"""
SOCAR Hackathon - Complete API with /ocr and /llm endpoints
Optimized based on comprehensive benchmarking:
- OCR: Llama-4-Maverick-17B (87.75% CSR)
- LLM: citation_focused + vanilla_k3 + Llama-4-Maverick (55.67% score)
"""

import os
import re
import time
import base64
import gc
from typing import List, Dict
from pathlib import Path
from io import BytesIO

import fitz  # PyMuPDF
from PIL import Image
from fastapi import FastAPI, HTTPException, File, UploadFile, Request
from fastapi.middleware.cors import CORSMiddleware
from fastapi.middleware.trustedhost import TrustedHostMiddleware
from fastapi.staticfiles import StaticFiles
from fastapi.templating import Jinja2Templates
from fastapi.responses import Response
from starlette.middleware.base import BaseHTTPMiddleware
from pydantic import BaseModel
from dotenv import load_dotenv
from openai import AzureOpenAI
from pinecone import Pinecone
from sentence_transformers import SentenceTransformer

# Load environment variables
load_dotenv()

# Get the directory where main.py is located for absolute path resolution
BASE_DIR = Path(__file__).resolve().parent

# Initialize FastAPI app
app = FastAPI(
    title="SOCAR Historical Documents AI System",
    description="RAG-based chatbot for SOCAR oil & gas historical documents with OCR capabilities",
    version="1.0.0"
)

# Security Headers Middleware for production
class SecurityHeadersMiddleware(BaseHTTPMiddleware):
    """Add security headers to all responses for production deployment."""

    async def dispatch(self, request: Request, call_next):
        response = await call_next(request)

        # Only add security headers in production (when HTTPS is enabled)
        if os.getenv("PRODUCTION", "false").lower() == "true":
            response.headers["Strict-Transport-Security"] = "max-age=63072000; includeSubDomains; preload"
            response.headers["X-Content-Type-Options"] = "nosniff"
            response.headers["X-Frame-Options"] = "SAMEORIGIN"
            response.headers["X-XSS-Protection"] = "1; mode=block"
            response.headers["Referrer-Policy"] = "strict-origin-when-cross-origin"
            response.headers["Permissions-Policy"] = "geolocation=(), microphone=(), camera=()"

        return response

# Add security headers middleware
app.add_middleware(SecurityHeadersMiddleware)

# Trusted Host Middleware for production (prevents host header attacks)
trusted_hosts = os.getenv("TRUSTED_HOSTS", "*").split(",")
if trusted_hosts != ["*"]:
    app.add_middleware(TrustedHostMiddleware, allowed_hosts=trusted_hosts)

# CORS middleware - configurable for production
# In production, set ALLOWED_ORIGINS environment variable to your domain(s)
# Example: ALLOWED_ORIGINS=https://yourdomain.com,https://www.yourdomain.com
allowed_origins = os.getenv("ALLOWED_ORIGINS", "*").split(",")
app.add_middleware(
    CORSMiddleware,
    allow_origins=allowed_origins if allowed_origins != ["*"] else ["*"],
    allow_credentials=True,
    allow_methods=["GET", "POST", "OPTIONS"],
    allow_headers=["Content-Type", "Authorization", "X-Requested-With"],
)

# Mount static files and templates using absolute paths for production reliability
STATIC_DIR = BASE_DIR / "static"
TEMPLATES_DIR = BASE_DIR / "templates"
app.mount("/static", StaticFiles(directory=str(STATIC_DIR)), name="static")
templates = Jinja2Templates(directory=str(TEMPLATES_DIR))

# Initialize clients (lazy loading for faster startup)
azure_client = None
pinecone_index = None
embedding_model = None


def get_azure_client():
    """Lazy load Azure OpenAI client"""
    global azure_client
    if azure_client is None:
        azure_client = AzureOpenAI(
            api_key=os.getenv("AZURE_OPENAI_API_KEY"),
            api_version=os.getenv("AZURE_OPENAI_API_VERSION", "2024-08-01-preview"),
            azure_endpoint=os.getenv("AZURE_OPENAI_ENDPOINT")
        )
    return azure_client


def get_pinecone_index():
    """Lazy load Pinecone index"""
    global pinecone_index
    if pinecone_index is None:
        pc = Pinecone(api_key=os.getenv("PINECONE_API_KEY"))
        pinecone_index = pc.Index(os.getenv("PINECONE_INDEX_NAME", "hackathon"))
    return pinecone_index


def get_embedding_model():
    """Lazy load local embedding model (same as ingestion: BAAI/bge-large-en-v1.5)"""
    global embedding_model
    if embedding_model is None:
        print("Loading BAAI/bge-large-en-v1.5 embedding model...")
        embedding_model = SentenceTransformer("BAAI/bge-large-en-v1.5")
        print("✅ Embedding model loaded")
    return embedding_model


def get_embedding(text: str) -> List[float]:
    """
    Generate embedding for semantic search.

    Uses BAAI/bge-large-en-v1.5 (same as document ingestion) for consistent embeddings.
    Returns 1024-dimensional vector matching Pinecone index.
    """
    try:
        model = get_embedding_model()
        embedding = model.encode(text).tolist()
        return embedding
    except Exception as e:
        print(f"Embedding error: {e}")
        # Return zero vector (will not match documents, but API won't crash)
        return [0.0] * 1024


# Request/Response models
class ChatMessage(BaseModel):
    role: str
    content: str


class ChatRequest(BaseModel):
    messages: List[ChatMessage]
    temperature: float = 0.2
    max_tokens: int = 1000


class ChatResponse(BaseModel):
    response: str
    sources: List[Dict[str, str]]
    response_time: float
    model: str


class QuestionRequest(BaseModel):
    question: str
    temperature: float = 0.2
    max_tokens: int = 1000


class AnswerResponse(BaseModel):
    answer: str
    sources: List[Dict]
    response_time: float


def retrieve_documents(query: str, top_k: int = 3) -> List[Dict]:
    """
    Retrieve relevant documents from Pinecone vector database.
    Best strategy from benchmark: vanilla top-3 with BAAI/bge-large-en-v1.5

    Uses BAAI/bge-large-en-v1.5 embeddings (1024-dim, same as ingestion).
    """
    index = get_pinecone_index()

    # Generate query embedding
    query_embedding = get_embedding(query)

    # Search vector database
    results = index.query(
        vector=query_embedding,
        top_k=top_k,
        include_metadata=True
    )

    # Extract documents
    documents = []
    for match in results['matches']:
        # Ensure page_number is always an integer (Pinecone may return float)
        page_num = match['metadata'].get('page_number', 0)
        page_num = int(page_num) if isinstance(page_num, (int, float)) else 0

        documents.append({
            'pdf_name': match['metadata'].get('pdf_name', 'unknown.pdf'),
            'page_number': page_num,
            'content': match['metadata'].get('content', ''),  # Changed from 'text' to 'content'
            'score': match.get('score', 0.0)
        })

    return documents


def generate_answer(query: str, documents: List[Dict], temperature: float = 0.2, max_tokens: int = 1000) -> tuple[str, float]:
    """
    Generate answer using best-performing configuration.
    Model: Llama-4-Maverick-17B (open-source)
    Prompt: citation_focused (best citation score: 73.33%)
    """
    client = get_azure_client()

    # Build context from retrieved documents
    context_parts = []
    for i, doc in enumerate(documents, 1):
        context_parts.append(
            f"Sənəd {i} (Mənbə: {doc['pdf_name']}, Səhifə {doc['page_number']}):\n{doc['content']}"
        )
    context = "\n\n".join(context_parts)

    # Citation-focused prompt (best performer: 55.67% score)
    prompt = f"""Siz SOCAR-ın tarixi sənədlər üzrə mütəxəssis köməkçisisiniz.

ÖNƏMLİ: Hər bir faktı mütləq mənbə ilə təsdiqləyin (PDF adı və səhifə nömrəsi).

Kontekst:
{context}

Sual: {query}

Cavab verərkən:
1. Dəqiq faktlar yazın
2. Hər faktı mənbə ilə göstərin: (PDF: fayl_adı.pdf, Səhifə: X) - səhifə nömrəsini tam ədəd (integer) olaraq yazın, məsələn "Səhifə: 11" (11.0 yox)
3. Kontekstdə olmayan məlumat əlavə etməyin"""

    try:
        start_time = time.time()

        # Use Llama-4-Maverick (open-source, best performer)
        response = client.chat.completions.create(
            model="Llama-4-Maverick-17B-128E-Instruct-FP8",
            messages=[{"role": "user", "content": prompt}],
            temperature=temperature,
            max_tokens=max_tokens
        )

        elapsed = time.time() - start_time
        answer = response.choices[0].message.content

        return answer, elapsed

    except Exception as e:
        raise HTTPException(status_code=500, detail=f"LLM Error: {str(e)}")


@app.get("/")
async def root(request: Request):
    """Serve the frontend web application"""
    return templates.TemplateResponse("index.html", {"request": request})


@app.get("/health")
async def health():
    """Detailed health check"""
    try:
        # Check if services are initialized
        index = get_pinecone_index()
        stats = index.describe_index_stats()

        return {
            "status": "healthy",
            "pinecone": {
                "connected": True,
                "total_vectors": stats.get('total_vector_count', 0)
            },
            "azure_openai": "connected",
            "embedding_model": "loaded"
        }
    except Exception as e:
        return {
            "status": "degraded",
            "error": str(e)
        }


@app.post("/llm")
async def llm_endpoint(request: Request):
    """
    LLM chatbot endpoint for SOCAR historical documents.

    Uses RAG (Retrieval Augmented Generation) with:
    - Embedding: BAAI/bge-large-en-v1.5 @ 1024-dim (local model)
    - Retrieval: Top-3 documents (Pinecone)
    - LLM: Llama-4-Maverick-17B (open-source)
    - Prompt: Citation-focused

    Expected performance:
    - Response time: ~3.6s
    - LLM Judge Score: 55.67%
    - Citation Score: 73.33%

    Accepts two formats:
    1. QuestionRequest: {"question": "...", "temperature": 0.2, "max_tokens": 1000}
    2. ChatRequest: {"messages": [{"role": "user", "content": "..."}], ...}

    ALWAYS returns: {"answer": str, "sources": List[Dict]}
    """
    try:
        # Parse request body
        try:
            body = await request.json()
        except:
            # Empty or invalid JSON - return error in expected format
            return AnswerResponse(
                answer="Error: Invalid JSON in request body. Please send valid JSON with 'question' field.",
                sources=[],
                response_time=0.0
            )

        # Handle list format (validator sends list directly)
        if isinstance(body, list):
            # Validator format: [{"role": "user", "content": "..."}]
            user_messages = [msg for msg in body if isinstance(msg, dict) and msg.get("role") == "user"]
            if not user_messages:
                return AnswerResponse(
                    answer="Error: No user message found in messages array.",
                    sources=[],
                    response_time=0.0
                )
            query = user_messages[-1].get("content")
            if not query or not query.strip():
                return AnswerResponse(
                    answer="Error: Empty message content provided.",
                    sources=[],
                    response_time=0.0
                )
            temperature = 0.2
            max_tokens = 1000
        # Determine request format and extract query
        elif "question" in body:
            # QuestionRequest format
            query = body.get("question")
            if not query or not query.strip():
                return AnswerResponse(
                    answer="Error: Empty question provided. Please provide a valid question.",
                    sources=[],
                    response_time=0.0
                )
            temperature = body.get("temperature", 0.2)
            max_tokens = body.get("max_tokens", 1000)
        elif "messages" in body:
            # ChatRequest format
            messages = body.get("messages", [])
            if not messages:
                return AnswerResponse(
                    answer="Error: No messages provided in request.",
                    sources=[],
                    response_time=0.0
                )

            user_messages = [msg for msg in messages if msg.get("role") == "user"]
            if not user_messages:
                return AnswerResponse(
                    answer="Error: No user message found in messages array.",
                    sources=[],
                    response_time=0.0
                )

            query = user_messages[-1].get("content")
            if not query or not query.strip():
                return AnswerResponse(
                    answer="Error: Empty message content provided.",
                    sources=[],
                    response_time=0.0
                )
            temperature = body.get("temperature", 0.2)
            max_tokens = body.get("max_tokens", 1000)
        else:
            # No question or messages field - return error in expected format
            return AnswerResponse(
                answer="Error: Invalid request format. Expected 'question' or 'messages' field in request body.",
                sources=[],
                response_time=0.0
            )

        # Retrieve relevant documents (top-3 is optimal per benchmarks)
        documents = retrieve_documents(query, top_k=3)

        # Generate answer
        answer, response_time = generate_answer(
            query=query,
            documents=documents,
            temperature=temperature,
            max_tokens=max_tokens
        )

        # Format sources for response (validator expects pdf_name, page_number, content)
        sources = [
            {
                "pdf_name": doc['pdf_name'],
                "page_number": doc['page_number'],  # Already converted to int
                "content": doc['content']  # The actual document text
            }
            for doc in documents
        ]

        # Always return AnswerResponse format (validator expects 'answer' and 'sources' keys)
        return AnswerResponse(
            answer=answer,
            sources=sources,
            response_time=round(response_time, 2)
        )

    except Exception as e:
        # Always return expected format, even for errors
        return AnswerResponse(
            answer=f"Error: {str(e)}",
            sources=[],
            response_time=0.0
        )


# ============================================================================
# OCR ENDPOINT
# ============================================================================

class OCRPageResponse(BaseModel):
    page_number: int
    MD_text: str


def process_pdf_page(pdf_bytes: bytes, page_num: int, dpi: int = 100) -> tuple[str, int]:
    """
    Process a single PDF page for OCR (memory efficient).

    Returns: (base64_image, num_embedded_images)
    """
    doc = fitz.open(stream=pdf_bytes, filetype="pdf")
    page = doc[page_num - 1]  # 0-indexed

    # Convert page to image
    zoom = dpi / 72
    mat = fitz.Matrix(zoom, zoom)
    pix = page.get_pixmap(matrix=mat)

    # Convert to PIL Image
    img = Image.frombytes("RGB", [pix.width, pix.height], pix.samples)

    # Count embedded images
    image_list = page.get_images()
    num_images = len(image_list)

    doc.close()
    del pix, page, doc  # Explicit cleanup

    # Convert to base64 JPEG with good quality
    buffered = BytesIO()
    img.save(buffered, format="JPEG", quality=85, optimize=True)
    img_base64 = base64.b64encode(buffered.getvalue()).decode("utf-8")

    del img, buffered  # Explicit cleanup
    gc.collect()  # Force garbage collection

    return img_base64, num_images


@app.post("/ocr", response_model=List[OCRPageResponse])
async def ocr_endpoint(file: UploadFile = File(...)):
    """
    OCR endpoint for PDF text extraction with image detection.

    **Memory-optimized**:
    - Processes ONE page at a time (not all pages in memory)
    - 100 DPI for best OCR accuracy
    - JPEG quality 85%
    - Immediate garbage collection after each page

    Uses VLM (Llama-4-Maverick-17B) for best accuracy:
    - Character Success Rate: 87.75%
    - Processing: ~6s per page

    Returns:
        List of {page_number, MD_text} with inline image references
    """
    try:
        # Read PDF
        pdf_bytes = await file.read()
        pdf_filename = file.filename or "document.pdf"

        # Get page count
        doc = fitz.open(stream=pdf_bytes, filetype="pdf")
        total_pages = len(doc)
        doc.close()

        # Optional page limit (configurable via env var, default: no limit)
        max_pages = int(os.getenv("OCR_MAX_PAGES", "0"))  # 0 = unlimited
        if max_pages > 0 and total_pages > max_pages:
            raise HTTPException(
                status_code=400,
                detail=f"PDF has {total_pages} pages. Current limit is {max_pages} pages. Please split your PDF or increase OCR_MAX_PAGES environment variable."
            )

        # OCR system prompt
        system_prompt = """You are an expert OCR system for historical oil & gas documents.

Extract ALL text from the image with 100% accuracy. Follow these rules:
1. Preserve EXACT spelling - including Azerbaijani, Russian, and English text
2. Maintain original Cyrillic characters - DO NOT transliterate
3. Keep all numbers, symbols, and special characters exactly as shown
4. Preserve layout structure (paragraphs, line breaks)
5. Include ALL text - headers, body, footnotes, tables, captions

Output ONLY the extracted text. No explanations, no descriptions."""

        # Process each page ONE AT A TIME (memory efficient)
        results = []
        client = get_azure_client()

        for page_num in range(1, total_pages + 1):
            # Process single page (returns base64 image and releases memory immediately)
            image_base64, num_images = process_pdf_page(pdf_bytes, page_num, dpi=100)

            # VLM OCR
            messages = [
                {"role": "system", "content": system_prompt},
                {
                    "role": "user",
                    "content": [
                        {"type": "text", "text": f"Extract all text from page {page_num}:"},
                        {"type": "image_url", "image_url": {"url": f"data:image/jpeg;base64,{image_base64}"}}
                    ]
                }
            ]

            response = client.chat.completions.create(
                model="Llama-4-Maverick-17B-128E-Instruct-FP8",
                messages=messages,
                temperature=0.0,  # Deterministic OCR
                max_tokens=4000
            )

            page_text = response.choices[0].message.content

            # Add image references if images exist on this page
            if num_images > 0:
                for img_idx in range(1, num_images + 1):
                    page_text += f"\n\n![Image]({pdf_filename}/page_{page_num}/image_{img_idx})\n\n"

            results.append({
                "page_number": page_num,
                "MD_text": page_text
            })

            # Force cleanup after each page
            del image_base64, messages, response
            gc.collect()

        return results

    except HTTPException:
        raise
    except Exception as e:
        raise HTTPException(status_code=500, detail=f"OCR Error: {str(e)}")


if __name__ == "__main__":
    import uvicorn
    uvicorn.run(app, host="0.0.0.0", port=8000)