from __future__ import annotations

import io
import html
import re
import struct
import tempfile
import zipfile
from dataclasses import dataclass
from pathlib import Path
from xml.etree import ElementTree as ET

import numpy as np


class KmlToTabError(RuntimeError):
    """Raised when a KML file cannot be converted to MapInfo TAB."""


@dataclass(frozen=True)
class TabLayerSummary:
    name: str
    geometry_type: str
    feature_count: int


@dataclass(frozen=True)
class TabConversionResult:
    zip_bytes: bytes
    layers: list[TabLayerSummary]
    files: list[str]


_WKB_GEOMETRY_TYPES = {
    1: "Point",
    2: "LineString",
    3: "Polygon",
    4: "MultiPoint",
    5: "MultiLineString",
    6: "MultiPolygon",
    7: "GeometryCollection",
}


def convert_kml_to_tab_zip(kml_bytes: bytes, source_name: str) -> TabConversionResult:
    """Convert one KML file to native MapInfo TAB tables packed into a ZIP."""

    if not kml_bytes:
        raise KmlToTabError("Le fichier KML est vide.")

    pyogrio = _import_pyogrio()
    base_name = _safe_stem(source_name)

    with tempfile.TemporaryDirectory(prefix="kml_to_tab_") as tmp_dir_name:
        tmp_dir = Path(tmp_dir_name)
        input_path = tmp_dir / f"{base_name}.kml"
        output_dir = tmp_dir / "tab_output"
        output_dir.mkdir()
        input_path.write_bytes(kml_bytes)

        try:
            metadata, _fids, geometry, field_data = pyogrio.raw.read(
                input_path,
                force_2d=True,
            )
        except Exception as exc:  # pragma: no cover - exact GDAL errors vary
            raise KmlToTabError(f"Lecture du KML impossible: {exc}") from exc

        if geometry is None or len(geometry) == 0:
            raise KmlToTabError("Aucune geometrie exploitable trouvee dans le KML.")

        fields, field_data = _append_kml_fields(
            metadata.get("fields"),
            field_data,
            kml_bytes,
            len(geometry),
        )
        crs = metadata.get("crs") or "EPSG:4326"
        geometry_groups = _group_geometry_indexes(geometry)
        layers: list[TabLayerSummary] = []

        for geometry_type, indexes in geometry_groups.items():
            layer_name = _layer_name(base_name, geometry_type, len(geometry_groups))
            output_path = output_dir / f"{layer_name}.tab"
            layer_geometry = geometry[indexes]
            layer_field_data = [column[indexes] for column in field_data]

            try:
                pyogrio.raw.write(
                    output_path,
                    layer_geometry,
                    layer_field_data,
                    fields,
                    driver="MapInfo File",
                    geometry_type=geometry_type,
                    crs=crs,
                    encoding=metadata.get("encoding") or "UTF-8",
                )
            except Exception as exc:  # pragma: no cover - exact GDAL errors vary
                raise KmlToTabError(
                    f"Ecriture du TAB impossible pour la couche {layer_name}: {exc}"
                ) from exc

            layers.append(
                TabLayerSummary(
                    name=layer_name,
                    geometry_type=geometry_type,
                    feature_count=len(indexes),
                )
            )

        files = sorted(path.name for path in output_dir.iterdir() if path.is_file())
        return TabConversionResult(
            zip_bytes=_zip_directory(output_dir),
            layers=layers,
            files=files,
        )


def _import_pyogrio():
    try:
        import pyogrio
    except ImportError as exc:  # pragma: no cover - depends on environment
        raise KmlToTabError(
            "La conversion TAB requiert pyogrio/GDAL. "
            "Installe les dependances avec `pip install -r requirements.txt`."
        ) from exc
    return pyogrio


def _safe_stem(filename: str) -> str:
    stem = Path(filename or "converted").stem
    stem = re.sub(r"[^A-Za-z0-9_-]+", "_", stem).strip("_")
    return (stem or "converted")[:60]


def _layer_name(base_name: str, geometry_type: str, group_count: int) -> str:
    if group_count == 1:
        return base_name
    suffix = re.sub(r"(?<!^)(?=[A-Z])", "_", geometry_type).lower()
    return f"{base_name}_{suffix}"[:80]


def _group_geometry_indexes(geometry) -> dict[str, list[int]]:
    groups: dict[str, list[int]] = {}

    for index, wkb in enumerate(geometry):
        geometry_type = _wkb_geometry_type(wkb)
        groups.setdefault(geometry_type, []).append(index)

    unsupported = sorted(
        geometry_type
        for geometry_type in groups
        if geometry_type == "GeometryCollection"
    )
    if unsupported:
        raise KmlToTabError(
            "Les GeometryCollection ne sont pas supportees pour l'export TAB."
        )

    return groups


def _append_kml_fields(fields, field_data, kml_bytes: bytes, feature_count: int):
    records = _extract_kml_records(kml_bytes)
    if len(records) != feature_count:
        return fields, field_data

    field_pairs = _output_field_pairs(records, fields)
    if not field_pairs:
        return fields, field_data

    extra_values = {
        output_name: _record_column(records, source_name)
        for source_name, output_name in field_pairs
    }

    return (
        np.array(
            [*fields, *[output_name for _source, output_name in field_pairs]],
            dtype=object,
        ),
        [
            *field_data,
            *[extra_values[output_name] for _source, output_name in field_pairs],
        ],
    )


def _extract_kml_records(kml_bytes: bytes) -> list[dict[str, object]]:
    try:
        root = ET.fromstring(kml_bytes)
    except ET.ParseError:
        return []

    records: list[dict[str, object]] = []

    for element in root.iter():
        tag = _local_name(element)
        if tag != "Placemark" or not _placemark_has_geometry(element):
            continue

        description = _child_text(element, "description")
        record = _parse_structured_description(description)
        value = float("nan") if record else _parse_measurement_value(description)
        if not record and np.isfinite(value):
            record["value"] = value

        records.append(record)

    return records


def _output_field_pairs(
    records: list[dict[str, object]],
    existing_fields,
) -> list[tuple[str, str]]:
    used = {str(field).lower() for field in existing_fields}
    pairs: list[tuple[str, str]] = []

    for source_name in _record_field_names(records):
        output_name = source_name
        if output_name.lower() in used:
            output_name = _unique_field_name(f"description_{source_name}", used)
        else:
            used.add(output_name.lower())
        pairs.append((source_name, output_name))

    return pairs


def _unique_field_name(name: str, used: set[str]) -> str:
    base = _safe_column_name(name)[:31]
    candidate = base
    suffix = 2

    while candidate.lower() in used:
        suffix_text = f"_{suffix}"
        candidate = f"{base[: 31 - len(suffix_text)]}{suffix_text}"
        suffix += 1

    used.add(candidate.lower())
    return candidate


def _record_field_names(records: list[dict[str, object]]) -> list[str]:
    names: list[str] = []

    if any("value" in record for record in records):
        names.append("value")

    for record in records:
        for name in record:
            if name != "value" and name not in names:
                names.append(name)

    return names


def _record_column(records: list[dict[str, object]], name: str):
    values = [record.get(name, "") for record in records]
    if name == "value":
        return np.array(
            [value if value != "" else float("nan") for value in values],
            dtype=float,
        )
    return np.array([_stringify_field_value(value) for value in values], dtype=object)


def _stringify_field_value(value: object) -> str:
    if value is None:
        return ""
    if isinstance(value, float) and not np.isfinite(value):
        return ""
    return str(value)


def _placemark_has_geometry(placemark) -> bool:
    geometry_tags = {
        "Point",
        "LineString",
        "LinearRing",
        "Polygon",
        "MultiGeometry",
        "Model",
        "Track",
        "MultiTrack",
    }
    return any(_local_name(child) in geometry_tags for child in placemark.iter())


def _child_text(element, child_name: str) -> str:
    child = _first_child(element, child_name)
    if child is None:
        return ""
    return " ".join("".join(child.itertext()).split())


def _first_child(element, child_name: str):
    for child in element:
        if _local_name(child) == child_name:
            return child
    return None


def _local_name(element) -> str:
    return str(element.tag).rsplit("}", maxsplit=1)[-1]


def _parse_measurement_value(description: str) -> float:
    match = re.match(
        r"(?s)^.*?\s+(-?\d+(?:\.\d+)?(?:[eE][+-]?\d+)?)\s*$",
        description,
    )
    if not match:
        return float("nan")
    return float(match.group(1))


def _parse_structured_description(description: str) -> dict[str, str]:
    text = html.unescape(description or "")
    text = re.sub(r"(?i)<br\s*/?>", "\n", text)
    text = re.sub(r"(?i)</?b>", "", text)
    text = re.sub(r"<[^>]+>", "", text)

    record: dict[str, str] = {}
    for line in text.splitlines():
        if ":" not in line:
            continue

        key, value = line.split(":", maxsplit=1)
        column = _safe_column_name(key)
        value = value.strip()
        if not column or not value:
            continue
        record[column] = value

    return record


def _safe_column_name(name: str) -> str:
    column = html.unescape(name or "").strip()
    column = re.sub(r"\s+", "_", column)
    column = re.sub(r"[^A-Za-z0-9_]+", "_", column).strip("_")
    if not column:
        return ""
    if column[0].isdigit():
        column = f"field_{column}"
    return column[:31]


def _wkb_geometry_type(wkb: bytes) -> str:
    if not wkb or len(wkb) < 5:
        raise KmlToTabError("Geometrie WKB invalide dans le KML.")

    endian = "<" if wkb[0] == 1 else ">"
    raw_code = struct.unpack(f"{endian}I", wkb[1:5])[0]
    base_code = raw_code & 0xFF
    geometry_type = _WKB_GEOMETRY_TYPES.get(base_code)

    if geometry_type is None:
        raise KmlToTabError(f"Type de geometrie non supporte: WKB {raw_code}.")

    return geometry_type


def _zip_directory(directory: Path) -> bytes:
    zip_buffer = io.BytesIO()
    with zipfile.ZipFile(zip_buffer, mode="w", compression=zipfile.ZIP_DEFLATED) as zf:
        for path in sorted(directory.iterdir()):
            if path.is_file():
                zf.write(path, arcname=path.name)
    return zip_buffer.getvalue()