import pandas as pd
import geopandas as gpd

from src.utils import PERIODS, CURRENT_YEAR, YEAR_FROM


def filter_by_period(gdf: gpd.GeoDataFrame, start: int, end: int) -> gpd.GeoDataFrame:
    return gdf[gdf["year"].between(start, end)].copy()


def filter_current_year(gdf: gpd.GeoDataFrame) -> gpd.GeoDataFrame:
    return gdf[gdf["year"] == CURRENT_YEAR].copy()


def compute_annual_trend(df: pd.DataFrame, year_from: int = YEAR_FROM,
                         year_to: int = CURRENT_YEAR) -> pd.DataFrame:
    if df.empty or "year" not in df.columns:
        years = range(year_from, year_to + 1)
        return pd.DataFrame({"year": list(years), "count": [0] * len(list(years))})

    counts = df.dropna(subset=["year"]).groupby("year").size().reset_index(name="count")
    all_years = pd.DataFrame({"year": range(year_from, year_to + 1)})
    trend = all_years.merge(counts, on="year", how="left").fillna(0)
    trend["count"] = trend["count"].astype(int)
    trend["year"] = trend["year"].astype(int)
    return trend


def period_label_for_year(year: int) -> str:
    for start, end, label in PERIODS:
        if start <= year <= end:
            return label
    if year == CURRENT_YEAR:
        return str(CURRENT_YEAR)
    return str(year)