"use client";

import type { ButtonHTMLAttributes, ReactNode } from "react";

// The primary-button class chain was written out by hand at a dozen call
// sites and the ghost/secondary ones at many more, each drifting slightly in
// padding and hover colour. Collecting them here also gives every button a
// visible keyboard focus ring, which none of them had.

const BASE =
  "inline-flex items-center justify-center gap-1.5 rounded font-semibold transition-colors " +
  "focus-visible:outline-2 focus-visible:outline-offset-2 focus-visible:outline-brand-500 " +
  "disabled:cursor-not-allowed disabled:opacity-50";

const VARIANTS = {
  primary: "bg-brand-500 text-white hover:bg-brand-600",
  secondary: "border border-border bg-white text-ink-body hover:bg-surface",
  ghost: "text-ink-body hover:bg-surface",
  danger: "bg-danger-solid text-white hover:brightness-110",
  // Square icon-only button; pair with an aria-label.
  icon: "text-ink-muted hover:bg-surface hover:text-ink",
} as const;

const SIZES = {
  sm: "px-3 py-1.5 text-xs",
  md: "px-4 py-2 text-sm",
  // Meets the 44px touch target without looking oversized on desktop.
  icon: "p-2",
} as const;

/**
 * For anchors that read as buttons (download links, cross-page actions). A
 * real <a> keeps middle-click and "open in new tab" working, which a button
 * with an onClick would throw away — so those stay anchors and borrow the
 * styling instead.
 */
export const LINK_BUTTON_CLASS = `${BASE} ${VARIANTS.secondary} ${SIZES.sm}`;

type ButtonProps = Omit<ButtonHTMLAttributes<HTMLButtonElement>, "className"> & {
  variant?: keyof typeof VARIANTS;
  size?: keyof typeof SIZES;
  /** Disables and shows the busy label; use for in-flight server actions. */
  pending?: boolean;
  pendingLabel?: string;
  fullWidth?: boolean;
  className?: string;
  children?: ReactNode;
};

export function Button({
  variant = "primary",
  size,
  pending = false,
  pendingLabel,
  fullWidth,
  disabled,
  className = "",
  children,
  type = "button",
  ...rest
}: ButtonProps) {
  const resolvedSize = size ?? (variant === "icon" ? "icon" : "md");
  return (
    <button
      {...rest}
      type={type}
      disabled={disabled || pending}
      aria-busy={pending || undefined}
      className={`${BASE} ${VARIANTS[variant]} ${SIZES[resolvedSize]} ${fullWidth ? "w-full" : ""} ${className}`}
    >
      {pending && pendingLabel ? pendingLabel : children}
    </button>
  );
}