/**
 * Chart colours.
 *
 * These are the validated data-viz slots, not the brand accent: the UI is warm
 * ember on paper, but a chart has to stay readable for colour-blind readers in
 * both themes, so identity colours come from the reference palette. Focus takes
 * the orange slot (nearest the brand's warmth), breaks take aqua, and anything
 * that encodes *magnitude* uses the single-hue blue ramp — this ordering was run
 * through the palette validator for all pairs in both modes.
 */

export interface VizPalette {
  work: string;
  shortBreak: string;
  longBreak: string;
  sequential: string[];
  grid: string;
  axis: string;
  empty: string;
}

const LIGHT: VizPalette = {
  work: "#eb6834",
  shortBreak: "#2a78d6",
  longBreak: "#1baf7a",
  // blue 100 → 600: "more pomodoros" reads as "darker".
  sequential: ["#cde2fb", "#9ec5f4", "#6da7ec", "#3987e5", "#256abf", "#184f95"],
  grid: "rgba(23, 21, 15, 0.12)",
  axis: "rgba(23, 21, 15, 0.45)",
  empty: "rgba(23, 21, 15, 0.07)",
};

const DARK: VizPalette = {
  work: "#d95926",
  shortBreak: "#3987e5",
  longBreak: "#199e70",
  sequential: ["#104281", "#184f95", "#256abf", "#3987e5", "#6da7ec", "#9ec5f4"],
  grid: "rgba(244, 241, 234, 0.14)",
  axis: "rgba(244, 241, 234, 0.55)",
  empty: "rgba(244, 241, 234, 0.08)",
};

export function vizPalette(dark: boolean): VizPalette {
  return dark ? DARK : LIGHT;
}

export function kindColor(kind: string, palette: VizPalette): string {
  if (kind === "work") return palette.work;
  if (kind === "long_break") return palette.longBreak;
  return palette.shortBreak;
}

/** Pick a ramp step for a count; null means "nothing happened". */
export function rampStep(count: number, goal: number, palette: VizPalette): string | null {
  if (count <= 0) return null;
  const ratio = goal > 0 ? count / goal : count / 8;
  const index = Math.min(
    palette.sequential.length - 1,
    Math.max(0, Math.round(ratio * (palette.sequential.length - 1))),
  );
  return palette.sequential[index];
}