"""
API REST para RAG Template usando FastAPI.

Endpoints principais:
- POST /api/v1/ingest - Ingestao de documentos
- POST /api/v1/query - Query RAG
- GET /api/v1/documents - Listar documentos
- DELETE /api/v1/documents/{id} - Deletar documento
- GET /api/v1/health - Health check
"""

from typing import List, Optional, Dict, Any
from datetime import datetime
from fastapi import FastAPI, HTTPException, Depends, status, File, UploadFile, Header
from fastapi.responses import JSONResponse
from fastapi.middleware.cors import CORSMiddleware
from pydantic import BaseModel, Field
import os
import tempfile
from pathlib import Path

from src.database import DatabaseManager
from src.embeddings import EmbeddingManager
from src.generation import GenerationManager
from src.document_processing import DocumentProcessor
from src.chunking import ChunkingStrategy
from src.metadata import MetadataManager, DocumentMetadata
from src.config import DATABASE_URL
from src.monitoring import get_metrics_collector, get_tracing_manager


# Schemas Pydantic

class IngestRequest(BaseModel):
    """Request para ingestao de documento."""
    text: str = Field(..., description="Texto do documento")
    title: str = Field(..., description="Titulo do documento")
    chunk_size: int = Field(default=1000, ge=100, le=5000, description="Tamanho dos chunks")
    chunk_overlap: int = Field(default=200, ge=0, le=1000, description="Overlap entre chunks")
    strategy: str = Field(default="recursive", description="Estrategia de chunking")
    metadata: Optional[Dict[str, Any]] = Field(default=None, description="Metadados do documento")


class IngestResponse(BaseModel):
    """Response da ingestao."""
    document_id: int
    num_chunks: int
    message: str
    metadata: Optional[Dict[str, Any]] = None


class QueryRequest(BaseModel):
    """Request para query RAG."""
    query: str = Field(..., min_length=1, description="Query do usuario")
    top_k: int = Field(default=5, ge=1, le=20, description="Numero de resultados")
    temperature: float = Field(default=0.3, ge=0.0, le=2.0, description="Temperature para geracao")
    max_tokens: int = Field(default=512, ge=50, le=2048, description="Tokens maximos")
    model: Optional[str] = Field(default=None, description="Modelo LLM a usar")
    filters: Optional[Dict[str, Any]] = Field(default=None, description="Filtros de metadata")


class QueryResponse(BaseModel):
    """Response da query."""
    query: str
    response: str
    contexts: List[Dict[str, Any]]
    metadata: Dict[str, Any]


class DocumentResponse(BaseModel):
    """Response de documento."""
    id: int
    title: str
    content: Optional[str] = None
    chunk_count: int
    created_at: Optional[str] = None
    metadata: Optional[Dict[str, Any]] = None


class HealthResponse(BaseModel):
    """Response do health check."""
    status: str
    timestamp: str
    database: str
    embeddings: str
    version: str


# API Key Authentication

API_KEYS = set(os.getenv("API_KEYS", "").split(","))


async def verify_api_key(x_api_key: str = Header(...)):
    """Verifica API key."""
    if not API_KEYS or x_api_key in API_KEYS:
        return x_api_key
    raise HTTPException(
        status_code=status.HTTP_401_UNAUTHORIZED,
        detail="Invalid API key"
    )


# FastAPI App

app = FastAPI(
    title="RAG Template API",
    description="API REST para sistema RAG com PostgreSQL + pgvector",
    version="1.6.0",
    docs_url="/api/docs",
    redoc_url="/api/redoc",
    openapi_url="/api/openapi.json"
)

# CORS
app.add_middleware(
    CORSMiddleware,
    allow_origins=["*"],
    allow_credentials=True,
    allow_methods=["*"],
    allow_headers=["*"],
)

# Monitoring
metrics_collector = get_metrics_collector()
tracing_manager = get_tracing_manager(
    service_name="rag-template-api",
    otlp_endpoint=os.getenv("OTLP_ENDPOINT")
)

# Inicializar managers (lazy loading)
_db_manager = None
_embedding_manager = None
_generation_manager = None
_metadata_manager = None


def get_db_manager():
    """Obtem instancia do DatabaseManager."""
    global _db_manager
    if _db_manager is None:
        _db_manager = DatabaseManager(DATABASE_URL)
    return _db_manager


def get_embedding_manager():
    """Obtem instancia do EmbeddingManager."""
    global _embedding_manager
    if _embedding_manager is None:
        _embedding_manager = EmbeddingManager()
    return _embedding_manager


def get_generation_manager():
    """Obtem instancia do GenerationManager."""
    global _generation_manager
    if _generation_manager is None:
        _generation_manager = GenerationManager()
    return _generation_manager


def get_metadata_manager():
    """Obtem instancia do MetadataManager."""
    global _metadata_manager
    if _metadata_manager is None:
        _metadata_manager = MetadataManager(get_db_manager())
    return _metadata_manager


# Endpoints

@app.get("/api/v1/health", response_model=HealthResponse)
async def health_check():
    """Health check do sistema."""
    db_status = "healthy"
    embeddings_status = "healthy"

    try:
        db = get_db_manager()
        db.get_database_stats()
    except Exception:
        db_status = "unhealthy"

    try:
        emb = get_embedding_manager()
        emb.encode("test")
    except Exception:
        embeddings_status = "unhealthy"

    status_overall = "healthy" if db_status == "healthy" and embeddings_status == "healthy" else "degraded"

    return HealthResponse(
        status=status_overall,
        timestamp=datetime.now().isoformat(),
        database=db_status,
        embeddings=embeddings_status,
        version="1.6.0"
    )


@app.get("/metrics")
async def metrics():
    """
    Endpoint de metricas Prometheus.

    Retorna metricas no formato Prometheus.
    """
    from fastapi.responses import Response
    from prometheus_client import CONTENT_TYPE_LATEST

    metrics_data = metrics_collector.get_metrics()
    return Response(content=metrics_data, media_type=CONTENT_TYPE_LATEST)


@app.post("/api/v1/ingest", response_model=IngestResponse, dependencies=[Depends(verify_api_key)])
async def ingest_document(request: IngestRequest):
    """
    Ingere documento no sistema.

    Processa texto, divide em chunks, gera embeddings e armazena no banco.
    """
    try:
        db = get_db_manager()
        emb = get_embedding_manager()
        metadata_manager = get_metadata_manager()

        # Criar chunking strategy
        strategy_map = {
            "fixed": ChunkingStrategy.FIXED_SIZE,
            "sentence": ChunkingStrategy.SENTENCE,
            "semantic": ChunkingStrategy.SEMANTIC,
            "recursive": ChunkingStrategy.RECURSIVE
        }
        strategy = strategy_map.get(request.strategy, ChunkingStrategy.RECURSIVE)

        # Processar chunks
        from src.chunking import chunk_text
        chunks = chunk_text(
            request.text,
            strategy=strategy,
            chunk_size=request.chunk_size,
            overlap=request.chunk_overlap
        )

        if not chunks:
            raise HTTPException(status_code=400, detail="No chunks generated from text")

        # Gerar embeddings
        chunk_texts = [c.text for c in chunks]
        embeddings = emb.encode_batch(chunk_texts)

        # Criar metadata
        doc_metadata = None
        if request.metadata:
            doc_metadata = DocumentMetadata.from_dict(request.metadata)
            metadata_manager.validate_metadata(doc_metadata)

        # Inserir no banco
        session_id = f"api_{datetime.now().timestamp()}"
        document_id = db.insert_document(
            title=request.title,
            content=request.text,
            chunks=chunk_texts,
            embeddings=embeddings,
            session_id=session_id
        )

        # Atualizar metadata se fornecido
        if doc_metadata:
            metadata_manager.update_document_metadata(document_id, doc_metadata)

        return IngestResponse(
            document_id=document_id,
            num_chunks=len(chunks),
            message="Document ingested successfully",
            metadata=request.metadata
        )

    except Exception as e:
        raise HTTPException(status_code=500, detail=str(e))


@app.post("/api/v1/query", response_model=QueryResponse, dependencies=[Depends(verify_api_key)])
async def query_rag(request: QueryRequest):
    """
    Executa query RAG.

    Busca contextos relevantes e gera resposta usando LLM.
    """
    try:
        db = get_db_manager()
        emb = get_embedding_manager()
        gen = get_generation_manager()
        metadata_manager = get_metadata_manager()

        # Gerar embedding da query
        query_embedding = emb.encode(request.query)

        # Buscar contextos (com filtros se fornecido)
        if request.filters:
            contexts = metadata_manager.search_with_filters(
                query_embedding=query_embedding,
                filters=request.filters,
                top_k=request.top_k
            )
        else:
            contexts = db.search_similar(
                query_embedding=query_embedding,
                top_k=request.top_k
            )

        if not contexts:
            return QueryResponse(
                query=request.query,
                response="Desculpe, nao encontrei informacoes relevantes.",
                contexts=[],
                metadata={"num_contexts": 0, "model": request.model or "default"}
            )

        # Gerar resposta
        context_texts = [c['content'] for c in contexts]
        response = gen.generate_response(
            query=request.query,
            contexts=context_texts,
            temperature=request.temperature,
            max_tokens=request.max_tokens,
            model=request.model
        )

        return QueryResponse(
            query=request.query,
            response=response,
            contexts=contexts,
            metadata={
                "num_contexts": len(contexts),
                "model": request.model or "default",
                "temperature": request.temperature,
                "max_tokens": request.max_tokens
            }
        )

    except Exception as e:
        raise HTTPException(status_code=500, detail=str(e))


@app.get("/api/v1/documents", response_model=List[DocumentResponse], dependencies=[Depends(verify_api_key)])
async def list_documents(
    limit: int = 100,
    offset: int = 0,
    session_id: Optional[str] = None
):
    """Lista documentos no sistema."""
    try:
        db = get_db_manager()

        docs = db.list_documents(session_id=session_id, limit=limit, offset=offset)

        return [
            DocumentResponse(
                id=doc['id'],
                title=doc['title'],
                content=doc.get('content'),
                chunk_count=doc.get('chunk_count', 0),
                created_at=doc.get('created_at'),
                metadata=doc.get('metadata')
            )
            for doc in docs
        ]

    except Exception as e:
        raise HTTPException(status_code=500, detail=str(e))


@app.delete("/api/v1/documents/{document_id}", dependencies=[Depends(verify_api_key)])
async def delete_document(document_id: int):
    """Deleta documento do sistema."""
    try:
        db = get_db_manager()

        success = db.delete_document(document_id)

        if not success:
            raise HTTPException(status_code=404, detail="Document not found")

        return {"message": "Document deleted successfully", "document_id": document_id}

    except HTTPException:
        raise
    except Exception as e:
        raise HTTPException(status_code=500, detail=str(e))


@app.get("/api/v1/stats", dependencies=[Depends(verify_api_key)])
async def get_stats():
    """Retorna estatisticas do sistema."""
    try:
        db = get_db_manager()
        metadata_manager = get_metadata_manager()

        db_stats = db.get_database_stats()
        metadata_stats = metadata_manager.get_documents_count_by_metadata()

        return {
            "database": db_stats,
            "metadata": metadata_stats,
            "timestamp": datetime.now().isoformat()
        }

    except Exception as e:
        raise HTTPException(status_code=500, detail=str(e))


@app.post("/api/v1/upload", response_model=IngestResponse, dependencies=[Depends(verify_api_key)])
async def upload_file(
    file: UploadFile = File(...),
    chunk_size: int = 1000,
    chunk_overlap: int = 200,
    strategy: str = "recursive"
):
    """
    Upload e ingestao de arquivo.

    Suporta PDF e TXT.
    """
    try:
        # Salvar arquivo temporariamente
        with tempfile.NamedTemporaryFile(delete=False, suffix=Path(file.filename).suffix) as tmp:
            content = await file.read()
            tmp.write(content)
            tmp_path = tmp.name

        # Processar arquivo
        processor = DocumentProcessor()
        result = processor.process_file(tmp_path)

        # Criar request de ingestao
        ingest_request = IngestRequest(
            text=result['text'],
            title=file.filename,
            chunk_size=chunk_size,
            chunk_overlap=chunk_overlap,
            strategy=strategy,
            metadata={
                "document_type": result['file_type'],
                "upload_date": datetime.now().isoformat()
            }
        )

        # Processar ingestao
        response = await ingest_document(ingest_request)

        # Limpar arquivo temporario
        Path(tmp_path).unlink(missing_ok=True)

        return response

    except Exception as e:
        raise HTTPException(status_code=500, detail=str(e))


# Error handlers

@app.exception_handler(404)
async def not_found_handler(request, exc):
    return JSONResponse(
        status_code=404,
        content={"detail": "Not found"}
    )


@app.exception_handler(500)
async def server_error_handler(request, exc):
    return JSONResponse(
        status_code=500,
        content={"detail": "Internal server error"}
    )