data_engine.py

import pandas as pd
import numpy as np
import plotly.express as px
import plotly.graph_objects as go
import os
import tempfile

def clean_numeric(df):
    df = df.copy()
    for col in df.columns:
        if pd.api.types.is_string_dtype(df[col]) or df[col].dtype == object:
            s = df[col].astype(str).str.strip()
            if s.str.contains("%", na=False).any():
                numeric_vals = pd.to_numeric(s.str.replace("%", "", regex=False), errors="coerce")
                if numeric_vals.notna().sum() / len(df) > 0.5:
                    df[col] = numeric_vals / 100.0
                    continue
            cleaned = s.str.replace(",", "", regex=False).str.replace("₹", "", regex=False).str.replace("$", "", regex=False)
            numeric_vals = pd.to_numeric(cleaned, errors="coerce")
            if numeric_vals.notna().sum() / len(df) > 0.5:
                df[col] = numeric_vals
    return df

def run_analysis(analysis_type, selected_columns, uploaded_df):
    if uploaded_df is None:
        return "Please upload a dataset first.", None
    if analysis_type == "None" or analysis_type is None:
        return "", None
    
    if 'title' in uploaded_df.columns:
        title_nulls = uploaded_df['title'].isnull().sum()
        print(f"DEBUG: Title column has {title_nulls} null values at analysis time")
    
    whole_dataset_analyses = ["Summary", "Top 5 Rows", "Bottom 5 Rows", "Missing Values"]
    if analysis_type in whole_dataset_analyses:
        df_to_analyze = uploaded_df
    else:
        if not selected_columns:
            return f"Please select columns for {analysis_type} analysis.", None
        df_to_analyze = uploaded_df[selected_columns]
    
    try:
        if analysis_type == "Summary":
            numeric_cols = uploaded_df.select_dtypes(include=[np.number]).columns
            categorical_cols = uploaded_df.select_dtypes(include=['object', 'category']).columns
            result = f"Dataset Summary:\nRows: {len(uploaded_df):,}\nColumns: {len(uploaded_df.columns)}\nNumeric Columns: {len(numeric_cols)}\nText Columns: {len(categorical_cols)}\n\n"
            if len(numeric_cols) > 0:
                result += "Numeric Columns: " + ", ".join(numeric_cols.tolist()) + "\n"
            if len(categorical_cols) > 0:
                result += "Text Columns: " + ", ".join(categorical_cols.tolist())
            return result, None
            
        elif analysis_type == "Describe":
            result = "Column Description:\n" + "=" * 30 + "\n\n"
            for col in selected_columns:
                if col in df_to_analyze.columns:
                    result += f"Column: {col}\n"
                    if pd.api.types.is_numeric_dtype(df_to_analyze[col]):
                        stats = df_to_analyze[col].describe()
                        result += f"  Type: Numeric\n  Count: {stats['count']:.0f}\n  Mean: {stats['mean']:.3f}\n  Std: {stats['std']:.3f}\n  Min: {stats['min']:.3f}\n  25%: {stats['25%']:.3f}\n  50%: {stats['50%']:.3f}\n  75%: {stats['75%']:.3f}\n  Max: {stats['max']:.3f}\n\n"
                    else:
                        unique_count = df_to_analyze[col].nunique()
                        null_count = df_to_analyze[col].isnull().sum()
                        most_common = df_to_analyze[col].mode().iloc[0] if len(df_to_analyze[col].mode()) > 0 else "N/A"
                        result += f"  Type: Categorical/Text\n  Unique Values: {unique_count}\n  Missing Values: {null_count}\n  Most Common: {most_common}\n"
                        top_values = df_to_analyze[col].value_counts().head(5)
                        result += "  Top Values:\n"
                        for val, count in top_values.items():
                            result += f"    {val}: {count} times\n"
                        result += "\n"
            return result, None
            
        elif analysis_type == "Top 5 Rows":
            return "Top 5 Rows - See data table below", df_to_analyze.head(5)
            
        elif analysis_type == "Bottom 5 Rows":
            return "Bottom 5 Rows - See data table below", df_to_analyze.tail(5)
            
        elif analysis_type == "Missing Values":
            result = "Missing Values Analysis:\n" + "=" * 30 + "\n\n"
            patterns = ['UNKNOWN', 'unknown', 'ERROR', 'error', 'NULL', 'null', 'NA', 'na', 'N/A', 
                       'Not Given', 'not given', 'NOT GIVEN', '', ' ', '-', '?', 'NaN', 'nan', 
                       'None', 'none', 'NONE', '#N/A', 'n/a', 'N.A.', 'n.a.']
            
            for col in uploaded_df.columns:
                nan_count = uploaded_df[col].isnull().sum()
                pseudo_missing_count = 0
                
                non_null_data = uploaded_df[col].dropna()
                if len(non_null_data) > 0:
                    col_str = non_null_data.astype(str).str.strip()
                    empty_count = (col_str == '').sum()
                    pattern_count = 0
                    for pattern in patterns:
                        if pattern != '':  
                            pattern_count += (col_str.str.lower() == pattern.lower()).sum()
                    pseudo_missing_count = empty_count + pattern_count
                
                total_missing = nan_count + pseudo_missing_count
                missing_percent = (total_missing / len(uploaded_df)) * 100
                
                if col == 'title':
                    print(f"DEBUG: Title analysis - NaN: {nan_count}, Pseudo: {pseudo_missing_count}, Total: {total_missing}")
                
                if total_missing > 0:
                    details = []
                    if nan_count > 0:
                        details.append(f"{nan_count} NaN")
                    if pseudo_missing_count > 0:
                        details.append(f"{pseudo_missing_count} text-missing")
                    detail_str = f" ({', '.join(details)})"
                else:
                    detail_str = ""
                    
                result += f"{col}: {total_missing} missing ({missing_percent:.2f}%){detail_str}\n"
            
            return result, None
            
        elif analysis_type == "Highest Correlation":
            numeric_cols = df_to_analyze.select_dtypes(include=[np.number]).columns
            if len(numeric_cols) < 2:
                return "Need at least 2 numeric columns for correlation analysis.", None
            corr_matrix = df_to_analyze[numeric_cols].corr()
            result = "Highest Correlations:\n" + "=" * 25 + "\n\n"
            correlations = []
            for i in range(len(corr_matrix.columns)):
                for j in range(i+1, len(corr_matrix.columns)):
                    col1, col2 = corr_matrix.columns[i], corr_matrix.columns[j]
                    corr_val = corr_matrix.iloc[i, j]
                    correlations.append((abs(corr_val), col1, col2, corr_val))
            correlations.sort(reverse=True)
            for _, col1, col2, corr_val in correlations[:10]:
                result += f"{col1} ↔ {col2}: {corr_val:.3f}\n"
            return result, None
        
        elif analysis_type == "Group & Aggregate":
            if not selected_columns:
                result = "Please select columns for grouping and aggregation."
            else:
                categorical_cols = [col for col in selected_columns if not pd.api.types.is_numeric_dtype(df_to_analyze[col])]
                numeric_cols = [col for col in selected_columns if pd.api.types.is_numeric_dtype(df_to_analyze[col])]
                
                if categorical_cols and numeric_cols:
                    group_col = categorical_cols[0]
                    agg_col = numeric_cols[0]
                    grouped = df_to_analyze.groupby(group_col)[agg_col].agg(['count', 'mean', 'sum']).round(2)
                    result = f"Group & Aggregate Analysis:\n" + "=" * 35 + "\n\n"
                    result += f"Grouped by: {group_col}\nAggregated: {agg_col}\n\n"
                    result += grouped.to_string()
                elif categorical_cols:
                    group_col = categorical_cols[0]
                    grouped = df_to_analyze[group_col].value_counts()
                    result = f"Group Count Analysis:\n" + "=" * 25 + "\n\n"
                    result += grouped.to_string()
                else:
                    result = "Please select at least one categorical column for grouping."
            return result, None
            
        elif analysis_type == "Calculate Expressions":
            numeric_cols = df_to_analyze.select_dtypes(include=[np.number]).columns
            
            if len(numeric_cols) >= 2:
                col1, col2 = numeric_cols[0], numeric_cols[1]
                df_calc = df_to_analyze.copy()
                df_calc['Sum'] = df_calc[col1] + df_calc[col2]
                df_calc['Difference'] = df_calc[col1] - df_calc[col2]
                
                result = f"Calculated Expressions:\n" + "=" * 30 + "\n\n"
                result += f"Using columns: {col1} and {col2}\n\n"
                result += f"New calculated columns:\nSum = {col1} + {col2}\nDifference = {col1} - {col2}\n\n"
                result += "Sample results:\n"
                result += df_calc[['Sum', 'Difference']].head().to_string()
            else:
                result = "Need at least 2 numeric columns for calculations."
            return result, None
        
        else:
            return f"Analysis type '{analysis_type}' is under development.", None
            
    except Exception as e:
        return f"Error in analysis: {str(e)}", None

def create_chart_explanation(viz_type, df_to_plot, selected_columns, fig_data=None):
    try:
        if viz_type == "Bar Chart" and len(selected_columns) >= 2:
            x_col, y_col = selected_columns[0], selected_columns[1]
            if pd.api.types.is_numeric_dtype(df_to_plot[y_col]):
                max_val_idx = df_to_plot[y_col].idxmax()
                max_category = df_to_plot.loc[max_val_idx, x_col]
                max_value = df_to_plot[y_col].max()
                y_mean = df_to_plot[y_col].mean()
            else:
                grouped = df_to_plot.groupby(x_col)[y_col].count()
                max_category = grouped.idxmax()
                max_value = grouped.max()
                y_mean = grouped.mean()
            return f"BAR CHART: {y_col} by {x_col}\nHighest: {max_category} ({max_value:.2f})\nAverage: {y_mean:.2f}\nCategories: {df_to_plot[x_col].nunique()}"
        elif viz_type == "Line Chart" and fig_data is not None:
            max_combo = fig_data.loc[fig_data['Count'].idxmax()]
            min_combo = fig_data.loc[fig_data['Count'].idxmin()]
            return f"LINE CHART: Distribution\nHighest: {max_combo[selected_columns[1]]} in {max_combo[selected_columns[0]]} ({max_combo['Count']})\nLowest: {min_combo[selected_columns[1]]} in {min_combo[selected_columns[0]]} ({min_combo['Count']})\nTotal: {len(df_to_plot)}"
    except:
        pass
    return f"{viz_type} visualization\nShows data patterns and relationships"

def create_visualization(viz_type, selected_columns, uploaded_df):
    if uploaded_df is None or viz_type == "None":
        return None, "", None
    if not selected_columns:
        return None, "Please select columns for visualization.", None
    df_to_plot = uploaded_df[selected_columns]
    
    try:
        if viz_type == "Bar Chart":
            if len(selected_columns) >= 2:
                x_col, y_col = selected_columns[0], selected_columns[1]
                color_col = selected_columns[2] if len(selected_columns) > 2 else None
                
                # Handle different data type combinations
                if pd.api.types.is_numeric_dtype(df_to_plot[y_col]):
                    # Numeric Y-axis: use as-is
                    plot_data = df_to_plot.head(100)
                    fig = px.bar(plot_data, x=x_col, y=y_col, color=color_col, title=f"{y_col} by {x_col}")
                else:
                    # Non-numeric Y-axis: count occurrences
                    if pd.api.types.is_numeric_dtype(df_to_plot[x_col]):
                        # If X is numeric, group and count Y values
                        grouped = df_to_plot.groupby(x_col)[y_col].count().reset_index()
                        grouped.columns = [x_col, f'Count of {y_col}']
                        fig = px.bar(grouped, x=x_col, y=f'Count of {y_col}', title=f"Count of {y_col} by {x_col}")
                    else:
                        # Both categorical: cross-tabulation
                        crosstab = pd.crosstab(df_to_plot[x_col], df_to_plot[y_col])
                        crosstab_reset = crosstab.reset_index().melt(id_vars=[x_col], var_name=y_col, value_name='Count')
                        fig = px.bar(crosstab_reset, x=x_col, y='Count', color=y_col, title=f"{y_col} distribution by {x_col}")
                
                explanation = create_chart_explanation(viz_type, df_to_plot, selected_columns)
            else:
                col = selected_columns[0]
                if pd.api.types.is_numeric_dtype(df_to_plot[col]):
                    fig = px.histogram(df_to_plot, x=col, title=f"Distribution of {col}")
                else:
                    value_counts = df_to_plot[col].value_counts().head(15)
                    fig = px.bar(x=value_counts.index, y=value_counts.values, title=f"Top Values in {col}")
                explanation = f"Chart showing distribution of {col}"
            fig.update_layout(width=800, height=500)
            return fig, explanation, fig
            
        elif viz_type == "Pie Chart":
            col = selected_columns[0]
            if len(selected_columns) >= 2 and pd.api.types.is_numeric_dtype(df_to_plot[selected_columns[1]]):
                grouped_data = df_to_plot.groupby(col)[selected_columns[1]].sum().reset_index()
                fig = px.pie(grouped_data, values=selected_columns[1], names=col, title=f"Total {selected_columns[1]} by {col}")
                legend_title = f"{col} Categories"
            else:
                value_counts = df_to_plot[col].value_counts().head(10)
                fig = px.pie(values=value_counts.values, names=value_counts.index, title=f"Distribution of {col}")
                legend_title = f"{col} Values"
            
            fig.update_layout(
                width=800, 
                height=500,
                showlegend=True,
                legend=dict(
                    title=dict(text=legend_title, font=dict(size=14, color="black")),
                    orientation="v",
                    yanchor="middle",
                    y=0.5,
                    xanchor="left",
                    x=1.05,
                    font=dict(size=12)
                )
            )
            explanation = f"PIE CHART: {col} Distribution\nShows proportion of each category\nUse to understand category distribution patterns"
            return fig, explanation, fig
            
        elif viz_type == "Scatter Plot":
            if len(selected_columns) >= 2:
                x_col, y_col = selected_columns[0], selected_columns[1]
                color_col = selected_columns[2] if len(selected_columns) > 2 else None
                
                # Check if both columns are suitable for scatter plot
                if not (pd.api.types.is_numeric_dtype(df_to_plot[x_col]) and pd.api.types.is_numeric_dtype(df_to_plot[y_col])):
                    return None, f"Scatter plot requires numeric data. {x_col} and {y_col} must be numeric.", None
                
                fig = px.scatter(df_to_plot, x=x_col, y=y_col, color=color_col, title=f"{y_col} vs {x_col}")
                explanation = f"Scatter plot showing relationship between {x_col} and {y_col}"
            else:
                return None, "Scatter plot requires at least 2 columns.", None
            fig.update_layout(width=800, height=500)
            return fig, explanation, fig
            
        elif viz_type == "Line Chart":
            if len(selected_columns) >= 2:
                x_col, y_col = selected_columns[0], selected_columns[1]
                
                if pd.api.types.is_numeric_dtype(df_to_plot[y_col]):
                    # Numeric Y: sort by X and plot trend
                    sorted_data = df_to_plot.sort_values(x_col)
                    fig = px.line(sorted_data, x=x_col, y=y_col, title=f"Trend of {y_col} over {x_col}", markers=True)
                    explanation = f"Line chart showing trend of {y_col} over {x_col}"
                else:
                    # Non-numeric Y: create cross-tabulation
                    crosstab = pd.crosstab(df_to_plot[x_col], df_to_plot[y_col])
                    melted = pd.melt(crosstab.reset_index(), id_vars=[x_col], var_name=y_col, value_name='Count')
                    fig = px.line(melted, x=x_col, y='Count', color=y_col, title=f"Distribution of {y_col} across {x_col}", markers=True)
                    explanation = create_chart_explanation(viz_type, df_to_plot, selected_columns, melted)
            else:
                return None, "Line chart requires at least 2 columns.", None
            fig.update_layout(width=800, height=500)
            return fig, explanation, fig
            
        elif viz_type == "Histogram":
            col = selected_columns[0]
            if pd.api.types.is_numeric_dtype(df_to_plot[col]):
                fig = px.histogram(df_to_plot, x=col, title=f"Distribution of {col}", nbins=30)
                explanation = f"Histogram showing distribution of {col}"
            else:
                return None, f"Histogram requires numeric data. Try Bar Chart instead.", None
            fig.update_layout(width=800, height=500)
            return fig, explanation, fig
        
        elif viz_type == "Heat Map":
            if len(selected_columns) >= 2:
                numeric_cols = [col for col in selected_columns if pd.api.types.is_numeric_dtype(df_to_plot[col])]
                if len(numeric_cols) >= 2:
                    corr_matrix = df_to_plot[numeric_cols].corr()
                    fig = px.imshow(corr_matrix, text_auto=True, aspect="auto", title="Correlation Heatmap", color_continuous_scale='RdBu')
                    explanation = f"Heatmap showing correlations between numeric columns"
                else:
                    x_col, y_col = selected_columns[0], selected_columns[1]
                    crosstab = pd.crosstab(df_to_plot[x_col], df_to_plot[y_col])
                    fig = px.imshow(crosstab.values, x=crosstab.columns, y=crosstab.index, text_auto=True, aspect="auto", title=f"Cross-tabulation: {y_col} vs {x_col}")
                    explanation = f"Heatmap showing cross-tabulation between {x_col} and {y_col}"
            else:
                return None, "Heat map requires at least 2 columns.", None
            fig.update_layout(width=800, height=500)
            return fig, explanation, fig
            
        elif viz_type == "Box Plot":
            if len(selected_columns) >= 1:
                y_col = selected_columns[0]
                if not pd.api.types.is_numeric_dtype(df_to_plot[y_col]):
                    return None, f"Box plot requires numeric Y-axis. {y_col} is not numeric.", None
                
                x_col = selected_columns[1] if len(selected_columns) > 1 else None
                fig = px.box(df_to_plot, x=x_col, y=y_col, title=f"Box Plot of {y_col}" + (f" by {x_col}" if x_col else ""))
                explanation = f"Box plot showing distribution of {y_col}" + (f" grouped by {x_col}" if x_col else "")
            else:
                return None, "Box plot requires at least 1 column.", None
            fig.update_layout(width=800, height=500)
            return fig, explanation, fig
        
        else:
            return None, f"Visualization type '{viz_type}' is under development.", None
            
    except Exception as e:
        return None, f"Error creating visualization: {str(e)}", None

def handle_missing_data(method, selected_columns, constant_value, uploaded_df, change_history):
    print(f"DEBUG: Starting {method} on columns {selected_columns}")
    
    if uploaded_df is None:
        return "Please upload a dataset first.", uploaded_df, change_history
    if method == "None":
        return "", uploaded_df, change_history
    if not selected_columns:
        return "Please select columns to apply data handling.", uploaded_df, change_history
    
    try:
        change_history.append(uploaded_df.copy())
        df_copy = uploaded_df.copy()
        
        if method == "Clean All Missing":
            return "Clean All Missing is not available", uploaded_df, change_history
        
        processed_columns = []
        dropped_columns = []
        
        for col in selected_columns:
            if col not in df_copy.columns:
                continue
            
            if method == "Forward Fill":
                if col == 'title':
                    print(f"DEBUG: Skipping title column due to data inconsistencies")
                    continue
                
                if df_copy[col].dtype == 'object':
                    patterns = ['UNKNOWN', 'unknown', 'ERROR', 'error', 'NULL', 'null', 'NA', 'na', 'N/A', 
                               'Not Given', 'not given', 'NOT GIVEN', '', ' ', '-', '?', 'NaN', 'nan', 
                               'None', 'none', 'NONE', '#N/A', 'n/a', 'N.A.', 'n.a.']
                    for pattern in patterns:
                        df_copy[col] = df_copy[col].replace(pattern, np.nan)
                    df_copy[col] = df_copy[col].replace('', np.nan)
                
                df_copy[col] = df_copy[col].ffill()
                processed_columns.append(col)
            elif method == "Backward Fill":
                if df_copy[col].dtype == 'object':
                    patterns = ['UNKNOWN', 'unknown', 'ERROR', 'error', 'NULL', 'null', 'NA', 'na', 'N/A', 
                               'Not Given', 'not given', 'NOT GIVEN', '', ' ', '-', '?', 'NaN', 'nan', 
                               'None', 'none', 'NONE', '#N/A', 'n/a', 'N.A.', 'n.a.']
                    for pattern in patterns:
                        df_copy[col] = df_copy[col].replace(pattern, np.nan)
                    df_copy[col] = df_copy[col].replace('', np.nan)
                
                df_copy[col] = df_copy[col].bfill()
                processed_columns.append(col)
            elif method == "Constant Fill":
                if df_copy[col].dtype == 'object':
                    patterns = ['UNKNOWN', 'unknown', 'ERROR', 'error', 'NULL', 'null', 'NA', 'na', 'N/A', 
                               'Not Given', 'not given', 'NOT GIVEN', '', ' ', '-', '?', 'NaN', 'nan', 
                               'None', 'none', 'NONE', '#N/A', 'n/a', 'N.A.', 'n.a.']
                    for pattern in patterns:
                        df_copy[col] = df_copy[col].replace(pattern, np.nan)
                    df_copy[col] = df_copy[col].replace('', np.nan)
                
                fill_val = constant_value.strip() if constant_value else "Unknown"
                df_copy[col] = df_copy[col].fillna(fill_val)
                processed_columns.append(col)
            elif method == "Mean Fill":
                if pd.api.types.is_numeric_dtype(df_copy[col]):
                    if not df_copy[col].isna().all():
                        mean_val = df_copy[col].mean()
                        df_copy[col] = df_copy[col].fillna(mean_val)
                        processed_columns.append(col)
                else:
                    numeric_col = pd.to_numeric(df_copy[col], errors='coerce')
                    if not numeric_col.isna().all():
                        mean_val = numeric_col.mean()
                        df_copy[col] = numeric_col.fillna(mean_val)
                        processed_columns.append(col)
            elif method == "Median Fill":
                if pd.api.types.is_numeric_dtype(df_copy[col]):
                    if not df_copy[col].isna().all():
                        median_val = df_copy[col].median()
                        df_copy[col] = df_copy[col].fillna(median_val)
                        processed_columns.append(col)
                else:
                    numeric_col = pd.to_numeric(df_copy[col], errors='coerce')
                    if not numeric_col.isna().all():
                        median_val = numeric_col.median()
                        df_copy[col] = numeric_col.fillna(median_val)
                        processed_columns.append(col)
            elif method == "Mode Fill":
                patterns = ['UNKNOWN', 'unknown', 'ERROR', 'error', 'NULL', 'null', 'NA', 'na', 'N/A', 
                           'Not Given', 'not given', 'NOT GIVEN', '', ' ', '-', '?', 'NaN', 'nan', 
                           'None', 'none', 'NONE', '#N/A', 'n/a', 'N.A.', 'n.a.']
                
                valid_values = df_copy[col][~df_copy[col].isin(patterns) & df_copy[col].notna()]
                
                if len(valid_values) > 0:
                    mode_value = valid_values.mode()
                    if len(mode_value) > 0:
                        most_common = mode_value.iloc[0]
                        print(f"DEBUG: Mode Fill - Most common value for {col}: {most_common}")
                        
                        for pattern in patterns:
                            df_copy[col] = df_copy[col].replace(pattern, most_common)
                        
                        df_copy[col] = df_copy[col].fillna(most_common)
                        
                processed_columns.append(col)
            elif method == "Drop Columns":
                df_copy = df_copy.drop(columns=[col])
                dropped_columns.append(col)
        
        uploaded_df = df_copy
        remaining_cols = [col for col in selected_columns if col not in dropped_columns]
        
        if 'title' in uploaded_df.columns:
            title_check = uploaded_df['title'].astype(str).str.contains('UNKNOWN', case=False, na=False).sum()
            print(f"DEBUG: After update, title has {title_check} UNKNOWN values")
        
        if processed_columns:
            result = f"Applied {method} to: {', '.join(processed_columns)}"
            for col in processed_columns:
                if col in uploaded_df.columns:
                    after_missing = uploaded_df[col].isnull().sum()
                    result += f"\n- {col}: {after_missing} missing values remaining"
        elif dropped_columns:
            result = f"Dropped columns: {', '.join(dropped_columns)}"
        else:
            result = "No columns processed - check column selection or data types"
            
        return result, uploaded_df, change_history
        
    except Exception as e:
        return f"Error: {str(e)}", uploaded_df, change_history

def undo_last_change(uploaded_df, change_history):
    if not change_history:
        return "No changes to undo.", uploaded_df, change_history
    uploaded_df = change_history.pop()
    return f"Undid last change. Dataset now has {uploaded_df.shape[0]} rows × {uploaded_df.shape[1]} columns", uploaded_df, change_history

def undo_all_changes(original_df, change_history):
    if original_df is None:
        return "No original dataset to restore.", None, change_history
    uploaded_df = original_df.copy()
    change_history = []
    return f"Dataset restored to original state ({uploaded_df.shape[0]} rows × {uploaded_df.shape[1]} columns)", uploaded_df, change_history

def download_dataset(uploaded_df, dataset_name):
    if uploaded_df is None:
        return None
    
    if dataset_name:
        base_name = dataset_name.replace('.csv', '').replace('.xlsx', '').replace('.xls', '')
        filename = f"{base_name}_modified.csv"
    else:
        filename = "modified_dataset.csv"
    
    temp_dir = tempfile.gettempdir()
    filepath = os.path.join(temp_dir, filename)
    uploaded_df.to_csv(filepath, index=False)
    return filepath

def display_data_format(format_type, selected_columns, uploaded_df):
    if uploaded_df is None or format_type == "None":
        return None
    df_to_show = uploaded_df[selected_columns] if selected_columns else uploaded_df
    return df_to_show.head(100) if format_type == "DataFrame" else None

def display_text_format(format_type, selected_columns, uploaded_df):
    if uploaded_df is None or format_type == "None":
        return ""
    df_to_show = uploaded_df[selected_columns] if selected_columns else uploaded_df
    if format_type == "JSON":
        return df_to_show.head(20).to_json(orient='records', indent=2)
    elif format_type == "Dictionary":
        return str(df_to_show.head(20).to_dict(orient='records'))