import { z } from 'zod';

// ── White-label Theming ───────────────────────────────────────────────────────
// Enterprise workspaces can override the Originmain UI with their own brand.
// The theming pipeline:
//   1. WorkspaceBrand (stored in workspace.metadata_jsonb) → BrandTokens
//   2. BrandTokens → Fluent 2 BrandVariants (via createLightTheme / createDarkTheme)
//   3. BrandVariants → FluentProvider theme prop
//
// Note: Actual Fluent 2 createLightTheme / createDarkTheme calls happen in
// packages/app/src/lib/workspace-theme.ts to avoid a @fluentui dep here.

export const BrandTokensSchema = z.object({
  /** Primary brand colour in 6-digit hex */
  primaryColor: z.string().regex(/^#[0-9a-f]{6}$/i),
  /** Optional secondary accent */
  secondaryColor: z.string().regex(/^#[0-9a-f]{6}$/i).optional(),
  /** Brand logo URL (SVG or PNG, ≤512KB) */
  logoUrl: z.string().url().optional(),
  /** Tab title prefix: e.g. "Acme Design" → "Acme Design — Originmain" */
  productName: z.string().max(40).optional(),
  /** Favicon URL (ICO, PNG, or SVG) */
  faviconUrl: z.string().url().optional(),
});

export type BrandTokens = z.infer<typeof BrandTokensSchema>;

/**
 * Derives the 10-shade Fluent 2 BrandVariants record from a single hex colour.
 * Shades are generated by interpolating HSL lightness across the standard scale.
 * The returned object is passed directly to createLightTheme / createDarkTheme.
 */
export function brandVariantsFromHex(hex: string): Record<`shade${10 | 20 | 30 | 40 | 50 | 60 | 70 | 80 | 90 | 100 | 110 | 120 | 130 | 140 | 150 | 160}`, string> {
  const [r, g, b] = hexToRgb(hex);
  const [h, s] = rgbToHsl(r, g, b);

  // Fluent 2 uses shades 10–160 in 10-step increments (16 shades).
  // shade10 = lightest, shade160 = darkest.
  const shadeNumbers = [10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160] as const;
  const result = {} as Record<string, string>;

  for (const shade of shadeNumbers) {
    // Map shade index to lightness: shade10 ≈ 95%, shade160 ≈ 10%
    const lightness = 95 - ((shade - 10) / 150) * 85;
    result[`shade${shade}`] = hslToHex(h, s, lightness);
  }

  return result as ReturnType<typeof brandVariantsFromHex>;
}

// ── HSL ↔ RGB ↔ Hex helpers ──────────────────────────────────────────────────

function hexToRgb(hex: string): [number, number, number] {
  const clean = hex.replace('#', '');
  const r = parseInt(clean.slice(0, 2), 16);
  const g = parseInt(clean.slice(2, 4), 16);
  const b = parseInt(clean.slice(4, 6), 16);
  if (Number.isNaN(r) || Number.isNaN(g) || Number.isNaN(b)) {
    throw new Error(`Invalid hex color: "${hex}"`);
  }
  return [r, g, b];
}

function rgbToHsl(r: number, g: number, b: number): [number, number, number] {
  const rn = r / 255, gn = g / 255, bn = b / 255;
  const max = Math.max(rn, gn, bn), min = Math.min(rn, gn, bn);
  const l = (max + min) / 2;
  if (max === min) return [0, 0, l * 100];

  const d = max - min;
  const s = l > 0.5 ? d / (2 - max - min) : d / (max + min);
  let h = 0;
  if (max === rn) h = ((gn - bn) / d + (gn < bn ? 6 : 0)) / 6;
  else if (max === gn) h = ((bn - rn) / d + 2) / 6;
  else h = ((rn - gn) / d + 4) / 6;

  return [h * 360, s * 100, l * 100];
}

function hslToHex(h: number, s: number, l: number): string {
  const sn = s / 100, ln = l / 100;
  const a = sn * Math.min(ln, 1 - ln);
  const f = (n: number): string => {
    const k = (n + h / 30) % 12;
    const color = ln - a * Math.max(Math.min(k - 3, 9 - k, 1), -1);
    return Math.round(255 * color).toString(16).padStart(2, '0');
  };
  return `#${f(0)}${f(8)}${f(4)}`;
}