import type { AnchorHTMLAttributes, ButtonHTMLAttributes, ReactNode } from "react";
import { forwardRef } from "react";
import Link from "next/link";
import { cva, type VariantProps } from "class-variance-authority";
import { cn } from "@/shared/utils";
import { Spinner } from "./spinner";

const buttonVariants = cva(
  "group inline-flex items-center justify-center rounded-lg text-sm font-medium transition-all duration-[var(--cp-duration-normal)] focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-ring focus-visible:ring-offset-2 focus-visible:ring-offset-background disabled:opacity-50 disabled:pointer-events-none hover:scale-[1.01] active:scale-[0.98]",
  {
    variants: {
      variant: {
        default:
          "bg-primary text-primary-foreground hover:bg-primary-hover shadow-[var(--cp-shadow-1)] hover:shadow-[var(--cp-shadow-2)]",
        destructive:
          "bg-danger text-danger-foreground hover:bg-danger/90 shadow-[var(--cp-shadow-1)] hover:shadow-[var(--cp-shadow-2)]",
        outline:
          "border border-border bg-background text-foreground hover:bg-muted shadow-[var(--cp-shadow-1)] hover:shadow-[var(--cp-shadow-2)]",
        secondary:
          "bg-secondary text-secondary-foreground hover:bg-secondary/80 shadow-[var(--cp-shadow-1)] hover:shadow-[var(--cp-shadow-2)]",
        ghost: "text-foreground hover:bg-muted",
        subtle:
          "bg-muted/50 text-foreground hover:bg-muted border border-transparent hover:border-border/40",
        link: "underline-offset-4 hover:underline text-primary",
        pill: "rounded-full bg-primary text-primary-foreground hover:bg-primary/90 shadow-md shadow-primary/20 hover:-translate-y-0.5",
        pillOutline: "rounded-full border border-border bg-card text-primary hover:bg-primary/5",
      },
      size: {
        default: "h-11 py-2.5 px-4",
        sm: "h-9 px-3 text-xs",
        lg: "h-12 px-6 text-base",
      },
    },
    defaultVariants: {
      variant: "default",
      size: "default",
    },
  }
);

interface ButtonContentProps {
  loading: boolean;
  leftIcon?: ReactNode;
  rightIcon?: ReactNode;
  loadingText?: ReactNode;
  children?: ReactNode;
}

function ButtonContent({
  loading,
  leftIcon,
  rightIcon,
  loadingText,
  children,
}: ButtonContentProps) {
  return (
    <span className="inline-flex items-center justify-center gap-2">
      {loading ? <Spinner size="sm" /> : leftIcon}
      <span>{loading ? (loadingText ?? children) : children}</span>
      {!loading && rightIcon && (
        <span className="transition-transform duration-200 group-hover:translate-x-0.5">
          {rightIcon}
        </span>
      )}
    </span>
  );
}

interface ButtonExtras {
  leftIcon?: ReactNode;
  rightIcon?: ReactNode;
  loading?: boolean;
  isLoading?: boolean;
  loadingText?: ReactNode;
}

type ButtonAsAnchorProps = {
  as: "a";
  href: string;
} & AnchorHTMLAttributes<HTMLAnchorElement> &
  VariantProps<typeof buttonVariants> &
  ButtonExtras;

type ButtonAsButtonProps = {
  as?: "button";
} & ButtonHTMLAttributes<HTMLButtonElement> &
  VariantProps<typeof buttonVariants> &
  ButtonExtras;

export type ButtonProps = ButtonAsAnchorProps | ButtonAsButtonProps;

const Button = forwardRef<HTMLButtonElement | HTMLAnchorElement, ButtonProps>((props, ref) => {
  const {
    leftIcon,
    rightIcon,
    loading: loadingProp,
    isLoading,
    loadingText,
    children,
    ...rest
  } = props;

  const loading = loadingProp ?? isLoading ?? false;
  const contentProps = { loading, leftIcon, rightIcon, loadingText, children };

  if (props.as === "a") {
    const { className, variant, size, as: _as, href, ...anchorProps } = rest as ButtonAsAnchorProps;
    void _as;

    const isExternal = href.startsWith("http") || href.startsWith("mailto:");
    const commonProps = {
      className: cn(buttonVariants({ variant, size, className })),
      "aria-busy": loading || undefined,
    };

    if (isExternal) {
      return (
        <a {...commonProps} href={href} ref={ref as React.Ref<HTMLAnchorElement>} {...anchorProps}>
          <ButtonContent {...contentProps} />
        </a>
      );
    }

    return (
      <Link
        {...commonProps}
        href={href}
        ref={ref as React.Ref<HTMLAnchorElement>}
        {...(anchorProps as Omit<typeof anchorProps, "onMouseEnter" | "onTouchStart" | "onClick">)}
      >
        <ButtonContent {...contentProps} />
      </Link>
    );
  }

  const {
    className,
    variant,
    size,
    as: _as,
    disabled,
    ...buttonProps
  } = rest as ButtonAsButtonProps;
  void _as;

  return (
    <button
      className={cn(buttonVariants({ variant, size, className }))}
      ref={ref as React.Ref<HTMLButtonElement>}
      disabled={loading || disabled}
      aria-busy={loading || undefined}
      {...buttonProps}
    >
      <ButtonContent {...contentProps} />
    </button>
  );
});
Button.displayName = "Button";

export { Button, buttonVariants };
