/**
 * W3C Design Token Community Group (DTCG) format types and Zod schemas.
 *
 * Implements the W3C DTCG specification for design token files.
 * @see https://www.designtokens.org/tr/2025.10/format/
 */

import { z } from 'zod';

// ---------------------------------------------------------------------------
// Token types per DTCG spec
// ---------------------------------------------------------------------------

export type DTCGTokenType =
  | 'color'
  | 'dimension'
  | 'fontFamily'
  | 'fontWeight'
  | 'duration'
  | 'cubicBezier'
  | 'number'
  | 'shadow'
  | 'border'
  | 'strokeStyle'
  | 'transition'
  | 'gradient'
  | 'typography';

// ---------------------------------------------------------------------------
// Value types per DTCG spec
// ---------------------------------------------------------------------------

/** Color value (sRGB) */
export interface DTCGColorValue {
  colorSpace: string;
  components: number[];
  hex?: string;
  alpha?: number;
}

/** Dimension value */
export interface DTCGDimensionValue {
  value: number;
  unit: 'px' | 'rem';
}

/** Shadow value (single layer) */
export interface DTCGShadowValue {
  color: string | DTCGColorValue;
  offsetX: string | DTCGDimensionValue;
  offsetY: string | DTCGDimensionValue;
  blur: string | DTCGDimensionValue;
  spread: string | DTCGDimensionValue;
  inset?: boolean;
}

/** Border value */
export interface DTCGBorderValue {
  color: string | DTCGColorValue;
  width: string | DTCGDimensionValue;
  style: string;
}

/** Typography value */
export interface DTCGTypographyValue {
  fontFamily: string | string[];
  fontSize: string | DTCGDimensionValue;
  fontWeight: number | string;
  letterSpacing?: string | DTCGDimensionValue;
  lineHeight?: string | number;
}

/** Transition value */
export interface DTCGTransitionValue {
  duration: string;
  delay?: string;
  timingFunction: number[];
}

/** Gradient stop */
export interface DTCGGradientStop {
  color: string | DTCGColorValue;
  position: number;
}

/** Cubic bezier value */
export type DTCGCubicBezierValue = [number, number, number, number];

// ---------------------------------------------------------------------------
// Token and group structures
// ---------------------------------------------------------------------------

/** A single design token */
export interface DTCGToken {
  $value: unknown;
  $type?: DTCGTokenType;
  $description?: string;
  $deprecated?: boolean | string;
  $extensions?: Record<string, unknown>;
}

/** A group (recursive container for tokens and sub-groups) */
export interface DTCGGroup {
  $type?: DTCGTokenType;
  $description?: string;
  $deprecated?: boolean | string;
  $extensions?: Record<string, unknown>;
  $extends?: string;
  [key: string]: DTCGToken | DTCGGroup | unknown;
}

/** Root file structure — a top-level group */
export type DTCGTokenFile = DTCGGroup;

// ---------------------------------------------------------------------------
// Resolved token (after parsing)
// ---------------------------------------------------------------------------

export interface ResolvedDTCGToken {
  /** Dot-separated path (e.g., "color.brand.primary") */
  path: string;
  /** Resolved type (inherited from group if not set on token) */
  type: DTCGTokenType;
  /** Raw $value from the token */
  rawValue: unknown;
  /** CSS-compatible string value */
  cssValue: string;
  /** Description */
  description?: string;
  /** Whether token is deprecated */
  deprecated?: boolean | string;
  /** Extensions data */
  extensions?: Record<string, unknown>;
}

// ---------------------------------------------------------------------------
// Zod schemas for runtime validation
// ---------------------------------------------------------------------------

const dtcgTokenTypeSchema = z.enum([
  'color', 'dimension', 'fontFamily', 'fontWeight',
  'duration', 'cubicBezier', 'number',
  'shadow', 'border', 'strokeStyle', 'transition',
  'gradient', 'typography',
]);

const dtcgColorValueSchema = z.union([
  z.string(),
  z.object({
    colorSpace: z.string().default('srgb'),
    components: z.array(z.number()),
    hex: z.string().optional(),
    alpha: z.number().optional(),
  }),
]);

const dtcgDimensionValueSchema = z.union([
  z.string(),
  z.object({
    value: z.number(),
    unit: z.enum(['px', 'rem']),
  }),
]);

const dtcgShadowValueSchema = z.object({
  color: dtcgColorValueSchema,
  offsetX: dtcgDimensionValueSchema,
  offsetY: dtcgDimensionValueSchema,
  blur: dtcgDimensionValueSchema,
  spread: dtcgDimensionValueSchema.optional(),
  inset: z.boolean().optional(),
});

const dtcgBorderValueSchema = z.object({
  color: dtcgColorValueSchema,
  width: dtcgDimensionValueSchema,
  style: z.string(),
});

const dtcgTypographyValueSchema = z.object({
  fontFamily: z.union([z.string(), z.array(z.string())]),
  fontSize: dtcgDimensionValueSchema,
  fontWeight: z.union([z.number(), z.string()]),
  letterSpacing: dtcgDimensionValueSchema.optional(),
  lineHeight: z.union([z.string(), z.number()]).optional(),
});

const dtcgTransitionValueSchema = z.object({
  duration: z.string(),
  delay: z.string().optional(),
  timingFunction: z.array(z.number()).length(4),
});

const dtcgGradientStopSchema = z.object({
  color: dtcgColorValueSchema,
  position: z.number(),
});

const dtcgCubicBezierValueSchema = z.tuple([
  z.number(), z.number(), z.number(), z.number(),
]);

/** Schema for a single token node (has $value) */
const dtcgTokenSchema = z.object({
  $value: z.unknown(),
  $type: dtcgTokenTypeSchema.optional(),
  $description: z.string().optional(),
  $deprecated: z.union([z.boolean(), z.string()]).optional(),
  $extensions: z.record(z.string(), z.unknown()).optional(),
}).passthrough();

/**
 * Top-level schema for a DTCG token file.
 * Validates the root structure — individual tokens are validated by type
 * during parsing since the tree is recursive.
 */
export const dtcgTokenFileSchema = z.record(z.string(), z.unknown()).refine(
  (data) => {
    // A valid DTCG file should not be empty and should not be an array
    return data !== null && typeof data === 'object' && !Array.isArray(data);
  },
  { message: 'DTCG token file must be a JSON object' },
);

// Export individual schemas for consumers
export {
  dtcgTokenTypeSchema,
  dtcgTokenSchema,
  dtcgColorValueSchema,
  dtcgDimensionValueSchema,
  dtcgShadowValueSchema,
  dtcgBorderValueSchema,
  dtcgTypographyValueSchema,
  dtcgTransitionValueSchema,
  dtcgGradientStopSchema,
  dtcgCubicBezierValueSchema,
};