import { useState } from "react";
import {
  CalendarDays,
  Check,
  ChevronDown,
  ChevronRight,
  ClipboardList,
  CircleHelp,
  FileSearch,
  FileText,
  ListChecks,
  Mail,
  Paperclip,
  PenLine,
  Send,
  Settings,
  Sparkles,
} from "lucide-react";
import AgentInsight from "./AgentInsight";
import AgentSpark from "./AgentSpark";
import SenderAvatar from "./SenderAvatar";
import { inboxContext } from "../utils/inboxSignals";

const ICON = { size: 14, strokeWidth: 1.75 };
const ICON_SM = { size: 13, strokeWidth: 1.75 };

const cards = [
  {
    key: "important",
    label: "Important emails",
    captionKey: "importantFromClients",
    captionSuffix: "from clients",
    hint: "In your inbox",
    icon: Mail,
    tone: "rose",
  },
  {
    key: "actionItems",
    label: "Action items",
    hint: "Need your response",
    icon: ClipboardList,
    tone: "blue",
  },
  {
    key: "meetings",
    label: "Meetings mentioned",
    hint: "In your emails",
    icon: CalendarDays,
    tone: "green",
  },
  {
    key: "invoices",
    label: "Invoices & bills",
    hint: "This week",
    icon: FileText,
    tone: "purple",
  },
];

function greeting(name) {
  const hour = new Date().getHours();
  const period = hour < 12 ? "Good morning" : hour < 17 ? "Good afternoon" : "Good evening";
  return `${period}, ${name}`;
}

function statCaption(card, stats) {
  const count = stats[card.key] || 0;
  if (count === 0) return card.hint;
  if (card.captionKey && stats[card.captionKey] > 0) {
    return `${stats[card.captionKey]} ${card.captionSuffix}`;
  }
  return card.hint;
}

function metricTotal(stats) {
  return cards.reduce((sum, card) => sum + (stats[card.key] || 0), 0);
}

function emailContextSummary(email) {
  const text = (email?.body_text || email?.snippet || "").trim().toLowerCase();
  const sender = email?.sender?.name || email?.sender_display_name || "The sender";
  if (!text) return "This message is open — a summary will appear here.";
  if (text.includes("check") && text.includes("inbox") && text.includes("repl")) {
    return `${sender} asks you to check the inbox and review messages and replies.`;
  }
  if (text.includes("check") && text.includes("inbox")) {
    return `${sender} asks you to check the inbox.`;
  }
  if (text.includes("repl")) {
    return `${sender} is following up about replies or responses.`;
  }
  if (text.includes("attach")) {
    return `${sender} references an attachment that may need review.`;
  }
  const snippet = (email?.body_text || email?.snippet || "").trim();
  const firstSentence = snippet.split(/[.!?\n]/).find((part) => part.trim().length > 8)?.trim();
  if (firstSentence) {
    return `${sender} wrote: “${firstSentence.length > 120 ? `${firstSentence.slice(0, 117)}…` : firstSentence}.”`;
  }
  return `${sender} sent a short message that may need a response.`;
}

function emailContextActions(email) {
  const text = (email?.body_text || email?.snippet || "").toLowerCase();
  const actions = [];
  if (text.includes("check") && text.includes("inbox")) actions.push("Check inbox");
  if (text.includes("message")) actions.push("Review messages");
  if (text.includes("repl")) actions.push("Review replies");
  if (text.includes("attach")) actions.push("Review attachments");
  if (!actions.length) actions.push("Review message");
  return actions.slice(0, 3);
}

export default function AgAgentPanel({
  account,
  emails,
  contextEmail,
  focus,
  insight,
  loading = false,
  mailboxEmpty = false,
  isBrandNewMailbox = false,
  onCompose,
  onQuickAction,
  onOpenEmail,
  onAgentAsk,
}) {
  const { stats, needsReply, today, deadlines } = inboxContext(emails);
  const [agentQuery, setAgentQuery] = useState("");
  const [panelOpen, setPanelOpen] = useState(true);
  const firstName = account?.first_name || "there";
  const allMetricsZero = metricTotal(stats) === 0;
  const hasQuery = agentQuery.trim().length > 0;
  const emailContextMode = Boolean(contextEmail) && !insight;
  const showOnboarding = !insight && !loading && mailboxEmpty && isBrandNewMailbox;
  const showQuietEmpty = !insight && !loading && mailboxEmpty && !isBrandNewMailbox;
  const showFullPanel = !insight && !loading && !mailboxEmpty && !emailContextMode;

  function submitAgentQuery(event) {
    event.preventDefault();
    const query = agentQuery.trim();
    if (!query) return;
    onAgentAsk?.(query);
    setAgentQuery("");
  }

  return (
    <section className={`agent-panel${emailContextMode ? " email-context" : ""}`} aria-label="AG Agent">
      <header className="agent-panel-head">
        <span className="agent-panel-mark" aria-hidden="true">
          <Sparkles {...ICON} />
        </span>
        <div className="agent-panel-title">
          <h2>AG Agent</h2>
          <p>Your email co-pilot</p>
        </div>
        <button
          type="button"
          className="agent-panel-toggle"
          aria-expanded={panelOpen}
          aria-label={panelOpen ? "Collapse agent panel" : "Expand agent panel"}
          onClick={() => setPanelOpen((open) => !open)}
        >
          <ChevronDown size={14} strokeWidth={1.75} className={panelOpen ? "open" : ""} />
        </button>
      </header>

      <AgentInsight insight={insight} />

      {panelOpen && (
        <div className="agent-panel-body">
          {!insight && (
            <div className="agent-panel-hello">
              <strong>{greeting(firstName)}</strong>
              <span>
                {emailContextMode
                  ? "About this email"
                  : showOnboarding
                    ? "Your new inbox is ready."
                    : showQuietEmpty
                      ? "Nothing needs your attention right now."
                      : "Here's what needs your attention today."}
              </span>
            </div>
          )}

          {emailContextMode && (
            <section className="agent-email-context">
              <h3>Summary</h3>
              <p>{emailContextSummary(contextEmail)}</p>
              <h3>Action items</h3>
              <ul className="agent-email-action-list">
                {emailContextActions(contextEmail).map((item) => (
                  <li key={item}>
                    <span className="agent-email-action-check" aria-hidden="true" />
                    {item}
                  </li>
                ))}
              </ul>
              <button type="button" className="agent-email-context-reply" onClick={() => onCompose?.()}>
                <PenLine {...ICON_SM} /> Draft reply
              </button>
            </section>
          )}

          {!insight && loading && (
            <div className="agent-loading-block" aria-hidden="true">
              <span className="agent-loading-pulse" />
              <span className="agent-loading-pulse short" />
            </div>
          )}

          {showOnboarding && (
            <div className="agent-ready-card">
              <p className="agent-ready-lead">
                <Check size={14} strokeWidth={2} /> AGMail is ready
              </p>
              <p>
                No messages yet. I&apos;ll start organizing and surfacing important
                items as email arrives.
              </p>
            </div>
          )}

          {showQuietEmpty && (
            <div className="agent-caught-up">
              <p className="agent-caught-up-lead">
                <Check size={14} strokeWidth={2} /> You&apos;re all caught up.
              </p>
              <p>Your inbox is clear for now.</p>
            </div>
          )}

          {showFullPanel && !emailContextMode && !allMetricsZero && (
            <div className="agent-stat-grid">
              {cards.map((card) => {
                const Icon = card.icon;
                const count = stats[card.key] || 0;
                const isEmpty = count === 0;
                return (
                  <button
                    key={card.key}
                    type="button"
                    className={`agent-stat agent-stat-${card.tone}${isEmpty ? " agent-stat-empty" : ""}`}
                    onClick={() => onQuickAction(card.key)}
                    disabled={isEmpty}
                    aria-label={`${card.label}: ${count}`}
                  >
                    <div className="agent-stat-top">
                      <span className="agent-stat-icon"><Icon {...ICON} /></span>
                      <strong>{count}</strong>
                    </div>
                    <span className="agent-stat-label">{card.label}</span>
                    <small>{statCaption(card, stats)}</small>
                  </button>
                );
              })}
            </div>
          )}

          {showFullPanel && allMetricsZero && (
            <div className="agent-caught-up">
              <p className="agent-caught-up-lead">
                <Check size={14} strokeWidth={2} /> You&apos;re all caught up.
              </p>
              <p>No urgent messages or outstanding actions.</p>
            </div>
          )}

          {!insight && focus && showFullPanel && !allMetricsZero && (
            <p className="agent-panel-note">{focus}</p>
          )}

          <section className="agent-quick">
            <h3>{showOnboarding ? "Quick start" : "Quick actions"}</h3>
            <div className="agent-quick-grid">
              {showOnboarding ? (
                <>
                  <button type="button" className="agent-quick-btn" onClick={() => onQuickAction("learn")}>
                    <AgentSpark className="agent-quick-icon agent-quick-icon-purple" />
                    <span>Meet AG Agent</span>
                  </button>
                  <button type="button" className="agent-quick-btn" onClick={() => onCompose?.()}>
                    <PenLine {...ICON_SM} className="agent-quick-icon agent-quick-icon-purple" />
                    <span>Compose email</span>
                  </button>
                  <button type="button" className="agent-quick-btn" onClick={() => onQuickAction("preferences")}>
                    <Settings {...ICON_SM} className="agent-quick-icon agent-quick-icon-muted" />
                    <span>Set preferences</span>
                  </button>
                  <button type="button" className="agent-quick-btn" onClick={() => onQuickAction("learn")}>
                    <CircleHelp {...ICON_SM} className="agent-quick-icon agent-quick-icon-slate" />
                    <span>Learn AGMail</span>
                  </button>
                </>
              ) : (
                <>
                  <button
                    type="button"
                    className="agent-quick-btn"
                    onClick={() => onQuickAction("summarize")}
                    disabled={mailboxEmpty}
                  >
                    <Sparkles {...ICON_SM} className="agent-quick-icon agent-quick-icon-purple" />
                    <span>Summarize inbox</span>
                  </button>
                  <button
                    type="button"
                    className="agent-quick-btn"
                    onClick={() => onQuickAction("draft")}
                    disabled={mailboxEmpty}
                  >
                    <PenLine {...ICON_SM} className="agent-quick-icon agent-quick-icon-purple" />
                    <span>Draft replies</span>
                  </button>
                  <button
                    type="button"
                    className="agent-quick-btn"
                    onClick={() => onQuickAction("attachments")}
                    disabled={mailboxEmpty}
                  >
                    <FileSearch {...ICON_SM} className="agent-quick-icon agent-quick-icon-muted" />
                    <span>Find attachments</span>
                  </button>
                  <button
                    type="button"
                    className="agent-quick-btn"
                    onClick={() => onQuickAction("actions")}
                    disabled={mailboxEmpty}
                  >
                    <ListChecks {...ICON_SM} className="agent-quick-icon agent-quick-icon-slate" />
                    <span>Show action items</span>
                  </button>
                </>
              )}
            </div>
          </section>

          {showFullPanel && !insight && (
            <section className="agent-context-block agent-agenda">
              <div className="agent-context-head">
                <h3>Today&apos;s agenda</h3>
                <button type="button" className="agent-context-link">View calendar</button>
              </div>
              {today.length > 0 ? (
                <ul className="agent-agenda-list">
                  {today.map((item) => (
                    <li key={`${item.time}-${item.label}`} className="agent-agenda-row">
                      <span className={`agent-agenda-bar tone-${item.tone || "green"}`} aria-hidden="true" />
                      <time>{item.time}</time>
                      <div className="agent-agenda-copy">
                        <strong>{item.label}</strong>
                        {item.venue && <small>{item.venue}</small>}
                      </div>
                      <ChevronRight size={12} strokeWidth={1.75} className="agent-agenda-chevron" />
                    </li>
                  ))}
                </ul>
              ) : (
                <p className="agent-empty-line">No meetings in your emails today.</p>
              )}
            </section>
          )}

          {showFullPanel && !insight && (
            <section className="agent-context-block agent-attention-block">
              <h3>Needs attention</h3>
              {needsReply.length > 0 ? (
                <ul className="agent-attention-list">
                  {needsReply.slice(0, 3).map((item) => (
                    <li key={item.id}>
                      <button type="button" onClick={() => onOpenEmail?.(item.id)}>
                        <SenderAvatar
                          email={emails.find((entry) => entry.id === item.id) || { sender: { name: item.name } }}
                          className="agent-attention-avatar"
                        />
                        <span className="agent-attention-copy">
                          <span className="agent-attention-name">{item.name}</span>
                          <span className="agent-attention-meta">{item.status}</span>
                        </span>
                        <em>{item.age}</em>
                      </button>
                    </li>
                  ))}
                </ul>
              ) : (
                <p className="agent-empty-line">Nothing needs your attention right now.</p>
              )}
            </section>
          )}

          {showFullPanel && !insight && deadlines.length > 0 && (
            <section className="agent-context-block agent-deadlines">
              <h3>Deadlines</h3>
              <ul>
                {deadlines.map((item) => (
                  <li key={`${item.label}-${item.due}`}>
                    <span>{item.label}</span>
                    <em>{item.due}</em>
                  </li>
                ))}
              </ul>
            </section>
          )}

          <form className="agent-ask-input" onSubmit={submitAgentQuery}>
            <input
              value={agentQuery}
              onChange={(event) => setAgentQuery(event.target.value)}
              placeholder="Ask about your emails..."
            />
            <button type="button" className="agent-ask-attach" aria-label="Attach context" title="Attach context">
              <Paperclip size={13} strokeWidth={1.75} />
            </button>
            <button
              type="submit"
              className={`agent-ask-send${hasQuery ? " active" : ""}`}
              aria-label="Send to agent"
              disabled={!hasQuery}
            >
              <Send size={13} strokeWidth={1.75} />
            </button>
          </form>
        </div>
      )}
    </section>
  );
}