// SPDX-License-Identifier: MIT
// SPDX-FileCopyrightText: 2026 Martino Ferrari

#include <plot/plot/axis.hpp>

#include <cmath>

namespace plot {

void Axis::format_value(f64 v, char* buf, usize n) const {
  // The one place a value on this axis becomes text, so the origin is applied here and
  // everything that goes through it -- tick labels, and the crosshair's readout -- reads in
  // the same frame of reference as the axis itself.
  // The subtraction leaves a residue when the value and the origin are the same distant number
  // (a tick exactly on the origin then formatted as `1.78e-12ms` instead of `0ms`). Snapping it
  // is a *relative* test, so a genuinely small value on a large axis is not swallowed -- what
  // this removes is arithmetic dust, not data.
  f64 shown = v - origin;
  if (std::fabs(shown) < 1.0e-12 * std::max(1.0, std::fabs(v))) shown = 0.0;
  if (format == TickFormat::Time) {
    format_time(shown, buf, n);
    return;
  }
  format_si(shown, buf, n);
}

void Axis::refresh(f32 px, f32 min_px, bool include_minors) {
  // The range first, so a following origin is this frame's edge and not the last one's: the
  // zero tick then sits exactly on the window start, which is the whole point of asking.
  if (origin_follows_range) origin = range.min;
  generate_ticks(range, px, min_px, ticks, include_minors, origin);
  if (format != TickFormat::Time) return;
  // generate_ticks labels with format_si; a time axis relabels its majors here,
  // because the tick generator has no business knowing about a clock -- through the one
  // function that says how a value on this axis is written.
  char buf[64];
  for (Tick& tick : ticks) {
    if (!tick.major) continue;
    format_value(tick.value, buf, sizeof buf);
    tick.label = buf;
  }
}

}  // namespace plot