"""
Hadith Scholar API — FastAPI application.

Endpoints:
  /hadiths     — hadith details, search by keyword/narrator/topic/collection
  /narrators   — narrator profiles, interactions, who-met-who
  /chains      — isnad chain visualization data
  /search      — semantic (Qdrant) + full-text Arabic (Elasticsearch)
"""
from fastapi import FastAPI
from fastapi.middleware.cors import CORSMiddleware
from contextlib import asynccontextmanager

from app.config import get_settings
from app.services.database import db
from app.routers import hadiths, narrators, chains, search


@asynccontextmanager
async def lifespan(app: FastAPI):
    """Connect all databases on startup, disconnect on shutdown."""
    await db.connect()
    yield
    await db.disconnect()


settings = get_settings()

TAGS_METADATA = [
    {
        "name": "Hadiths",
        "description": (
            "Access and search hadith texts from 8+ major collections "
            "(Sahih Bukhari, Sahih Muslim, Sunan Abu Dawood, Jami` at-Tirmidhi, "
            "Sunan an-Nasa'i, Sunan Ibn Majah, Musnad Ahmad, and more). "
            "Retrieve full hadith details including narrator chains, topic tags, "
            "and sanad/matn separation. Search by Arabic keyword, narrator name, "
            "topic, or collection."
        ),
    },
    {
        "name": "Narrators",
        "description": (
            "Narrator (رجال الحديث) profiles and relationships. "
            "Each narrator includes biographical data from classical scholarship "
            "(Tahdhib al-Kamal, Taqrib al-Tahdhib, etc.): full nasab, kunya, nisba, "
            "generation (طبقة), reliability grading (جرح وتعديل), birth/death dates, "
            "teachers, students, places, and tribal affiliations. "
            "Use the who-met-who endpoint to explore narrator connections."
        ),
    },
    {
        "name": "Isnad Chains",
        "description": (
            "Isnad (chain of narration / إسناد) visualization data. "
            "Returns graph-ready structures (nodes + links) for rendering "
            "narrator chains using D3.js, vis.js, Cytoscape, or any graph library. "
            "Each node includes narrator metadata; each link includes the "
            "transmission verb (حدثنا، أخبرنا، عن، سمعت)."
        ),
    },
    {
        "name": "Search",
        "description": (
            "Multi-modal hadith search. **Semantic search** uses BGE-M3 multilingual "
            "embeddings + Qdrant to find hadiths by meaning (supports Arabic, English, "
            "and cross-language queries). **Full-text search** uses Elasticsearch with "
            "Arabic morphological analysis for exact and fuzzy keyword matching. "
            "**Combined search** runs both in parallel for the best results."
        ),
    },
    {
        "name": "Root",
        "description": "Health checks, statistics, and API metadata.",
    },
]

app = FastAPI(
    title=settings.app_name,
    version=settings.app_version,
    description="""
# Hadith Scholar API — حَدِيثٌ

Production-grade REST API for analyzing Islamic hadith literature across 8+ major collections.

## Core Capabilities

| Feature | Backend | Endpoint |
|---------|---------|----------|
| Hadith lookup & keyword search | PostgreSQL | `GET /hadiths/*` |
| Narrator profiles & biography | Neo4j | `GET /narrators/*` |
| Isnad chain visualization | Neo4j | `GET /chains/*` |
| Semantic search (by meaning) | Qdrant + BGE-M3 | `GET /search/semantic` |
| Full-text Arabic search | Elasticsearch | `GET /search/fulltext` |
| Narrator relationships | Neo4j | `GET /narrators/who-met-who` |

## Data Sources
- **~41,000 hadiths** from Sahih Bukhari, Sahih Muslim, Sunan Abu Dawood, Jami` at-Tirmidhi, Sunan an-Nasa'i, Sunan Ibn Majah, Musnad Ahmad, Muwatta Malik, and more
- **Narrator knowledge graph** with biographies, teacher/student networks, places, tribes
- **1024-dim multilingual embeddings** (BGE-M3) for semantic search across Arabic/English/Urdu

## Authentication
Currently open (no auth required). API keys will be added in a future version.

## Arabic Text
All Arabic text preserves original diacritics (تشكيل). Search endpoints accept both vocalized and unvocalized Arabic.

## Example Queries
- Search for hadiths about prayer: `GET /hadiths/search/keyword?q=صلاة`
- Find narrator profile: `GET /narrators/profile/أبو هريرة`
- Semantic search: `GET /search/semantic?q=what did the prophet say about fasting`
- Who met who: `GET /narrators/who-met-who?narrator_a=الزهري&narrator_b=أنس بن مالك`
    """,
    docs_url="/docs",
    redoc_url="/redoc",
    openapi_url="/openapi.json",
    openapi_tags=TAGS_METADATA,
    lifespan=lifespan,
    license_info={
        "name": "MIT",
    },
    contact={
        "name": "Hadith Scholar API",
        "url": "https://betelgeusebytes.io",
    },
)

# CORS — allow all for development; tighten for production
app.add_middleware(
    CORSMiddleware,
    allow_origins=["*"],
    allow_credentials=True,
    allow_methods=["*"],
    allow_headers=["*"],
)

# Register routers
app.include_router(hadiths.router)
app.include_router(narrators.router)
app.include_router(chains.router)
app.include_router(search.router)


@app.get("/", tags=["Root"])
async def root():
    return {
        "name": settings.app_name,
        "version": settings.app_version,
        "docs": "/docs",
        "endpoints": {
            "hadiths": "/hadiths",
            "narrators": "/narrators",
            "chains": "/chains",
            "search": "/search",
        },
    }


@app.get("/health", tags=["Root"])
async def health():
    """Health check — verifies all service connections."""
    status = {"status": "ok", "services": {}}

    # PostgreSQL
    try:
        db.pg_query_one("SELECT 1 AS ok")
        status["services"]["postgresql"] = "ok"
    except Exception as e:
        status["services"]["postgresql"] = f"error: {e}"
        status["status"] = "degraded"

    # Neo4j
    try:
        db.neo4j_query_one("RETURN 1 AS ok")
        status["services"]["neo4j"] = "ok"
    except Exception as e:
        status["services"]["neo4j"] = f"error: {e}"
        status["status"] = "degraded"

    # Qdrant
    try:
        db.qdrant.get_collections()
        status["services"]["qdrant"] = "ok"
    except Exception as e:
        status["services"]["qdrant"] = f"error: {e}"
        status["status"] = "degraded"

    # Elasticsearch
    try:
        if db.es.ping():
            status["services"]["elasticsearch"] = "ok"
        else:
            status["services"]["elasticsearch"] = "unreachable"
            status["status"] = "degraded"
    except Exception as e:
        status["services"]["elasticsearch"] = f"error: {e}"
        status["status"] = "degraded"

    return status


@app.get("/stats", tags=["Root"])
async def stats():
    """Database statistics."""
    pg_stats = db.pg_query_one("""
        SELECT
            (SELECT COUNT(*) FROM hadiths) AS total_hadiths,
            (SELECT COUNT(*) FROM collections) AS total_collections
    """)

    neo4j_stats = db.neo4j_query_one("""
        MATCH (h:Hadith) WITH count(h) AS hadiths
        MATCH (n:Narrator) WITH hadiths, count(n) AS narrators
        MATCH (p:Place) WITH hadiths, narrators, count(p) AS places
        MATCH (t:Tribe) WITH hadiths, narrators, places, count(t) AS tribes
        MATCH ()-[r]->() WITH hadiths, narrators, places, tribes, count(r) AS relationships
        RETURN hadiths, narrators, places, tribes, relationships
    """)

    return {
        "postgresql": pg_stats,
        "neo4j_graph": neo4j_stats,
    }