import asyncio
import hashlib
import logging
import os
from typing import List

from db.db import get_db
from db.models import CompanyTable
from langchain_core.prompts import ChatPromptTemplate
from langchain_openai import ChatOpenAI
from schemas.router_schemas import CompanyData, PaginatedResponse
from sqlalchemy import text
from sqlalchemy.orm import selectinload

logger = logging.getLogger(__name__)


class CompanyQueryProcessor:
    def __init__(self):
        self.llm = ChatOpenAI(
            api_key=os.getenv("OPENROUTER_API_KEY"),
            base_url="https://openrouter.ai/api/v1",
            model="openai/gpt-4o-mini",
            temperature=0,
        )

        # Query cache for performance
        self.query_cache = {}

        # SQL generation prompt
        self.sql_prompt = ChatPromptTemplate.from_messages(
            [
                (
                    "system",
                    """You are a SQL expert. Generate a SQLite query to find company IDs based on user requirements.

Database Schema:
- companies: id, name, industry, location, description, founded_year, website
- company_sector: company_id, sector_id
- sectors: id, name
- investor_companies: investor_id, company_id
- investors: id, name, aum
- team_members: id, company_id, name, title

IMPORTANT RULES:
1. ALWAYS return ONLY company IDs (companies.id) - use SELECT DISTINCT c.id
2. For industry: Check BOTH industry field AND sectors table with synonyms
   - Use LEFT JOIN for sectors so companies without sector tags still match
   - Include related terms: 'Fintech' → c.industry LIKE '%Fintech%' OR c.industry LIKE '%Finance%' OR sec.name LIKE '%Fintech%' OR sec.name LIKE '%Financial%'
   - 'AI' → c.industry LIKE '%AI%' OR c.industry LIKE '%Artificial Intelligence%' OR c.industry LIKE '%Machine Learning%' OR sec.name LIKE '%AI%' OR sec.name LIKE '%ML%'
3. For location: Be FLEXIBLE with variations and abbreviations
   - 'San Francisco' → c.location LIKE '%San Francisco%' OR c.location LIKE '%SF%' OR c.location LIKE '%Bay Area%'
   - 'New York' → c.location LIKE '%New York%' OR c.location LIKE '%NYC%' OR c.location LIKE '%NY%'
   - 'Europe' → c.location LIKE '%Europe%' OR c.location LIKE '%UK%' OR c.location LIKE '%London%' OR c.location LIKE '%Berlin%' OR c.location LIKE '%Paris%'
4. For sectors: Use LEFT JOIN and include multiple synonyms
   - 'Healthcare' → sec.name LIKE '%Healthcare%' OR sec.name LIKE '%Health%' OR sec.name LIKE '%Medical%' OR sec.name LIKE '%Biotech%' OR c.industry LIKE '%Health%'
5. For founding year filters (include NULL to be inclusive):
   - "founded after 2020" → WHERE (founded_year >= 2020 OR founded_year IS NULL)
   - "founded before 2018" → WHERE (founded_year <= 2018 OR founded_year IS NULL)
   - "founded in 2020" → WHERE founded_year = 2020
6. For investor-related queries: Use JOIN investor_companies
7. Use LEFT JOIN for sectors so companies without tags still match
8. Use DISTINCT to avoid duplicates from joins
9. Be INCLUSIVE - use OR conditions with synonyms and variations
10. Return a single, complete SELECT query

Example Queries:
Q: "Fintech companies founded in 2020"
A: SELECT DISTINCT c.id FROM companies c 
   LEFT JOIN company_sector cs ON c.id = cs.company_id 
   LEFT JOIN sectors sec ON cs.sector_id = sec.id 
   WHERE (c.industry LIKE '%Fintech%' OR c.industry LIKE '%Finance%' OR c.industry LIKE '%Financial%' OR sec.name LIKE '%Fintech%' OR sec.name LIKE '%Financial Services%') 
   AND c.founded_year = 2020

Q: "AI companies in San Francisco"
A: SELECT DISTINCT c.id FROM companies c 
   LEFT JOIN company_sector cs ON c.id = cs.company_id 
   LEFT JOIN sectors sec ON cs.sector_id = sec.id 
   WHERE (c.industry LIKE '%AI%' OR c.industry LIKE '%Artificial Intelligence%' OR c.industry LIKE '%Machine Learning%' OR sec.name LIKE '%AI%' OR sec.name LIKE '%Machine Learning%' OR sec.name LIKE '%ML%') 
   AND (c.location LIKE '%San Francisco%' OR c.location LIKE '%SF%' OR c.location LIKE '%Bay Area%')

Q: "Healthcare companies"
A: SELECT DISTINCT c.id FROM companies c 
   LEFT JOIN company_sector cs ON c.id = cs.company_id 
   LEFT JOIN sectors sec ON cs.sector_id = sec.id 
   WHERE c.industry LIKE '%Healthcare%' OR c.industry LIKE '%Health%' OR c.industry LIKE '%Medical%' OR sec.name LIKE '%Healthcare%' OR sec.name LIKE '%Medical%' OR sec.name LIKE '%Biotech%' OR sec.name LIKE '%Pharma%'

Q: "Companies funded by Sequoia"
A: SELECT DISTINCT c.id FROM companies c 
   JOIN investor_companies ic ON c.id = ic.company_id 
   JOIN investors i ON ic.investor_id = i.id 
   WHERE i.name LIKE '%Sequoia%'

Q: "European startups founded after 2019"
A: SELECT DISTINCT c.id FROM companies c 
   WHERE (c.location LIKE '%Europe%' OR c.location LIKE '%UK%' OR c.location LIKE '%London%' OR c.location LIKE '%Germany%' OR c.location LIKE '%Berlin%' OR c.location LIKE '%France%' OR c.location LIKE '%Paris%') 
   AND (c.founded_year > 2019 OR c.founded_year IS NULL)

Q: "SaaS companies"
A: SELECT DISTINCT c.id FROM companies c 
   LEFT JOIN company_sector cs ON c.id = cs.company_id 
   LEFT JOIN sectors sec ON cs.sector_id = sec.id 
   WHERE c.industry LIKE '%SaaS%' OR c.industry LIKE '%Software%' OR c.industry LIKE '%Cloud%' OR sec.name LIKE '%SaaS%' OR sec.name LIKE '%Software%'

IMPORTANT: 
- Use LEFT JOIN so companies without sector tags still match via industry field
- Use OR conditions with related keywords/synonyms to cast a wider net
- Include NULL checks for optional filters to avoid excluding companies with missing data

Return ONLY the SQL query, no explanations or markdown.""",
                ),
                ("user", "{question}"),
            ]
        )

    def _get_cache_key(self, question: str) -> str:
        """Generate cache key from normalized question."""
        return hashlib.md5(question.lower().strip().encode()).hexdigest()

    # synchronous helper is provided below as `_process_query_sync` and an
    # async wrapper `process_query` runs it in a thread. This keeps the
    # FastAPI event loop non-blocking while reusing the existing sync code.
    async def process_query(self, question: str) -> PaginatedResponse[CompanyData]:
        """Async wrapper for process_query. Runs blocking work in a thread to avoid
        blocking the event loop.
        """
        return await asyncio.to_thread(self._process_query_sync, question)

    def _process_query_sync(self, question: str) -> PaginatedResponse[CompanyData]:
        """Synchronous implementation of process_query. This is run in a thread by
        the async wrapper above.
        """
        cache_key = self._get_cache_key(question)

        # Check cache first
        if cache_key in self.query_cache:
            sql_query = self.query_cache[cache_key]
            logger.info(f"Using cached SQL: {sql_query}")
        else:
            # Generate SQL query
            messages = self.sql_prompt.format_messages(question=question)
            response = self.llm.invoke(messages)
            sql_query = response.content.strip()

            # Clean up SQL (remove markdown code blocks if present)
            sql_query = sql_query.replace("```sql", "").replace("```", "").strip()

            # Cache the query
            self.query_cache[cache_key] = sql_query
            logger.info(f"Generated SQL: {sql_query}")

        # Execute query to get company IDs
        db_session = next(get_db())
        try:
            result = db_session.execute(text(sql_query))
            company_ids = [row[0] for row in result.fetchall()]
            logger.info(
                f"Found {len(company_ids)} company IDs: {company_ids[:10]}{'...' if len(company_ids) > 10 else ''}"
            )

            return self._fetch_companies_by_ids(company_ids)
        except Exception as e:
            logger.error(f"SQL execution error: {e}")
            logger.error(f"Failed SQL: {sql_query}")
            # Return empty result
            return PaginatedResponse(
                items=[], total=0, page=1, page_size=10, total_pages=0
            )
        finally:
            db_session.close()

    def _fetch_companies_by_ids(
        self, company_ids: List[int]
    ) -> PaginatedResponse[CompanyData]:
        """Fetch companies with all their relationships from the database using company IDs.

        Args:
            company_ids: List of company IDs to fetch
        """
        if not company_ids:
            return PaginatedResponse(
                items=[],
                total=0,
                page=1,
                page_size=10,
                total_pages=0,
            )

        # Get database session
        db_session = next(get_db())

        try:
            # Query companies with all necessary relationships loaded
            companies = (
                db_session.query(CompanyTable)
                .options(
                    selectinload(CompanyTable.investors),
                    selectinload(CompanyTable.members),
                    selectinload(CompanyTable.sectors),
                )
                .filter(CompanyTable.id.in_(company_ids))
                .all()
            )

            # Transform to CompanyData format
            company_data_list = []
            for company in companies:
                company_data = CompanyData(
                    company=company,
                    investors=company.investors,
                    members=company.members,
                    sectors=company.sectors,
                )
                company_data_list.append(company_data)

            total_count = len(company_data_list)
            total_pages = 1 if total_count > 0 else 0

            return PaginatedResponse(
                items=company_data_list,
                total=total_count,
                page=1,
                page_size=total_count,
                total_pages=total_pages,
            )

        finally:
            db_session.close()