIn):
    require_permission(request, "ticket.edit")
    ticket = Ticket.objects.get(id=ticket_id)
    return transition_ticket(
        ticket,
        payload.status,
        payload.remark,
        request.user if request.user.is_authenticated else None,
    )


@router.post("/{ticket_id}/comments", response=TicketCommentOut)
def add_ticket_comment(request, ticket_id: int, payload: TicketCommentIn):
    require_permission(request, "ticket.edit")
    ticket = Ticket.objects.get(id=ticket_id)
    comment = TicketComment.objects.create(
        ticket=ticket,
        content=payload.content,
        comment_type=payload.comment_type,
        visibility=payload.visibility,
        created_by=request.user if request.user.is_authenticated else None,
    )
    TicketEvent.objects.create(
        ticket=ticket,
        event_type="commented",
        to_value={"comment_id": comment.id, "comment_type": comment.comment_type},
        operator=request.user if request.user.is_authenticated else None,
    )
    return comment


@router.post("/{ticket_id}/attachments", response=TicketAttachmentOut)
def add_ticket_attachment(request, ticket_id: int, payload: TicketAttachmentIn):
    require_permission(request, "ticket.edit")
    ticket = Ticket.objects.get(id=ticket_id)
    attachment = TicketAttachment.objects.create(ticket=ticket, **payload.dict())
    TicketEvent.objects.create(
        ticket=ticket,
        event_type="attachment_added",
        to_value={"attachment_id": attachment.id, "file_name": attachment.file_name},
    )
    return attachment