from collections import Counter
from datetime import date, timedelta

from fastapi import APIRouter, Depends, Request
from fastapi.templating import Jinja2Templates
from sqlalchemy.orm import Session

from database import get_db
from models import Film
from services.countries import (
    ISO_NUMERIC_TO_COUNTRY_NAME,
    country_name_to_iso_numeric,
    split_country_names,
)
from services.film_people import split_credit_names

router = APIRouter(tags=["stats"])
templates = Jinja2Templates(directory="templates")


def _build_stats_payload(films: list[Film]) -> dict:
    countries = Counter()
    country_codes = Counter()
    directors = Counter()
    star_counts = Counter({0: 0, 1: 0, 2: 0, 3: 0})
    months = Counter()
    days = Counter()
    watched_with = Counter()

    for film in films:
        country_names = split_country_names(film.country)
        countries.update(country_names)
        for country in country_names:
            iso_numeric = country_name_to_iso_numeric(country)
            if iso_numeric is not None:
                country_codes[iso_numeric] += 1

        directors.update(split_credit_names(film.director))

        stars = film.stars if film.stars in {0, 1, 2, 3} else 0
        star_counts[stars] += 1

        if film.date_watched:
            months[film.date_watched.strftime("%Y-%m")] += 1
            days[film.date_watched.isoformat()] += 1

        companions = split_credit_names(film.watched_with)
        if companions:
            watched_with.update(companions)
        else:
            watched_with["solo"] += 1

    total_watched = len(films)
    rewatched = sum(1 for film in films if film.rewatch or film.rewatch_count > 0)

    today = date.today()
    start_day = today - timedelta(days=364)
    trailing_days = []
    cursor = start_day
    while cursor <= today:
        trailing_days.append({"date": cursor.isoformat(), "count": days[cursor.isoformat()]})
        cursor += timedelta(days=1)

    return {
        "scope": {
            "shelf": "diary",
            "requires_date_watched": True,
        },
        "total_watched": total_watched,
        "films_per_country": [
            {"country": country, "count": count}
            for country, count in sorted(countries.items(), key=lambda item: (-item[1], item[0]))
        ],
        "films_per_country_codes": [
            {"code": code, "count": count}
            for code, count in sorted(country_codes.items(), key=lambda item: (-item[1], item[0]))
        ],
        "country_labels_by_code": {
            str(code): ISO_NUMERIC_TO_COUNTRY_NAME.get(code, str(code)) for code in country_codes
        },
        "most_watched_directors": [
            {"director": director, "count": count}
            for director, count in sorted(directors.items(), key=lambda item: (-item[1], item[0]))
        ],
        "star_distribution": [{"stars": stars, "count": star_counts[stars]} for stars in (0, 1, 2, 3)],
        "films_per_month": [
            {"month": month, "count": count}
            for month, count in sorted(months.items())
        ],
        "films_per_day": [
            {"date": watched_date, "count": count}
            for watched_date, count in sorted(days.items())
        ],
        "films_per_day_365": trailing_days,
        "rewatch_rate": {
            "rewatched": rewatched,
            "total_watched": total_watched,
            "rate": round(rewatched / total_watched, 4) if total_watched else 0,
        },
        "watched_with_breakdown": [
            {"watched_with": watched_with_value, "count": count}
            for watched_with_value, count in sorted(watched_with.items(), key=lambda item: (-item[1], item[0]))
        ],
    }


def _diary_films(db: Session) -> list[Film]:
    return (
        db.query(Film)
        .filter(Film.shelf == "diary", Film.date_watched.is_not(None))
        .all()
    )


@router.get("/stats")
def stats_page(request: Request):
    return templates.TemplateResponse(
        request=request,
        name="stats.html",
        context={"request": request, "active_page": "stats"},
    )


@router.get("/stats/data")
def stats_data(db: Session = Depends(get_db)):
    return _build_stats_payload(_diary_films(db))