// Theme-aware color palette for projects
// Uses oklch for better perceptual uniformity and theme compatibility
// These are base hues that work in both light and dark modes

import { isValidProjectColor } from "./color";

// Default color for unassigned/fallback - neutral gray that works in both themes
export const UNASSIGNED_COLOR = "oklch(0.55 0.02 260)";

// Golden angle distribution for visually distinct hues (based on Fibonacci)
const GOLDEN_ANGLE = 137.508;

// Base hues distributed using golden angle for maximum visual distinction
const BASE_HUES = [
  0, // red/rose
  34, // orange
  60, // yellow-gold
  145, // teal/cyan
  210, // blue
  265, // purple/violet
  300, // pink/magenta
  90, // lime/green
  180, // cyan
  240, // indigo
] as const;

let colorIndex = 0;

/**
 * Generate a simple hash from a string
 */
function hashString(str: string): number {
  let hash = 0;
  for (let i = 0; i < str.length; i++) {
    const char = str.charCodeAt(i);
    hash = (hash << 5) - hash + char;
    hash = hash & hash; // Convert to 32bit integer
  }
  return Math.abs(hash);
}

/**
 * Generate a deterministic oklch color from a string
 * Uses oklch for better perceptual uniformity across light/dark themes
 * Returns an oklch string that works with CSS
 */
export function getColorForName(name: string): string {
  const hash = hashString(name);
  // Use golden angle distribution for better hue spread
  const hueIndex = hash % BASE_HUES.length;
  const baseHue = BASE_HUES[hueIndex];
  // Add small variation based on hash for uniqueness within same hue family
  const hueVariation = ((hash >> 8) % 30) - 15; // -15 to +15 degrees
  const hue = (baseHue + hueVariation + 360) % 360;

  // oklch values tuned for both light and dark mode visibility
  // L: 0.6 works in both modes (not too light, not too dark)
  // C: 0.15 is vibrant but not overwhelming
  const lightness = 0.55 + ((hash >> 4) % 10) / 100; // 0.55-0.65
  const chroma = 0.12 + ((hash >> 6) % 6) / 100; // 0.12-0.18

  return `oklch(${lightness} ${chroma} ${hue})`;
}

/**
 * Get the next color using golden angle distribution
 */
export function getNextColor(): string {
  const hue = (colorIndex * GOLDEN_ANGLE) % 360;
  colorIndex++;
  return `oklch(0.6 0.15 ${hue})`;
}

/**
 * Reset the color index (useful when starting fresh)
 */
export function resetColorIndex(): void {
  colorIndex = 0;
}

/**
 * Get a color at a specific index using golden angle distribution
 */
export function getColorAt(index: number): string {
  const hue = (index * GOLDEN_ANGLE) % 360;
  return `oklch(0.6 0.15 ${hue})`;
}

/**
 * Deterministic default accent color for a team, derived from its stable id so
 * a team that has never chosen an explicit themeColor still gets a distinct,
 * theme-aware color. Same hashing as project colors for a consistent palette.
 */
export function getDefaultTeamColor(teamId: string): string {
  return getColorForName(teamId);
}

/**
 * Resolve a team's accent color: the stored `themeColor` when it is a valid
 * persistable color (strict hex / numeric oklch), otherwise the deterministic
 * per-team default. Used by app chrome that inherits the active team's color.
 */
export function resolveTeamColor(
  teamId: string,
  themeColor?: string | null,
): string {
  return typeof themeColor === "string" && isValidProjectColor(themeColor)
    ? themeColor.trim()
    : getDefaultTeamColor(teamId);
}