import litellm
import logging
import os
import textwrap
import time
import json
import copy
import re
import asyncio
import threading
import weakref
import PyPDF2
import pymupdf
import yaml
from datetime import datetime
from io import BytesIO
from pathlib import Path
from pprint import pprint
# Aliased with a leading underscore so `from .utils import *` (used by the
# page_index modules) doesn't export a name `config` that would shadow the real
# `pageindex.config` submodule for those modules.
from types import SimpleNamespace as _config

from ..config import get_llm_params, get_max_concurrency
from ..tokens import count_tokens  # re-exported for backward compat

logger = logging.getLogger(__name__)


# One shared semaphore per event loop, bounding concurrent in-flight LLM calls.
# Keyed by the loop object (WeakKeyDictionary drops the entry once the loop is
# closed and garbage-collected) so each asyncio.run() gets its own, correctly
# loop-bound semaphore. The lock only guards the tiny get-or-create against two
# threads (each driving its own loop) racing to insert; within a single loop
# everything is single-threaded, so no lock is needed on the hot path.
_LLM_SEMAPHORES: "weakref.WeakKeyDictionary" = weakref.WeakKeyDictionary()
_LLM_SEMAPHORES_LOCK = threading.Lock()


def _llm_semaphore() -> asyncio.Semaphore:
    """Shared per-loop cap on concurrent in-flight LLM calls.

    Acquired only around the leaf ``litellm.acompletion`` call in
    ``llm_acompletion`` — the single point every LLM request funnels through —
    so the cap is a TRUE global bound no matter how deeply the indexing gathers
    nest (``tree_parser`` → ``process_large_node_recursively`` → …). Bounding at
    the leaf rather than at each gather call site is also deadlock-free: a parent
    coroutine awaiting its children holds no slot, so children can always
    acquire one.

    Sized from ``get_max_concurrency()`` the first time it's needed in a loop, so
    a per-index ``max_concurrency_scope`` override in effect at that moment is
    honored. Without this bound a many-node document opens one socket per node at
    once and exhausts the process file-descriptor limit (Errno 24).
    """
    loop = asyncio.get_running_loop()
    sem = _LLM_SEMAPHORES.get(loop)
    if sem is None:
        with _LLM_SEMAPHORES_LOCK:
            sem = _LLM_SEMAPHORES.get(loop)
            if sem is None:
                sem = asyncio.Semaphore(get_max_concurrency())
                _LLM_SEMAPHORES[loop] = sem
    return sem


def llm_completion(model, prompt, chat_history=None, return_finish_reason=False):
    if model:
        model = model.removeprefix("litellm/")
    max_retries = 10
    messages = list(chat_history) + [{"role": "user", "content": prompt}] if chat_history else [{"role": "user", "content": prompt}]
    for i in range(max_retries):
        try:
            response = litellm.completion(
                model=model,
                messages=messages,
                # Per-call litellm kwargs (default temperature=0, drop_params=True);
                # configure via config.set_llm_params(...) — never the litellm global.
                **get_llm_params(),
            )
            content = response.choices[0].message.content
            if return_finish_reason:
                finish_reason = "max_output_reached" if response.choices[0].finish_reason == "length" else "finished"
                return content, finish_reason
            return content
        except Exception as e:
            logger.warning("Retrying LLM completion (%d/%d)", i + 1, max_retries)
            logger.error(f"Error: {e}")
            if i < max_retries - 1:
                time.sleep(1)
            else:
                logger.error('Max retries reached for prompt: ' + prompt)
                raise RuntimeError(f"LLM call failed after {max_retries} retries") from e



async def llm_acompletion(model, prompt):
    if model:
        model = model.removeprefix("litellm/")
    max_retries = 10
    messages = [{"role": "user", "content": prompt}]
    for i in range(max_retries):
        try:
            # Hold a concurrency slot only around the actual network call — not
            # across retry backoff — so the cap counts real in-flight requests.
            async with _llm_semaphore():
                response = await litellm.acompletion(
                    model=model,
                    messages=messages,
                    **get_llm_params(),  # per-call kwargs; never the litellm global
                )
            return response.choices[0].message.content
        except Exception as e:
            logger.warning("Retrying async LLM completion (%d/%d)", i + 1, max_retries)
            logger.error(f"Error: {e}")
            if i < max_retries - 1:
                await asyncio.sleep(1)
            else:
                logger.error('Max retries reached for prompt: ' + prompt)
                raise RuntimeError(f"LLM call failed after {max_retries} retries") from e


def extract_json(content):
    try:
        # First, try to extract JSON enclosed within ```json and ```
        start_idx = content.find("```json")
        if start_idx != -1:
            start_idx += 7  # Adjust index to start after the delimiter
            end_idx = content.rfind("```")
            json_content = content[start_idx:end_idx].strip()
        else:
            # If no delimiters, assume entire content could be JSON
            json_content = content.strip()

        # Clean up common issues that might cause parsing errors
        json_content = json_content.replace('None', 'null')  # Replace Python None with JSON null
        json_content = json_content.replace('\n', ' ').replace('\r', ' ')  # Remove newlines
        json_content = ' '.join(json_content.split())  # Normalize whitespace

        # Attempt to parse and return the JSON object
        return json.loads(json_content)
    except json.JSONDecodeError as e:
        logging.error(f"Failed to extract JSON: {e}")
        # Try to clean up the content further if initial parsing fails
        try:
            # Remove any trailing commas before closing brackets/braces
            json_content = json_content.replace(',]', ']').replace(',}', '}')
            return json.loads(json_content)
        except Exception:
            logging.error("Failed to parse JSON even after cleanup")
            return {}
    except Exception as e:
        logging.error(f"Unexpected error while extracting JSON: {e}")
        return {}


def get_json_content(response):
    start_idx = response.find("```json")
    if start_idx != -1:
        start_idx += 7
        response = response[start_idx:]

    end_idx = response.rfind("```")
    if end_idx != -1:
        response = response[:end_idx]

    json_content = response.strip()
    return json_content


def write_node_id(data, node_id=0):
    if isinstance(data, dict):
        data['node_id'] = str(node_id).zfill(4)
        node_id += 1
        for key in list(data.keys()):
            if 'nodes' in key:
                node_id = write_node_id(data[key], node_id)
    elif isinstance(data, list):
        for index in range(len(data)):
            node_id = write_node_id(data[index], node_id)
    return node_id


def remove_fields(data, fields=None, max_len=None):
    fields = fields or ["text"]
    if isinstance(data, dict):
        return {k: remove_fields(v, fields, max_len)
            for k, v in data.items() if k not in fields}
    elif isinstance(data, list):
        return [remove_fields(item, fields, max_len) for item in data]
    elif isinstance(data, str):
        return data[:max_len] + '...' if max_len is not None and len(data) > max_len else data
    return data


def structure_to_list(structure):
    if isinstance(structure, dict):
        nodes = []
        nodes.append(structure)
        if 'nodes' in structure:
            nodes.extend(structure_to_list(structure['nodes']))
        return nodes
    elif isinstance(structure, list):
        nodes = []
        for item in structure:
            nodes.extend(structure_to_list(item))
        return nodes


def get_nodes(structure):
    if isinstance(structure, dict):
        structure_node = copy.deepcopy(structure)
        structure_node.pop('nodes', None)
        nodes = [structure_node]
        for key in list(structure.keys()):
            if 'nodes' in key:
                nodes.extend(get_nodes(structure[key]))
        return nodes
    elif isinstance(structure, list):
        nodes = []
        for item in structure:
            nodes.extend(get_nodes(item))
        return nodes


def get_leaf_nodes(structure):
    if isinstance(structure, dict):
        # .get() — clean_node deletes the 'nodes' key on leaf nodes, so direct
        # indexing raises KeyError on a standard tree (issue #330 / #331).
        if not structure.get('nodes'):
            structure_node = copy.deepcopy(structure)
            structure_node.pop('nodes', None)
            return [structure_node]
        else:
            leaf_nodes = []
            for key in list(structure.keys()):
                if 'nodes' in key:
                    leaf_nodes.extend(get_leaf_nodes(structure[key]))
            return leaf_nodes
    elif isinstance(structure, list):
        leaf_nodes = []
        for item in structure:
            leaf_nodes.extend(get_leaf_nodes(item))
        return leaf_nodes


async def generate_node_summary(node, model=None):
    prompt = f"""You are given a part of a document, your task is to generate a description of the partial document about what are main points covered in the partial document.

    Partial Document Text: {node['text']}

    Directly return the description, do not include any other text.
    """
    response = await llm_acompletion(model, prompt)
    return response


async def generate_summaries_for_structure(structure, model=None):
    nodes = structure_to_list(structure)
    tasks = [generate_node_summary(node, model=model) for node in nodes]
    summaries = await asyncio.gather(*tasks)

    for node, summary in zip(nodes, summaries):
        node['summary'] = summary
    return structure


def generate_doc_description(structure, model=None):
    prompt = f"""Your are an expert in generating descriptions for a document.
    You are given a structure of a document. Your task is to generate a one-sentence description for the document, which makes it easy to distinguish the document from other documents.

    Document Structure: {structure}

    Directly return the description, do not include any other text.
    """
    response = llm_completion(model, prompt)
    return response


def list_to_tree(data):
    def get_parent_structure(structure):
        """Helper function to get the parent structure code"""
        if not structure:
            return None
        parts = str(structure).split('.')
        return '.'.join(parts[:-1]) if len(parts) > 1 else None

    # First pass: Create nodes and track parent-child relationships
    nodes = {}
    root_nodes = []

    for item in data:
        structure = item.get('structure')
        node = {
            'title': item.get('title'),
            'start_index': item.get('start_index'),
            'end_index': item.get('end_index'),
            'nodes': []
        }

        nodes[structure] = node

        # Find parent
        parent_structure = get_parent_structure(structure)

        if parent_structure:
            # Add as child to parent if parent exists
            if parent_structure in nodes:
                nodes[parent_structure]['nodes'].append(node)
            else:
                root_nodes.append(node)
        else:
            # No parent, this is a root node
            root_nodes.append(node)

    # Helper function to clean empty children arrays
    def clean_node(node):
        if not node['nodes']:
            del node['nodes']
        else:
            for child in node['nodes']:
                clean_node(child)
        return node

    # Clean and return the tree
    return [clean_node(node) for node in root_nodes]


def post_processing(structure, end_physical_index):
    # First convert page_number to start_index in flat list
    for i, item in enumerate(structure):
        item['start_index'] = item.get('physical_index')
        if i < len(structure) - 1:
            if structure[i + 1].get('appear_start') == 'yes':
                item['end_index'] = structure[i + 1]['physical_index']-1
            else:
                item['end_index'] = structure[i + 1]['physical_index']
        else:
            item['end_index'] = end_physical_index
    tree = list_to_tree(structure)
    if len(tree)!=0:
        return tree
    else:
        ### remove appear_start
        for node in structure:
            node.pop('appear_start', None)
            node.pop('physical_index', None)
        return structure


def reorder_dict(data, key_order):
    if not key_order:
        return data
    return {key: data[key] for key in key_order if key in data}


def format_structure(structure, order=None):
    if not order:
        return structure
    if isinstance(structure, dict):
        if 'nodes' in structure:
            structure['nodes'] = format_structure(structure['nodes'], order)
        if not structure.get('nodes'):
            structure.pop('nodes', None)
        structure = reorder_dict(structure, order)
    elif isinstance(structure, list):
        structure = [format_structure(item, order) for item in structure]
    return structure


def create_clean_structure_for_description(structure):
    """
    Create a clean structure for document description generation,
    excluding unnecessary fields like 'text'.
    """
    if isinstance(structure, dict):
        clean_node = {}
        # Only include essential fields for description
        for key in ['title', 'node_id', 'summary', 'prefix_summary']:
            if key in structure:
                clean_node[key] = structure[key]

        # Recursively process child nodes
        if 'nodes' in structure and structure['nodes']:
            clean_node['nodes'] = create_clean_structure_for_description(structure['nodes'])

        return clean_node
    elif isinstance(structure, list):
        return [create_clean_structure_for_description(item) for item in structure]
    else:
        return structure


def _get_text_of_pages(page_list, start_page, end_page):
    """Concatenate text from page_list for pages [start_page, end_page] (1-indexed)."""
    text = ""
    for page_num in range(start_page - 1, end_page):
        text += page_list[page_num][0]
    return text


def add_node_text(node, page_list):
    """Recursively add 'text' field to each node from page_list content.

    Each node must have 'start_index' and 'end_index' (1-indexed page numbers).
    page_list is [(page_text, token_count), ...].
    """
    if isinstance(node, dict):
        start_page = node.get('start_index')
        end_page = node.get('end_index')
        if start_page is not None and end_page is not None:
            node['text'] = _get_text_of_pages(page_list, start_page, end_page)
        if 'nodes' in node:
            add_node_text(node['nodes'], page_list)
    elif isinstance(node, list):
        for item in node:
            add_node_text(item, page_list)


def remove_structure_text(data):
    if isinstance(data, dict):
        data.pop('text', None)
        if 'nodes' in data:
            remove_structure_text(data['nodes'])
    elif isinstance(data, list):
        for item in data:
            remove_structure_text(item)
    return data


# ── Functions migrated from retrieve.py ──────────────────────────────────────

def parse_pages(pages: str) -> list[int]:
    """Parse a pages string like '5-7', '3,8', or '12' into a sorted list of ints."""
    result = []
    for part in pages.split(','):
        part = part.strip()
        if '-' in part:
            start, end = int(part.split('-', 1)[0].strip()), int(part.split('-', 1)[1].strip())
            if start > end:
                raise ValueError(f"Invalid range '{part}': start must be <= end")
            result.extend(range(start, end + 1))
        else:
            result.append(int(part))
    result = [p for p in result if p >= 1]
    result = sorted(set(result))
    if len(result) > 1000:
        raise ValueError(f"Page range too large: {len(result)} pages (max 1000)")
    return result


def get_pdf_page_content(file_path: str, page_nums: list[int]) -> list[dict]:
    """Extract text for specific PDF pages (1-indexed), opening the PDF once."""
    with open(file_path, 'rb') as f:
        pdf_reader = PyPDF2.PdfReader(f)
        total = len(pdf_reader.pages)
        valid_pages = [p for p in page_nums if 1 <= p <= total]
        return [
            {'page': p, 'content': pdf_reader.pages[p - 1].extract_text() or ''}
            for p in valid_pages
        ]


def get_md_page_content(structure: list, page_nums: list[int]) -> list[dict]:
    """
    For Markdown documents, 'pages' are line numbers.
    Return only the nodes whose line_num is one of ``page_nums`` (exact match),
    mirroring the PDF path. A non-contiguous spec like [5, 100] returns just
    those two lines, not the whole [5, 100] range.
    """
    if not page_nums:
        return []
    wanted = set(page_nums)
    results = []
    seen = set()

    def _traverse(nodes):
        for node in nodes:
            ln = node.get('line_num')
            if ln in wanted and ln not in seen:
                seen.add(ln)
                results.append({'page': ln, 'content': node.get('text', '')})
            if node.get('nodes'):
                _traverse(node['nodes'])

    _traverse(structure)
    results.sort(key=lambda x: x['page'])
    return results



# ─────────────────────────────────────────────────────────────────────
# Legacy 0.2.x / OSS utility API — kept here so this module is the single
# source of truth for the indexing pipeline. Previously duplicated in the
# top-level pageindex/utils.py (now a deprecation shim re-exporting this).
# ─────────────────────────────────────────────────────────────────────

async def call_llm(prompt, api_key, model="gpt-4.1", temperature=0):
    """Call an LLM to generate a response to a prompt.

    Kept for compatibility with the pageindex 0.2.x SDK utility API.
    """
    import openai

    async with openai.AsyncOpenAI(api_key=api_key) as client:
        response = await client.chat.completions.create(
            model=model,
            messages=[{"role": "user", "content": prompt}],
            temperature=temperature,
        )
    return response.choices[0].message.content.strip()


def is_leaf_node(data, node_id):
    # Helper function to find the node by its node_id
    def find_node(data, node_id):
        if isinstance(data, dict):
            if data.get('node_id') == node_id:
                return data
            for key in data.keys():
                if 'nodes' in key:
                    result = find_node(data[key], node_id)
                    if result:
                        return result
        elif isinstance(data, list):
            for item in data:
                result = find_node(item, node_id)
                if result:
                    return result
        return None

    # Find the node with the given node_id
    node = find_node(data, node_id)

    # Check if the node is a leaf node
    if node and not node.get('nodes'):
        return True
    return False


def get_last_node(structure):
    return structure[-1]


def extract_text_from_pdf(pdf_path):
    pdf_reader = PyPDF2.PdfReader(pdf_path)
    ###return text not list 
    text=""
    for page_num in range(len(pdf_reader.pages)):
        page = pdf_reader.pages[page_num]
        text+=page.extract_text()
    return text


def get_pdf_title(pdf_path):
    pdf_reader = PyPDF2.PdfReader(pdf_path)
    meta = pdf_reader.metadata
    title = meta.title if meta and meta.title else 'Untitled'
    return title


def get_text_of_pages(pdf_path, start_page, end_page, tag=True):
    pdf_reader = PyPDF2.PdfReader(pdf_path)
    text = ""
    for page_num in range(start_page-1, end_page):
        page = pdf_reader.pages[page_num]
        page_text = page.extract_text()
        if tag:
            text += f"<start_index_{page_num+1}>\n{page_text}\n<end_index_{page_num+1}>\n"
        else:
            text += page_text
    return text


def get_first_start_page_from_text(text):
    start_page = -1
    start_page_match = re.search(r'<start_index_(\d+)>', text)
    if start_page_match:
        start_page = int(start_page_match.group(1))
    return start_page


def get_last_start_page_from_text(text):
    start_page = -1
    # Find all matches of start_index tags
    start_page_matches = re.finditer(r'<start_index_(\d+)>', text)
    # Convert iterator to list and get the last match if any exist
    matches_list = list(start_page_matches)
    if matches_list:
        start_page = int(matches_list[-1].group(1))
    return start_page


def sanitize_filename(filename, replacement='-'):
    # In Linux, only '/' and '\0' (null) are invalid in filenames.
    # Null can't be represented in strings, so we only handle '/'.
    return filename.replace('/', replacement)


def get_pdf_name(pdf_path):
    # Extract PDF name
    if isinstance(pdf_path, str):
        pdf_name = os.path.basename(pdf_path)
    elif isinstance(pdf_path, BytesIO):
        pdf_reader = PyPDF2.PdfReader(pdf_path)
        meta = pdf_reader.metadata
        pdf_name = meta.title if meta and meta.title else 'Untitled'
        pdf_name = sanitize_filename(pdf_name)
    return pdf_name


class JsonLogger:
    def __init__(self, file_path):
        # Extract PDF name for logger name
        pdf_name = get_pdf_name(file_path)
            
        current_time = datetime.now().strftime("%Y%m%d_%H%M%S")
        self.filename = f"{pdf_name}_{current_time}.json"
        os.makedirs("./logs", exist_ok=True)
        # Initialize empty list to store all messages
        self.log_data = []

    def log(self, level, message, **kwargs):
        if isinstance(message, dict):
            self.log_data.append(message)
        else:
            self.log_data.append({'message': message})
        # Add new message to the log data
        
        # Write entire log data to file
        with open(self._filepath(), "w") as f:
            json.dump(self.log_data, f, indent=2)

    def info(self, message, **kwargs):
        self.log("INFO", message, **kwargs)

    def error(self, message, **kwargs):
        self.log("ERROR", message, **kwargs)

    def debug(self, message, **kwargs):
        self.log("DEBUG", message, **kwargs)

    def exception(self, message, **kwargs):
        kwargs["exception"] = True
        self.log("ERROR", message, **kwargs)

    def _filepath(self):
        return os.path.join("logs", self.filename)


def add_preface_if_needed(data):
    if not isinstance(data, list) or not data:
        return data

    if data[0]['physical_index'] is not None and data[0]['physical_index'] > 1:
        preface_node = {
            "structure": "0",
            "title": "Preface",
            "physical_index": 1,
        }
        data.insert(0, preface_node)
    return data


def get_page_tokens(pdf_path, model=None, pdf_parser="PyPDF2"):
    if pdf_parser == "PyPDF2":
        pdf_reader = PyPDF2.PdfReader(pdf_path)
        page_list = []
        for page_num in range(len(pdf_reader.pages)):
            page = pdf_reader.pages[page_num]
            page_text = page.extract_text()
            token_length = litellm.token_counter(model=model, text=page_text)
            page_list.append((page_text, token_length))
        return page_list
    elif pdf_parser == "PyMuPDF":
        if isinstance(pdf_path, BytesIO):
            pdf_stream = pdf_path
            doc = pymupdf.open(stream=pdf_stream, filetype="pdf")
        elif isinstance(pdf_path, str) and os.path.isfile(pdf_path) and pdf_path.lower().endswith(".pdf"):
            doc = pymupdf.open(pdf_path)
        page_list = []
        for page in doc:
            page_text = page.get_text()
            token_length = litellm.token_counter(model=model, text=page_text)
            page_list.append((page_text, token_length))
        return page_list
    else:
        raise ValueError(f"Unsupported PDF parser: {pdf_parser}")


def get_text_of_pdf_pages(pdf_pages, start_page, end_page):
    text = ""
    for page_num in range(start_page-1, end_page):
        text += pdf_pages[page_num][0]
    return text


def get_text_of_pdf_pages_with_labels(pdf_pages, start_page, end_page):
    text = ""
    for page_num in range(start_page-1, end_page):
        text += f"<physical_index_{page_num+1}>\n{pdf_pages[page_num][0]}\n<physical_index_{page_num+1}>\n"
    return text


def get_number_of_pages(pdf_path):
    pdf_reader = PyPDF2.PdfReader(pdf_path)
    num = len(pdf_reader.pages)
    return num


def clean_structure_post(data):
    if isinstance(data, dict):
        data.pop('page_number', None)
        data.pop('start_index', None)
        data.pop('end_index', None)
        if 'nodes' in data:
            clean_structure_post(data['nodes'])
    elif isinstance(data, list):
        for section in data:
            clean_structure_post(section)
    return data


def print_toc(tree, indent=0):
    for node in tree:
        print('  ' * indent + node['title'])
        if node.get('nodes'):
            print_toc(node['nodes'], indent + 1)


def print_json(data, max_len=40, indent=2):
    def simplify_data(obj):
        if isinstance(obj, dict):
            return {k: simplify_data(v) for k, v in obj.items()}
        elif isinstance(obj, list):
            return [simplify_data(item) for item in obj]
        elif isinstance(obj, str) and len(obj) > max_len:
            return obj[:max_len] + '...'
        else:
            return obj
    
    simplified = simplify_data(data)
    print(json.dumps(simplified, indent=indent, ensure_ascii=False))


def check_token_limit(structure, limit=110000):
    list = structure_to_list(structure)
    for node in list:
        num_tokens = count_tokens(node['text'], model=None)
        if num_tokens > limit:
            print(f"Node ID: {node['node_id']} has {num_tokens} tokens")
            print("Start Index:", node['start_index'])
            print("End Index:", node['end_index'])
            print("Title:", node['title'])
            print("\n")


def convert_physical_index_to_int(data):
    if isinstance(data, list):
        for i in range(len(data)):
            # Check if item is a dictionary and has 'physical_index' key
            if isinstance(data[i], dict) and 'physical_index' in data[i]:
                if isinstance(data[i]['physical_index'], str):
                    if data[i]['physical_index'].startswith('<physical_index_'):
                        data[i]['physical_index'] = int(data[i]['physical_index'].split('_')[-1].rstrip('>').strip())
                    elif data[i]['physical_index'].startswith('physical_index_'):
                        data[i]['physical_index'] = int(data[i]['physical_index'].split('_')[-1].strip())
    elif isinstance(data, str):
        if data.startswith('<physical_index_'):
            data = int(data.split('_')[-1].rstrip('>').strip())
        elif data.startswith('physical_index_'):
            data = int(data.split('_')[-1].strip())
        # Check data is int
        if isinstance(data, int):
            return data
        else:
            return None
    return data


def convert_page_to_int(data):
    for item in data:
        if 'page' in item and isinstance(item['page'], str):
            try:
                item['page'] = int(item['page'])
            except ValueError:
                # Keep original value if conversion fails
                pass
    return data


def add_node_text_with_labels(node, pdf_pages):
    if isinstance(node, dict):
        start_page = node.get('start_index')
        end_page = node.get('end_index')
        node['text'] = get_text_of_pdf_pages_with_labels(pdf_pages, start_page, end_page)
        if 'nodes' in node:
            add_node_text_with_labels(node['nodes'], pdf_pages)
    elif isinstance(node, list):
        for index in range(len(node)):
            add_node_text_with_labels(node[index], pdf_pages)
    return


class ConfigLoader:
    """Legacy 0.2.x config helper. Defaults now come from IndexConfig — the
    old ``config.yaml`` no longer ships. Prefer ``pageindex.IndexConfig``.
    """

    def __init__(self, default_path=None):
        from ..config import IndexConfig
        self._default_dict = IndexConfig().model_dump()

    def _validate_keys(self, user_dict):
        unknown_keys = set(user_dict) - set(self._default_dict)
        if unknown_keys:
            raise ValueError(f"Unknown config keys: {unknown_keys}")

    def load(self, user_opt=None) -> _config:
        """Merge user options over IndexConfig defaults, returning a namespace."""
        if user_opt is None:
            user_dict = {}
        elif isinstance(user_opt, _config):
            user_dict = vars(user_opt)
        elif isinstance(user_opt, dict):
            user_dict = user_opt
        else:
            raise TypeError("user_opt must be dict, config(SimpleNamespace) or None")

        self._validate_keys(user_dict)
        merged = {**self._default_dict, **user_dict}
        return _config(**merged)


def create_node_mapping(tree, include_page_ranges=False, max_page=None):
    """Create a mapping of node_id to node for quick lookup.

    The optional page-range arguments are kept for compatibility with the
    pageindex 0.2.x SDK utility API.
    """
    def get_all_nodes(nodes):
        if isinstance(nodes, dict):
            return [nodes] + [
                child_node
                for child in nodes.get('nodes', [])
                for child_node in get_all_nodes(child)
            ]
        elif isinstance(nodes, list):
            return [
                child_node
                for item in nodes
                for child_node in get_all_nodes(item)
            ]
        return []

    all_nodes = get_all_nodes(tree)

    if not include_page_ranges:
        return {node["node_id"]: node for node in all_nodes if node.get("node_id")}

    mapping = {}
    for i, node in enumerate(all_nodes):
        if not node.get("node_id"):
            continue
        start_page = node.get("page_index", node.get("start_index"))
        if node.get("end_index") is not None:
            end_page = node.get("end_index")
        elif i + 1 < len(all_nodes):
            next_node = all_nodes[i + 1]
            end_page = next_node.get("page_index", next_node.get("start_index"))
        else:
            end_page = max_page

        mapping[node["node_id"]] = {
            "node": node,
            "start_index": start_page,
            "end_index": end_page,
        }

    return mapping


def print_tree(tree, exclude_fields=None, indent=None):
    if exclude_fields is None:
        exclude_fields = ['text', 'page_index']
    if isinstance(exclude_fields, int):
        indent = exclude_fields
        exclude_fields = None
    if indent is None and exclude_fields is not None:
        cleaned_tree = remove_fields(copy.deepcopy(tree), exclude_fields, max_len=40)
        pprint(cleaned_tree, sort_dicts=False, width=100)
        return

    indent = indent or 0
    for node in tree:
        summary = node.get('summary') or node.get('prefix_summary', '')
        summary_str = f"  —  {summary[:60]}..." if summary else ""
        print('  ' * indent + f"[{node.get('node_id', '?')}] {node.get('title', '')}{summary_str}")
        if node.get('nodes'):
            print_tree(node['nodes'], exclude_fields=exclude_fields, indent=indent + 1)


def print_wrapped(text, width=100):
    for line in text.splitlines():
        print(textwrap.fill(line, width=width))