from __future__ import annotations

import json
import re
from typing import Any

NEXT_FLIGHT_RE = re.compile(r"self\.__next_f\.push\(\[1,\"(.*?)\"\]\)", re.DOTALL)


def extract_next_flight_strings(html: str) -> list[str]:
    """Extract decoded Next.js Flight chunks from mobile.de HTML."""
    chunks: list[str] = []
    for match in NEXT_FLIGHT_RE.finditer(html):
        raw = match.group(1)
        try:
            chunks.append(json.loads(f'"{raw}"'))
        except json.JSONDecodeError:
            # Резервный вариант: сохраняем работоспособность парсера,
            # даже если один из фрагментов имеет нестандартное экранирование.
            chunks.append(raw.encode("utf-8", errors="ignore").decode("unicode_escape", errors="ignore"))
    return chunks


def extract_json_object_after(text: str, marker: str) -> dict[str, Any] | None:
    """Return JSON object that starts immediately after a marker in a decoded Flight chunk."""
    marker_index = text.find(marker)
    if marker_index < 0:
        return None
    start = text.find("{", marker_index + len(marker))
    if start < 0:
        return None

    depth = 0
    in_string = False
    escaped = False
    for index in range(start, len(text)):
        char = text[index]
        if in_string:
            if escaped:
                escaped = False
            elif char == "\\":
                escaped = True
            elif char == '"':
                in_string = False
            continue
        if char == '"':
            in_string = True
        elif char == "{":
            depth += 1
        elif char == "}":
            depth -= 1
            if depth == 0:
                candidate = text[start : index + 1]
                try:
                    return json.loads(candidate)
                except json.JSONDecodeError:
                    return None
    return None


def extract_search_results(html: str) -> dict[str, Any]:
    """Extract searchResults from mobile.de SRP HTML."""
    for chunk in extract_next_flight_strings(html):
        if '"eventScope":"page-srp"' not in chunk or '"searchResults"' not in chunk:
            continue
        results = extract_json_object_after(chunk, '"searchResults":')
        if isinstance(results, dict):
            return results
    return {}


def extract_detail_listing(html: str) -> dict[str, Any]:
    """Extract listing object from mobile.de VIP/detail HTML."""
    for chunk in extract_next_flight_strings(html):
        if '"eventScope":"page-vip"' not in chunk or '"listing"' not in chunk:
            continue
        listing = extract_json_object_after(chunk, '"listing":')
        if isinstance(listing, dict):
            return listing
    return {}