/**
 * @file WorkspaceTree — the sidebar's Workspaces section, shaped like Claude
 * Desktop's project list: every workspace (lane) on one line in the stored drag
 * order (`laneOrderStorage.ts`), each expanding to ITS sessions
 * (`WorkspaceSessionList.tsx`) — no repo grouping, no worktree rows. Picking a
 * workspace — or `+` on its row — opens its home (`/workspace?lane=<id>`); a
 * live tab is opened from its session row. Live status comes from the shared
 * lane list (`useLanes`), live panes from `GET /api/run`, re-read whenever a
 * lane's status or session moves and handed over by the Workspace page's own
 * poll (`LIVE_RUNS_EVENT`). Owns its own Add-workspace and
 * destructive modals so the row menu works from any page. Which rows are
 * expanded lives in `projectTreePrefs.ts` (`expanded`).
 * @author Nguyễn Ngọc Trí Vĩ <vinnt@smartgift.vn>
 */

import { useCallback, useEffect, useMemo, useRef, useState, type DragEvent } from "react";
import { useTranslation } from "react-i18next";
import { useLocation, useNavigate } from "react-router-dom";
import { Plus, Search } from "lucide-react";
import { api, type CwdSuggestion, type RunHandle } from "../lib/api";
import type { Lane } from "../lib/types";
import { useLanes } from "../hooks/useLanes";
import { useAiTools } from "../hooks/useAiTools";
import {
  insertionIndex,
  moveBefore,
  moveLane,
  readLaneOrder,
  sortByStoredOrder,
  writeLaneOrder,
} from "../lib/laneOrderStorage";
import { useProjectTreePrefs, writeProjectTreePrefs } from "../lib/projectTreePrefs";
import { LANE_DRAG_TYPE, WorkspaceRow, isLaneDrag, workspaceName } from "./lanes/WorkspaceRow";
import { WorkspaceSessionList } from "./lanes/WorkspaceSessionList";
import { WorkspaceRowMenu, type WorkspaceMenuAction } from "./lanes/WorkspaceRowMenu";
import { AddLaneModal } from "./lanes/AddLaneModal";
import { DestructiveLaneModal } from "./lanes/DestructiveLaneModal";

/** The workspace (and attached run) the Workspace page shows, from its URL. */
/** The workspace, pane run and replayed session the URL names (Workspace page only). */
export function selectedFrom(pathname: string, search: string) {
  if (!pathname.startsWith("/workspace")) return { lane: null, run: null, session: null };
  const p = new URLSearchParams(search);
  const v = p.get("lane");
  return { lane: v === null ? null : Number(v), run: p.get("run"), session: p.get("session") };
}

/** The Workspace page's polled run list, handed to the sidebar as it lands. */
export const LIVE_RUNS_EVENT = "agenthub:live-runs";

export function WorkspaceTree() {
  const { t } = useTranslation("lanes");
  const navigate = useNavigate();
  const location = useLocation();
  const selected = selectedFrom(location.pathname, location.search);
  const { lanes, refresh: refreshLanes } = useLanes();
  const prefs = useProjectTreePrefs();
  const [liveRuns, setLiveRuns] = useState<RunHandle[]>([]);
  const [query, setQuery] = useState("");
  const [searching, setSearching] = useState(false);
  const [error, setError] = useState<string | null>(null);
  const [menu, setMenu] = useState<{ lane: Lane; x: number; y: number } | null>(null);
  const [renamingId, setRenamingId] = useState<number | null>(null);
  const [destructive, setDestructive] = useState<{ lane: Lane; action: "reset" | "remove" } | null>(
    null
  );
  const [addOpen, setAddOpen] = useState(false);
  const [addPrefill, setAddPrefill] = useState<{ sourceRepo?: string } | null>(null);
  const [cwdSuggestions, setCwdSuggestions] = useState<CwdSuggestion[]>([]);
  const [orderTick, setOrderTick] = useState(0);

  // A slot-0 pane starts, ends or learns its session id exactly when a lane's
  // status or session moves, so that is when the live-pane list is re-read;
  // the Workspace page also hands over every run list it polls (a tab in
  // slots 1–3 moves no lane column).
  const runKey = lanes.map((l) => `${l.id}:${l.status}:${l.session_id}:${l.run_id}`).join(",");
  useEffect(() => {
    let live = true;
    api.run
      .list()
      .then((r) => live && setLiveRuns(r.items))
      .catch(() => undefined);
    return () => {
      live = false;
    };
  }, [runKey]);
  useEffect(() => {
    const take = (e: Event) => setLiveRuns((e as CustomEvent<RunHandle[]>).detail);
    window.addEventListener(LIVE_RUNS_EVENT, take);
    return () => window.removeEventListener(LIVE_RUNS_EVENT, take);
  }, []);

  const openAdd = (sourceRepo?: string) => {
    setAddPrefill(sourceRepo ? { sourceRepo } : null);
    setAddOpen(true);
    api.run
      .cwds()
      .then((r) => setCwdSuggestions(r.items))
      .catch(() => undefined);
  };

  const select = useCallback((id: number) => navigate(`/workspace?lane=${id}`), [navigate]);
  const expanded = (id: number) => !!prefs.expanded[id] || !!query.trim();
  const setExpanded = (id: number, open: boolean) =>
    writeProjectTreePrefs({ expanded: { ...prefs.expanded, [id]: open } });

  const order = useMemo(() => readLaneOrder(), [orderTick]); // eslint-disable-line react-hooks/exhaustive-deps
  // The tool filter, offered once workspaces of two tools exist; a stored
  // tool no workspace has any more filters nothing.
  const aiTools = useAiTools();
  const tools = useMemo(() => [...new Set(lanes.map((l) => l.tool))], [lanes]);
  const toolFilter =
    tools.length > 1 && prefs.tool && tools.includes(prefs.tool) ? prefs.tool : null;
  const sorted = useMemo(
    () => sortByStoredOrder(lanes, order).filter((l) => !toolFilter || l.tool === toolFilter),
    [lanes, order, toolFilter]
  );
  const q = query.trim().toLowerCase();
  const nameHit = (l: Lane) =>
    workspaceName(l).toLowerCase().includes(q) || l.cwd.toLowerCase().includes(q);
  // A search also finds a workspace by a session's name: every workspace's
  // list stays mounted (hidden) to load and count its matches.
  const [hits, setHits] = useState<Record<number, number>>({});
  const onMatches = useCallback(
    (id: number, n: number) => setHits((h) => (h[id] === n ? h : { ...h, [id]: n })),
    []
  );
  // A cleared search unmounts the collapsed lists; their old counts must not
  // surface workspaces in the next search before its fetch answers.
  useEffect(() => {
    if (!q) setHits({});
  }, [q]);
  const visible = (l: Lane) => !q || nameHit(l) || (hits[l.id] ?? 0) > 0;

  const reorder = (move: (ids: number[]) => number[]) => {
    const ids = sorted.map((l) => l.id);
    const moved = move(ids);
    if (moved === ids) return;
    // Under a tool filter the shown ids go back into the slots they held in
    // the full order, so the hidden workspaces keep their places.
    const shownIds = new Set(ids);
    let k = 0;
    const full = sortByStoredOrder(lanes, order).map((l) =>
      shownIds.has(l.id) ? (moved[k++] ?? l.id) : l.id
    );
    writeLaneOrder(full);
    setOrderTick((n) => n + 1);
  };

  // A row only starts a drag; the whole section takes the drop, so a gap — a
  // workspace's session list, the space above or below a row — lands too.
  // `dropAt` is the insertion point in `sorted`, drawn as a line.
  const listRef = useRef<HTMLDivElement>(null);
  const [dropAt, setDropAt] = useState<number | null>(null);
  const dropIndexAt = (y: number) => {
    const rows = [...(listRef.current?.querySelectorAll<HTMLElement>("[data-lane-index]") ?? [])];
    const mids = rows.map((r) => {
      const b = r.getBoundingClientRect();
      return b.top + b.height / 2;
    });
    const row = rows[insertionIndex(mids, y)];
    return row ? Number(row.dataset.laneIndex) : sorted.length;
  };
  const dragHandlers = {
    onDragOver: (e: DragEvent) => {
      if (!isLaneDrag(e)) return;
      e.preventDefault();
      e.dataTransfer.dropEffect = "move";
      const at = dropIndexAt(e.clientY);
      setDropAt((d) => (d === at ? d : at));
    },
    onDragLeave: (e: DragEvent) => {
      if (!e.currentTarget.contains(e.relatedTarget as Node | null)) setDropAt(null);
    },
    onDragEnd: () => setDropAt(null),
    onDrop: (e: DragEvent) => {
      setDropAt(null);
      if (!isLaneDrag(e)) return;
      e.preventDefault();
      const raw = e.dataTransfer.getData(LANE_DRAG_TYPE);
      // Number("") is 0: an empty payload must not move the first row.
      const from = raw === "" ? NaN : Number(raw);
      const before = dropIndexAt(e.clientY);
      if (Number.isInteger(from)) reorder((ids) => moveBefore(ids, from, before));
    },
  };

  const rename = async (lane: Lane, title: string | null) => {
    setRenamingId(null);
    if (title === null || title === (lane.title || "")) return;
    try {
      await api.lanes.update(lane.id, { title });
      await refreshLanes();
    } catch (err) {
      setError(err instanceof Error ? err.message : String(err));
    }
  };

  const onMenuAction = (lane: Lane, action: WorkspaceMenuAction) => {
    if (action === "rename") setRenamingId(lane.id);
    else if (action === "new-here") openAdd(lane.source_repo || lane.cwd);
    else if (action === "reset" || action === "remove") setDestructive({ lane, action });
  };

  const confirmDestructive = async (body?: { expect?: unknown; force?: boolean }) => {
    if (!destructive) return;
    const { lane, action } = destructive;
    setDestructive(null);
    try {
      await api.lanes.action(lane.id, action, {
        confirm: true,
        expect: body?.expect,
        ...(body?.force === true ? { force: true } : {}),
      });
      await refreshLanes();
      if (action === "remove" && selected.lane === lane.id) navigate("/workspace");
    } catch (err) {
      setError(err instanceof Error ? err.message : String(err));
    }
  };

  // ≥24px targets (WCAG 2.5.8); each carries an aria-label.
  const headBtn = "btn-icon";
  return (
    <section
      data-testid="workspace-tree"
      // The bottom padding is a drop strip below the last workspace.
      className="mt-3 border-t border-border pb-6 pt-3"
      {...dragHandlers}
    >
      <div className="mb-1 flex items-center gap-1 px-2">
        <span className="flex-1 text-[11px] font-semibold uppercase tracking-wide text-fg-muted">
          {t("tree.title")}
        </span>
        {tools.length > 1 && (
          <select
            value={toolFilter ?? ""}
            onChange={(e) => writeProjectTreePrefs({ tool: e.target.value || null })}
            aria-label={t("tree.toolFilter")}
            title={t("tree.toolFilter")}
            className="select max-w-[6.5rem] !rounded !py-0.5 !pl-1 !pr-5 !text-[11px] text-fg-secondary"
          >
            <option value="">{t("tree.allTools")}</option>
            {tools.map((id) => (
              <option key={id} value={id}>
                {aiTools.label(id)}
              </option>
            ))}
          </select>
        )}
        <button
          type="button"
          onClick={() => {
            setSearching((v) => !v);
            setQuery("");
          }}
          aria-label={t("tree.search")}
          aria-pressed={searching}
          title={t("tree.search")}
          className={headBtn}
        >
          <Search className="h-3.5 w-3.5" />
        </button>
        <button
          type="button"
          data-testid="workspace-tree-add"
          onClick={() => openAdd()}
          aria-label={t("addLane")}
          title={t("addLane")}
          className={headBtn}
        >
          <Plus className="h-3.5 w-3.5" />
        </button>
      </div>
      {searching && (
        <input
          type="search"
          autoFocus
          value={query}
          onChange={(e) => setQuery(e.target.value)}
          onKeyDown={(e) => {
            if (e.key === "Escape") {
              setQuery("");
              setSearching(false);
            }
          }}
          placeholder={t("tree.search")}
          aria-label={t("tree.search")}
          className="mx-2 mb-1 w-[calc(100%-1rem)] rounded border border-border bg-surface-1 px-2 py-1 text-xs text-fg-primary"
        />
      )}

      <div ref={listRef} className="space-y-px px-1">
        {sorted.map((lane, i) => (
          <div key={lane.id} className="relative">
            {dropAt === i && <DropLine />}
            {visible(lane) && (
              <WorkspaceRow
                lane={lane}
                index={i}
                selected={selected.lane === lane.id && !selected.run && !selected.session}
                expanded={expanded(lane.id)}
                renaming={renamingId === lane.id}
                onSelect={() => {
                  select(lane.id);
                  if (!expanded(lane.id)) setExpanded(lane.id, true);
                }}
                onToggle={() => setExpanded(lane.id, !expanded(lane.id))}
                onNewSession={() => select(lane.id)}
                onReorder={(from, to) => reorder((ids) => moveLane(ids, from, to))}
                onMenu={(x, y) => setMenu({ lane, x, y })}
                onRenameStart={() => setRenamingId(lane.id)}
                onRenameEnd={(title) => void rename(lane, title)}
              />
            )}
            {expanded(lane.id) && (
              <WorkspaceSessionList
                lane={lane}
                liveRuns={liveRuns}
                // A workspace found by its name shows all of its sessions.
                query={q && nameHit(lane) ? "" : query}
                selectedRunId={selected.lane === lane.id ? selected.run : null}
                selectedSessionId={selected.lane === lane.id ? selected.session : null}
                onMatches={q ? (n) => onMatches(lane.id, n) : undefined}
                hidden={!visible(lane)}
              />
            )}
          </div>
        ))}
        {dropAt === sorted.length && (
          <div className="relative">
            <DropLine />
          </div>
        )}
      </div>

      {error && (
        <p role="alert" className="mx-2 mt-2 text-[11px] text-status-danger">
          {error}
        </p>
      )}

      {menu && (
        <WorkspaceRowMenu
          lane={menu.lane}
          x={menu.x}
          y={menu.y}
          onClose={() => setMenu(null)}
          onAction={(a) => onMenuAction(menu.lane, a)}
        />
      )}
      {destructive && (
        <DestructiveLaneModal
          lane={destructive.lane}
          action={destructive.action}
          open
          onClose={() => setDestructive(null)}
          onConfirm={(body) => void confirmDestructive(body)}
        />
      )}
      <AddLaneModal
        open={addOpen}
        cwdSuggestions={cwdSuggestions}
        prefill={addPrefill}
        onClose={() => {
          setAddOpen(false);
          setAddPrefill(null);
        }}
        onAdded={(lane) => {
          void refreshLanes();
          select(lane.id);
        }}
      />
    </section>
  );
}

/** Where a dragged workspace would land: a line on its parent's top edge. */
function DropLine() {
  return (
    <div
      aria-hidden
      data-testid="workspace-drop-line"
      className="pointer-events-none absolute inset-x-1 -top-px z-10 h-0.5 rounded-full bg-accent-solid"
    />
  );
}