import type { StyleProp, TextStyle, ViewStyle } from 'react-native';
import type { ColorToken, ShapeToken, SpacingToken, StyleWire, TypeToken } from '@proulr/sdui-contract';
import { m3Colors, m3Shape, m3Type, spacing } from './proulr-theme';

function resolveColor(token: ColorToken | undefined): string | undefined {
  if (!token) return undefined;
  return m3Colors[token as keyof typeof m3Colors];
}

function resolveSpacing(token: SpacingToken | number | undefined): number | undefined {
  if (token == null) return undefined;
  if (typeof token === 'number') return token;
  return spacing[token];
}

function resolveShape(token: ShapeToken | number | undefined): number | undefined {
  if (token == null) return undefined;
  if (typeof token === 'number') return token;
  return m3Shape[token];
}

function resolveTypography(token: TypeToken | undefined): TextStyle | undefined {
  if (!token) return undefined;
  return m3Type[token];
}

function camelToSnake(key: string): string {
  return key.replace(/[A-Z]/g, (c) => `_${c.toLowerCase()}`);
}

/**
 * Canonical StyleWire is snake_case. Accept camelCase inputs from older wires
 * without dropping underscore keys (previous normalize converted to camel and
 * broke every `*_` token read).
 */
function normalizeStyleWire(style: StyleWire | Record<string, unknown> | undefined): StyleWire {
  if (!style) return {};
  const normalized: Record<string, unknown> = {};
  for (const [key, value] of Object.entries(style)) {
    const snakeKey = key.includes('_') ? key : camelToSnake(key);
    normalized[snakeKey] = value;
  }
  return normalized as StyleWire;
}

export function resolveViewStyleProps(
  styleWire: StyleWire | Record<string, unknown> | undefined,
): StyleProp<ViewStyle> {
  const style = normalizeStyleWire(styleWire);
  return {
    backgroundColor: resolveColor(style.background_color),
    padding: resolveSpacing(style.padding),
    paddingHorizontal: resolveSpacing(style.padding_horizontal),
    paddingVertical: resolveSpacing(style.padding_vertical),
    marginTop: resolveSpacing(style.margin_top),
    gap: resolveSpacing(style.gap),
    borderRadius: resolveShape(style.border_radius),
    borderWidth: style.border_width,
    borderColor: resolveColor(style.border_color),
    opacity: style.opacity,
    flex: style.flex,
    alignItems: style.align_items,
  };
}

export function resolveTextStyleProps(
  styleWire: StyleWire | Record<string, unknown> | undefined,
  variant?: string,
): StyleProp<TextStyle> {
  const style = normalizeStyleWire(styleWire);
  const variantType = (style.typography ?? variant) as TypeToken | undefined;
  return {
    ...resolveTypography(variantType),
    color: resolveColor(style.color),
    marginTop: resolveSpacing(style.margin_top),
    opacity: style.opacity,
    textAlign: style.text_align,
  };
}

export function resolveGapProp(gap: unknown, fallback: number): number {
  if (typeof gap === 'number') return gap;
  if (typeof gap === 'string' && gap in spacing) return spacing[gap as SpacingToken];
  return fallback;
}

export function resolvePaddingProp(padding: unknown, fallback = 0): number {
  if (typeof padding === 'number') return padding;
  if (typeof padding === 'string' && padding in spacing) return spacing[padding as SpacingToken];
  return fallback;
}