"""Ticket CRUD endpoints, photo uploads, SLA checks, and category listing."""

from __future__ import annotations

import logging
import uuid
from datetime import datetime
from pathlib import Path
from typing import Annotated

from fastapi import APIRouter, Depends, HTTPException, Query, UploadFile, status
from sqlalchemy import select
from sqlalchemy.ext.asyncio import AsyncSession
from app.core.config import settings
from app.core.database import get_db
from app.core.security import get_current_user, require_roles
from app.models.category import Category
from app.models.ticket import Ticket, TicketPhoto
from app.models.unit import Unit
from app.models.user import User
from app.schemas.ticket import (
    CategoryOut,
    CategoryTreeOut,
    SLAStatusOut,
    TicketBrief,
    TicketCreate,
    TicketListResponse,
    TicketOut,
    TicketPhotoOut,
    TicketUpdate,
    UnitOut,
)
from app.services import ticket as ticket_service
from app.services.sla import get_sla_status

logger = logging.getLogger(__name__)

router = APIRouter(prefix="/api/tickets", tags=["tickets"])

# Ensure uploads directory exists
UPLOADS_DIR = settings.BASE_DIR / "uploads"
UPLOADS_DIR.mkdir(parents=True, exist_ok=True)


# ── Units ──────────────────────────────────────────────────────────
@router.get("/units", response_model=list[UnitOut])
async def list_units(
    db: Annotated[AsyncSession, Depends(get_db)],
    property_filter: str | None = Query(None, alias="property"),
    building: str | None = Query(None),
) -> list[Unit]:
    """List all units, optionally filtered by property (East/West) and building."""
    query = select(Unit).order_by(Unit.apartment_code)
    if property_filter:
        query = query.where(Unit.property == property_filter)
    if building:
        query = query.where(Unit.building == building)
    result = await db.execute(query)
    return list(result.scalars().all())


@router.get("/units/grouped")
async def list_units_grouped(
    db: Annotated[AsyncSession, Depends(get_db)],
    property_filter: str | None = Query(None, alias="property"),
) -> dict[str, dict[str, list[dict]]]:
    """Return units grouped as ``{property: {building: [units]}}``.

    Additive convenience variant of ``GET /api/tickets/units`` for the
    Property → Building → Apartment cascade. Units without a building are
    grouped under an empty-string key.
    """
    query = select(Unit).order_by(Unit.property, Unit.building, Unit.apartment_code)
    if property_filter:
        query = query.where(Unit.property == property_filter)
    result = await db.execute(query)
    grouped: dict[str, dict[str, list[dict]]] = {}
    for unit in result.scalars().all():
        prop = unit.property or ""
        building = unit.building or ""
        grouped.setdefault(prop, {}).setdefault(building, []).append(
            UnitOut.model_validate(unit).model_dump()
        )
    return grouped


# ── Categories ──────────────────────────────────────────────────────
async def _build_category_tree(db: AsyncSession, parent_id: int | None = None, include_hidden: bool = False) -> list[CategoryTreeOut]:
    """Build a nested category tree."""
    query = select(Category).where(Category.parent_id == parent_id).order_by(Category.name)
    if not include_hidden:
        query = query.where(Category.show_in_form.is_(True))
    result = await db.execute(query)
    categories = result.scalars().all()
    tree = []
    for cat in categories:
        children = await _build_category_tree(db, cat.id, include_hidden=include_hidden)
        tree.append(CategoryTreeOut(
            id=cat.id,
            type=cat.type,
            name=cat.name,
            parent_id=cat.parent_id,
            sla_urgency=cat.sla_urgency,
            show_in_form=cat.show_in_form,
            children=children,
        ))
    return tree


@router.get("/categories", response_model=list[CategoryTreeOut])
async def list_categories(
    db: Annotated[AsyncSession, Depends(get_db)],
    type_filter: str | None = Query(None, alias="type"),
    include_hidden: bool = Query(False, description="Include alert-only categories (e.g. Gas Leak)"),
) -> list[CategoryTreeOut]:
    """Return the full category tree, optionally filtered by type (maintenance, cs, emergency).

    Alert-only categories (``show_in_form=False``, e.g. Gas Leak) are excluded
    unless ``include_hidden=true`` is passed (used by the emergency quick path).
    """
    if type_filter:
        # Return flat list of top-level categories of the given type
        query = select(Category).where(Category.parent_id.is_(None), Category.type == type_filter).order_by(Category.name)
        if not include_hidden:
            query = query.where(Category.show_in_form.is_(True))
        result = await db.execute(query)
        parents = result.scalars().all()
        tree = []
        for parent in parents:
            children_query = select(Category).where(Category.parent_id == parent.id).order_by(Category.name)
            if not include_hidden:
                children_query = children_query.where(Category.show_in_form.is_(True))
            children_result = await db.execute(children_query)
            children = children_result.scalars().all()
            tree.append(CategoryTreeOut(
                id=parent.id,
                type=parent.type,
                name=parent.name,
                parent_id=parent.parent_id,
                sla_urgency=parent.sla_urgency,
                show_in_form=parent.show_in_form,
                children=[CategoryOut.model_validate(c) for c in children],
            ))
        return tree
    return await _build_category_tree(db, include_hidden=include_hidden)


@router.get("/categories/flat", response_model=list[CategoryOut])
async def list_categories_flat(
    db: Annotated[AsyncSession, Depends(get_db)],
    type_filter: str | None = Query(None, alias="type"),
    include_hidden: bool = Query(False, description="Include alert-only categories (e.g. Gas Leak)"),
) -> list[CategoryOut]:
    """Return a flat list of all categories (no nesting), optionally filtered by type.

    Alert-only categories are excluded by default; children of alert-only parents
    are excluded too so no orphaned picker entries leak through.
    """
    query = select(Category).order_by(Category.type, Category.name)
    if type_filter:
        query = query.where(Category.type == type_filter)
    result = await db.execute(query)
    categories = result.scalars().all()
    if include_hidden:
        return [CategoryOut.model_validate(c) for c in categories]
    # Exclude alert-only categories and any children whose parent is alert-only.
    hidden_ids = {
        c.id
        for c in categories
        if not c.show_in_form and c.parent_id is None
    }
    visible = [
        c
        for c in categories
        if c.show_in_form and (c.parent_id is None or c.parent_id not in hidden_ids)
    ]
    return [CategoryOut.model_validate(c) for c in visible]


# ── Ticket CRUD ──────────────────────────────────────────────────────
@router.post("", response_model=TicketOut, status_code=status.HTTP_201_CREATED)
async def create_ticket(
    body: TicketCreate,
    db: Annotated[AsyncSession, Depends(get_db)],
    current_user: Annotated[User, Depends(get_current_user)],
) -> Ticket:
    """Create a new ticket. Auto-generates ticket number PAV-YYYY-NNNNN."""
    ticket = await ticket_service.create_ticket(db, body.model_dump(exclude_none=True), user=current_user)
    # Reload with relationships
    ticket = await ticket_service.get_ticket(db, ticket.id)
    sla = await get_sla_status(ticket)
    ticket.sla_status = sla  # type: ignore[attr-defined]
    return ticket


@router.get("", response_model=TicketListResponse)
async def list_tickets(
    db: Annotated[AsyncSession, Depends(get_db)],
    page: int = Query(1, ge=1),
    page_size: int = Query(50, ge=1, le=200),
    status: str | None = Query(None),
    priority: str | None = Query(None),
    property: str | None = Query(None),
    building: str | None = Query(None),
    unit_id: int | None = Query(None),
    category_id: int | None = Query(None),
    assigned_to: int | None = Query(None),
    date_from: datetime | None = Query(None),
    date_to: datetime | None = Query(None),
) -> TicketListResponse:
    """List tickets with optional filtering and pagination."""
    tickets, total = await ticket_service.list_tickets(
        db,
        status_filter=status,
        priority_filter=priority,
        property_filter=property,
        building_filter=building,
        unit_id=unit_id,
        category_id=category_id,
        assigned_to=assigned_to,
        date_from=date_from,
        date_to=date_to,
        page=page,
        page_size=page_size,
    )
    items = [TicketBrief.model_validate(t) for t in tickets]
    return TicketListResponse(items=items, total=total, page=page, page_size=page_size)


@router.get("/{ticket_id}/transitions")
async def get_ticket_transitions(
    ticket_id: int,
    db: Annotated[AsyncSession, Depends(get_db)],
) -> dict:
    """Return the valid next statuses for a ticket's current status."""
    ticket = await ticket_service.get_ticket(db, ticket_id)
    return {
        "current_status": ticket.status,
        "transitions": ticket_service.VALID_TRANSITIONS.get(ticket.status, []),
    }


@router.get("/{ticket_id}", response_model=TicketOut)
async def get_ticket(
    ticket_id: int,
    db: Annotated[AsyncSession, Depends(get_db)],
) -> Ticket:
    """Get a single ticket by ID with full details, timeline, photos, and SLA status."""
    ticket = await ticket_service.get_ticket(db, ticket_id)
    sla = await get_sla_status(ticket)
    ticket.sla_status = sla  # type: ignore[attr-defined]
    return ticket


@router.patch("/{ticket_id}", response_model=TicketOut)
async def update_ticket(
    ticket_id: int,
    body: TicketUpdate,
    db: Annotated[AsyncSession, Depends(get_db)],
    current_user: Annotated[User, Depends(get_current_user)],
) -> Ticket:
    """Update a ticket. Validates status transitions and logs timeline."""
    ticket = await ticket_service.update_ticket(db, ticket_id, body.model_dump(exclude_none=True), user=current_user)
    sla = await get_sla_status(ticket)
    ticket.sla_status = sla  # type: ignore[attr-defined]
    return ticket


@router.delete("/{ticket_id}", status_code=status.HTTP_204_NO_CONTENT)
async def delete_ticket(
    ticket_id: int,
    db: Annotated[AsyncSession, Depends(get_db)],
    current_user: Annotated[User, Depends(require_roles("Admin/Jerome", "Admin/Wahab"))],
) -> None:
    """Delete a ticket and its children (timeline, photos, escalations).

    Admin-only: intended for removing test/scratch tickets from the demo
    database, never for routine workflow use.
    """
    ticket = await ticket_service.delete_ticket(db, ticket_id)
    # Remove orphaned photo files from disk after the DB rows are gone.
    for photo in ticket.photos:
        if photo.photo_url:
            name = photo.photo_url.rsplit("/", 1)[-1]
            try:
                (UPLOADS_DIR / name).unlink(missing_ok=True)
            except OSError:
                logger.warning(
                    "Could not remove orphaned photo file %s for ticket %s",
                    name,
                    ticket_id,
                )


# ── Status Transitions (convenience endpoints) ───────────────────────
@router.post("/{ticket_id}/status", response_model=TicketOut)
async def change_ticket_status(
    ticket_id: int,
    body: dict,
    db: Annotated[AsyncSession, Depends(get_db)],
    current_user: Annotated[User, Depends(get_current_user)],
) -> Ticket:
    """Change a ticket's status with optional note.

    Request body:
    ```json
    {"status": "Logged", "note": "Verified with customer"}
    ```
    """
    status_val = body.get("status")
    if not status_val:
        raise HTTPException(status_code=status.HTTP_400_BAD_REQUEST, detail="status is required")
    update_data = {"status": status_val}
    if "note" in body:
        update_data["note"] = body["note"]

    ticket = await ticket_service.update_ticket(db, ticket_id, update_data, user=current_user)
    sla = await get_sla_status(ticket)
    ticket.sla_status = sla  # type: ignore[attr-defined]
    return ticket


# ── SLA ──────────────────────────────────────────────────────────────
@router.get("/{ticket_id}/sla", response_model=SLAStatusOut)
async def check_sla(
    ticket_id: int,
    db: Annotated[AsyncSession, Depends(get_db)],
) -> dict:
    """Check SLA status for a ticket — response deadline, resolution deadline, breach flags."""
    ticket = await ticket_service.get_ticket(db, ticket_id)
    return await get_sla_status(ticket)


# ── Photo Uploads ────────────────────────────────────────────────────
ALLOWED_EXTENSIONS = {".jpg", ".jpeg", ".png", ".gif", ".webp"}
ALLOWED_MIME_TYPES = {"image/jpeg", "image/png", "image/gif", "image/webp"}


@router.post("/{ticket_id}/photos", response_model=list[TicketPhotoOut], status_code=status.HTTP_201_CREATED)
async def upload_photos(
    ticket_id: int,
    db: Annotated[AsyncSession, Depends(get_db)],
    current_user: Annotated[User, Depends(get_current_user)],
    files: list[UploadFile],
    is_before: bool = True,
) -> list[TicketPhoto]:
    """Upload photos for a ticket (before/after). Stores files under uploads/."""
    # Verify ticket exists
    await ticket_service.get_ticket(db, ticket_id)

    # Validate all files before any write operations
    for file in files:
        if file.content_type not in ALLOWED_MIME_TYPES:
            raise HTTPException(
                status_code=status.HTTP_400_BAD_REQUEST,
                detail=f"Unsupported content type '{file.content_type}'. Allowed: image/jpeg, image/png, image/gif, image/webp",
            )
        ext = Path(file.filename or "photo.jpg").suffix.lower() if file.filename else ".jpg"
        if ext not in ALLOWED_EXTENSIONS:
            raise HTTPException(
                status_code=status.HTTP_400_BAD_REQUEST,
                detail=f"Unsupported file extension '{ext}'. Allowed: .jpg, .jpeg, .png, .gif, .webp",
            )

    created_photos: list[TicketPhoto] = []
    file_data: list[tuple[Path, bytes]] = []
    for file in files:
        # Generate unique filename
        ext = Path(file.filename or "photo.jpg").suffix.lower() if file.filename else ".jpg"
        unique_name = f"{uuid.uuid4().hex}{ext}"
        file_path = UPLOADS_DIR / unique_name

        content = await file.read()
        file_data.append((file_path, content))

        # Database record (no file write yet)
        photo = TicketPhoto(
            ticket_id=ticket_id,
            photo_url=f"/uploads/{unique_name}",
            is_before=is_before,
        )
        db.add(photo)
        created_photos.append(photo)

    await db.flush()
    for p in created_photos:
        await db.refresh(p)

    # Write files to disk only after successful DB flush
    for file_path, content in file_data:
        file_path.write_bytes(content)

    return created_photos


@router.get("/{ticket_id}/photos", response_model=list[TicketPhotoOut])
async def list_photos(
    ticket_id: int,
    db: Annotated[AsyncSession, Depends(get_db)],
) -> list[TicketPhoto]:
    """List all photos for a ticket."""
    await ticket_service.get_ticket(db, ticket_id)
    result = await db.execute(
        select(TicketPhoto)
        .where(TicketPhoto.ticket_id == ticket_id)
        .order_by(TicketPhoto.id)
    )
    return list(result.scalars().all())