# File: frequency.py
# Copyright (C) 2026 Erick Ahmed
# SPDX-License-Identifier: AGPL-3.0-or-later

import argparse
import json
from pathlib import Path
import fastparquet
import pandas as pd
import plotly.express as px
import plotly.graph_objects as go


def _extract_identifier(row: pd.Series) -> str:
    """Extracts PGN from metadata or falls back to CAN ID."""
    meta = row.get('j1939_metadata')
    if pd.isna(meta):
        return f"{row['ID']} "
    if isinstance(meta, str):
        try:
            meta = json.loads(meta)
        except json.JSONDecodeError:
            return f"{row['ID']}"
    if isinstance(meta, dict) and 'PGN' in meta:
        return f"PGN: {meta['PGN']} "
    return f"{row['ID']}"


def load_data(file_path: Path) -> pd.DataFrame:
    """Loads Parquet file and adds an Identifier column."""
    df = pd.read_parquet(file_path)
    df['Identifier'] = df.apply(_extract_identifier, axis=1)
    return df


def calculate_frequency(df: pd.DataFrame) -> pd.DataFrame:
    """Calculates frequency counts and percentages for identifiers."""
    freq_df = df['Identifier'].value_counts().reset_index()
    freq_df.columns = ['Identifier', 'Count']
    total_messages = freq_df['Count'].sum()
    freq_df['Percentage'] = (freq_df['Count'] / total_messages * 100).round(2)
    return freq_df.sort_values('Count', ascending=True)


def visualize_frequency(stats_df: pd.DataFrame, title: str = "CAN Bus Message Frequency") -> go.Figure:
    """Generates an interactive Plotly horizontal bar chart with a logarithmic x-axis."""
    fig = px.bar(
        stats_df, y='Identifier', x='Count', orientation='h', title=title, log_x=True,
        labels={'Identifier': 'PGN / CAN ID', 'Count': 'Message Count'},
        color='Count', color_continuous_scale='Turbo',
        hover_data={'Percentage': ':.2f', 'Count': True, 'Identifier': True}
    )

    fig.update_layout(
        height=max(600, len(stats_df) * 18), width=1000,
        xaxis_title='Total Message Count (Log Scale)', yaxis_title='PGN or CAN ID',
        yaxis={'categoryorder': 'total ascending'},
        plot_bgcolor='rgba(0,0,0,0)', paper_bgcolor='white',
        font=dict(family="Segoe UI, Arial, sans-serif", size=12),
        hoverlabel=dict(bgcolor="white", font_size=13, font_family="Segoe UI"),
        margin=dict(l=250, r=50, t=80, b=50),
        title=dict(font=dict(size=20), x=0.5)
    )

    fig.update_traces(
        hovertemplate="<b>%{y}</b><br>Count: %{x:,}<br>Share: %{customdata[0]}%<extra></extra>"
    )
    return fig

if __name__ == "__main__":
    parser = argparse.ArgumentParser(description="Analyze CAN bus Parquet data.")
    parser.add_argument("-i", "--input", type=Path, required=True)
    parser.add_argument("-o", "--output", type=Path, default=Path("can_analysis_report.html"))
    parser.add_argument("-t", "--title", type=str, default="CAN Bus Message Frequency by PGN / ID")
    args = parser.parse_args()

    df = load_data(args.input)
    stats_df = calculate_frequency(df)
    fig = visualize_frequency(stats_df, title=args.title)
    fig.write_html(str(args.output), include_plotlyjs='cdn')