/**
 * @file A server-backed folder (or file) browser for the path inputs' Browse
 * button, laid out like the OS's own picker. Browsers refuse to expose an
 * absolute filesystem path from a native picker, so path selection here is
 * done by browsing `GET /api/lanes/browse` instead: back/forward/up, a
 * clickable breadcrumb that turns into a path field (Ctrl+L), a Places column
 * (Home, the user's workspaces, recent picks), a filter, Name/Modified columns,
 * hidden entries on demand and New folder (`POST /api/lanes/browse/mkdir`).
 * A click selects, a double-click or Enter opens a folder (picks a file),
 * Backspace goes up and typing jumps to a name.
 * An admin with a Linux account of their own (S3; the listing carries
 * `hostHome`) opens in THEIR home; the "Server folder" tick switches the
 * browser to the host account's home, where a workspace runs as the shared
 * host account. It is never remembered: every open starts at the admin's own.
 * @author Nguyễn Ngọc Trí Vĩ <vinnt@smartgift.vn>
 */

import { useEffect, useMemo, useRef, useState, type KeyboardEvent } from "react";
import { useTranslation } from "react-i18next";
import {
  ArrowLeft,
  ArrowRight,
  ArrowUp,
  Clock,
  Eye,
  File,
  FolderGit2,
  FolderOpen,
  FolderPlus,
  Home,
  Pencil,
  Server,
  Star,
} from "lucide-react";
import { api } from "../../lib/api";
import { formatDateTime } from "../../lib/format";
import { isSubmitEnter } from "../../lib/keys";
import { useDialog } from "../../hooks/useDialog";
import { useWorkLanes } from "../../hooks/useLanes";

type Listing = Awaited<ReturnType<typeof api.lanes.browse>>;
type Entry = Listing["entries"][number];

const RECENT_KEY = "agenthub.browse.recent";
const HIDDEN_KEY = "agenthub.browse.hidden";
const RECENT_MAX = 8;

function readStored<T>(key: string, fallback: T): T {
  try {
    const raw = localStorage.getItem(key);
    return raw ? (JSON.parse(raw) as T) : fallback;
  } catch {
    return fallback;
  }
}

function writeStored(key: string, value: unknown) {
  try {
    localStorage.setItem(key, JSON.stringify(value));
  } catch {
    // A private window or blocked storage: the preference just isn't kept.
  }
}

/** `[label, path]` for each level of `p`, root first. */
function crumbs(p: string): [string, string][] {
  const win = /^[A-Za-z]:\\/.test(p);
  const sep = win ? "\\" : "/";
  const parts = p.split(sep).filter(Boolean);
  const out: [string, string][] = win ? [] : [["/", "/"]];
  let acc = "";
  for (const part of parts) {
    acc = win ? (acc ? `${acc}\\${part}` : `${part}\\`) : `${acc}/${part}`;
    out.push([part, acc]);
  }
  return out;
}

const baseName = (p: string) => p.split(/[\\/]/).filter(Boolean).pop() || p;

type Props = {
  open: boolean;
  /** `file` lists files too, and picking one is the only way to select. */
  kind?: "dir" | "file";
  /** Path to start browsing from; omitted defaults server-side to the home dir. */
  initialPath?: string;
  onSelect: (path: string) => void;
  onClose: () => void;
};

/**
 * Mounted only while open, so a closed picker (one behind every Browse
 * button) asks the server for nothing, and each opening starts fresh.
 */
export function FolderBrowseModal(props: Props) {
  return props.open ? <BrowseDialog {...props} /> : null;
}

function BrowseDialog({
  open,
  kind = "dir",
  initialPath,
  onSelect,
  onClose,
}: {
  open: boolean;
  /** `file` lists files too, and picking one is the only way to select. */
  kind?: "dir" | "file";
  /** Path to start browsing from; omitted defaults server-side to the home dir. */
  initialPath?: string;
  onSelect: (path: string) => void;
  onClose: () => void;
}) {
  const { t } = useTranslation(["lanes"]);
  const { lanes } = useWorkLanes();
  const [listing, setListing] = useState<Listing | null>(null);
  const [error, setError] = useState<string | null>(null);
  const [history, setHistory] = useState<{ stack: string[]; at: number }>({ stack: [], at: -1 });
  const [selected, setSelected] = useState<string | null>(null);
  const [filter, setFilter] = useState("");
  const [editing, setEditing] = useState(false);
  const [pathText, setPathText] = useState("");
  const [sort, setSort] = useState<{ key: "name" | "mtime"; dir: 1 | -1 }>({
    key: "name",
    dir: 1,
  });
  const [showHidden, setShowHidden] = useState(() => readStored(HIDDEN_KEY, false));
  const [creating, setCreating] = useState(false);
  const [newName, setNewName] = useState("");
  const [recent, setRecent] = useState<string[]>(() => readStored(RECENT_KEY, []));
  // The highest folder this user may open (a member's own folder answers no
  // parent) — breadcrumbs above it are not links.
  const [floor, setFloor] = useState<string | null>(null);
  const [home, setHome] = useState<string | null>(null);
  // An admin's "Server folder" tick (S3): browse the host account's home.
  const [hostHome, setHostHome] = useState<string | null>(null);
  const [onHost, setOnHost] = useState(false);
  const listRef = useRef<HTMLDivElement>(null);
  const crumbRef = useRef<HTMLDivElement>(null);
  const typeAhead = useRef({ text: "", at: 0 });

  const load = async (
    target?: string,
    { push = true, hidden = showHidden, select = null as string | null, host = onHost } = {}
  ) => {
    setError(null);
    try {
      const next = await api.lanes.browse(target, kind === "file", hidden, host);
      setListing(next);
      setSelected(select);
      setFilter("");
      setEditing(false);
      if (next.home) setHome(next.home);
      setHostHome(next.hostHome ?? null);
      if (next.parent === null && crumbs(next.path).length > 1) setFloor(next.path);
      if (push) {
        setHistory((h) => {
          if (h.stack[h.at] === next.path) return h;
          const stack = [...h.stack.slice(0, h.at + 1), next.path];
          return { stack, at: stack.length - 1 };
        });
      }
      return true;
    } catch (err) {
      setError(err instanceof Error ? err.message : String(err));
      return false;
    }
  };

  useEffect(() => {
    if (!open) return;
    setHistory({ stack: [], at: -1 });
    setCreating(false);
    setOnHost(false);
    void load(initialPath, { host: false });
    // Only re-run when the modal actually opens - not on every initialPath
    // keystroke in the field behind it.
    // eslint-disable-next-line react-hooks/exhaustive-deps
  }, [open]);

  // The shared dialog contract: focus in, Tab trapped, Escape closes (only
  // this one when it sits over the Add-workspace modal), focus restored.
  const panel = useRef<HTMLDivElement>(null);
  useDialog(open, panel, onClose);

  const entries = useMemo(() => {
    const needle = filter.trim().toLowerCase();
    const list = (listing?.entries ?? []).filter(
      (e) => !needle || e.name.toLowerCase().includes(needle)
    );
    const by = (a: Entry, b: Entry) =>
      sort.key === "mtime"
        ? ((a.mtime ?? 0) - (b.mtime ?? 0)) * sort.dir
        : a.name.localeCompare(b.name, undefined, { numeric: true, sensitivity: "base" }) *
          sort.dir;
    // Folders first, as every file picker lists them.
    return [...list].sort((a, b) => Number(!!a.file) - Number(!!b.file) || by(a, b));
  }, [listing, filter, sort]);

  const places = useMemo(() => {
    const seen = new Set<string>();
    return lanes
      .filter((l) => l.cwd && !seen.has(l.cwd) && seen.add(l.cwd))
      .map((l) => ({ label: l.title || baseName(l.cwd), path: l.cwd }));
  }, [lanes]);

  // A deep path keeps its LAST levels in view, like a native path bar.
  useEffect(() => {
    const el = crumbRef.current;
    if (el) el.scrollLeft = el.scrollWidth;
  }, [listing?.path, editing]);

  useEffect(() => {
    if (!selected) return;
    const el = Array.from(listRef.current?.querySelectorAll<HTMLElement>("[data-path]") ?? []).find(
      (x) => x.dataset.path === selected
    );
    el?.scrollIntoView?.({ block: "nearest" });
  }, [selected]);

  if (!open) return null;

  const finish = (picked: string) => {
    const folder = kind === "file" ? (listing?.path ?? picked) : picked;
    const next = [folder, ...recent.filter((r) => r !== folder)].slice(0, RECENT_MAX);
    setRecent(next);
    writeStored(RECENT_KEY, next);
    onSelect(picked);
    onClose();
  };

  const activate = (entry: Entry) => {
    if (entry.file) finish(entry.path);
    else void load(entry.path);
  };

  const go = (delta: -1 | 1) => {
    const at = history.at + delta;
    const target = history.stack[at];
    if (target === undefined) return;
    void load(target, { push: false }).then((ok) => {
      if (ok) setHistory((h) => ({ ...h, at }));
    });
  };

  const goUp = () => {
    if (!listing?.parent) return;
    const from = listing.path;
    void load(listing.parent, { select: from });
  };

  const selectedEntry = entries.find((e) => e.path === selected) ?? null;
  const target =
    kind === "file"
      ? selectedEntry?.file
        ? selectedEntry.path
        : null
      : selectedEntry && !selectedEntry.file
        ? selectedEntry.path
        : (listing?.path ?? null);

  const onListKey = (e: KeyboardEvent<HTMLDivElement>) => {
    const idx = entries.findIndex((x) => x.path === selected);
    if (e.key === "ArrowDown" || e.key === "ArrowUp") {
      e.preventDefault();
      if (e.altKey && e.key === "ArrowUp") return goUp();
      const next =
        e.key === "ArrowDown" ? Math.min(entries.length - 1, idx + 1) : Math.max(0, idx - 1);
      if (entries[next]) setSelected(entries[next].path);
      return;
    }
    if (e.key === "Home" || e.key === "End") {
      e.preventDefault();
      const pick = e.key === "Home" ? entries[0] : entries[entries.length - 1];
      if (pick) setSelected(pick.path);
      return;
    }
    if (e.key === "Enter") {
      e.preventDefault();
      if (selectedEntry) activate(selectedEntry);
      else if (kind === "dir" && target) finish(target);
      return;
    }
    if (e.key === "Backspace") {
      e.preventDefault();
      goUp();
      return;
    }
    if (e.key.length === 1 && !e.ctrlKey && !e.metaKey && !e.altKey) {
      // Typing jumps to the first name that starts with what was typed.
      const now = Date.now();
      const ta = typeAhead.current;
      ta.text = now - ta.at > 800 ? e.key.toLowerCase() : ta.text + e.key.toLowerCase();
      ta.at = now;
      const hit = entries.find((x) => x.name.toLowerCase().startsWith(ta.text));
      if (hit) setSelected(hit.path);
    }
  };

  const onPanelKey = (e: KeyboardEvent<HTMLDivElement>) => {
    if ((e.ctrlKey || e.metaKey) && e.key.toLowerCase() === "l") {
      e.preventDefault();
      setPathText(listing?.path ?? "");
      setEditing(true);
    } else if (e.altKey && e.key === "ArrowLeft") {
      e.preventDefault();
      go(-1);
    } else if (e.altKey && e.key === "ArrowRight") {
      e.preventDefault();
      go(1);
    }
  };

  const createFolder = async () => {
    const name = newName.trim();
    if (!name || !listing) return;
    setError(null);
    try {
      const made = await api.lanes.mkdir(listing.path, name);
      setCreating(false);
      setNewName("");
      await load(listing.path, { push: false, select: made.path });
    } catch (err) {
      setError(err instanceof Error ? err.message : String(err));
    }
  };

  // Switch between the admin's own home and the host account's, and open it.
  const toggleHost = () => {
    const next = !onHost;
    setOnHost(next);
    void load(undefined, { host: next });
  };

  const toggleHidden = () => {
    const next = !showHidden;
    setShowHidden(next);
    writeStored(HIDDEN_KEY, next);
    if (listing) void load(listing.path, { push: false, hidden: next, select: selected });
  };

  const iconBtn =
    "flex h-7 w-7 items-center justify-center rounded-md text-fg-secondary hover:bg-surface-2 disabled:opacity-40 disabled:hover:bg-transparent";
  const placeBtn = (active: boolean) =>
    `flex w-full items-center gap-2 rounded px-2 py-1 text-left text-xs ${
      active ? "bg-surface-2 text-fg-primary" : "text-fg-secondary hover:bg-surface-2"
    }`;
  const path = listing?.path ?? "";
  const floorDepth = floor ? crumbs(floor).length : 0;

  return (
    <div
      className="fixed inset-0 z-50 flex items-center justify-center bg-black/60 p-4"
      onClick={onClose}
      role="presentation"
    >
      <div
        ref={panel}
        className="relative flex h-[min(80vh,640px)] w-full max-w-3xl flex-col rounded-xl border border-border bg-surface-1 shadow-xl shadow-black/40"
        onClick={(e) => e.stopPropagation()}
        onKeyDown={onPanelKey}
        role="dialog"
        aria-modal="true"
        aria-label={kind === "file" ? t("browse.fileTitle") : t("browse.title")}
        data-tour="folder-browse"
      >
        {/* Toolbar: history, up, and the breadcrumb / path field. */}
        <div className="flex items-center gap-1 border-b border-border p-2">
          <button
            type="button"
            className={iconBtn}
            onClick={() => go(-1)}
            disabled={history.at <= 0}
            title={t("browse.back")}
            aria-label={t("browse.back")}
          >
            <ArrowLeft className="h-4 w-4" />
          </button>
          <button
            type="button"
            className={iconBtn}
            onClick={() => go(1)}
            disabled={history.at >= history.stack.length - 1}
            title={t("browse.forward")}
            aria-label={t("browse.forward")}
          >
            <ArrowRight className="h-4 w-4" />
          </button>
          <button
            type="button"
            className={iconBtn}
            onClick={goUp}
            disabled={!listing?.parent}
            title={t("browse.up")}
            aria-label={t("browse.up")}
          >
            <ArrowUp className="h-4 w-4" />
          </button>
          {editing ? (
            <input
              autoFocus
              value={pathText}
              onChange={(e) => setPathText(e.target.value)}
              onKeyDown={(e) => {
                if (isSubmitEnter(e)) {
                  e.preventDefault();
                  if (pathText.trim()) void load(pathText.trim());
                } else if (e.key === "Escape") {
                  e.preventDefault();
                  e.stopPropagation();
                  setEditing(false);
                }
              }}
              onBlur={() => setEditing(false)}
              aria-label={t("browse.editPath")}
              spellCheck={false}
              className="input min-w-0 flex-1 font-mono text-xs"
            />
          ) : (
            <div
              ref={crumbRef}
              className="flex min-w-0 flex-1 items-center overflow-x-auto rounded-md border border-border-light px-1 py-0.5"
              onDoubleClick={() => {
                setPathText(path);
                setEditing(true);
              }}
            >
              {crumbs(path).map(([label, p], i, all) => {
                const last = i === all.length - 1;
                const locked = i + 1 < floorDepth;
                return (
                  <span key={p} className="flex shrink-0 items-center">
                    {i > 0 && all[i - 1]?.[0] !== "/" && (
                      <span className="px-0.5 text-fg-muted">›</span>
                    )}
                    <button
                      type="button"
                      disabled={last || locked}
                      onClick={() => void load(p, { select: all[i + 1]?.[1] ?? null })}
                      className={`rounded px-1 py-0.5 font-mono text-xs ${
                        last
                          ? "font-medium text-fg-primary"
                          : locked
                            ? "text-fg-muted"
                            : "text-fg-secondary hover:bg-surface-2"
                      }`}
                    >
                      {label}
                    </button>
                  </span>
                );
              })}
            </div>
          )}
          <button
            type="button"
            className={iconBtn}
            onMouseDown={(e) => e.preventDefault()}
            onClick={() => {
              setPathText(path);
              setEditing((v) => !v);
            }}
            title={t("browse.editPath")}
            aria-label={t("browse.editPath")}
          >
            <Pencil className="h-3.5 w-3.5" />
          </button>
        </div>

        <div className="flex min-h-0 flex-1">
          {/* Places */}
          <nav
            className="hidden w-44 shrink-0 overflow-y-auto border-r border-border p-2 sm:block"
            aria-label={t("browse.places")}
          >
            {home && (
              <button
                type="button"
                className={placeBtn(path === home)}
                onClick={() => void load(home)}
                title={home}
              >
                <Home className="h-3.5 w-3.5 shrink-0" />
                <span className="truncate">{t("browse.home")}</span>
              </button>
            )}
            {places.length > 0 && (
              <>
                <div className="mt-3 flex items-center gap-1 px-2 pb-1 text-[10px] font-medium uppercase tracking-wide text-fg-muted">
                  <Star className="h-3 w-3" />
                  {t("browse.workspaces")}
                </div>
                {places.map((pl) => (
                  <button
                    key={pl.path}
                    type="button"
                    className={placeBtn(path === pl.path)}
                    onClick={() => void load(pl.path)}
                    title={pl.path}
                  >
                    <FolderGit2 className="h-3.5 w-3.5 shrink-0 text-accent" />
                    <span className="truncate">{pl.label}</span>
                  </button>
                ))}
              </>
            )}
            {recent.length > 0 && (
              <>
                <div className="mt-3 flex items-center gap-1 px-2 pb-1 text-[10px] font-medium uppercase tracking-wide text-fg-muted">
                  <Clock className="h-3 w-3" />
                  {t("browse.recent")}
                </div>
                {recent.map((r) => (
                  <button
                    key={r}
                    type="button"
                    className={placeBtn(path === r)}
                    onClick={() => void load(r)}
                    title={r}
                  >
                    <FolderOpen className="h-3.5 w-3.5 shrink-0" />
                    <span className="truncate">{baseName(r)}</span>
                  </button>
                ))}
              </>
            )}
          </nav>

          {/* Listing */}
          <div className="flex min-w-0 flex-1 flex-col">
            <div className="flex items-center gap-2 border-b border-border p-2">
              <input
                value={filter}
                onChange={(e) => setFilter(e.target.value)}
                onKeyDown={(e) => {
                  if (e.key === "ArrowDown") {
                    e.preventDefault();
                    if (entries[0]) setSelected(entries[0].path);
                    listRef.current?.focus();
                  } else if (isSubmitEnter(e) && entries.length === 1 && entries[0]) {
                    e.preventDefault();
                    activate(entries[0]);
                  }
                }}
                placeholder={t("browse.filter")}
                aria-label={t("browse.filter")}
                className="input min-w-0 flex-1 text-xs"
              />
            </div>
            <div className="flex items-center border-b border-border px-3 py-1 text-[10px] font-medium uppercase tracking-wide text-fg-muted">
              {(["name", "mtime"] as const).map((key) => (
                <button
                  key={key}
                  type="button"
                  onClick={() =>
                    setSort((s) => ({ key, dir: s.key === key ? (s.dir === 1 ? -1 : 1) : 1 }))
                  }
                  className={`${key === "name" ? "flex-1 text-left" : "hidden w-32 text-right sm:block"} hover:text-fg-secondary`}
                >
                  {key === "name" ? t("browse.name") : t("browse.modified")}
                  {sort.key === key && (sort.dir === 1 ? " ↑" : " ↓")}
                </button>
              ))}
            </div>
            <div
              ref={listRef}
              tabIndex={0}
              role="listbox"
              aria-label={path}
              onKeyDown={onListKey}
              className="min-h-0 flex-1 overflow-y-auto p-1 outline-none"
            >
              {error && (
                <p role="alert" className="p-2 text-xs text-status-danger">
                  {error}
                </p>
              )}
              {creating && (
                <div className="flex items-center gap-2 px-2 py-1">
                  <FolderPlus className="h-3.5 w-3.5 shrink-0 text-fg-muted" />
                  <input
                    autoFocus
                    value={newName}
                    onChange={(e) => setNewName(e.target.value)}
                    onKeyDown={(e) => {
                      e.stopPropagation();
                      if (isSubmitEnter(e)) {
                        e.preventDefault();
                        void createFolder();
                      } else if (e.key === "Escape") {
                        e.preventDefault();
                        setCreating(false);
                      }
                    }}
                    placeholder={t("browse.newFolderName")}
                    aria-label={t("browse.newFolderName")}
                    className="input min-w-0 flex-1 text-xs"
                  />
                  <button
                    type="button"
                    onClick={() => void createFolder()}
                    disabled={!newName.trim()}
                    className="btn-primary text-xs disabled:opacity-50"
                  >
                    {t("browse.create")}
                  </button>
                </div>
              )}
              {entries.map((entry) => {
                const isSel = entry.path === selected;
                return (
                  <div
                    key={entry.path}
                    data-path={entry.path}
                    role="option"
                    aria-selected={isSel}
                    onClick={() => setSelected(entry.path)}
                    onDoubleClick={() => activate(entry)}
                    className={`flex cursor-default select-none items-center gap-2 rounded px-2 py-1.5 text-xs ${
                      isSel ? "bg-accent-solid text-white" : "text-fg-primary hover:bg-surface-2"
                    }`}
                  >
                    {entry.file ? (
                      <File className={`h-3.5 w-3.5 shrink-0 ${isSel ? "" : "text-fg-muted"}`} />
                    ) : entry.isGitRepo ? (
                      <FolderGit2
                        className={`h-3.5 w-3.5 shrink-0 ${isSel ? "" : "text-accent"}`}
                      />
                    ) : (
                      <FolderOpen
                        className={`h-3.5 w-3.5 shrink-0 ${isSel ? "" : "text-fg-muted"}`}
                      />
                    )}
                    <span className="min-w-0 flex-1 truncate">{entry.name}</span>
                    <span
                      className={`hidden w-32 shrink-0 text-right tabular-nums sm:block ${isSel ? "" : "text-fg-muted"}`}
                    >
                      {entry.mtime ? formatDateTime(new Date(entry.mtime).toISOString()) : ""}
                    </span>
                  </div>
                );
              })}
              {listing && entries.length === 0 && (
                <p className="p-2 text-xs text-fg-muted">
                  {filter.trim() ? t("browse.noMatch") : t("browse.empty")}
                </p>
              )}
            </div>
          </div>
        </div>

        {/* Footer: what will be picked, and the actions. */}
        <div className="border-t border-border p-2">
          <div
            // rtl so a long path loses its START to the ellipsis, not the folder.
            className="truncate px-1 pb-2 text-left font-mono text-xs text-fg-secondary [direction:rtl]"
            title={target ?? undefined}
          >
            <bdi>{target ?? "…"}</bdi>
          </div>
          <div className="flex flex-wrap items-center gap-2">
            <button
              type="button"
              onClick={() => {
                setNewName("");
                setCreating(true);
              }}
              disabled={!listing}
              className="btn-ghost flex items-center gap-1 border border-border text-xs disabled:opacity-50"
            >
              <FolderPlus className="h-3.5 w-3.5" />
              {t("browse.newFolder")}
            </button>
            <label className="flex cursor-pointer items-center gap-1 text-xs text-fg-secondary">
              <input type="checkbox" checked={showHidden} onChange={toggleHidden} />
              <Eye className="h-3.5 w-3.5" />
              {t("browse.showHidden")}
            </label>
            {hostHome && (
              <label
                className="flex cursor-pointer items-center gap-1 text-xs text-fg-secondary"
                title={t("browse.hostFolderHint", { path: hostHome })}
              >
                <input
                  type="checkbox"
                  checked={onHost}
                  onChange={toggleHost}
                  data-testid="browse-host-folder"
                />
                <Server className="h-3.5 w-3.5" />
                {t("browse.hostFolder")}
              </label>
            )}
            <span className="hidden flex-1 truncate text-[10px] text-fg-muted md:block">
              {t("browse.hint")}
            </span>
            <div className="ml-auto flex items-center gap-2">
              <button
                type="button"
                onClick={onClose}
                className="btn-ghost border border-border text-xs"
              >
                {t("destructive.cancel")}
              </button>
              <button
                type="button"
                disabled={!target}
                onClick={() => target && finish(target)}
                className="btn-primary text-xs disabled:opacity-50"
              >
                {kind === "file" ? t("browse.selectFile") : t("browse.select")}
              </button>
            </div>
          </div>
        </div>
      </div>
    </div>
  );
}