from collections import defaultdict
from datetime import datetime, MINYEAR
from typing import Optional

from fastapi import APIRouter, Depends, Request
from fastapi.responses import HTMLResponse
from sqlalchemy.sql.expression import func

from app.sql import models

from ..templates import jinja_templates
from ..sql.database import get_db

api_router = APIRouter(prefix="/stats", tags=["stats"])
html_router = APIRouter(
    prefix="/stats", include_in_schema=False, default_response_class=HTMLResponse
)


@api_router.get("/graph")
def stats_graph_api(
    deck_ids: Optional[str] = None,
    normalize_final_datapoint: bool = False,
    db=Depends(get_db),
):
    # TODO - parallelize? (Probably not worth it :P )

    # SO Answer on row_number: https://stackoverflow.com/a/38160409/1040915
    # Docs: https://docs.sqlalchemy.org/en/20/core/sqlelement.html#sqlalchemy.sql.expression.over
    row_number_column = (
        func.row_number()
        .over(
            partition_by=[models.Deck.name, models.Game.date],
            order_by=models.EloScore.id.desc(),
        )
        .label("row_number")
    )
    sub_query = (
        db.query(models.Deck.name, models.EloScore.score, models.Game.date)
        .outerjoin(models.EloScore, models.Deck.id == models.EloScore.deck_id)
        .join(models.Game, models.EloScore.after_game_id == models.Game.id)
        .add_column(row_number_column)
    )
    if deck_ids is not None:
        sub_query = sub_query.filter(models.Deck.id.in_(deck_ids.split(",")))

    sub_query = sub_query.subquery()
    query = db.query(sub_query).filter(sub_query.c.row_number == 1)
    results = query.all()

    data_grouped_by_deck = defaultdict(list)
    latest_date_so_far = datetime(MINYEAR, 1, 1, 0, 0, 0, 0)
    for result in results:
        # TODO - how to index results by name instead of tuple-number
        date = result[2]
        latest_date_so_far = max(latest_date_so_far, date)
        data_grouped_by_deck[result[0]].append(
            {"score": result[1], "date": date.strftime("%Y-%m-%d")}
        )

    if normalize_final_datapoint:
        # Add a fake final datapoint to the series for any decks that weren't played in the latest game, so that lines
        # continue all the way to the end of the graph
        latest_date_formatted = latest_date_so_far.strftime("%Y-%m-%d")
        for games in data_grouped_by_deck.values():
            if games[-1]["date"] != latest_date_formatted:
                games.append(
                    {"score": games[-1]["score"], "date": latest_date_formatted}
                )

    return {
        "datasets": [
            {"label": key, "data": data_grouped_by_deck[key]}
            for key in data_grouped_by_deck
        ]
    }


@html_router.get("/graph")
def stats_graph(request: Request, db=Depends(get_db)):
    return jinja_templates.TemplateResponse(request, "stats/graph.html")