import os
import time
import pandas as pd
import numpy as np
from io import StringIO
from huggingface_hub import InferenceClient
import google.generativeai as genai

# ======================================================
# 🔧 HELPER FUNCTIONS
# ======================================================

def safe_hf_generate(client, prompt, temperature=0.3, max_tokens=512, retries=2):
    """Safely call Hugging Face text generation with retry and graceful fallback."""
    for attempt in range(retries + 1):
        try:
            resp = client.text_generation(
                prompt,
                temperature=temperature,
                max_new_tokens=max_tokens,
                return_full_text=False,
            )
            return resp.strip()
        except Exception as e:
            err = str(e)
            if "503" in err or "Service Temporarily Unavailable" in err:
                time.sleep(2)
                if attempt < retries:
                    continue
                else:
                    return "⚠️ The Hugging Face model is temporarily unavailable. Please try again later."
            elif "Supported task: conversational" in err:
                chat_resp = client.chat_completion(
                    messages=[{"role": "user", "content": prompt}],
                    max_tokens=max_tokens,
                    temperature=temperature,
                )
                return chat_resp["choices"][0]["message"]["content"].strip()
            else:
                raise e
    return "⚠️ Failed after multiple retries."

# ======================================================
# 🧼 DATA CLEANING
# ======================================================

def fallback_clean(df: pd.DataFrame) -> pd.DataFrame:
    """Perform a basic fallback cleaning if AI-based cleaning fails."""
    df = df.copy()
    df.dropna(axis=1, how="all", inplace=True)
    df.columns = [c.strip().replace(" ", "_").lower() for c in df.columns]

    for col in df.columns:
        if df[col].dtype == "O":
            if not df[col].mode().empty:
                df[col].fillna(df[col].mode()[0], inplace=True)
            else:
                df[col].fillna("Unknown", inplace=True)
        else:
            df[col].fillna(df[col].median(), inplace=True)

    df.drop_duplicates(inplace=True)
    return df


def ai_clean_dataset(df: pd.DataFrame, cleaner_client: InferenceClient) -> (pd.DataFrame, str):
    """Clean dataset intelligently using the chosen Hugging Face model."""
    if len(df) > 50:
        return df, "⚠️ AI cleaning skipped: dataset has more than 50 rows."

    csv_text = df.to_csv(index=False)
    prompt = f"""
You are a professional data cleaning assistant.
Clean and standardize the dataset below dynamically:
1. Handle missing values
2. Fix column name inconsistencies
3. Convert data types (dates, numbers, categories)
4. Remove irrelevant or duplicate rows
Return ONLY a valid CSV text (no markdown, no explanations).

Dataset:
{csv_text}
"""
    try:
        cleaned_str = safe_hf_generate(cleaner_client, prompt, temperature=0.1, max_tokens=4096)
        cleaned_str = cleaned_str.replace("```csv", "").replace("```", "").strip()
        cleaned_df = pd.read_csv(StringIO(cleaned_str), on_bad_lines="skip")
        cleaned_df.columns = [c.strip().replace(" ", "_").lower() for c in cleaned_df.columns]
        return cleaned_df, "✅ AI cleaning completed successfully."
    except Exception as e:
        return fallback_clean(df), f"⚠️ AI cleaning failed, used fallback cleaning instead: {str(e)}"

# ======================================================
# 📊 DATA SUMMARIZATION
# ======================================================

def summarize_for_analysis(df: pd.DataFrame, sample_rows: int = 10) -> str:
    """Generate a concise textual summary of the dataset for AI models."""
    summary = [f"Rows: {len(df)}, Columns: {len(df.columns)}"]

    for col in df.columns:
        non_null = int(df[col].notnull().sum())
        if pd.api.types.is_numeric_dtype(df[col]):
            desc = df[col].describe().to_dict()
            summary.append(
                f"- {col}: mean={desc.get('mean', np.nan):.2f}, median={df[col].median():.2f}, non_null={non_null}"
            )
        else:
            top = df[col].value_counts().head(3).to_dict()
            summary.append(f"- {col}: top_values={top}, non_null={non_null}")

    sample = df.head(sample_rows).to_csv(index=False)
    summary.append("--- Sample Data ---")
    summary.append(sample)
    return "\n".join(summary)

# ======================================================
# 🧠 ANALYSIS LOGIC
# ======================================================

def query_analysis_model(
    df: pd.DataFrame,
    user_query: str,
    dataset_name: str,
    analyst_model: str,
    hf_client: InferenceClient = None,
    temperature: float = 0.3,
    max_tokens: int = 1024,
    gemini_api_key: str = None
) -> str:
    """Query the selected AI model (Hugging Face or Gemini) to analyze the dataset."""
    prompt_summary = summarize_for_analysis(df)
    prompt = f"""
You are a professional data analyst.
Analyze the dataset '{dataset_name}' and answer the user's question.

--- DATA SUMMARY ---
{prompt_summary}

--- USER QUESTION ---
{user_query}

Respond with:
1. Key insights and patterns
2. Quantitative findings
3. Notable relationships or anomalies
4. Data-driven recommendations
"""

    try:
        if analyst_model == "Gemini 2.5 Flash (Google)":
            if not gemini_api_key:
                return "⚠️ Gemini API key missing. Cannot use Gemini."
            genai.configure(api_key=gemini_api_key)
            response = genai.GenerativeModel("gemini-2.5-flash").generate_content(
                prompt,
                generation_config={
                    "temperature": temperature,
                    "max_output_tokens": max_tokens
                }
            )
            return response.text if hasattr(response, "text") else "No valid text response."

        # Otherwise, use Hugging Face model
        result = safe_hf_generate(hf_client, prompt, temperature=temperature, max_tokens=max_tokens)

        # fallback to Gemini if Hugging Face fails
        if "temporarily unavailable" in result.lower() and gemini_api_key:
            genai.configure(api_key=gemini_api_key)
            alt = genai.GenerativeModel("gemini-2.5-flash").generate_content(prompt)
            return f"🔄 Fallback to Gemini:\n\n{alt.text}"
        return result

    except Exception as e:
        if "503" in str(e) and gemini_api_key:
            genai.configure(api_key=gemini_api_key)
            response = genai.GenerativeModel("gemini-2.5-flash").generate_content(prompt)
            return f"🔄 Fallback to Gemini due to 503 error:\n\n{response.text}"
        return f"⚠️ Analysis failed: {str(e)}"

# ======================================================
# 🔍 END OF MODULE
# ======================================================