"use client";

import { forwardRef } from "react";

import { SnowflakeIcon } from "@/components/icons";
import { cn } from "@/lib/utils";

type ButtonVariant = "primary" | "secondary" | "ghost" | "danger" | "success";
type ButtonSize = "sm" | "md" | "lg";

/**
 * ChatGPT-flavoured buttons: pill-shaped, near-black primary in light mode and
 * white in dark mode, quiet secondaries with hairline borders.
 */
const VARIANTS: Record<ButtonVariant, string> = {
  primary: "btn-primary",
  secondary: "btn-secondary",
  ghost: "btn-ghost",
  danger: "btn-primary !bg-rose-600 hover:!bg-rose-700 dark:!bg-rose-500 dark:!text-white dark:hover:!bg-rose-600",
  success: "btn-primary !bg-emerald-600 hover:!bg-emerald-700 dark:!bg-emerald-500 dark:!text-white dark:hover:!bg-emerald-600",
};

const SIZES: Record<ButtonSize, string> = {
  sm: "h-9 px-3.5 text-[13px] rounded-full",
  md: "h-10 px-4 text-sm rounded-full",
  lg: "h-11 px-5 text-[15px] rounded-full",
};

export type ButtonProps = React.ButtonHTMLAttributes<HTMLButtonElement> & {
  variant?: ButtonVariant;
  size?: ButtonSize;
  loading?: boolean;
};

export const Button = forwardRef<HTMLButtonElement, ButtonProps>(function Button(
  { className, variant = "primary", size = "md", loading, children, disabled, ...props },
  ref,
) {
  return (
    <button
      ref={ref}
      disabled={disabled || loading}
      className={cn(
        "inline-flex select-none items-center justify-center whitespace-nowrap font-medium transition disabled:cursor-not-allowed disabled:opacity-40",
        VARIANTS[variant],
        SIZES[size],
        className,
      )}
      {...props}
    >
      {loading ? <Spinner className="size-4" /> : null}
      {children}
    </button>
  );
});

export function Spinner({ className }: { className?: string }) {
  return (
    <svg className={cn("animate-spin", className)} viewBox="0 0 24 24" fill="none" aria-hidden="true">
      <circle cx="12" cy="12" r="9" stroke="currentColor" strokeOpacity="0.25" strokeWidth="3" />
      <path d="M21 12a9 9 0 0 0-9-9" stroke="currentColor" strokeWidth="3" strokeLinecap="round" />
    </svg>
  );
}

/** Small neutral pill. Colour is reserved for meaning, not decoration. */
export function Chip({
  children,
  className,
  tone = "neutral",
}: {
  children: React.ReactNode;
  className?: string;
  tone?: "neutral" | "accent" | "success" | "warning" | "danger";
}) {
  const tones: Record<string, string> = {
    neutral: "bg-[var(--surface-sunken)] text-[var(--text-muted)]",
    accent: "bg-accent-500/12 text-accent-700 dark:text-accent-200",
    success: "bg-emerald-500/12 text-emerald-700 dark:text-emerald-300",
    warning: "bg-amber-500/14 text-amber-800 dark:text-amber-300",
    danger: "bg-rose-500/12 text-rose-700 dark:text-rose-300",
  };
  return (
    <span
      className={cn(
        "inline-flex items-center gap-1.5 rounded-full px-2.5 py-1 text-[12px] font-medium leading-none",
        tones[tone],
        className,
      )}
    >
      {children}
    </span>
  );
}

export function ProgressBar({
  value,
  max,
  className,
  label,
}: {
  value: number;
  max: number;
  className?: string;
  label?: string;
}) {
  const percent = max <= 0 ? 0 : Math.min(100, Math.max(0, (value / max) * 100));
  return (
    <div
      className={cn("h-1 w-full overflow-hidden rounded-full bg-[var(--surface-sunken)]", className)}
      role="progressbar"
      aria-valuenow={Math.round(percent)}
      aria-valuemin={0}
      aria-valuemax={100}
      aria-label={label ?? "Progress"}
    >
      <div
        className="h-full rounded-full bg-[var(--text)]/75 transition-[width] duration-500 ease-out"
        style={{ width: `${percent}%` }}
      />
    </div>
  );
}

export function EmptyState({
  title,
  children,
  icon,
  action,
}: {
  title: string;
  children?: React.ReactNode;
  icon?: React.ReactNode;
  action?: React.ReactNode;
}) {
  return (
    <div className="animate-rise flex flex-col items-center px-6 py-16 text-center sm:py-24">
      <span
        className="mb-4 grid size-12 place-items-center rounded-2xl border border-[var(--hairline)] bg-[var(--surface-strong)] text-[var(--text-subtle)]"
        aria-hidden
      >
        {icon ?? <SnowflakeIcon className="size-6" />}
      </span>
      <h2 className="text-[17px] font-semibold tracking-[-0.01em] text-[var(--text)]">{title}</h2>
      {children ? (
        <p className="mt-2 max-w-md text-sm leading-relaxed text-[var(--text-muted)]">{children}</p>
      ) : null}
      {action ? <div className="mt-6">{action}</div> : null}
    </div>
  );
}