from __future__ import annotations

from typing import List, Optional

import aiosqlite
from fastapi import APIRouter, Depends, Query, Response

import persons
from common import Page
from main import get_db

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


@router.get(
    "",
    operation_id="listPersons",
    response_model=Page[persons.Person],
    summary="List persons (paginated)",
    responses={
        200: {
            "description": "A page of persons",
            "content": {
                "application/json": {
                    "example": {
                        "items": [
                            {
                                "id": 1,
                                "name": "Ada Lovelace"
                            }
                        ],
                        "nextCursor": "2",
                        "prevCursor": "0",
                        "total": 1
                    }
                }
            },
        }
    },
)
async def list_persons(
    q: Optional[str] = Query(
        default=None,
        description="Optional case-insensitive name filter (applied after page read; may be pushed to SQL in the future).",
    ),
    cursor: Optional[str] = Query(
        default=None,
        description="Opaque cursor for pagination. Pass the value returned in nextCursor to fetch the next page.",
    ),
    limit: int = Query(
        50,
        ge=1,
        le=200,
        description="Maximum number of items to return (1-200).",
    ),
    conn: aiosqlite.Connection = Depends(get_db),
) -> Page[persons.Person]:
    # v1: DB-backed pagination
    last_id = None
    if cursor:
        try:
            last_id = int(cursor)
        except ValueError:
            last_id = None

    fetch_limit = limit + 1
    paged: List[persons.Person] = []
    if q:
        async for p in persons.search_by_name_paged(conn, q, last_id, fetch_limit):
            paged.append(p)
    else:
        async for p in persons.get_all_paged(conn, last_id, fetch_limit):
            paged.append(p)

    has_more = len(paged) > limit
    items = paged[:limit]
    next_cursor = str(items[-1].id) if has_more and items else None
    # Compute prevCursor via DB helper
    prev_cursor: Optional[str] = None
    if items:
        first_id = items[0].id
        prev_cursor = await persons.compute_prev_cursor(conn, first_id, limit, q)
    total = await (persons.count_by_name(conn, q) if q else persons.count_all(conn))
    return Page(items=items, nextCursor=next_cursor, prevCursor=prev_cursor, total=total)


@router.post(
    "",
    operation_id="createPerson",
    summary="Create a person",
    response_model=persons.Person,
)
async def create_person(
    person: persons.Person, response: Response, conn: aiosqlite.Connection = Depends(get_db)
) -> persons.Person:
    await persons.insert_person(conn, person)
    response.headers["Location"] = f"/api/v1/persons/{person.id}"
    return person