import os
import logging
import time

import asyncpg
import httpx
from fastapi import FastAPI, HTTPException
from pydantic import BaseModel

logger = logging.getLogger("memory-service")
logging.basicConfig(level=logging.INFO)

DB_DSN = os.environ.get("DATABASE_URL", "postgresql://memory:memory@memory-db:5432/memories")
LITELLM_URL = os.environ.get("LITELLM_BASE_URL", "")
LITELLM_KEY = os.environ.get("LITELLM_API_KEY", "not-needed")
EMBED_MODEL = os.environ.get("EMBED_MODEL", "text-embedding-3-small")
EMBED_DIMS = int(os.environ.get("EMBED_DIMS", "1536"))
DEDUP_THRESHOLD = float(os.environ.get("DEDUP_THRESHOLD", "0.92"))

app = FastAPI(title="Memory Service")
pool: asyncpg.Pool | None = None


class StoreRequest(BaseModel):
    user_id: str
    fact: str
    source_room: str = ""


class QueryRequest(BaseModel):
    user_id: str
    query: str
    top_k: int = 10


async def _embed(text: str) -> list[float]:
    """Get embedding vector from LiteLLM /embeddings endpoint."""
    async with httpx.AsyncClient(timeout=30.0) as client:
        resp = await client.post(
            f"{LITELLM_URL}/embeddings",
            json={"model": EMBED_MODEL, "input": text},
            headers={"Authorization": f"Bearer {LITELLM_KEY}"},
        )
        resp.raise_for_status()
        return resp.json()["data"][0]["embedding"]


async def _init_db():
    """Create pgvector extension and memories table if not exists."""
    global pool
    pool = await asyncpg.create_pool(DB_DSN, min_size=2, max_size=10)
    async with pool.acquire() as conn:
        await conn.execute("CREATE EXTENSION IF NOT EXISTS vector")
        await conn.execute(f"""
            CREATE TABLE IF NOT EXISTS memories (
                id BIGSERIAL PRIMARY KEY,
                user_id TEXT NOT NULL,
                fact TEXT NOT NULL,
                source_room TEXT DEFAULT '',
                created_at DOUBLE PRECISION NOT NULL,
                embedding vector({EMBED_DIMS}) NOT NULL
            )
        """)
        await conn.execute("""
            CREATE INDEX IF NOT EXISTS idx_memories_user_id ON memories (user_id)
        """)
        await conn.execute(f"""
            CREATE INDEX IF NOT EXISTS idx_memories_embedding
            ON memories USING ivfflat (embedding vector_cosine_ops)
            WITH (lists = 10)
        """)
    logger.info("Database initialized (dims=%d)", EMBED_DIMS)


@app.on_event("startup")
async def startup():
    await _init_db()


@app.on_event("shutdown")
async def shutdown():
    if pool:
        await pool.close()


@app.get("/health")
async def health():
    if pool:
        async with pool.acquire() as conn:
            count = await conn.fetchval("SELECT count(*) FROM memories")
        return {"status": "ok", "total_memories": count}
    return {"status": "no_db"}


@app.post("/memories/store")
async def store_memory(req: StoreRequest):
    """Embed fact, deduplicate by cosine similarity, insert."""
    if not req.fact.strip():
        raise HTTPException(400, "Empty fact")

    embedding = await _embed(req.fact)
    vec_literal = "[" + ",".join(str(v) for v in embedding) + "]"

    async with pool.acquire() as conn:
        # Check for duplicates (cosine similarity > threshold)
        dup = await conn.fetchval(
            """
            SELECT id FROM memories
            WHERE user_id = $1
              AND 1 - (embedding <=> $2::vector) > $3
            LIMIT 1
            """,
            req.user_id, vec_literal, DEDUP_THRESHOLD,
        )
        if dup:
            logger.info("Duplicate memory for %s (similar to id=%d), skipping", req.user_id, dup)
            return {"stored": False, "reason": "duplicate"}

        await conn.execute(
            """
            INSERT INTO memories (user_id, fact, source_room, created_at, embedding)
            VALUES ($1, $2, $3, $4, $5::vector)
            """,
            req.user_id, req.fact.strip(), req.source_room, time.time(), vec_literal,
        )
    logger.info("Stored memory for %s: %s", req.user_id, req.fact[:60])
    return {"stored": True}


@app.post("/memories/query")
async def query_memories(req: QueryRequest):
    """Embed query, return top-K similar facts for user."""
    embedding = await _embed(req.query)
    vec_literal = "[" + ",".join(str(v) for v in embedding) + "]"

    async with pool.acquire() as conn:
        rows = await conn.fetch(
            """
            SELECT fact, source_room, created_at,
                   1 - (embedding <=> $1::vector) AS similarity
            FROM memories
            WHERE user_id = $2
            ORDER BY embedding <=> $1::vector
            LIMIT $3
            """,
            vec_literal, req.user_id, req.top_k,
        )

    results = [
        {
            "fact": r["fact"],
            "source_room": r["source_room"],
            "created_at": r["created_at"],
            "similarity": float(r["similarity"]),
        }
        for r in rows
    ]
    return {"results": results}


@app.delete("/memories/{user_id}")
async def delete_user_memories(user_id: str):
    """GDPR delete — remove all memories for a user."""
    async with pool.acquire() as conn:
        result = await conn.execute("DELETE FROM memories WHERE user_id = $1", user_id)
    count = int(result.split()[-1])
    logger.info("Deleted %d memories for %s", count, user_id)
    return {"deleted": count}


@app.get("/memories/{user_id}")
async def list_user_memories(user_id: str):
    """List all memories for a user (for UI/debug)."""
    async with pool.acquire() as conn:
        rows = await conn.fetch(
            """
            SELECT fact, source_room, created_at
            FROM memories
            WHERE user_id = $1
            ORDER BY created_at DESC
            """,
            user_id,
        )
    return {
        "user_id": user_id,
        "count": len(rows),
        "memories": [
            {"fact": r["fact"], "source_room": r["source_room"], "created_at": r["created_at"]}
            for r in rows
        ],
    }