#!/usr/bin/env python3
"""Drop faces that reference out-of-range vertex indices in CityJSON files."""
from __future__ import annotations

import argparse
import json
import sys
from pathlib import Path
from typing import Any, Iterable


def parse_args(argv: Iterable[str] | None = None) -> argparse.Namespace:
    parser = argparse.ArgumentParser(
        description="Remove faces referencing invalid vertex indices from CityJSON files."
    )
    parser.add_argument(
        "--input-dir",
        type=Path,
        default=Path("work/cityjson"),
        help="Directory containing CityJSON exports (files or citygml-tools folders).",
    )
    parser.add_argument(
        "--output-dir",
        type=Path,
        default=Path("work/cityjson_clean"),
        help="Directory to write cleaned CityJSON files.",
    )
    parser.add_argument(
        "--pattern",
        default="**/*.json",
        help="Glob pattern for input files (defaults to any .json under the input dir).",
    )
    return parser.parse_args(argv)


def read_json(path: Path) -> dict[str, Any]:
    with path.open("r", encoding="utf-8") as handle:
        return json.load(handle)


def write_json(path: Path, payload: dict[str, Any]) -> None:
    path.parent.mkdir(parents=True, exist_ok=True)
    with path.open("w", encoding="utf-8") as handle:
        json.dump(payload, handle, ensure_ascii=True, indent=2)
        handle.write("\n")


def base_name(path: Path) -> str:
    name = path.name
    if name.endswith(".city.json"):
        return name[: -len(".city.json")]
    if name.endswith(".json"):
        return name[: -len(".json")]
    return path.stem


def resolve_input_file(path: Path) -> Path | None:
    if path.is_file():
        return path
    if path.is_dir():
        candidate = path / f"{path.stem}.json"
        if candidate.is_file():
            return candidate
        matches = list(path.glob("*.json"))
        if len(matches) == 1:
            return matches[0]
    return None


def boundary_valid(boundary: Any, vertex_count: int) -> bool:
    if isinstance(boundary, int):
        return 0 <= boundary < vertex_count
    if isinstance(boundary, list):
        return all(boundary_valid(item, vertex_count) for item in boundary)
    return False


def filter_boundaries(boundaries: list[Any], values: list[Any], vertex_count: int) -> tuple[list[Any], list[Any]]:
    filtered_boundaries: list[Any] = []
    filtered_values: list[Any] = []

    for boundary, value in zip(boundaries, values):
        if isinstance(value, list):
            nested_boundaries, nested_values = filter_boundaries(boundary, value, vertex_count)
            if nested_boundaries:
                filtered_boundaries.append(nested_boundaries)
                filtered_values.append(nested_values)
            continue

        if boundary_valid(boundary, vertex_count):
            filtered_boundaries.append(boundary)
            filtered_values.append(value)

    return filtered_boundaries, filtered_values


def filter_geometry(geometry: dict[str, Any], vertex_count: int) -> dict[str, Any] | None:
    semantics = geometry.get("semantics")
    boundaries = geometry.get("boundaries")
    values = semantics.get("values") if semantics else None
    if boundaries is None or values is None:
        return geometry

    filtered_boundaries, filtered_values = filter_boundaries(boundaries, values, vertex_count)
    if not filtered_boundaries:
        return None

    filtered_geometry = dict(geometry)
    filtered_geometry["boundaries"] = filtered_boundaries
    filtered_geometry["semantics"] = dict(semantics)
    filtered_geometry["semantics"]["values"] = filtered_values
    return filtered_geometry


def filter_cityobject(cityobject: dict[str, Any], vertex_count: int) -> dict[str, Any] | None:
    geometries = cityobject.get("geometry") or []
    filtered_geometries = []
    for geometry in geometries:
        filtered_geometry = filter_geometry(geometry, vertex_count)
        if filtered_geometry:
            filtered_geometries.append(filtered_geometry)

    if not filtered_geometries:
        return None

    filtered_object = dict(cityobject)
    filtered_object["geometry"] = filtered_geometries
    return filtered_object


def clean_cityjson(cityjson: dict[str, Any]) -> dict[str, Any]:
    vertices = cityjson.get("vertices") or []
    vertex_count = len(vertices)

    cityobjects = cityjson.get("CityObjects") or {}
    cleaned_objects = {}
    for object_id, cityobject in cityobjects.items():
        cleaned_object = filter_cityobject(cityobject, vertex_count)
        if cleaned_object:
            cleaned_objects[object_id] = cleaned_object

    cleaned_cityjson = {k: v for k, v in cityjson.items() if k != "CityObjects"}
    cleaned_cityjson["CityObjects"] = cleaned_objects
    return cleaned_cityjson


def process_file(path: Path, output_dir: Path) -> int:
    resolved = resolve_input_file(path)
    if not resolved:
        print(f"[skip] cannot resolve CityJSON file for {path}", file=sys.stderr)
        return 0

    cityjson = read_json(resolved)
    cleaned = clean_cityjson(cityjson)
    output_path = output_dir / f"{base_name(path)}.city.json"
    write_json(output_path, cleaned)
    return 1


def main(argv: Iterable[str] | None = None) -> int:
    args = parse_args(argv)
    files = sorted(args.input_dir.glob(args.pattern))
    if not files:
        print(f"No input files matched pattern '{args.pattern}' in {args.input_dir}", file=sys.stderr)
        return 1

    total = 0
    for path in files:
        total += process_file(path, args.output_dir)

    print(f"Wrote {total} cleaned file(s) to {args.output_dir}")
    return 0 if total else 1


if __name__ == "__main__":
    sys.exit(main())