/**
 * pi-shimmer-quotes-spinner — Spinner animation module
 *
 * Provides frame generators for each spinner style, speed calculation,
 * and the colour-sweep shimmer engine used on the verb text.
 */

import type { WorkingIndicatorOptions } from "@earendil-works/pi-coding-agent";
import type { SpinnerStyle } from "./config";

// ─── Shimmer Glyphs (Claude Code style) ────────────────────────────────

const SHIMMER_CHARS = ["·", "✢", "✳", "✶", "✻", "✽"];

/**
 * Ping-pong sequence: forward then immediately reverse.
 * Claude Code uses this exact pattern.
 */
export const SHIMMER_FRAMES: string[] = [
  ...SHIMMER_CHARS,
  ...[...SHIMMER_CHARS].reverse(),
];

// ─── Other Style Frames ────────────────────────────────────────────────

const CLASSIC_FRAMES = ["⠋", "⠙", "⠹", "⠸", "⠼", "⠴", "⠦", "⠧", "⠇", "⠏"];

const MINIMAL_FRAMES = ["·", "•", "●", "•"];

const DOTS_FRAMES = ["⣀", "⣠", "⣴", "⣾", "⣿", "⣾", "⣴", "⣠"];

const BRAILLE_FRAMES = [
  "⠋⠙", "⠙⠸", "⠹⠴", "⠸⠦", "⠼⠧", "⠴⠇", "⠦⠏", "⠧⠋", "⠇⠙", "⠏⠹",
];

// ─── Style Registry ────────────────────────────────────────────────────

interface StyleEntry {
  frames: string[];
  defaultIntervalMs: number;
}

const STYLE_MAP: Record<SpinnerStyle, StyleEntry> = {
  shimmer: {
    frames: SHIMMER_FRAMES,
    defaultIntervalMs: 120,
  },
  classic: {
    frames: CLASSIC_FRAMES,
    defaultIntervalMs: 100,
  },
  minimal: {
    frames: MINIMAL_FRAMES,
    defaultIntervalMs: 150,
  },
  dots: {
    frames: DOTS_FRAMES,
    defaultIntervalMs: 130,
  },
  braille: {
    frames: BRAILLE_FRAMES,
    defaultIntervalMs: 110,
  },
};

// ─── Public API ────────────────────────────────────────────────────────

/**
 * Return the spinner frame array for a given style.
 */
export function getSpinnerFrames(style: SpinnerStyle): string[] {
  return STYLE_MAP[style]?.frames ?? STYLE_MAP.shimmer.frames;
}

/**
 * Compute the interval between frames based on speed multiplier.
 */
export function intervalMs(style: SpinnerStyle, speedMultiplier: number): number {
  const entry = STYLE_MAP[style] ?? STYLE_MAP.shimmer;
  const base = entry.defaultIntervalMs;
  return Math.max(40, Math.min(400, base / Math.max(0.25, speedMultiplier)));
}

/**
 * Build a WorkingIndicatorOptions object for `ctx.ui.setWorkingIndicator()`.
 */
export function buildIndicatorOptions(
  style: SpinnerStyle,
  speed: number,
  colorFn: (text: string) => string,
): WorkingIndicatorOptions {
  const frames = getSpinnerFrames(style);
  return {
    frames: frames.map((f) => colorFn(f)),
    intervalMs: intervalMs(style, speed),
  };
}

// ─── Shimmer Color-Sweep Engine ────────────────────────────────────────

const SHIMMER_BAND = 4; // highlight-band width in characters

function hexToRgb(hex: string): [number, number, number] {
  const h = hex.replace("#", "");
  return [
    parseInt(h.slice(0, 2), 16),
    parseInt(h.slice(2, 4), 16),
    parseInt(h.slice(4, 6), 16),
  ];
}

function blend(
  a: [number, number, number],
  b: [number, number, number],
  t: number,
): [number, number, number] {
  return [
    Math.round(a[0] + (b[0] - a[0]) * t),
    Math.round(a[1] + (b[1] - a[1]) * t),
    Math.round(a[2] + (b[2] - a[2]) * t),
  ];
}

/**
 * Apply a moving colour-sweep highlight across the verb text.
 * Each character gets an ANSI 24-bit colour depending on its
 * distance from a moving "band" position.
 *
 * @param text   – the verb (e.g. "Brewing")
 * @param frame  – animation frame index (increments each tick)
 * @param baseHex  – base colour for un-highlighted characters
 * @param shimmerHex – peak colour at the centre of the band
 * @param reverse   – sweep direction (true = right-to-left)
 */
export function colorSweep(
  text: string,
  frame: number,
  baseHex: string,
  shimmerHex: string,
  reverse: boolean,
): string {
  const base = hexToRgb(baseHex);
  const shimmer = hexToRgb(shimmerHex);
  const total = text.length + SHIMMER_BAND * 2;
  const rawPos = frame % total;
  const pos = reverse ? total - 1 - rawPos : rawPos;

  let out = "";
  for (let i = 0; i < text.length; i++) {
    const dist = Math.abs(i - pos);
    const t = Math.max(0, 1 - dist / SHIMMER_BAND);
    const c = blend(base, shimmer, t);
    out += `\x1b[38;2;${c[0]};${c[1]};${c[2]}m${text[i]}`;
  }
  return out + "\x1b[0m";
}

/**
 * Static colour (no shimmer sweep).
 */
export function staticColor(text: string, hex: string): string {
  const c = hexToRgb(hex);
  return `\x1b[38;2;${c[0]};${c[1]};${c[2]}m${text}\x1b[0m`;
}