import { useEffect, useRef } from "react";
import clsx from "clsx";
import { Loader2, X } from "lucide-react";

export const cx = clsx;

// ---------- formatting ----------
const nf = new Intl.NumberFormat("en-CA");
export const fmt = (n) => (n == null || Number.isNaN(n) ? "—" : nf.format(n));
export const fmtCompact = (n) =>
  n == null ? "—" : n >= 10000 ? new Intl.NumberFormat("en-CA", { notation: "compact", maximumFractionDigits: 1 }).format(n) : nf.format(n);
export const fmtDate = (iso, opts = { month: "short", day: "numeric" }) => (iso ? new Date(iso).toLocaleDateString("en-CA", opts) : "—");
export const fmtDateTime = (iso) =>
  iso ? new Date(iso).toLocaleString("en-CA", { month: "short", day: "numeric", hour: "numeric", minute: "2-digit" }) : "—";
export function timeAgo(iso) {
  if (!iso) return "never";
  const s = (Date.now() - new Date(iso)) / 1000;
  if (s < 60) return "just now";
  if (s < 3600) return `${Math.floor(s / 60)} min ago`;
  if (s < 86400) return `${Math.floor(s / 3600)} h ago`;
  const d = Math.floor(s / 86400);
  return d === 1 ? "yesterday" : `${d} days ago`;
}
export const plural = (n, word) => `${fmt(n)} ${word}${n === 1 ? "" : "s"}`;

// ---------- primitives ----------
export function Button({ variant = "secondary", size = "md", loading, icon: Icon, className, children, ...props }) {
  return (
    <button
      {...props}
      disabled={props.disabled || loading}
      className={cx(
        "inline-flex items-center justify-center gap-1.5 rounded-md font-medium whitespace-nowrap transition-colors disabled:opacity-50 disabled:cursor-not-allowed",
        size === "sm" ? "h-7 px-2.5 text-[12.5px]" : "h-9 px-3.5 text-[13.5px]",
        variant === "primary" && "bg-brand text-white hover:bg-brand-deep",
        variant === "secondary" && "bg-white text-ink border border-line-strong hover:bg-canvas",
        variant === "ghost" && "text-ink-2 hover:bg-canvas",
        variant === "danger" && "bg-white text-bad border border-line-strong hover:bg-bad-soft",
        className
      )}
    >
      {loading ? <Loader2 className="size-3.5 animate-spin" /> : Icon ? <Icon className="size-3.5" strokeWidth={2.2} /> : null}
      {children}
    </button>
  );
}

export function Panel({ title, action, children, className, bodyClass, subtitle }) {
  return (
    <section className={cx("panel", className)}>
      {(title || action) && (
        <header className="flex items-center justify-between gap-3 px-4 pt-3.5 pb-3 border-b border-line">
          <div>
            <h2 className="text-[14px] font-bold">{title}</h2>
            {subtitle && <p className="text-[12px] text-muted mt-0.5">{subtitle}</p>}
          </div>
          {action}
        </header>
      )}
      <div className={bodyClass}>{children}</div>
    </section>
  );
}

const TONES = {
  neutral: "bg-canvas text-ink-2 border-line",
  brand: "bg-brand-soft text-brand-deep border-[#cfe0f1]",
  ok: "bg-ok-soft text-ok border-[#cfe6d7]",
  warn: "bg-warn-soft text-warn border-[#f1dcb8]",
  bad: "bg-bad-soft text-bad border-[#f2cdc8]",
};
export function Badge({ tone = "neutral", children, className, dot }) {
  return (
    <span className={cx("inline-flex items-center gap-1.5 h-[22px] px-2 rounded-full border text-[11.5px] font-medium whitespace-nowrap", TONES[tone], className)}>
      {dot && <span className="size-1.5 rounded-full bg-current" />}
      {children}
    </span>
  );
}

/** Headline number with label and optional comparison/note. */
export function Stat({ label, value, note, tone, loading }) {
  return (
    <div className="min-w-0">
      <div className="eyebrow truncate">{label}</div>
      {loading ? (
        <div className="skeleton h-7 w-20 mt-1.5" />
      ) : (
        <div className={cx("font-display text-[24px] font-extrabold num leading-tight mt-1", tone === "bad" ? "text-bad" : tone === "warn" ? "text-warn" : "text-ink")}>
          {value}
        </div>
      )}
      {note && <div className="text-[12px] text-muted mt-0.5 truncate">{note}</div>}
    </div>
  );
}

export function StatRow({ children, className }) {
  return <div className={cx("panel grid divide-x divide-line", className)}>{children}</div>;
}
export const StatCell = ({ children }) => <div className="px-5 py-4 min-w-0">{children}</div>;

export function Spinner({ label }) {
  return (
    <div className="flex items-center gap-2 text-muted text-[13px] py-10 justify-center">
      <Loader2 className="size-4 animate-spin" /> {label || "Loading…"}
    </div>
  );
}

export function Empty({ icon: Icon, title, children, action }) {
  return (
    <div className="flex flex-col items-center text-center px-6 py-12">
      {Icon && <Icon className="size-6 text-faint mb-3" strokeWidth={1.6} />}
      <div className="font-display font-bold text-[14px]">{title}</div>
      {children && <p className="text-muted text-[13px] max-w-sm mt-1">{children}</p>}
      {action && <div className="mt-4">{action}</div>}
    </div>
  );
}

export function ErrorNote({ error, className }) {
  if (!error) return null;
  return <div className={cx("rounded-md border border-[#f2cdc8] bg-bad-soft text-bad px-3 py-2 text-[13px]", className)}>{String(error.message || error)}</div>;
}

export function Tabs({ tabs, value, onChange }) {
  return (
    <div className="flex gap-1 border-b border-line">
      {tabs.map((t) => (
        <button
          key={t.value}
          onClick={() => onChange(t.value)}
          className={cx(
            "relative px-3 h-9 text-[13.5px] font-medium transition-colors",
            value === t.value ? "text-ink" : "text-muted hover:text-ink"
          )}
        >
          {t.label}
          {t.count != null && <span className="ml-1.5 text-[11.5px] text-faint num">{t.count}</span>}
          {value === t.value && <span className="absolute left-2 right-2 -bottom-px h-[2px] bg-brand rounded-full" />}
        </button>
      ))}
    </div>
  );
}

/** Modal dialog on top of the native <dialog> element (focus trap + Esc for free). */
export function Dialog({ open, onClose, title, children, footer, wide }) {
  const ref = useRef(null);
  useEffect(() => {
    const d = ref.current;
    if (!d) return;
    if (open && !d.open) d.showModal();
    if (!open && d.open) d.close();
  }, [open]);
  return (
    <dialog
      ref={ref}
      onClose={onClose}
      onClick={(e) => e.target === ref.current && onClose()}
      className={cx("m-auto rounded-xl p-0 backdrop:bg-[#1f2024]/40 shadow-[0_20px_60px_-15px_rgba(15,23,42,0.35)] border border-line", wide ? "w-[min(880px,94vw)]" : "w-[min(520px,94vw)]")}
    >
      {open && (
        <div className="flex flex-col max-h-[86vh]">
          <header className="flex items-center justify-between px-5 py-3.5 border-b border-line">
            <h2 className="text-[15px] font-bold">{title}</h2>
            <button onClick={onClose} className="p-1 rounded hover:bg-canvas text-muted" aria-label="Close">
              <X className="size-4" />
            </button>
          </header>
          <div className="px-5 py-4 overflow-y-auto">{children}</div>
          {footer && <footer className="flex justify-end gap-2 px-5 py-3 border-t border-line bg-[#fafbfc] rounded-b-xl">{footer}</footer>}
        </div>
      )}
    </dialog>
  );
}

export function Field({ label, hint, children }) {
  return (
    <label className="block">
      <span className="block text-[12.5px] font-medium text-ink-2 mb-1">{label}</span>
      {children}
      {hint && <span className="block text-[12px] text-muted mt-1">{hint}</span>}
    </label>
  );
}

/** Tiny bar sparkline (no axes) for tables. */
export function Spark({ values, width = 96, height = 26 }) {
  if (!values?.length) return <span className="text-faint">—</span>;
  const max = Math.max(...values, 1);
  const w = width / values.length;
  return (
    <svg width={width} height={height} aria-hidden="true" className="block">
      {values.map((v, i) => {
        const h = Math.max(2, (v / max) * (height - 2));
        return <rect key={i} x={i * w + 1} y={height - h} width={Math.max(2, w - 2)} height={h} rx={1} fill={i === values.length - 1 ? "#fc6d45" : "#c9c7e0"} />;
      })}
    </svg>
  );
}

export const STATUS_TONE = { queued: "neutral", running: "brand", succeeded: "ok", failed: "bad", cancelled: "neutral", interrupted: "warn" };