import React, { useState, useEffect, useRef } from "react";
import type { SessionDetailResponse } from "../lib/types";

interface Props {
  session: SessionDetailResponse;
  visibleMessageUuids: string[];
  redactedMessageUuids: string[];
  autoRedactEnabled: boolean;
}

export function ExportButton({
  session,
  visibleMessageUuids,
  redactedMessageUuids,
  autoRedactEnabled,
}: Props) {
  const [state, setState] = useState<"idle" | "exporting" | "success" | "error">("idle");
  const timerRef = useRef<ReturnType<typeof setTimeout>>();

  useEffect(() => {
    return () => {
      if (timerRef.current) clearTimeout(timerRef.current);
    };
  }, []);

  async function handleExport() {
    setState("exporting");
    try {
      const res = await fetch("/api/export", {
        method: "POST",
        headers: { "Content-Type": "application/json" },
        body: JSON.stringify({
          session,
          visibleMessageUuids,
          redactedMessageUuids,
          autoRedactEnabled,
        }),
      });
      if (!res.ok) throw new Error(`Export failed: HTTP ${res.status}`);

      const blob = await res.blob();
      const url = URL.createObjectURL(blob);
      const a = document.createElement("a");
      a.href = url;
      a.download = `session-${session.id}.html`;
      document.body.appendChild(a);
      a.click();
      document.body.removeChild(a);
      URL.revokeObjectURL(url);

      setState("success");
      timerRef.current = setTimeout(() => setState("idle"), 2000);
    } catch (err) {
      console.error("Export failed:", err);
      setState("error");
      timerRef.current = setTimeout(() => setState("idle"), 3000);
    }
  }

  return (
    <button
      onClick={handleExport}
      disabled={state === "exporting"}
      className={`
        btn btn-sm flex-shrink-0 gap-1.5 transition-all duration-200
        ${state === "success" ? "text-white shadow-glow-success" : ""}
        ${state === "error" ? "text-white" : ""}
        ${state === "idle" || state === "exporting" ? "btn-secondary" : ""}
      `}
      style={
        state === "success"
          ? { background: "linear-gradient(135deg, #22c55e, #16a34a)" }
          : state === "error"
          ? { background: "linear-gradient(135deg, #dc2626, #b91c1c)" }
          : undefined
      }
    >
      {state === "idle" && (
        <>
          <svg className="w-3.5 h-3.5" fill="none" viewBox="0 0 24 24" stroke="currentColor" strokeWidth={2}>
            <path strokeLinecap="round" strokeLinejoin="round" d="M3 16.5v2.25A2.25 2.25 0 005.25 21h13.5A2.25 2.25 0 0021 18.75V16.5M16.5 12L12 16.5m0 0L7.5 12m4.5 4.5V3" />
          </svg>
          Export
        </>
      )}
      {state === "exporting" && (
        <>
          <svg className="w-3.5 h-3.5 animate-spin" fill="none" viewBox="0 0 24 24">
            <circle className="opacity-25" cx="12" cy="12" r="10" stroke="currentColor" strokeWidth="4" />
            <path className="opacity-75" fill="currentColor" d="M4 12a8 8 0 018-8V0C5.373 0 0 5.373 0 12h4zm2 5.291A7.962 7.962 0 014 12H0c0 3.042 1.135 5.824 3 7.938l3-2.647z" />
          </svg>
          Exporting...
        </>
      )}
      {state === "success" && (
        <>
          <svg className="w-3.5 h-3.5" fill="none" viewBox="0 0 24 24" stroke="currentColor" strokeWidth={2}>
            <path strokeLinecap="round" strokeLinejoin="round" d="M4.5 12.75l6 6 9-13.5" />
          </svg>
          Downloaded
        </>
      )}
      {state === "error" && (
        <>
          <svg className="w-3.5 h-3.5" fill="none" viewBox="0 0 24 24" stroke="currentColor" strokeWidth={2}>
            <path strokeLinecap="round" strokeLinejoin="round" d="M12 9v3.75m9-.75a9 9 0 11-18 0 9 9 0 0118 0zm-9 3.75h.008v.008H12v-.008z" />
          </svg>
          Failed
        </>
      )}
    </button>
  );
}