"""Printer CRUD API — POST /printers, DELETE /printers/{id}, PATCH /printers/{id}."""
from __future__ import annotations

from fastapi import APIRouter, Form, Request
from fastapi.responses import HTMLResponse, RedirectResponse, Response
from peewee import JOIN

from imptune.api.pages import build_driver_data, group_printers_by_client
from imptune.db.models import Client, Driver, Printer
from imptune.templating import templates

router = APIRouter(prefix="/printers")

_VALID_DUPLEX = {"OneSided", "LongEdge", "ShortEdge"}
_VALID_PAPER = {"A4", "Letter", "Legal"}


def _error_response(message: str, status_code: int = 400) -> HTMLResponse:
    """Return an HTMX-friendly error fragment swapped into #printer-list."""
    return HTMLResponse(
        content=f"<div id='printer-list' class='error'><p>{message}</p></div>",
        status_code=status_code,
    )


def _validate_fields(
    name: str, ip_address: str, port_name: str, duplex_mode: str, paper_size: str
) -> HTMLResponse | None:
    """Shared field validation for create and update — None when everything is valid."""
    if not name:
        return _error_response("Printer name is required.")
    if not ip_address:
        return _error_response("IP address is required.")
    if not port_name:
        return _error_response("Port name is required.")
    if duplex_mode not in _VALID_DUPLEX:
        return _error_response(f"Invalid duplex mode: {duplex_mode}.")
    if paper_size not in _VALID_PAPER:
        return _error_response(f"Invalid paper size: {paper_size}.")
    return None


def _resolve_client(raw: str, owner) -> tuple[int | None, HTMLResponse | None]:
    """Resolve the optional client_id form field to an owned Client id.

    The form value is attacker-controlled text: a non-numeric value used to
    raise ValueError (HTTP 500) instead of the 400 the HTMX form can render.
    """
    raw = raw.strip()
    if not raw:
        return None, None
    try:
        client_fk = int(raw)
    except ValueError:
        return None, _error_response(f"Invalid client id: {raw}.")
    if Client.get_or_none((Client.id == client_fk) & (Client.owner == owner)) is None:
        return None, _error_response(f"Client {client_fk} not found.", status_code=404)
    return client_fk, None


def _resolve_driver(raw: str) -> tuple[int | None, HTMLResponse | None]:
    """Resolve the optional driver_id form field. Drivers are global/shared.

    Existence is checked here because an unknown id otherwise reaches SQLite as
    a FOREIGN KEY violation — an IntegrityError (HTTP 500) rather than a 404.
    """
    raw = raw.strip()
    if not raw:
        return None, None
    try:
        driver_fk = int(raw)
    except ValueError:
        return None, _error_response(f"Invalid driver id: {raw}.")
    if Driver.get_or_none(Driver.id == driver_fk) is None:
        return None, _error_response(f"Driver {driver_fk} not found.", status_code=404)
    return driver_fk, None


def _render_printer_list(request: Request) -> HTMLResponse:
    """Query printers with LEFT JOIN on client and render grouped partial."""
    owner = request.state.owner
    query = (
        Printer.select(Printer, Client)
        .join(Client, JOIN.LEFT_OUTER)
        .where(Printer.owner == owner)
        .order_by(Client.name, Printer.name)
    )
    grouped = group_printers_by_client(query)

    clients = list(Client.select().where(Client.owner == owner).order_by(Client.name))
    all_drivers = Driver.select().order_by(Driver.uploaded_at.desc())
    driver_data = build_driver_data(all_drivers)

    return templates.TemplateResponse(
        request=request,
        name="partials/printer_list.html",
        context={"grouped": grouped, "clients": clients, "driver_data": driver_data},
    )


@router.post("", response_class=HTMLResponse)
def create_printer(
    request: Request,
    name: str = Form(...),
    ip_address: str = Form(...),
    port_name: str = Form(...),
    duplex_mode: str = Form("OneSided"),
    color_mode: str = Form(""),
    paper_size: str = Form("A4"),
    collate: str = Form(""),
    client_id: str = Form(""),
    driver_id: str = Form(""),
) -> Response:
    """Create a new printer configuration.

    Redirects to /printers on success; returns an inline HTMX error fragment
    (400/404) on validation failure.
    """
    name = name.strip()
    ip_address = ip_address.strip()
    port_name = port_name.strip()

    invalid = _validate_fields(name, ip_address, port_name, duplex_mode, paper_size)
    if invalid is not None:
        return invalid

    owner = request.state.owner

    # Resolve optional FK IDs — client must belong to this owner
    client_fk, error = _resolve_client(client_id, owner)
    if error is not None:
        return error
    driver_fk, error = _resolve_driver(driver_id)
    if error is not None:
        return error

    Printer.create(
        name=name,
        ip_address=ip_address,
        port_name=port_name,
        duplex_mode=duplex_mode,
        # HTML checkbox convention: "on" = True, absent/empty = False
        color_mode=color_mode == "on",
        paper_size=paper_size,
        collate=collate == "on",
        owner=owner,
        client=client_fk,
        driver=driver_fk,
    )

    return RedirectResponse(url="/printers", status_code=303)


@router.delete("/{printer_id}", response_class=HTMLResponse)
def delete_printer(request: Request, printer_id: int) -> HTMLResponse:
    """Delete a printer by ID. Returns updated printer list partial."""
    deleted = (
        Printer.delete()
        .where((Printer.id == printer_id) & (Printer.owner == request.state.owner))
        .execute()
    )
    if not deleted:
        return _error_response(f"Printer {printer_id} not found.", status_code=404)

    return _render_printer_list(request)


@router.patch("/{printer_id}", response_class=HTMLResponse)
def update_printer(
    request: Request,
    printer_id: int,
    name: str = Form(...),
    ip_address: str = Form(""),
    port_name: str = Form(""),
    duplex_mode: str = Form("OneSided"),
    color_mode: str = Form(""),
    paper_size: str = Form("A4"),
    collate: str = Form(""),
    client_id: str = Form(""),
    driver_id: str = Form(""),
) -> HTMLResponse:
    """Update an existing printer configuration in-place."""
    from datetime import UTC, datetime

    owner = request.state.owner
    printer = Printer.get_or_none((Printer.id == printer_id) & (Printer.owner == owner))
    if printer is None:
        return _error_response(f"Printer {printer_id} not found.", status_code=404)

    name = name.strip()
    ip_address = ip_address.strip() or printer.ip_address
    port_name = port_name.strip() or printer.port_name

    invalid = _validate_fields(name, ip_address, port_name, duplex_mode, paper_size)
    if invalid is not None:
        return invalid

    client_fk, error = _resolve_client(client_id, owner)
    if error is not None:
        return error
    driver_fk, error = _resolve_driver(driver_id)
    if error is not None:
        return error

    printer.name = name
    printer.ip_address = ip_address
    printer.port_name = port_name
    printer.duplex_mode = duplex_mode
    printer.color_mode = color_mode == "on"
    printer.paper_size = paper_size
    printer.collate = collate == "on"
    printer.client = client_fk
    printer.driver = driver_fk
    printer.updated_at = datetime.now(UTC).replace(tzinfo=None)
    printer.save()

    return _render_printer_list(request)