import {
  ChevronRight,
  Cloud,
  Download,
  Folder,
  FolderOpen,
  HardDrive,
  LoaderCircle,
  TriangleAlert,
} from "lucide-react";
import { useEffect, useState } from "react";
import { type FileRoot, useDirChildren } from "~/api/files.ts";
import { useListPagination } from "~/components/console/use-list-pagination.ts";
import { Pagination } from "~/components/ui/pagination.tsx";
import { healthLabel } from "~/lib/labels.ts";
import { cn } from "~/lib/utils.ts";
import { displayPath, groupRoots, joinRel, segments } from "./model.ts";

type Loc = { root: string; path: string };
type DropHandler = (target: Loc, e: React.DragEvent) => void;

const nodeKey = (root: string, path: string) => `${root}\u0000${path}`;

/**
 * 登记目录 + 懒加载目录树。下载目录在前、媒体库在后,每个登记目录带健康点与剩余空间;
 * 目录节点可作为拖放目标(onDropTo),并自动展开到当前路径。
 * pickOnly:目标选择器模式(移动/复制到…),不可写根整根禁用。
 */
export function DirTree({
  roots,
  current,
  onSelect,
  onDropTo,
  pickOnly = false,
  paginate = false,
  defaultOpen = [],
  className,
}: {
  roots: FileRoot[];
  current: Loc | null;
  onSelect: (loc: Loc) => void;
  onDropTo?: DropHandler;
  pickOnly?: boolean;
  /** 目录选择小窗按页展示子目录;主文件树保持懒展开。 */
  paginate?: boolean;
  /** 初始展开的根 id(目标选择器里默认展开可写根) */
  defaultOpen?: string[];
  className?: string;
}) {
  const [open, setOpen] = useState<Set<string>>(() => new Set(defaultOpen.map((id) => nodeKey(id, ""))));

  // 当前路径的各级祖先自动展开
  useEffect(() => {
    if (!current) return;
    setOpen((prev) => {
      const next = new Set(prev);
      const segs = segments(current.path);
      next.add(nodeKey(current.root, ""));
      for (let i = 1; i < segs.length; i++) next.add(nodeKey(current.root, segs.slice(0, i).join("/")));
      return next.size === prev.size ? prev : next;
    });
  }, [current]);

  const toggle = (k: string) =>
    setOpen((prev) => {
      const next = new Set(prev);
      if (next.has(k)) next.delete(k);
      else next.add(k);
      return next;
    });

  const groups = groupRoots(roots);

  return (
    <nav aria-label="登记目录" className={cn("space-y-4", className)}>
      {groups.map((g) => (
        <section key={g.title} aria-label={g.title}>
          <p className="mb-1 px-2 text-micro font-semibold tracking-[0.15em] text-muted-foreground/75 uppercase">
            {g.title}
          </p>
          <div className="space-y-0.5">
            {g.items.map((r) => (
              <RootNode
                key={r.id}
                root={r}
                current={current}
                open={open}
                toggle={toggle}
                onSelect={onSelect}
                onDropTo={onDropTo}
                pickOnly={pickOnly}
                paginate={paginate}
              />
            ))}
          </div>
        </section>
      ))}
    </nav>
  );
}

function RootNode({
  root,
  current,
  open,
  toggle,
  onSelect,
  onDropTo,
  pickOnly,
  paginate,
}: {
  root: FileRoot;
  current: Loc | null;
  open: Set<string>;
  toggle: (k: string) => void;
  onSelect: (loc: Loc) => void;
  onDropTo?: DropHandler;
  pickOnly: boolean;
  paginate: boolean;
}) {
  const k = nodeKey(root.id, "");
  const offline = root.health === "offline";
  const disabled = pickOnly && (!root.writable || offline);
  const isOpen = open.has(k) && !offline;
  const active = current?.root === root.id && current.path === "";
  const h = healthLabel(root.health);
  const Icon = root.kind === "download" ? Download : root.kind === "storage" ? Cloud : HardDrive;
  return (
    <div>
      <TreeRow
        depth={0}
        active={active}
        disabled={disabled}
        expandable={!offline}
        expanded={isOpen}
        onToggle={() => toggle(k)}
        onClick={() => {
          if (disabled) return;
          onSelect({ root: root.id, path: "" });
          if (!open.has(k)) toggle(k);
        }}
        onDrop={onDropTo && root.writable && !offline ? (e) => onDropTo({ root: root.id, path: "" }, e) : undefined}
        title={disabled ? (offline ? "目录离线" : "只读目录，不能作为目标") : displayPath(root)}
      >
        <Icon className="h-4 w-4 shrink-0 text-muted-foreground" />
        <span className="min-w-0 flex-1">
          <span className="block truncate text-body text-foreground">{root.name}</span>
          <span className="flex items-center gap-1.5 text-meta text-muted-foreground">
            {root.health !== "healthy" ? (
              <span
                className={cn(
                  "inline-flex items-center gap-1",
                  h.tone === "destructive" && "text-destructive",
                  h.tone === "warning" && "text-warning",
                )}
              >
                {h.tone !== "neutral" ? <TriangleAlert className="h-3 w-3" /> : null}
                {h.label}
              </span>
            ) : null}
            {root.pendingCount ? (
              <span className="shrink-0 text-warning">
                未识别 {root.pendingCount}
                {root.pendingPartial ? "+" : ""}
              </span>
            ) : null}
            {!root.writable && root.kind === "library" ? <span>只读</span> : null}
          </span>
        </span>
      </TreeRow>
      {isOpen ? (
        <Children
          root={root}
          path=""
          depth={1}
          current={current}
          open={open}
          toggle={toggle}
          onSelect={onSelect}
          onDropTo={onDropTo}
          pickOnly={pickOnly}
          paginate={paginate}
        />
      ) : null}
    </div>
  );
}

function Children({
  root,
  path,
  depth,
  current,
  open,
  toggle,
  onSelect,
  onDropTo,
  pickOnly,
  paginate,
}: {
  root: FileRoot;
  path: string;
  depth: number;
  current: Loc | null;
  open: Set<string>;
  toggle: (k: string) => void;
  onSelect: (loc: Loc) => void;
  onDropTo?: DropHandler;
  pickOnly: boolean;
  paginate: boolean;
}) {
  const q = useDirChildren(root.id, path, true);
  const dirs = q.data?.dirs ?? [];
  const paged = useListPagination(dirs, { resetKey: JSON.stringify({ root: root.id, path }) });
  const selectedIndex =
    current?.root === root.id
      ? dirs.findIndex((dir) => {
          const childPath = dir.path || joinRel(path, dir.name);
          return current.path === childPath || current.path.startsWith(`${childPath}/`);
        })
      : -1;
  // biome-ignore lint/correctness/useExhaustiveDependencies: 选中目录改变时定位;手动翻页不改变已有选择
  useEffect(() => {
    if (paginate && selectedIndex >= 0)
      paged.pagination.onPageChange(Math.floor(selectedIndex / paged.pagination.pageSize) + 1);
  }, [paginate, root.id, path, selectedIndex, paged.pagination.pageSize]);
  if (q.isPending)
    return (
      <div
        className="flex items-center gap-2 py-1 text-meta text-muted-foreground"
        style={{ paddingLeft: depth * 14 + 28 }}
      >
        <LoaderCircle className="h-3 w-3 animate-spin" /> 加载中
      </div>
    );
  if (q.error)
    return (
      <p className="py-1 text-meta text-destructive" style={{ paddingLeft: depth * 14 + 28 }}>
        读取失败
      </p>
    );
  if (!dirs.length)
    return (
      <p className="py-1 text-meta text-muted-foreground" style={{ paddingLeft: depth * 14 + 28 }}>
        无子目录
      </p>
    );
  return (
    <div>
      {(paginate ? paged.items : dirs)?.map((d) => {
        const p = d.path || joinRel(path, d.name);
        const k = nodeKey(root.id, p);
        const isOpen = open.has(k);
        const active = current?.root === root.id && current.path === p;
        const disabled = pickOnly && !root.writable;
        return (
          <div key={k}>
            <TreeRow
              depth={depth}
              active={active}
              disabled={disabled}
              expandable={d.hasChildren}
              expanded={isOpen && d.hasChildren}
              onToggle={() => toggle(k)}
              onClick={() => !disabled && onSelect({ root: root.id, path: p })}
              onDrop={onDropTo && root.writable ? (e) => onDropTo({ root: root.id, path: p }, e) : undefined}
              title={d.name}
            >
              {isOpen ? (
                <FolderOpen className="h-4 w-4 shrink-0 text-muted-foreground" />
              ) : (
                <Folder className="h-4 w-4 shrink-0 text-muted-foreground" />
              )}
              <span className="min-w-0 flex-1 truncate text-body">{d.name}</span>
            </TreeRow>
            {isOpen && d.hasChildren ? (
              <Children
                root={root}
                path={p}
                depth={depth + 1}
                current={current}
                open={open}
                toggle={toggle}
                onSelect={onSelect}
                onDropTo={onDropTo}
                pickOnly={pickOnly}
                paginate={paginate}
              />
            ) : null}
          </div>
        );
      })}
      {paginate && dirs.length > 0 ? <Pagination {...paged.pagination} /> : null}
      {q.data?.truncated ? (
        <p className="py-1 text-meta text-muted-foreground" style={{ paddingLeft: depth * 14 + 28 }}>
          子目录过多，只列出一部分
        </p>
      ) : null}
    </div>
  );
}

function TreeRow({
  depth,
  active,
  disabled,
  expandable,
  expanded,
  onToggle,
  onClick,
  onDrop,
  title,
  children,
}: {
  depth: number;
  active: boolean;
  disabled?: boolean;
  expandable: boolean;
  expanded: boolean;
  onToggle: () => void;
  onClick: () => void;
  onDrop?: (e: React.DragEvent) => void;
  title?: string;
  children: React.ReactNode;
}) {
  const [over, setOver] = useState(false);
  return (
    // biome-ignore lint/a11y/noStaticElementInteractions: 整行是拖放目标,交互本体是里面的两个按钮
    <div
      className={cn(
        "group flex items-center gap-1 rounded-lg pr-2 transition-colors duration-micro",
        active
          ? "pill-selected text-foreground"
          : "text-muted-foreground hover:bg-foreground/[0.04] hover:text-foreground",
        disabled && "opacity-50",
        over && "bg-foreground/[0.08] ring-1 ring-ring",
      )}
      style={{ paddingLeft: depth * 14 }}
      onDragOver={
        onDrop
          ? (e) => {
              e.preventDefault();
              e.dataTransfer.dropEffect = e.altKey ? "copy" : "move";
              setOver(true);
            }
          : undefined
      }
      onDragLeave={onDrop ? () => setOver(false) : undefined}
      onDrop={
        onDrop
          ? (e) => {
              e.preventDefault();
              setOver(false);
              onDrop(e);
            }
          : undefined
      }
    >
      <button
        type="button"
        tabIndex={-1}
        aria-label={expanded ? "收起" : "展开"}
        aria-expanded={expanded}
        onClick={onToggle}
        className={cn("grid h-7 w-6 shrink-0 place-items-center rounded-md", !expandable && "invisible")}
      >
        <ChevronRight className={cn("h-3.5 w-3.5 transition-transform duration-base", expanded && "rotate-90")} />
      </button>
      <button
        type="button"
        onClick={onClick}
        title={title}
        aria-current={active ? "location" : undefined}
        aria-disabled={disabled || undefined}
        className={cn(
          "flex min-w-0 flex-1 items-center gap-2 py-1.5 text-left outline-none focus-visible:underline",
          disabled && "cursor-not-allowed",
        )}
      >
        {children}
      </button>
    </div>
  );
}