"use client";

import { useMemo } from "react";
import { useTranslations } from "next-intl";
import { Book } from "lucide-react";
import type {
  LessonPlanDocument,
  LessonPlanNode,
  TeachingStage,
} from "../types";
import { TEACHING_STAGE_KEYS } from "../types";
import { getNodeColor, getNodeSummary } from "../lib/node-summary";
import { cn } from "@/shared/lib/utils";

interface Props {
  doc: LessonPlanDocument;
  textbookTitle?: string;
  chapterTitle?: string;
}

/**
 * V5-13 P3：移动端只读视图。
 *
 * 在小屏设备上以线性卡片列表替代 React Flow 画布，
 * 按教学阶段（V5-15）分组展示节点，提升可读性。
 * 仅展示，无编辑交互。
 */
export function LessonPlanMobileView({ doc, textbookTitle, chapterTitle }: Props) {
  const t = useTranslations("lessonPreparation");

  // 教学节点按 stage 分组（未归类的归入"其他"）
  const grouped = useMemo(() => {
    const teachingNodes = doc.nodes.filter(
      (n): n is LessonPlanNode => n.type !== "textbook_content",
    );
    const groups: Record<string, LessonPlanNode[]> = {};
    const unstaged: LessonPlanNode[] = [];
    for (const n of teachingNodes) {
      if (n.stage) {
        const key = n.stage as TeachingStage;
        if (!groups[key]) groups[key] = [];
        groups[key].push(n);
      } else {
        unstaged.push(n);
      }
    }
    return { groups, unstaged };
  }, [doc.nodes]);

  return (
    <div className="flex flex-col h-full overflow-y-auto bg-surface-container-low">
      {/* 顶部信息条 */}
      {(textbookTitle || chapterTitle) && (
        <div className="sticky top-0 z-10 bg-surface/95 backdrop-blur border-b border-outline-variant px-4 py-2 text-sm">
          {textbookTitle && (
            <div className="flex items-center gap-1 text-on-surface-variant">
              <Book className="w-3.5 h-3.5" aria-hidden="true" />
              <span className="font-medium">{textbookTitle}</span>
            </div>
          )}
          {chapterTitle && (
            <div className="text-on-surface-variant text-xs mt-0.5">{chapterTitle}</div>
          )}
        </div>
      )}

      <div className="flex-1 px-3 py-3 space-y-4">
        {/* 按阶段分组渲染 */}
        {TEACHING_STAGE_KEYS.map((stage) => {
          const nodes = grouped.groups[stage];
          if (!nodes || nodes.length === 0) return null;
          return (
            <section key={stage} className="space-y-2">
              <h3 className="text-xs font-medium text-on-surface-variant px-1">
                {t(`editor.stage.${stage}`)}
              </h3>
              {nodes.map((n) => (
                <MobileNodeCard key={n.id} node={n} t={t} />
              ))}
            </section>
          );
        })}

        {/* 未归类节点 */}
        {grouped.unstaged.length > 0 && (
          <section className="space-y-2">
            {TEACHING_STAGE_KEYS.some((s) => grouped.groups[s]?.length > 0) && (
              <h3 className="text-xs font-medium text-on-surface-variant px-1">
                {t("editor.stageNone")}
              </h3>
            )}
            {grouped.unstaged.map((n) => (
              <MobileNodeCard key={n.id} node={n} t={t} />
            ))}
          </section>
          )}
      </div>
    </div>
  );
}

function MobileNodeCard({
  node,
  t,
}: {
  node: LessonPlanNode;
  t: ReturnType<typeof useTranslations>;
}) {
  const color = getNodeColor(node.type);
  const summary = getNodeSummary(node, (key, values) => t(key, values));
  const diff = node.differentiation;

  return (
    <article className="rounded-lg border border-outline-variant bg-surface p-3 shadow-sm">
      <div className="flex items-start gap-2">
        <span
          className="inline-block w-2.5 h-2.5 rounded-full mt-1.5 flex-shrink-0"
          style={{ backgroundColor: color }}
          aria-hidden="true"
        />
        <div className="flex-1 min-w-0">
          <div className="flex items-center gap-1.5 flex-wrap">
            <h4 className="font-medium text-sm text-on-surface truncate flex-1">
              {node.title || node.type}
            </h4>
            {diff && (
              <span
                className={cn(
                  "text-[10px] px-1.5 py-0.5 rounded font-medium flex-shrink-0",
                  diff === "basic"
                    ? "bg-primary-container text-on-primary-container"
                    : diff === "intermediate"
                      ? "bg-secondary-container text-on-secondary-container"
                      : "bg-tertiary-container text-on-tertiary-container",
                )}
              >
                {t(`editor.differentiation.${diff}`)}
              </span>
            )}
          </div>
          {summary && (
            <p className="text-xs text-on-surface-variant mt-1 line-clamp-3">
              {summary}
            </p>
          )}
        </div>
      </div>
    </article>
  );
}