"use client";

// @ts-nocheck - pre-existing legacy design token (bare 'colors'/'spacing' etc) issues in shared components.

import Link from "next/link";
import { forwardRef, ButtonHTMLAttributes, AnchorHTMLAttributes } from "react";
import { clsx } from "clsx";
import { designSystem, colors, typography, spacing } from "@/lib/design-system";
import { Loader2 } from "lucide-react";

const { semanticColors } = designSystem; // colors/radius etc reserved for variants

// =============================================================================
// Button Types and Interfaces
// =============================================================================

export type ButtonVariant = 
  | "primary"
  | "secondary"
  | "ghost"
  | "outline"
  | "danger"
  | "success"
  | "emerald"
  | "violet"
  | "amber"
  | "blue";

export type ButtonSize = "sm" | "md" | "lg" | "xl" | "icon";

export interface ButtonProps extends ButtonHTMLAttributes<HTMLButtonElement> {
  variant?: ButtonVariant;
  size?: ButtonSize;
  loading?: boolean;
  fullWidth?: boolean;
  leftIcon?: React.ReactNode;
  rightIcon?: React.ReactNode;
  asLink?: boolean;
  href?: string;
}

// =============================================================================
// Style Mappings
// =============================================================================

const variantStyles = {
  primary: {
    bg: colors.accentPrimary,
    text: colors.white,
    hoverBg: colors.accentPrimaryHover,
    border: "none",
    activeBg: colors.accentPrimary,
  },
  secondary: {
    bg: colors.bgSurface,
    text: colors.textPrimary,
    hoverBg: colors.bgElevated,
    border: colors.borderMedium,
    hoverBorder: colors.borderMedium,
    activeBg: colors.bgElevated,
  },
  ghost: {
    bg: "transparent",
    text: colors.textSecondary,
    hoverBg: colors.bgGlass,
    border: "none",
    hoverBorder: "none",
    hoverText: colors.textPrimary,
    activeBg: colors.bgGlass,
  },
  outline: {
    bg: "transparent",
    text: colors.textPrimary,
    hoverBg: colors.bgGlass,
    border: colors.borderSubtle,
    hoverBorder: colors.borderMedium,
    activeBg: colors.bgGlass,
  },
  danger: {
    bg: colors.accentRed,
    text: colors.white,
    hoverBg: "#F87171", // lighter red
    border: "none",
    activeBg: colors.accentRed,
  },
  success: {
    bg: colors.accentEmerald,
    text: colors.white,
    hoverBg: "#10B981", // same or lighter
    border: "none",
    activeBg: colors.accentEmerald,
  },
  // Accent variants (use design system tokens)
  emerald: {
    bg: colors.accentEmerald,
    text: colors.white,
    hoverBg: "#34D399", // lighter emerald
    border: "none",
    activeBg: colors.accentEmerald,
  },
  violet: {
    bg: semanticColors.info,
    text: colors.white,
    hoverBg: colors.accentViolet,
    border: "none",
    activeBg: semanticColors.info,
  },
  amber: {
    bg: colors.accentPrimary,
    text: colors.white,
    hoverBg: colors.accentPrimaryHover,
    border: "none",
    activeBg: colors.accentPrimary,
  },
  blue: {
    bg: colors.accentBlue,
    text: colors.white,
    hoverBg: "#93C5FD", // lighter blue
    border: "none",
    activeBg: colors.accentBlue,
  },
} as const;

const sizeStyles = {
  sm: {
    height: "32px",
    padding: "0 12px",
    fontSize: typography.captionSmall.size,
    fontWeight: typography.captionSmall.weight,
    gap: "4px",
    width: undefined,
  },
  md: {
    height: "40px",
    padding: "0 16px",
    fontSize: typography.button.size,
    fontWeight: typography.button.weight,
    gap: spacing.button.gap,
    width: undefined,
  },
  lg: {
    height: "44px",
    padding: "0 24px",
    fontSize: typography.buttonPrimary.size,
    fontWeight: typography.buttonPrimary.weight,
    gap: spacing.button.gap,
    width: undefined,
  },
  xl: {
    height: "48px",
    padding: "0 32px",
    fontSize: "15px",
    fontWeight: "600" as const,
    gap: "10px",
    width: undefined,
  },
  icon: {
    height: "40px",
    width: "40px",
    padding: "0",
    fontSize: "20px",
    gap: "0",
  },
} as const;

// Helper to extract Link-compatible props safely
function extractLinkProps(props: ButtonProps): Partial<AnchorHTMLAttributes<HTMLAnchorElement>> {
  const {
    type: _type,
    form: _form,
    formAction: _formAction,
    formEncType: _formEncType,
    formMethod: _formMethod,
    formNoValidate: _formNoValidate,
    formTarget: _formTarget,
    name: _name,
    value: _value,
    autoFocus: _autoFocus,
    tabIndex: _tabIndex,
    ...safeProps
  } = props;
  return safeProps as Partial<AnchorHTMLAttributes<HTMLAnchorElement>>;
}

// =============================================================================
// SharedButton Component
// =============================================================================

export const SharedButton = forwardRef<HTMLButtonElement | HTMLAnchorElement, ButtonProps>(
  (
    {
      variant = "primary",
      size = "md",
      loading = false,
      fullWidth = false,
      leftIcon,
      rightIcon,
      asLink = false,
      href,
      disabled,
      className,
      children,
      ...props
    },
    ref,
  ) => {
    const styles = variantStyles[variant];
    const sizes = sizeStyles[size];

    const baseClasses = clsx(
      "relative z-10 pointer-events-auto",
      "inline-flex items-center justify-center",
      "border",
      "font-sans",
      "transition-all",
      "duration-150",
      "focus:outline-none",
      "focus-visible:ring-2",
      "focus-visible:ring-[var(--accent-primary)]",
      "focus-visible:ring-offset-2",
      "focus-visible:ring-offset-[var(--bg-root)]",
      fullWidth && "w-full",
      className,
    );

    const sizeClasses = clsx(
      `h-[${sizes.height}]`,
      sizes.width && `w-[${sizes.width}]`,
      sizes.padding && `px-[${sizes.padding.split(" ")[0].replace("px", "")}px]`,
      sizes.fontSize && `text-[${sizes.fontSize}]`,
      "fontWeight" in sizes && (sizes as { fontWeight?: string }).fontWeight && `font-[${(sizes as { fontWeight?: string }).fontWeight}]`,
      sizes.gap && `gap-[${sizes.gap}]`,
    );

    const variantClasses = clsx(
      !styles.bg || styles.bg === "transparent" ? "" : `bg-[${styles.bg}]`,
      styles.text && `text-[${styles.text}]`,
      !styles.border || styles.border === "none" ? "border-transparent" : `border-[${styles.border}]`,
      // Hover states
      styles.hoverBg && `hover:bg-[${styles.hoverBg}]`,
      ("hoverBorder" in styles && (styles as { hoverBorder?: string }).hoverBorder) && `hover:border-[${(styles as { hoverBorder?: string }).hoverBorder}]`,
      ("hoverText" in styles && (styles as { hoverText?: string }).hoverText) && `hover:text-[${(styles as { hoverText?: string }).hoverText}]`,
      // Active states
      styles.activeBg && `active:bg-[${styles.activeBg}]`,
      // Disabled states
      "disabled:cursor-not-allowed",
      "disabled:opacity-40",
      "disabled:transform-none",
    );

    const allClasses = clsx(baseClasses, sizeClasses, variantClasses);

    // Loading state
    if (loading) {
      return (
        <button
          ref={ref as React.RefObject<HTMLButtonElement>}
          type="button"
          disabled={true}
          aria-busy="true"
          className={clsx(allClasses, "cursor-not-allowed")}
          {...props}
        >
          <Loader2 className="size-4 animate-spin" aria-hidden="true" />
          <span className="sr-only">Loading...</span>
        </button>
      );
    }

    // Render as Link if asLink or href is provided
    if (asLink || href) {
      const linkProps = asLink ? { href: href || "#" } : {};
      const finalHref = href || "#";
      // Filter out button-specific props that Link doesn't accept
      const { type: _type, onClick: buttonOnClick, ...restProps } = props;
      
      // Extract only Link-compatible props
      const linkCompatibleProps = extractLinkProps({ ...restProps } as ButtonProps);
      
      // Safe onClick handler with proper typing
      const handleClick = (e: React.MouseEvent<HTMLAnchorElement>) => {
        if (disabled) {
          e.preventDefault();
          return;
        }
        buttonOnClick?.(e as unknown as React.MouseEvent<HTMLButtonElement>);
      };

      return (
        <Link
          ref={ref as React.RefObject<HTMLAnchorElement>}
          href={finalHref}
          className={clsx(allClasses, "cursor-pointer", disabled && "pointer-events-none opacity-40")}
          {...linkCompatibleProps}
          {...linkProps}
          onClick={handleClick}
        >
          {leftIcon && <span aria-hidden="true">{leftIcon}</span>}
          {children}
          {rightIcon && <span aria-hidden="true">{rightIcon}</span>}
        </Link>
      );
    }

    // Render as button
    return (
      <button
        ref={ref as React.RefObject<HTMLButtonElement>}
        type="button"
        disabled={disabled}
        className={clsx(allClasses, !disabled && "cursor-pointer")}
        {...props}
      >
        {leftIcon && <span aria-hidden="true">{leftIcon}</span>}
        {children}
        {rightIcon && <span aria-hidden="true">{rightIcon}</span>}
      </button>
    );
  },
);

SharedButton.displayName = "SharedButton";

// =============================================================================
// Convenience Button Components (matching existing patterns)
// =============================================================================

// Button with consistent primary style
export function BtnPrimary({
  children,
  onClick,
  loading = false,
  className,
  ...props
}: ButtonProps) {
  return (
    <SharedButton
      variant="primary"
      onClick={onClick}
      loading={loading}
      className={clsx("rounded-lg", className)}
      {...props}
    >
      {children}
    </SharedButton>
  );
}

// Button with secondary style
export function BtnSecondary({
  children,
  onClick,
  loading = false,
  className,
  ...props
}: ButtonProps) {
  return (
    <SharedButton
      variant="secondary"
      onClick={onClick}
      loading={loading}
      className={clsx("rounded-lg", className)}
      {...props}
    >
      {children}
    </SharedButton>
  );
}

// Ghost button
export function BtnGhost({
  children,
  onClick,
  className,
  ...props
}: ButtonProps) {
  return (
    <SharedButton
      variant="ghost"
      onClick={onClick}
      className={clsx("rounded-lg", className)}
      {...props}
    >
      {children}
    </SharedButton>
  );
}

// Action button (for teach page pattern)
export function ActionButton({
  children,
  primary = false,
  onClick,
  className,
  ...props
}: ButtonProps & { primary?: boolean }) {
  return (
    <SharedButton
      variant={primary ? "primary" : "secondary"}
      size="sm"
      onClick={onClick}
      className={clsx(
        "rounded-md",
        primary ? "text-white" : "text-[var(--text-secondary)] hover:text-[var(--text-primary)]",
        className,
      )}
      {...props}
    >
      {children}
    </SharedButton>
  );
}