"""The steps a country's geo import may share with another's."""
import argparse
import collections
import math
import sys
from pathlib import Path

DATA = Path(__file__).resolve().parent.parent / "data"
CACHE = Path(__file__).resolve().parent / "cache"


def parser(doc, country, **own):
    """A parser for the options every country's import takes, plus the script's own: each keyword names one option, with
    "_" standing for "-"."""
    options = {"cache": {"default": str(CACHE)}, "out": {"default": str(DATA / ("geo" + country.lower()))}, "streets_per_locality": {"type": int, "default": 10}, **own}
    p = argparse.ArgumentParser(description=doc.splitlines()[0])
    for name in sorted(options):
        p.add_argument("--" + name.replace("_", "-"), **options[name])
    return p


def directories(args):
    """The cache and out directories of the parsed options, both created."""
    cache, out = Path(args.cache), Path(args.out)
    cache.mkdir(parents=True, exist_ok=True)
    out.mkdir(parents=True, exist_ok=True)
    return cache, out


def centroid(rows):
    """The mean lat and lon of the rows with a point, or None where no row has one."""
    points = [r for r in rows if r["lat"] is not None]
    if not points:
        return None
    return sum(r["lat"] for r in points) / len(points), sum(r["lon"] for r in points) / len(points)


class Nearest:
    """Nearest point by an equirectangular distance, over a degree grid."""

    def __init__(self, points, cell=0.05):
        self.cell = cell
        self.grid = collections.defaultdict(list)
        for lat, lon, value in points:
            self.grid[(int(lat // cell), int(lon // cell))].append((lat, lon, value))

    def find(self, lat, lon):
        ci, cj = int(lat // self.cell), int(lon // self.cell)
        best, best_d = None, math.inf
        ring = 0
        while ring < 400:
            for i in range(ci - ring, ci + ring + 1):
                for j in range(cj - ring, cj + ring + 1):
                    if max(abs(i - ci), abs(j - cj)) != ring:
                        continue
                    for plat, plon, value in self.grid.get((i, j), ()):
                        d = (plat - lat) ** 2 + ((plon - lon) * math.cos(math.radians(lat))) ** 2
                        if d < best_d:
                            best, best_d = value, d
            if best is not None and math.sqrt(best_d) < ring * self.cell * math.cos(math.radians(lat)):
                return best
            ring += 1
        return best


def top_streets(count, per_locality, column):
    """count maps (locality, street name) to a count. Returns, per locality, rows for the per_locality names counted
    most, ties broken by name; each row holds its count under column."""
    of = collections.defaultdict(list)
    for (locality, name), n in count.items():
        of[locality].append((n, name))
    return {locality: [{"name": name, "locality": locality, column: n} for n, name in sorted(named, key=lambda s: (-s[0], s[1]))[:per_locality]] for locality, named in of.items()}


def fence(regions, municipalities, localities, streets, postal_codes):
    """Meet the loader's fence that every parent row has a child row. Keeps each locality with entries in both streets
    and postal_codes, then each municipality and region left with a child.

    regions and municipalities map a code to a row; a municipality row names its region under "region". localities,
    streets and postal_codes map a locality's key to its row, its streets and its postal codes. A locality row holds
    name, municipality, population, lat and lon, plus its country's own keys.

    Returns kept, then dropped: each maps "locality", "municipality" and "region" to that table's rows."""
    kept = {"locality": {k: l for k, l in localities.items() if streets.get(k) and postal_codes.get(k)}}
    municipality_codes = {l["municipality"] for l in kept["locality"].values()}
    kept["municipality"] = {c: m for c, m in municipalities.items() if c in municipality_codes}
    region_codes = {m["region"] for m in kept["municipality"].values()}
    kept["region"] = {c: r for c, r in regions.items() if c in region_codes}
    every = {"locality": localities, "municipality": municipalities, "region": regions}
    dropped = {table: {k: row for k, row in rows.items() if k not in kept[table]} for table, rows in every.items()}
    return kept, dropped


def log_dropped_localities(rows):
    """Logs each locality row as dropped, by its key, plus its name where that differs."""
    for key, row in rows.items():
        label = key if key == row["name"] else f"{key} {row['name']}"
        print(f"{label}: no street or no postal code, dropped", file=sys.stderr)