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

import argparse
from pathlib import Path
from concurrent.futures import ThreadPoolExecutor

import numpy as np
import pandas as pd
import plotly.graph_objects as go

from stats.utils.extractor import load_data
from stats.utils.extractor import to_int

def _format_can_id_vec(s: pd.Series) -> pd.Series:
    s = s.astype('string').str.strip()
    s = s.str.replace(r'^0x', '', case=False, regex=True)
    s = s.str.upper()
    return s.fillna('UNKNOWN').replace('', 'UNKNOWN')

def _ensure_int_bytes(df: pd.DataFrame, cols: list) -> pd.DataFrame:
    needs = [c for c in cols if not pd.api.types.is_numeric_dtype(df[c])]
    if needs:
        df = df.copy()
        for c in needs:
            df[c] = df[c].apply(to_int)
    return df

def calculate_correlation(df: pd.DataFrame, method: str, target_id: str | None = None) -> pd.DataFrame:
    available_cols = [f"b{i}" for i in range(8) if f"b{i}" in df.columns]

    if not available_cols:
        raise ValueError("No byte columns (b0-b7) found in the DataFrame")

    can_id_col = 'ID' if 'ID' in df.columns else 'Identifier'
    identifiers = _format_can_id_vec(df[can_id_col]).to_numpy()

    df_bytes = _ensure_int_bytes(df, available_cols)[available_cols]
    data = df_bytes.to_numpy(dtype=np.float64, copy=False)

    if target_id is not None:
        target_id = _format_can_id_vec(pd.Series([target_id])).iloc[0]
        mask = identifiers == target_id
        if not mask.any():
            raise ValueError(f"Identifier '{target_id}' not found in data")
        sub = data[mask]
        mask = ~np.isnan(sub).any(axis=1)
        sub = sub[mask]
        if method == 'spearman' and sub.shape[0] > 1:
            sub = pd.DataFrame(sub).rank().to_numpy()
        if sub.shape[0] > 1:
            with np.errstate(divide='ignore', invalid='ignore'):
                c = np.corrcoef(sub, rowvar=False)
            np.nan_to_num(c, copy=False, nan=0.0)
        else:
            c = np.zeros((len(available_cols), len(available_cols)))
        return pd.DataFrame(c, index=available_cols, columns=available_cols)

    unique_ids, inverse = np.unique(identifiers, return_inverse=True)
    n_cols = len(available_cols)

    sort_idx = np.argsort(inverse, kind='stable')
    data_sorted = data[sort_idx]
    inverse_sorted = inverse[sort_idx]

    if len(inverse_sorted) > 0:
        split_points = np.flatnonzero(np.diff(inverse_sorted)) + 1
        groups = np.split(data_sorted, split_points)
    else:
        groups = []

    def _process_group(sub):
        mask = ~np.isnan(sub).any(axis=1)
        sub = sub[mask]
        if len(sub) > 1:
            if method == 'spearman':
                sub = pd.DataFrame(sub).rank().to_numpy()
            with np.errstate(divide='ignore', invalid='ignore'):
                c = np.abs(np.corrcoef(sub, rowvar=False))
            np.nan_to_num(c, copy=False, nan=0.0)
            np.fill_diagonal(c, 0.0)
            return c.max(axis=0)
        return np.zeros(n_cols, dtype=np.float64)

    out = np.zeros((len(unique_ids), n_cols), dtype=np.float64)
    if len(groups) > 0:
        with ThreadPoolExecutor() as executor:
            results = list(executor.map(_process_group, groups))
            for i, res in enumerate(results):
                out[i] = res

    result = pd.DataFrame(out, index=unique_ids, columns=available_cols)
    result.index.name = 'Identifier'
    return result


def plot_correlation_heatmap(corr_df: pd.DataFrame, target_id: str | None, title: str) -> go.Figure:
    is_8x8 = target_id is not None

    x = corr_df.columns.tolist()
    y = corr_df.index.tolist()
    z = corr_df.values

    if is_8x8:
        z_min, z_max = -1.0, 1.0
        colorscale = [[0.0, "#2c7bb6"], [0.25, "#abd9e9"], [0.5, "#ffffff"], [0.75, "#fdae61"], [1.0, "#d7191c"]]
        hover_template = "<b>%{y}</b> vs <b>%{x}</b><br>Correlation: %{z:.2f}<extra></extra>"
    else:
        z_min, z_max = 0.0, 1.0
        colorscale = [[0.0, "#ffffff"], [0.2, "#fff5f0"], [0.4, "#fecc5c"], [0.6, "#fd8d3c"], [0.8, "#e31a1c"], [1.0, "#800026"]]
        hover_template = "<b>%{y}</b><br>Byte %{x} max correlation: %{z:.2f}<extra></extra>"

    fig = go.Figure(
        data=go.Heatmap(
            z=z, x=x, y=y,
            zmin=z_min, zmax=z_max,
            colorscale=colorscale,
            xgap=3, ygap=3,
            text=np.round(z, 2),
            texttemplate="%{text}",
            textfont={"size": 11, "color": "#2a2a2a", "family": "Segoe UI, Arial, sans-serif"},
            hoverongaps=False,
            hovertemplate=hover_template,
            colorbar=dict(
                title=dict(text="Correlation", side="top", font=dict(size=13, color="#1a1a1a")),
                orientation="h", thickness=15, len=0.35,
                x=1.0, xanchor="right", y=1.02, yanchor="bottom",
                tickfont=dict(size=11, color="#2a2a2a"),
                tickformat=".1f", outlinewidth=0.5, outlinecolor="#cccccc",
            ),
        )
    )

    fig.update_layout(
        title=dict(text=title, font=dict(size=20, color="#1a1a1a"), x=0.5, xanchor="center", pad=dict(b=20)),
        height=600 if is_8x8 else max(600, len(y) * 28 + 150),
        autosize=True,
        template="plotly_white",
        xaxis=dict(
            title=dict(text="Byte Position", font=dict(size=13, color="#1a1a1a")),
            side="bottom" if is_8x8 else "top",
            dtick=1, showgrid=False, linecolor="#bdbdbd",
            tickfont=dict(size=12, color="#2a2a2a"), ticks="outside", ticklen=4, tickcolor="#cccccc",
        ),
        yaxis=dict(
            title=dict(text="Byte Position" if is_8x8 else "PGN or CAN ID", font=dict(size=13, color="#1a1a1a")),
            autorange="reversed", showgrid=False, linecolor="#bdbdbd",
            tickfont=dict(size=12, color="#2a2a2a"), ticks="outside", ticklen=4, tickcolor="#cccccc", automargin=True,
        ),
        font=dict(family="Segoe UI, Arial, sans-serif", size=12, color="#2a2a2a"),
        hoverlabel=dict(bgcolor="white", font_size=13, font_family="Segoe UI", bordercolor="#cccccc"),
        margin=dict(l=200, r=40, t=120, b=60),
    )
    return fig


if __name__ == "__main__":
    parser = argparse.ArgumentParser(description="Analyze CAN bus inter-byte correlation")
    parser.add_argument("method", choices=["pearson", "spearman"], help="Correlation method to use")
    parser.add_argument("input", type=Path, help="Path to the input CAN log file")
    parser.add_argument("output", type=Path, nargs="?", default=Path("correlation_report.html"))
    parser.add_argument("title", nargs="?", default="CAN Bus Inter-Byte Correlation")
    parser.add_argument("--identifier", type=str, default=None)
    args = parser.parse_args()

    df = load_data(args.input)
    corr_df = calculate_correlation(df, method=args.method, target_id=args.identifier)
    display_title = f"{args.title} ({args.identifier})" if args.identifier else args.title
    fig = plot_correlation_heatmap(corr_df, target_id=args.identifier, title=display_title)
    config = {
        "responsive": True,
        "displaylogo": False,
        "scrollZoom": True,
        "modeBarButtonsToAdd": ["toggleSpikelines"],
        "toImageButtonOptions": {"format": "png", "scale": 2},
    }
    fig.write_html(str(args.output), include_plotlyjs="cdn", config=config)