"use client";

import { useEffect, useState } from "react";
import { useTranslations } from "next-intl";
import {
  X,
  Layers,
  Loader2,
  AlertCircle,
  Users,
  CheckCircle2,
  XCircle,
  BookCheck,
  ClipboardList,
  GraduationCap,
} from "lucide-react";
import { FocusTrap } from "@/shared/components/a11y/focus-trap";
import { Button } from "@/shared/components/ui/button";
import {
  generateDifferentiationSuggestionsAction,
  checkCurriculumAlignmentAction,
  generateExplainableAssessmentAction,
  getKnowledgePointsForAlignmentAction,
} from "../actions-ai";
import type { LessonPlanDocument, DifferentiationLevel } from "../types";
import type {
  DifferentiationSuggestion,
  CurriculumCheckItem,
  ExplainableAssessment,
} from "../lib/ai-differentiation";

interface Props {
  doc: LessonPlanDocument;
  /** 课案所属教材 ID（用于 A4 课标核对按需加载知识点） */
  textbookId?: string;
  onClose: () => void;
}

type TabKey = "differentiation" | "curriculum" | "assessment";

const TABS: TabKey[] = ["differentiation", "curriculum", "assessment"];

/**
 * V5-21 A3/A4/A5：AI 差异化对话框。
 *
 * 三个 Tab 分别承载：
 * - A3 差异化教学建议（基础/提高/拓展）
 * - A4 课标实时核对（按 textbookId 按需加载知识点）
 * - A5 可解释评估（练习节点的评分依据）
 */
export function AiDifferentiationDialog({ doc, textbookId, onClose }: Props) {
  const t = useTranslations("lessonPreparation");
  const [activeTab, setActiveTab] = useState<TabKey>("differentiation");

  // ESC 关闭
  useEffect(() => {
    function handleEsc(e: KeyboardEvent) {
      if (e.key === "Escape") onClose();
    }
    document.addEventListener("keydown", handleEsc);
    return () => document.removeEventListener("keydown", handleEsc);
  }, [onClose]);

  return (
    <div className="fixed inset-0 z-50 flex items-center justify-center bg-black/30">
      {/* arbitrary-value: dialog fixed width */}
      <div
        role="dialog"
        aria-modal="true"
        aria-label={t("aiDifferentiation.title")}
        className="bg-surface rounded-lg shadow-xl w-[680px] max-h-[85vh] flex flex-col"
      >
        <FocusTrap className="contents">
          <div className="flex justify-between items-center p-4 border-b border-outline-variant">
            <h3 className="font-title-md flex items-center gap-2">
              <Layers className="w-4 h-4 text-primary" aria-hidden="true" />
              {t("aiDifferentiation.title")}
            </h3>
            <button onClick={onClose} aria-label={t("editor.consistencyClose")}>
              <X className="w-4 h-4" aria-hidden="true" />
            </button>
          </div>

          {/* Tab 切换 */}
          <div className="flex border-b border-outline-variant" role="tablist">
            {TABS.map((tab) => (
              <button
                key={tab}
                role="tab"
                aria-selected={activeTab === tab}
                onClick={() => setActiveTab(tab)}
                className={`px-4 py-2 text-sm font-medium border-b-2 transition-colors ${
                  activeTab === tab
                    ? "border-primary text-primary"
                    : "border-transparent text-on-surface-variant hover:text-on-surface"
                }`}
              >
                {t(`aiDifferentiation.tabs.${tab}`)}
              </button>
            ))}
          </div>

          <div className="p-4 overflow-y-auto flex-1">
            {activeTab === "differentiation" && (
              <DifferentiationTab doc={doc} t={t} />
            )}
            {activeTab === "curriculum" && (
              <CurriculumTab doc={doc} textbookId={textbookId} t={t} />
            )}
            {activeTab === "assessment" && <AssessmentTab doc={doc} t={t} />}
          </div>

          <div className="p-3 border-t border-outline-variant flex justify-end">
            <Button variant="outline" size="sm" onClick={onClose}>
              {t("editor.consistencyClose")}
            </Button>
          </div>
        </FocusTrap>
      </div>
    </div>
  );
}

/** A3：差异化教学建议 Tab */
function DifferentiationTab({
  doc,
  t,
}: {
  doc: LessonPlanDocument;
  t: ReturnType<typeof useTranslations>;
}) {
  const [loading, setLoading] = useState(true);
  const [items, setItems] = useState<DifferentiationSuggestion[]>([]);
  const [error, setError] = useState<string | null>(null);

  useEffect(() => {
    let cancelled = false;
    (async () => {
      setLoading(true);
      setError(null);
      try {
        const res = await generateDifferentiationSuggestionsAction(doc);
        if (cancelled) return;
        if (res.success && res.data) {
          setItems(res.data.items);
        } else {
          setError(res.message ?? t("aiDifferentiation.loadFailed"));
        }
      } catch {
        if (!cancelled) setError(t("aiDifferentiation.loadFailed"));
      } finally {
        if (!cancelled) setLoading(false);
      }
    })();
    return () => {
      cancelled = true;
    };
  }, [doc, t]);

  if (loading) return <LoadingBlock label={t("aiDifferentiation.loading")} />;
  if (error) return <ErrorBlock message={error} />;
  if (items.length === 0) return <EmptyBlock label={t("aiDifferentiation.empty")} />;

  // 按层次排序：basic → intermediate → advanced
  const order: DifferentiationLevel[] = ["basic", "intermediate", "advanced"];
  const sorted = [...items].sort(
    (a, b) => order.indexOf(a.level) - order.indexOf(b.level),
  );

  return (
    <div className="space-y-3">
      {sorted.map((item) => (
        <section
          key={item.level}
          className="rounded border border-outline-variant p-3 bg-surface"
        >
          <h4 className="text-sm font-medium flex items-center gap-1.5 mb-2">
            <Users className="w-3.5 h-3.5 text-primary" aria-hidden="true" />
            {t(`aiDifferentiation.level.${item.level}`)}
            <span className="text-xs text-on-surface-variant">— {item.targetStudents}</span>
          </h4>
          <ul className="space-y-1.5 text-sm text-on-surface-variant">
            {item.suggestions.map((s, idx) => (
              <li key={idx} className="flex items-start gap-1.5">
                <span className="text-primary mt-1">·</span>
                <span>{s}</span>
              </li>
            ))}
          </ul>
        </section>
      ))}
    </div>
  );
}

/** A4：课标实时核对 Tab（按 textbookId 按需加载知识点） */
function CurriculumTab({
  doc,
  textbookId,
  t,
}: {
  doc: LessonPlanDocument;
  textbookId?: string;
  t: ReturnType<typeof useTranslations>;
}) {
  const [loading, setLoading] = useState(true);
  const [items, setItems] = useState<CurriculumCheckItem[]>([]);
  const [error, setError] = useState<string | null>(null);

  useEffect(() => {
    let cancelled = false;
    (async () => {
      // 无教材 ID 时无法获取知识点
      if (!textbookId) {
        setLoading(false);
        setError(t("aiDifferentiation.noKnowledgePoints"));
        return;
      }
      setLoading(true);
      setError(null);
      try {
        // 先按需加载知识点列表
        const kpRes = await getKnowledgePointsForAlignmentAction(textbookId);
        if (cancelled) return;
        if (!kpRes.success || !kpRes.data || kpRes.data.items.length === 0) {
          setError(t("aiDifferentiation.noKnowledgePoints"));
          return;
        }
        // 再调用课标核对
        const res = await checkCurriculumAlignmentAction(doc, kpRes.data.items);
        if (cancelled) return;
        if (res.success && res.data) {
          setItems(res.data.items);
        } else {
          setError(res.message ?? t("aiDifferentiation.loadFailed"));
        }
      } catch {
        if (!cancelled) setError(t("aiDifferentiation.loadFailed"));
      } finally {
        if (!cancelled) setLoading(false);
      }
    })();
    return () => {
      cancelled = true;
    };
  }, [doc, textbookId, t]);

  if (loading) return <LoadingBlock label={t("aiDifferentiation.loading")} />;
  if (error) return <ErrorBlock message={error} />;
  if (items.length === 0) return <EmptyBlock label={t("aiDifferentiation.empty")} />;

  const covered = items.filter((i) => i.covered).length;
  const missed = items.length - covered;

  return (
    <div className="space-y-3">
      <div className="flex items-center gap-3 text-sm">
        <span className="inline-flex items-center gap-1 text-primary">
          <CheckCircle2 className="w-3.5 h-3.5" aria-hidden="true" />
          {t("aiDifferentiation.covered", { count: covered })}
        </span>
        <span className="inline-flex items-center gap-1 text-tertiary">
          <XCircle className="w-3.5 h-3.5" aria-hidden="true" />
          {t("aiDifferentiation.missed", { count: missed })}
        </span>
      </div>
      <ul className="space-y-2">
        {items.map((item, idx) => (
          <li
            key={idx}
            className="rounded border border-outline-variant p-2.5 bg-surface text-sm"
          >
            <div className="flex items-center gap-1.5 font-medium">
              {item.covered ? (
                <CheckCircle2 className="w-3.5 h-3.5 text-primary" aria-hidden="true" />
              ) : (
                <XCircle className="w-3.5 h-3.5 text-tertiary" aria-hidden="true" />
              )}
              <span>{item.requirement}</span>
            </div>
            {item.explanation && (
              <p className="text-xs text-on-surface-variant mt-1 ml-5">{item.explanation}</p>
            )}
          </li>
        ))}
      </ul>
    </div>
  );
}

/** A5：可解释评估 Tab */
function AssessmentTab({
  doc,
  t,
}: {
  doc: LessonPlanDocument;
  t: ReturnType<typeof useTranslations>;
}) {
  const [loading, setLoading] = useState(true);
  const [items, setItems] = useState<ExplainableAssessment[]>([]);
  const [error, setError] = useState<string | null>(null);

  useEffect(() => {
    let cancelled = false;
    (async () => {
      setLoading(true);
      setError(null);
      try {
        const res = await generateExplainableAssessmentAction(doc);
        if (cancelled) return;
        if (res.success && res.data) {
          setItems(res.data.items);
        } else {
          setError(res.message ?? t("aiDifferentiation.loadFailed"));
        }
      } catch {
        if (!cancelled) setError(t("aiDifferentiation.loadFailed"));
      } finally {
        if (!cancelled) setLoading(false);
      }
    })();
    return () => {
      cancelled = true;
    };
  }, [doc, t]);

  if (loading) return <LoadingBlock label={t("aiDifferentiation.loading")} />;
  if (error) return <ErrorBlock message={error} />;
  if (items.length === 0) return <EmptyBlock label={t("aiDifferentiation.empty")} />;

  return (
    <ul className="space-y-2">
      {items.map((item, idx) => (
        <li
          key={idx}
          className="rounded border border-outline-variant p-2.5 bg-surface text-sm"
        >
          <div className="font-medium flex items-center gap-1.5">
            <BookCheck className="w-3.5 h-3.5 text-primary" aria-hidden="true" />
            <span>{item.conclusion}</span>
          </div>
          {item.rationale && (
            <p className="text-xs text-on-surface-variant mt-1 ml-5 flex items-start gap-1">
              <ClipboardList className="w-3 h-3 mt-0.5 flex-shrink-0" aria-hidden="true" />
              <span>{item.rationale}</span>
            </p>
          )}
          {item.suggestion && (
            <p className="text-xs text-on-surface-variant mt-1 ml-5 flex items-start gap-1">
              <GraduationCap className="w-3 h-3 mt-0.5 flex-shrink-0" aria-hidden="true" />
              <span>{item.suggestion}</span>
            </p>
          )}
        </li>
      ))}
    </ul>
  );
}

function LoadingBlock({ label }: { label: string }) {
  return (
    <div className="flex flex-col items-center justify-center py-12 gap-2">
      <Loader2 className="w-6 h-6 animate-spin text-primary" aria-hidden="true" />
      <p className="text-sm text-on-surface-variant">{label}</p>
    </div>
  );
}

function ErrorBlock({ message }: { message: string }) {
  return (
    <div className="flex items-center gap-2 p-3 rounded border border-error/40 bg-error-container/30 text-sm">
      <AlertCircle className="w-4 h-4 text-error" aria-hidden="true" />
      {message}
    </div>
  );
}

function EmptyBlock({ label }: { label: string }) {
  return <div className="text-sm text-on-surface-variant text-center py-6">{label}</div>;
}