# analysis_modules.py

import base64
import io
import logging

import pandas as pd
import plotly.express as px
import plotly.graph_objects as go
from sklearn.cluster import KMeans
from sklearn.preprocessing import StandardScaler
from statsmodels.tsa.seasonal import seasonal_decompose
from statsmodels.tsa.stattools import adfuller
from wordcloud import WordCloud

# --- Time-Series Module ---
def analyze_time_series(df: pd.DataFrame, date_col: str, value_col: str):
    """Performs time-series decomposition and stationarity testing."""
    if not date_col or not value_col:
        return go.Figure(), "Please select both a date/time column and a value column."

    try:
        # Prepare data
        ts_df = df.copy()
        ts_df[date_col] = pd.to_datetime(ts_df[date_col])
        ts_df = ts_df.set_index(date_col).sort_index()
        ts_data = ts_df[value_col].dropna()

        if len(ts_data) < 24: # Need at least 2 periods for decomposition
             return go.Figure(), "Not enough data points (< 24) for time-series decomposition."

        # Decomposition (assuming monthly data for period=12)
        result = seasonal_decompose(ts_data, model='additive', period=12)
        fig_decomp = px.line(
            pd.DataFrame({'Trend': result.trend, 'Seasonal': result.seasonal, 'Residual': result.resid}),
            title=f"<b>Time-Series Decomposition of '{value_col}'</b>",
            labels={'value': 'Value', 'index': 'Date'},
            template="plotly_white",
        )
        fig_decomp.update_layout(legend_title_text='Components')
                         
        # Stationarity Test (ADF)
        adf_result = adfuller(ts_data)
        conclusion = 'likely **stationary** (p < 0.05)' if adf_result[1] < 0.05 else 'likely **non-stationary** (p >= 0.05)'
        adf_md = f"""
        ### Stationarity Analysis (ADF Test)
        - **ADF Statistic:** `{adf_result[0]:.4f}`
        - **p-value:** `{adf_result[1]:.4f}`
        - **Conclusion:** The time-series is {conclusion}. A non-stationary series may require differencing for forecasting models.
        """
        return fig_decomp, adf_md
    except Exception as e:
        logging.error(f"Time-series analysis failed: {e}", exc_info=True)
        return go.Figure(), f"❌ **Error:** Could not perform time-series analysis. Reason: {e}"

# --- Text Analysis Module ---
def generate_word_cloud(df: pd.DataFrame, text_col: str):
    """Generates a word cloud from a text column and returns it as a data URI."""
    if not text_col:
        return None # Return None to hide the HTML component
        
    try:
        text = ' '.join(df[text_col].dropna().astype(str))
        if not text:
            return "<p style='text-align:center;'>No text data available in this column to generate a cloud.</p>"

        wordcloud = WordCloud(width=800, height=400, background_color='white', colormap='viridis').generate(text)
        
        # Convert matplotlib plot to a base64 encoded string for Gradio HTML
        buf = io.BytesIO()
        wordcloud.to_image().save(buf, format='png')
        img_str = base64.b64encode(buf.getvalue()).decode('utf-8')
        html_content = f'<div style="text-align:center;"><img src="data:image/png;base64,{img_str}" alt="Word Cloud"></div>'
        return html_content
    except Exception as e:
        logging.error(f"Word cloud generation failed: {e}", exc_info=True)
        return f"❌ **Error:** Could not generate word cloud. Reason: {e}"

# --- Clustering Module ---
def perform_clustering(df: pd.DataFrame, numeric_cols: list, n_clusters: int = 4):
    """Performs K-Means clustering and returns a scatter plot."""
    if len(numeric_cols) < 2:
        return go.Figure(), "Clustering requires at least 2 numeric features."
        
    try:
        cluster_data = df[numeric_cols].dropna()
        if len(cluster_data) < n_clusters:
            return go.Figure(), f"Not enough data points ({len(cluster_data)}) for {n_clusters} clusters."

        # Scale data for better clustering performance
        scaler = StandardScaler()
        scaled_data = scaler.fit_transform(cluster_data)

        kmeans = KMeans(n_clusters=int(n_clusters), random_state=42, n_init='auto').fit(scaled_data)
        cluster_data['Cluster'] = kmeans.labels_.astype(str)
        
        # Visualize using the first two principal components for a more holistic view
        fig_cluster = px.scatter(
            cluster_data, x=numeric_cols[0], y=numeric_cols[1], color='Cluster',
            title=f"<b>K-Means Clustering Result (k={int(n_clusters)})</b>",
            template="plotly_white", color_discrete_sequence=px.colors.qualitative.Vivid
        )
        cluster_md = f"""
        ### Clustering Summary
        - **Features Used:** {', '.join(numeric_cols)}
        - **Number of Clusters (K):** {int(n_clusters)}
        - **Insight:** The plot shows the separation of data into {int(n_clusters)} distinct groups based on the selected features.
        """
        return fig_cluster, cluster_md
    except Exception as e:
        logging.error(f"Clustering failed: {e}", exc_info=True)
        return go.Figure(), f"❌ **Error:** Could not perform clustering. Reason: {e}"