"""Widget graphique bande passante RX/TX (QPainter, sans dépendance externe)."""
from __future__ import annotations
from collections import deque
from PyQt6.QtWidgets import QWidget
from PyQt6.QtGui import QPainter, QColor, QPen, QBrush, QFont, QPainterPath
from PyQt6.QtCore import Qt, QRect, QPointF


def _fmt(bps: float) -> str:
    if bps >= 1_048_576:
        return f"{bps/1_048_576:.1f} MB/s"
    if bps >= 1_024:
        return f"{bps/1_024:.0f} KB/s"
    return f"{bps:.0f} B/s"


class BandwidthGraph(QWidget):
    """Affiche RX (bleu) et TX (vert) sur les N dernières secondes."""

    POINTS = 30   # nombre de points conservés

    def __init__(self, parent=None):
        super().__init__(parent)
        self._rx: deque[float] = deque([0.0] * self.POINTS, maxlen=self.POINTS)
        self._tx: deque[float] = deque([0.0] * self.POINTS, maxlen=self.POINTS)
        self.setMinimumHeight(70)
        self.setStyleSheet("background: transparent;")

    def push(self, rx_bps: float, tx_bps: float) -> None:
        self._rx.append(max(0.0, rx_bps))
        self._tx.append(max(0.0, tx_bps))
        self.update()

    def reset(self) -> None:
        self._rx = deque([0.0] * self.POINTS, maxlen=self.POINTS)
        self._tx = deque([0.0] * self.POINTS, maxlen=self.POINTS)
        self.update()

    def paintEvent(self, _):
        p = QPainter(self)
        p.setRenderHint(QPainter.RenderHint.Antialiasing)
        w, h = self.width(), self.height()
        pad_l, pad_r, pad_t, pad_b = 42, 8, 6, 20

        # Fond
        p.fillRect(0, 0, w, h, QColor("#17202a"))

        plot_w = w - pad_l - pad_r
        plot_h = h - pad_t - pad_b

        max_val = max(max(self._rx), max(self._tx), 1.0)

        def _path(data: deque, color: str, fill: str):
            pts = list(data)
            path = QPainterPath()
            xs = [pad_l + i * plot_w / (len(pts) - 1) for i in range(len(pts))]
            ys = [pad_t + plot_h - (v / max_val) * plot_h for v in pts]
            path.moveTo(QPointF(xs[0], pad_t + plot_h))
            path.lineTo(QPointF(xs[0], ys[0]))
            for x, y in zip(xs[1:], ys[1:]):
                path.lineTo(QPointF(x, y))
            path.lineTo(QPointF(xs[-1], pad_t + plot_h))
            path.closeSubpath()
            p.fillPath(path, QBrush(QColor(fill)))
            pen = QPen(QColor(color))
            pen.setWidthF(1.5)
            p.setPen(pen)
            line = QPainterPath()
            line.moveTo(QPointF(xs[0], ys[0]))
            for x, y in zip(xs[1:], ys[1:]):
                line.lineTo(QPointF(x, y))
            p.drawPath(line)

        _path(self._rx, "#5dade2", "#1a3a52")   # RX bleu
        _path(self._tx, "#58d68d", "#1a3d2b")   # TX vert

        # Axes
        p.setPen(QPen(QColor("#2e4057")))
        p.drawLine(pad_l, pad_t, pad_l, pad_t + plot_h)
        p.drawLine(pad_l, pad_t + plot_h, w - pad_r, pad_t + plot_h)

        # Labels Y
        font = QFont("Arial", 8)
        p.setFont(font)
        p.setPen(QPen(QColor("#5d6d7e")))
        for frac, label in [(0.0, _fmt(max_val)), (0.5, _fmt(max_val / 2)), (1.0, "0")]:
            y = int(pad_t + frac * plot_h)
            p.drawText(QRect(0, y - 8, pad_l - 2, 16),
                       Qt.AlignmentFlag.AlignRight | Qt.AlignmentFlag.AlignVCenter,
                       label)

        # Légende
        p.setPen(QPen(QColor("#5dade2")))
        p.drawText(pad_l + 4, pad_t + 12, f"↓ {_fmt(self._rx[-1])}")
        p.setPen(QPen(QColor("#58d68d")))
        p.drawText(pad_l + 90, pad_t + 12, f"↑ {_fmt(self._tx[-1])}")

        p.end()