import re
import logging
import time
from typing import List, Dict, Any, Optional, Tuple
from random import sample, shuffle

from langchain_core.output_parsers import StrOutputParser, JsonOutputParser
from langchain_core.runnables import Runnable, RunnablePassthrough
from langchain_core.pydantic_v1 import Field, BaseModel as V1BaseModel # For grader models if needed

from .config import settings
from .graph_client import neo4j_client # Use the central client
from .llm_interface import get_llm, invoke_llm
from .prompts import (
    CYPHER_GENERATION_PROMPT, CONCEPT_SELECTION_PROMPT,
    BINARY_GRADER_PROMPT, SCORE_GRADER_PROMPT
)
from .schemas import KeyIssue # Import if needed here, maybe not

logger = logging.getLogger(__name__)

# --- Helper Functions ---
def extract_cypher(text: str) -> str:
    """Extracts the first Cypher code block or returns the text itself."""
    pattern = r"```(?:cypher)?\s*(.*?)\s*```"
    match = re.search(pattern, text, re.DOTALL | re.IGNORECASE)
    return match.group(1).strip() if match else text.strip()

def format_doc_for_llm(doc: Dict[str, Any]) -> str:
    """Formats a document dictionary into a string for LLM context."""
    return "\n".join(f"**{key}**: {value}" for key, value in doc.items() if value)


# --- Cypher Generation ---
def generate_cypher_auto(question: str) -> str:
    """Generates Cypher using the 'auto' method."""
    logger.info("Generating Cypher using 'auto' method.")
    # Schema fetching needs implementation if required by the prompt/LLM
    # schema_info = neo4j_client.get_schema() # Placeholder
    schema_info = "Schema not available." # Default if not implemented

    cypher_llm = get_llm(settings.main_llm_model) # Or a specific cypher model
    chain = (
        {"question": RunnablePassthrough(), "schema": lambda x: schema_info}
        | CYPHER_GENERATION_PROMPT
        | cypher_llm
        | StrOutputParser()
        | extract_cypher
    )
    return invoke_llm(chain,question)

def generate_cypher_guided(question: str, plan_step: int) -> str:
    """Generates Cypher using the 'guided' method based on concepts."""
    logger.info(f"Generating Cypher using 'guided' method for plan step {plan_step}.")
    try:
        concepts = neo4j_client.get_concepts()
        if not concepts:
            logger.warning("No concepts found in Neo4j for guided cypher generation.")
            return "" # Or raise error

        concept_llm = get_llm(settings.main_llm_model) # Or a specific concept model
        concept_chain = (
            CONCEPT_SELECTION_PROMPT
            | concept_llm
            | StrOutputParser()
        )
        selected_concept = invoke_llm(concept_chain,{
            "question": question,
            "concepts": "\n".join(concepts)
        }).strip()

        logger.info(f"Concept selected by LLM: {selected_concept}")

        # Basic check if the selected concept is valid
        if selected_concept not in concepts:
             logger.warning(f"LLM selected concept '{selected_concept}' not in the known list. Attempting fallback or ignoring.")
             # Optional: Add fuzzy matching or similarity search here
             # For now, we might default or return empty
             # Let's try a simple substring check as a fallback
             found_match = None
             for c in concepts:
                 if selected_concept.lower() in c.lower():
                     found_match = c
                     logger.info(f"Found potential match: '{found_match}'")
                     break
             if not found_match:
                 logger.error(f"Could not validate selected concept: {selected_concept}")
                 return "" # Return empty query if concept is invalid
             selected_concept = found_match


        # Determine the target node type based on plan step (example logic)
        # This mapping might need adjustment based on the actual plan structure
        if plan_step <= 1: # Steps 0 and 1: Context gathering
             target = "(ts:TechnicalSpecification)"
             fields = "ts.title, ts.scope, ts.description"
        elif plan_step == 2: # Step 2: Research papers?
             target = "(rp:ResearchPaper)"
             fields = "rp.title, rp.abstract"
        else: # Later steps might involve KeyIssues themselves or other types
             target = "(n)" # Generic fallback
             fields = "n.title, n.description" # Assuming common fields

        # Construct Cypher query
        # Ensure selected_concept is properly escaped if needed, though parameters are safer
        cypher = f"MATCH (c:Concept {{name: $conceptName}})-[:RELATED_TO]-{target} RETURN {fields}"
        # We return the query and the parameters separately for safe execution
        # However, the planner currently expects just the string. Let's construct it directly for now.
        # Be cautious about injection if concept names can contain special chars. Binding is preferred.
        escaped_concept = selected_concept.replace("'", "\\'") # Basic escaping
        cypher = f"MATCH (c:Concept {{name: '{escaped_concept}'}})-[:RELATED_TO]-{target} RETURN {fields}"

        logger.info(f"Generated guided Cypher: {cypher}")
        return cypher

    except Exception as e:
        logger.error(f"Error during guided cypher generation: {e}", exc_info=True)
        time.sleep(60)
        return "" # Return empty on error


# --- Document Retrieval ---
def retrieve_documents(cypher_query: str) -> List[Dict[str, Any]]:
    """Retrieves documents from Neo4j using a Cypher query."""
    if not cypher_query:
        logger.warning("Received empty Cypher query, skipping retrieval.")
        return []
    logger.info(f"Retrieving documents with Cypher: {cypher_query} limit 10")
    try:
        # Use the centralized client's query method
        raw_results = neo4j_client.query(cypher_query + " limit 10")
        # Basic cleaning/deduplication (can be enhanced)
        processed_results = []
        seen = set()
        for doc in raw_results:
             # Create a frozenset of items for hashable representation to detect duplicates
             doc_items = frozenset(doc.items())
             if doc_items not in seen:
                 processed_results.append(doc)
                 seen.add(doc_items)
        logger.info(f"Retrieved {len(processed_results)} unique documents.")
        return processed_results
    except (ConnectionError, ValueError, RuntimeError) as e:
        # Errors already logged in neo4j_client
        logger.error(f"Document retrieval failed: {e}")
        return [] # Return empty list on failure


# --- Document Evaluation ---
# Define Pydantic models for structured LLM grader output (if not using built-in LCEL structured output)
class GradeDocumentsBinary(V1BaseModel):
    """Binary score for relevance check."""
    binary_score: str = Field(description="Relevant? 'yes' or 'no'")

class GradeDocumentsScore(V1BaseModel):
     """Score for relevance check."""
     rationale: str = Field(description="Rationale for the score.")
     score: float = Field(description="Relevance score (0.0 to 1.0)")

def evaluate_documents(
    docs: List[Dict[str, Any]],
    query: str
) -> List[Dict[str, Any]]:
    """Evaluates document relevance to a query using configured method."""
    if not docs:
        return []

    logger.info(f"Evaluating {len(docs)} documents for relevance to query: '{query}' using method: {settings.eval_method}")
    eval_llm = get_llm(settings.eval_llm_model)
    valid_docs_with_scores: List[Tuple[Dict[str, Any], float]] = []

    # Consider using LCEL's structured output capabilities directly if the model supports it well
    # This simplifies parsing. Example for binary:
    # binary_grader = BINARY_GRADER_PROMPT | eval_llm.with_structured_output(GradeDocumentsBinary)

    if settings.eval_method == "binary":
        binary_grader = BINARY_GRADER_PROMPT | eval_llm | StrOutputParser() # Fallback to string parsing
        for doc in docs:
            formatted_doc = format_doc_for_llm(doc)
            if not formatted_doc.strip(): continue
            try:
                result = invoke_llm(binary_grader,{"question": query, "document": formatted_doc})
                logger.debug(f"Binary grader result for doc '{doc.get('title', 'N/A')}': {result}")
                if result and 'yes' in result.lower():
                    valid_docs_with_scores.append((doc, 1.0)) # Score 1.0 for relevant
            except Exception as e:
                logger.warning(f"Binary grading failed for a document: {e}", exc_info=True)

    elif settings.eval_method == "score":
        # Using JSON parser as a robust fallback for score extraction
        score_grader = SCORE_GRADER_PROMPT | eval_llm | JsonOutputParser(pydantic_object=GradeDocumentsScore)
        for doc in docs:
            formatted_doc = format_doc_for_llm(doc)
            if not formatted_doc.strip(): continue
            try:
                result: GradeDocumentsScore = invoke_llm(score_grader,{"query": query, "document": formatted_doc})
                logger.debug(f"Score grader result for doc '{doc.get('title', 'N/A')}': Score={result.score}, Rationale={result.rationale}")
                if result.score >= settings.eval_threshold:
                    valid_docs_with_scores.append((doc, result.score))
            except Exception as e:
                logger.warning(f"Score grading failed for a document: {e}", exc_info=True)
                # Optionally treat as relevant on failure? Or skip? Skipping for now.

    # Sort by score if applicable, then limit
    if settings.eval_method == 'score':
        valid_docs_with_scores.sort(key=lambda item: item[1], reverse=True)

    # Limit to max_docs
    final_docs = [doc for doc, score in valid_docs_with_scores[:settings.max_docs]]
    logger.info(f"Found {len(final_docs)} relevant documents after evaluation and filtering.")

    return final_docs