import torch
import os
import glob
import json
import pandas as pd
from sentence_transformers import SentenceTransformer
import numpy as np
from langchain_text_splitters import RecursiveCharacterTextSplitter, CharacterTextSplitter
from langchain_experimental.text_splitter import SemanticChunker
from langchain_community.embeddings import HuggingFaceEmbeddings
from . import base_utils as bu

def load_model(model_name):
    return SentenceTransformer(model_name, device="cpu")

def get_text_splitter(splitter, chunk_size, chunk_overlap):
    """
    Retrieve the appropriate text splitter based on a specified type.
    """
    if splitter == "recursive":
        return RecursiveCharacterTextSplitter(
            chunk_size=chunk_size,
            chunk_overlap=chunk_overlap,
            length_function=len,
        )
    elif splitter == "tokens":
        return CharacterTextSplitter.from_tiktoken_encoder(
            encoding_name="cl100k_base",
            chunk_size=chunk_size,
            chunk_overlap=chunk_overlap,
        )
    elif splitter == "semantic":
        embeddings_model = HuggingFaceEmbeddings(
            model_name=bu.config["embeddings"]["model_name"])
        return SemanticChunker(
            embeddings=embeddings_model,
        )
    else:
        return RecursiveCharacterTextSplitter(
            chunk_size=chunk_size,
            chunk_overlap=chunk_overlap,
            length_function=len
        )

def generate_embeddings(input_path, output_folder, model_name, splitter, chunk_size, chunk_overlap, retrieval_model, export_numpy=False, numpy_output_dir=None, max_files=None):
    text_splitter = get_text_splitter(splitter, chunk_size, chunk_overlap)
    md_files = glob.glob(input_path)
    if not md_files:
        print(f"No .md files found in path: {input_path}")
        return

    os.makedirs(output_folder, exist_ok=True)

    emb_files = glob.glob(os.path.join(output_folder, "*.h5"))
    for file in emb_files:
        filename_without_ext = os.path.splitext(os.path.basename(file))[0]
        corresponding_doc = os.path.join(os.path.dirname(input_path), filename_without_ext + ".md")
        if not os.path.exists(corresponding_doc):
            print(f"Embeddings file {file} has no corresponding .md. Deleting it.")
            os.remove(file)

    all_embeddings = []
    all_metadata = []
    global_idx = 0

    if max_files is not None:
        md_files = md_files[:max_files]

    total_files = len(md_files)
    for i, file in enumerate(md_files, start=1):
        file_name = os.path.basename(file)
        doc_id = os.path.splitext(file_name)[0]
        output_file = os.path.join(output_folder, f"{doc_id}.h5")

        if os.path.exists(output_file):
            print(f"Embeddings already exists for {file_name}. Skipping generation and loading existing file for export...")
            embeddings_df = pd.read_hdf(output_file, key="df")
        else:
            progress = (i / total_files) * 100
            print(f"[{i}/{total_files}] ({progress:.1f}%) Generating embeddings for: {file_name}")
            text = bu.load_md(file)

            embeddings_list = []
            content_list = []

            if text.strip():
                chunks = text_splitter.create_documents([text])
                print(f"Chunks generated for document {file_name} : {len(chunks)}")

                for chunk in chunks:
                    embedding = retrieval_model.encode(chunk.page_content)
                    embeddings_list.append(embedding)
                    content_list.append(chunk.page_content)

                embeddings_df = pd.DataFrame(embeddings_list)
                embeddings_df["segment_content"] = content_list
                embeddings_df["model_name"] = model_name
                embeddings_df["segment_content"] = embeddings_df["segment_content"].astype(str)
                embeddings_df["model_name"] = embeddings_df["model_name"].astype(str)

                embeddings_df.to_hdf(output_file, key="df", mode="w", format="table")
            else:
                embeddings_df = pd.DataFrame()

        from . import base_utils as _bu_internal  # import local para evitar ciclos en tiempo de carga
        doc_title = _bu_internal.extract_title_from_md(text if 'text' in locals() else bu.load_md(file), default=file_name)

        if export_numpy and not embeddings_df.empty:
            emb_values = embeddings_df.iloc[:, :-2].values.astype("float32")
            contents = embeddings_df["segment_content"].tolist()

            for local_idx, (vec, content) in enumerate(zip(emb_values, contents)):
                all_embeddings.append(vec)
                all_metadata.append(
                    {
                        "idx": global_idx,
                        "document_id": doc_id,
                        "document_title": doc_title,
                        "fragment_id": local_idx,
                        "content": content,
                    }
                )
                global_idx += 1

    if export_numpy and all_embeddings:
        numpy_output_dir = numpy_output_dir or os.path.join("data", "embeddings")
        os.makedirs(numpy_output_dir, exist_ok=True)

        embeddings_array = np.vstack(all_embeddings).astype("float32")
        np.save(os.path.join(numpy_output_dir, "embeddings.npy"), embeddings_array)

        metadata_path = os.path.join(numpy_output_dir, "metadata.jsonl")
        with open(metadata_path, "w", encoding="utf-8") as f:
            for meta in all_metadata:
                f.write(json.dumps(meta, ensure_ascii=False) + "\n")

        print(f"Exported consolidated embeddings to {numpy_output_dir}")

def search_query(query, corpus_embeddings, retrieval_model, segment_contents):

    query_embedding = retrieval_model.encode(query, convert_to_tensor=True)
    similarity_scores = retrieval_model.similarity(query_embedding, corpus_embeddings)[0]

    top_similarities, topk_indices = torch.topk(similarity_scores, k=bu.config['retrieve']['top_k'])
    top_segments = [segment_contents[idx] for idx in topk_indices]
    
    return top_segments, top_similarities

def load_embeddings(embeddings_dir):
    embeddings_list = []
    segment_contents_list = []
    model_names_set = set()

    num_documents = 0
    for file_path in glob.glob(os.path.join(embeddings_dir, "*.h5")):
        num_documents += 1
        embeddings_df = pd.read_hdf(file_path, key='df')
        embeddings = embeddings_df.iloc[:, :-2].values
        segment_contents = embeddings_df['segment_content'].values
        model_name = embeddings_df['model_name'].values[0]

        embeddings_list.extend(embeddings)
        segment_contents_list.extend(segment_contents)
        model_names_set.add(model_name)
    
    embeddings_array = np.array(embeddings_list)
    embeddings_tensor = torch.tensor(embeddings_array, dtype=torch.float32, device='cuda' if torch.cuda.is_available() else 'cpu')

    num_segment_contents = len(segment_contents_list)
    model_name = model_names_set.pop() if len(model_names_set) == 1 else "Multiple Models"

    return {
        "embeddings": embeddings_tensor,
        "segment_contents": segment_contents_list,
        "num_documents": num_documents,
        "num_segment_contents": num_segment_contents,
    }