"use client";

import { useState, useTransition, useRef, useEffect } from "react";
import { useRouter } from "next/navigation";
import type { Comment } from "@/db/schema";
import { useChatContext } from "./ChatProvider";

// TODO: Email-on-tag (admin→client notification when admin posts on a phase/task) is OUT OF SCOPE
// Hook point: after db.insert(comments) in /src/app/api/client/comment/route.ts and
// postAdminComment in /src/app/admin/clients/[id]/actions.ts — send Resend email here.

function formatTime(ts: Date | string): string {
  const d = typeof ts === "string" ? new Date(ts) : ts;
  return d.toLocaleString("it-IT", {
    day: "2-digit",
    month: "short",
    hour: "2-digit",
    minute: "2-digit",
  });
}

interface ChatPanelProps {
  token: string;
  comments: Comment[];
}

export function ChatPanel({ token, comments }: ChatPanelProps) {
  const { isOpen, selectedPhaseId, phases, clientId, openChat, closeChat } = useChatContext();
  const [body, setBody] = useState("");
  const [error, setError] = useState<string | null>(null);
  const [, startTransition] = useTransition();
  const router = useRouter();
  const bottomRef = useRef<HTMLDivElement>(null);

  // Build entity list: Generale + phases
  type EntityOption = { id: string; type: "general" | "phase"; label: string };
  const entityOptions: EntityOption[] = [
    { id: clientId, type: "general", label: "Generale" },
    ...phases.map((p) => ({ id: p.id, type: "phase" as const, label: p.title })),
  ];

  // Build label map for displaying tags on existing messages
  const labelMap = new Map<string, string>();
  labelMap.set(clientId, "Generale");
  for (const p of phases) {
    labelMap.set(p.id, p.title);
    for (const t of p.tasks) {
      labelMap.set(t.id, `${p.title} — ${t.title}`);
      for (const d of t.deliverables) {
        labelMap.set(d.id, `${t.title} — ${d.title}`);
      }
    }
  }

  // Current selection: sync with selectedPhaseId from context
  const [currentEntityId, setCurrentEntityId] = useState<string>(clientId);
  useEffect(() => {
    setCurrentEntityId(selectedPhaseId ?? clientId);
  }, [selectedPhaseId, clientId]);

  // Sort all comments chronologically
  const sorted = [...comments].sort(
    (a, b) => new Date(a.created_at).getTime() - new Date(b.created_at).getTime()
  );

  useEffect(() => {
    if (isOpen) {
      bottomRef.current?.scrollIntoView({ behavior: "smooth" });
    }
  }, [isOpen, comments.length]);

  function handleSend(e: React.FormEvent) {
    e.preventDefault();
    const trimmed = body.trim();
    if (!trimmed) return;

    const selectedEntity = entityOptions.find((en) => en.id === currentEntityId);
    if (!selectedEntity) return;

    setError(null);
    startTransition(async () => {
      try {
        const res = await fetch("/api/client/comment", {
          method: "POST",
          headers: { "Content-Type": "application/json" },
          body: JSON.stringify({
            token,
            entity_type: selectedEntity.type,
            entity_id: selectedEntity.id,
            body: trimmed,
          }),
        });
        if (!res.ok) {
          const data = await res.json();
          setError(data.error ?? "Errore nell'invio");
          return;
        }
        setBody("");
        router.refresh();
      } catch {
        setError("Errore di rete");
      }
    });
  }

  return (
    <>
      {/* FAB — floating action button bottom-right */}
      <button
        type="button"
        onClick={() => (isOpen ? closeChat() : openChat())}
        aria-label="Apri messaggi"
        className="fixed bottom-6 right-6 z-40 w-14 h-14 rounded-full bg-[#1A463C] text-white shadow-lg hover:bg-[#163a31] transition-colors flex items-center justify-center"
      >
        {isOpen ? (
          /* X close icon */
          <svg className="w-6 h-6" fill="none" stroke="currentColor" strokeWidth={2} viewBox="0 0 24 24" aria-hidden="true">
            <path strokeLinecap="round" strokeLinejoin="round" d="M6 18L18 6M6 6l12 12" />
          </svg>
        ) : (
          /* Chat bubble + plus SVG */
          <svg className="w-6 h-6" fill="none" stroke="currentColor" strokeWidth={1.8} viewBox="0 0 24 24" aria-hidden="true">
            <path strokeLinecap="round" strokeLinejoin="round" d="M8 10h.01M12 10h.01M16 10h.01M21 12c0 4.418-4.03 8-9 8a9.77 9.77 0 01-4-.83L3 20l1.09-3.27C3.39 15.56 3 13.83 3 12c0-4.418 4.03-8 9-8s9 3.582 9 8z" />
          </svg>
        )}
      </button>

      {/* Overlay — subtle backdrop on mobile */}
      {isOpen && (
        <div
          className="fixed inset-0 z-30 bg-black/10 lg:hidden"
          onClick={closeChat}
          aria-hidden="true"
        />
      )}

      {/* Slide-in panel */}
      <div
        className={`fixed top-0 right-0 h-full z-40 w-full sm:w-[420px] bg-white shadow-2xl flex flex-col transition-transform duration-300 ease-in-out ${
          isOpen ? "translate-x-0" : "translate-x-full"
        }`}
        aria-label="Messaggi & Revisioni"
        role="dialog"
        aria-modal="true"
      >
        {/* Panel header */}
        <div className="flex items-center justify-between px-5 py-4 border-b border-[#e5e7eb] shrink-0">
          <h2 className="text-base font-bold text-[#1a1a1a]">Messaggi & Revisioni</h2>
          <button
            type="button"
            onClick={closeChat}
            aria-label="Chiudi"
            className="p-1.5 rounded-md text-[#71717a] hover:text-[#1a1a1a] hover:bg-[#f4f4f5] transition-colors"
          >
            <svg className="w-5 h-5" fill="none" stroke="currentColor" strokeWidth={2} viewBox="0 0 24 24" aria-hidden="true">
              <path strokeLinecap="round" strokeLinejoin="round" d="M6 18L18 6M6 6l12 12" />
            </svg>
          </button>
        </div>

        {/* Chat feed */}
        <div className="flex-1 overflow-y-auto p-4 space-y-3">
          {sorted.length === 0 && (
            <p className="text-sm text-[#71717a] italic text-center py-10">
              Nessun messaggio ancora. Scrivi qui sotto per iniziare.
            </p>
          )}
          {sorted.map((c) => {
            const isClient = c.author === "client";
            const entityLabel = labelMap.get(c.entity_id);
            const showTag = c.entity_id !== clientId && entityLabel;

            return (
              <div
                key={c.id}
                className={`flex flex-col gap-1 ${isClient ? "items-end" : "items-start"}`}
              >
                {/* Author + tag */}
                <div className={`flex items-center gap-2 ${isClient ? "flex-row-reverse" : ""}`}>
                  <span
                    className={`text-[10px] font-bold uppercase tracking-wide px-2 py-0.5 rounded-full ${
                      isClient
                        ? "bg-[#DEF168] text-[#1A463C]"
                        : "bg-[#1A463C] text-white"
                    }`}
                  >
                    {isClient ? "Tu" : "iamcavalli"}
                  </span>
                  {showTag && (
                    <span className="text-[10px] text-[#71717a] bg-[#f4f4f5] px-2 py-0.5 rounded-full truncate max-w-[160px]">
                      {entityLabel}
                    </span>
                  )}
                </div>

                {/* Bubble */}
                <div
                  className={`max-w-[80%] rounded-2xl px-4 py-2.5 text-sm leading-relaxed ${
                    isClient
                      ? "bg-[#1A463C] text-white rounded-tr-sm"
                      : "bg-[#f4f4f5] text-[#1a1a1a] rounded-tl-sm"
                  }`}
                >
                  {c.body}
                </div>

                {/* Timestamp */}
                <span className="text-[10px] text-[#71717a]">{formatTime(c.created_at)}</span>
              </div>
            );
          })}
          <div ref={bottomRef} />
        </div>

        {/* Divider */}
        <div className="border-t border-[#e5e7eb]" />

        {/* Composer */}
        <form onSubmit={handleSend} className="p-3 space-y-2 bg-[#fafafa] shrink-0">
          {/* Tag selector: Generale + phases */}
          <select
            value={currentEntityId}
            onChange={(e) => setCurrentEntityId(e.target.value)}
            className="w-full text-xs border border-[#e5e7eb] rounded-lg px-3 py-1.5 bg-white text-[#1a1a1a] focus:outline-none focus:ring-2 focus:ring-[#1A463C]/30"
          >
            {entityOptions.map((en) => (
              <option key={en.id} value={en.id}>
                {en.label}
              </option>
            ))}
          </select>

          <div className="flex gap-2">
            <textarea
              value={body}
              onChange={(e) => setBody(e.target.value)}
              onKeyDown={(e) => {
                if (e.key === "Enter" && !e.shiftKey) {
                  e.preventDefault();
                  handleSend(e as unknown as React.FormEvent);
                }
              }}
              placeholder="Scrivi un messaggio… (Invio per inviare)"
              rows={2}
              className="flex-1 text-sm border border-[#e5e7eb] rounded-lg px-3 py-2 bg-white resize-none focus:outline-none focus:ring-2 focus:ring-[#1A463C]/30"
            />
            <button
              type="submit"
              disabled={!body.trim()}
              className="self-end px-4 py-2 rounded-lg bg-[#1A463C] text-white text-sm font-semibold disabled:opacity-40 hover:bg-[#1A463C]/90 transition-colors"
            >
              Invia
            </button>
          </div>
          {error && <p className="text-xs text-red-600">{error}</p>}
        </form>
      </div>
    </>
  );
}