import litellm
import logging
import time
import json
import copy
import re
import asyncio
import PyPDF2

logger = logging.getLogger(__name__)


def count_tokens(text, model=None):
    if not text:
        return 0
    return litellm.token_counter(model=model, text=text)


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:
            litellm.drop_params = True
            response = litellm.completion(
                model=model,
                messages=messages,
                temperature=0,
            )
            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:
            litellm.drop_params = True
            response = await litellm.acompletion(
                model=model,
                messages=messages,
                temperature=0,
            )
            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):
    fields = fields or ["text"]
    if isinstance(data, dict):
        return {k: remove_fields(v, fields)
            for k, v in data.items() if k not in fields}
    elif isinstance(data, list):
        return [remove_fields(item, fields) for item in 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):
        if not structure['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.
    Find nodes whose line_num falls within [min(page_nums), max(page_nums)] and return their text.
    """
    if not page_nums:
        return []
    min_line, max_line = min(page_nums), max(page_nums)
    results = []
    seen = set()

    def _traverse(nodes):
        for node in nodes:
            ln = node.get('line_num')
            if ln and min_line <= ln <= max_line 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