import os
import torch
from dotenv import load_dotenv
from pinecone import Pinecone, ServerlessSpec
from langchain_community.document_loaders import PyPDFLoader, TextLoader
from langchain.text_splitter import RecursiveCharacterTextSplitter
from sentence_transformers import SentenceTransformer
from tqdm import tqdm

load_dotenv()

# ── Config ───────────────────────────────────────────────────────────────────
PINECONE_API_KEY = os.getenv("PINECONE_API_KEY")
PINECONE_INDEX   = os.getenv("PINECONE_INDEX", "study-saathi")
EMBEDDING_MODEL  = "intfloat/multilingual-e5-large"
DATA_DIR         = "data/os_notes"
CHUNK_SIZE       = 512
CHUNK_OVERLAP    = 64
BATCH_SIZE       = 32
DIMENSION        = 1024

# ── Device ───────────────────────────────────────────────────────────────────
device = "cuda" if torch.cuda.is_available() else "cpu"
print(f"[INFO] Using device: {device}")

# ── Load Embedding Model ──────────────────────────────────────────────────────
print("[INFO] Loading embedding model...")
embedder = SentenceTransformer(EMBEDDING_MODEL, device=device)

# ── Pinecone Setup ────────────────────────────────────────────────────────────
pc = Pinecone(api_key=PINECONE_API_KEY)

if PINECONE_INDEX not in [i.name for i in pc.list_indexes()]:
    print(f"[INFO] Creating Pinecone index: {PINECONE_INDEX}")
    pc.create_index(
        name=PINECONE_INDEX,
        dimension=DIMENSION,
        metric="cosine",
        spec=ServerlessSpec(cloud="aws", region="us-east-1")
    )

index = pc.Index(PINECONE_INDEX)

# ── Check if file already ingested ───────────────────────────────────────────
def is_already_ingested(filename: str) -> bool:
    """
    Query Pinecone for any vector whose metadata source == filename.
    If found, the file was already ingested — skip it.
    """
    topic = os.path.splitext(filename)[0]

    # use a dummy zero vector just to run a metadata filter query
    dummy_vector = [0.0] * DIMENSION

    results = index.query(
        vector=dummy_vector,
        top_k=1,
        include_metadata=True,
        filter={"source": {"$eq": filename}}
    )

    return len(results["matches"]) > 0

# ── Load Documents ────────────────────────────────────────────────────────────
def load_documents(filepath: str, filename: str) -> list:
    if filename.endswith(".pdf"):
        loader = PyPDFLoader(filepath)
    elif filename.endswith(".txt"):
        loader = TextLoader(filepath, encoding="utf-8")
    else:
        return []

    loaded = loader.load()
    topic  = os.path.splitext(filename)[0]

    for doc in loaded:
        doc.metadata["topic"]  = topic
        doc.metadata["source"] = filename

    print(f"[LOADED] {filename} — {len(loaded)} page(s)")
    return loaded

# ── Chunk Documents ───────────────────────────────────────────────────────────
def chunk_documents(docs: list) -> list:
    splitter = RecursiveCharacterTextSplitter(
        chunk_size=CHUNK_SIZE,
        chunk_overlap=CHUNK_OVERLAP
    )
    chunks = splitter.split_documents(docs)
    print(f"[INFO] Total chunks: {len(chunks)}")
    return chunks

# ── Embed & Upsert ────────────────────────────────────────────────────────────
def embed_and_upsert(chunks: list, filename: str):
    texts = [f"passage: {chunk.page_content}" for chunk in chunks]
    print("[INFO] Generating embeddings...")
    all_vectors = []

    for i in tqdm(range(0, len(texts), BATCH_SIZE)):
        batch_texts  = texts[i: i + BATCH_SIZE]
        batch_chunks = chunks[i: i + BATCH_SIZE]
        embeddings   = embedder.encode(
            batch_texts,
            normalize_embeddings=True,
            show_progress_bar=False
        )
        for j, (emb, chunk) in enumerate(zip(embeddings, batch_chunks)):
            all_vectors.append({
                "id":     f"{os.path.splitext(filename)[0]}-chunk-{i + j}",
                "values": emb.tolist(),
                "metadata": {
                    "text":   chunk.page_content,
                    "topic":  chunk.metadata.get("topic", "unknown"),
                    "source": chunk.metadata.get("source", "unknown"),
                }
            })

    print("[INFO] Upserting to Pinecone...")
    for i in tqdm(range(0, len(all_vectors), 100)):
        index.upsert(vectors=all_vectors[i: i + 100])

    print(f"[DONE] Upserted {len(all_vectors)} chunks for '{filename}'.")

# ── Main ──────────────────────────────────────────────────────────────────────
if __name__ == "__main__":
    files = [f for f in os.listdir(DATA_DIR) if f.endswith((".pdf", ".txt"))]

    if not files:
        print("[ERROR] No files found in data/os_notes/")
        exit(1)

    print(f"[INFO] Found {len(files)} file(s): {files}\n")

    for filename in files:
        filepath = os.path.join(DATA_DIR, filename)

        # ── SKIP CHECK ────────────────────────────────────────────────────
        if is_already_ingested(filename):
            print(f"[SKIP] '{filename}' already in Pinecone. Skipping...\n")
            continue

        print(f"[NEW]  Processing '{filename}'...")
        docs   = load_documents(filepath, filename)
        if not docs:
            print(f"[WARN] Could not load '{filename}'. Skipping.\n")
            continue

        chunks = chunk_documents(docs)
        embed_and_upsert(chunks, filename)
        print()

    print("[ALL DONE] Ingestion complete. Existing embeddings are untouched.")