"use client";

import { memo, useState, useCallback, useEffect, useRef, useMemo } from "react";
import { PanelRoot, PanelBody, PanelHeaderBarSplit } from "./panel-primitives";
import { TaskPlanRevisions } from "./task-plan-revisions";
import dynamic from "@/lib/routing/client-dynamic";
import { IconLoader2, IconFileText, IconRobot, IconMessage, IconClick } from "@tabler/icons-react";
import { cn } from "@/lib/utils";
import { useTaskPlan } from "@/hooks/domains/session/use-task-plan";
import { useAppStore } from "@/components/state-provider";
import { PlanSelectionPopover } from "./plan-selection-popover";
import { usePlanComments } from "@/hooks/domains/comments/use-plan-comments";
import { useRunComment } from "@/hooks/domains/comments/use-run-comment";
import type { PlanComment } from "@/lib/state/slices/comments";
import type {
  TextSelection,
  CommentForEditor,
} from "@/components/editors/tiptap/tiptap-plan-editor";
import type { TaskPlanRevision } from "@/lib/types/http";
import type { Editor } from "@tiptap/core";
import { PanelSearchBar } from "@/components/search/panel-search-bar";
import { usePlanFindShortcut } from "./use-plan-find-shortcut";

// Dynamic import to avoid SSR issues with TipTap
const PlanEditor = dynamic(
  () =>
    import("@/components/editors/tiptap/tiptap-plan-editor").then((mod) => mod.TipTapPlanEditor),
  {
    ssr: false,
    loading: () => (
      <div className="flex h-full items-center justify-center text-muted-foreground text-sm">
        Loading editor...
      </div>
    ),
  },
);

/** Debounce delay for auto-saving plan content (ms) */
const AUTO_SAVE_DELAY = 1500;

type TaskPlanPanelProps = {
  taskId: string | null;
  visible?: boolean;
};

function useTaskPlanPanelState(taskId: string | null, visible: boolean) {
  const {
    plan,
    isLoading,
    isSaving,
    savePlan,
    revisions,
    isLoadingRevisions,
    loadRevisions,
    loadRevisionContent,
    revertTo,
    previewRevisionId,
    setPreviewRevision,
    comparePair,
    toggleCompareSelection,
    clearComparePair,
  } = useTaskPlan(taskId, { visible });
  const activeSessionId = useAppStore((state) => state.tasks.activeSessionId);
  const activeSession = useAppStore((state) =>
    activeSessionId ? (state.taskSessions.items[activeSessionId] ?? null) : null,
  );
  const sessionState = activeSession?.state;
  const isAgentBusy = sessionState === "STARTING" || sessionState === "RUNNING";

  const editorWrapperRef = useRef<HTMLDivElement>(null);
  const editorInstanceRef = useRef<Editor | null>(null);
  const [editorInstance, setEditorInstance] = useState<Editor | null>(null);
  const {
    draftContent,
    setDraftContent,
    editorKey,
    isEditorFocused,
    handleEmptyStateClick,
    hasUnsavedChanges,
  } = usePlanDraft(plan, isSaving, savePlan, editorWrapperRef);
  const commentState = usePlanComments(activeSessionId);
  const selectionState = usePlanSelection(activeSessionId, commentState);

  const handleEditorReady = useCallback((editor: Editor) => {
    editorInstanceRef.current = editor;
    setEditorInstance(editor);
  }, []);

  const handleCommentDeleted = useCallback(
    (ids: string[]) => {
      for (const id of ids) {
        commentState.handleDeleteComment(id);
      }
    },
    [commentState],
  );

  const commentHighlights: CommentForEditor[] = useMemo(
    () =>
      commentState.comments.map((c) => ({
        id: c.id,
        selectedText: c.selectedText,
        from: c.from,
        to: c.to,
      })),
    [commentState.comments],
  );

  const isAgentCreatingPlan = isAgentBusy && !plan && draftContent.trim() === "";

  return {
    plan,
    isLoading,
    isSaving,
    savePlan,
    activeSessionId,
    draftContent,
    setDraftContent,
    editorKey,
    isEditorFocused,
    handleEmptyStateClick,
    hasUnsavedChanges,
    commentState,
    selectionState,
    handleEditorReady,
    handleCommentDeleted,
    commentHighlights,
    isAgentBusy,
    isAgentCreatingPlan,
    editorWrapperRef,
    editorInstanceRef,
    editorInstance,
    revisions,
    isLoadingRevisions,
    loadRevisions,
    loadRevisionContent,
    revertTo,
    previewRevisionId,
    setPreviewRevision,
    comparePair,
    toggleCompareSelection,
    clearComparePair,
  };
}

export const TaskPlanPanel = memo(function TaskPlanPanel({
  taskId,
  visible = true,
}: TaskPlanPanelProps) {
  const state = useTaskPlanPanelState(taskId, visible);
  // Ctrl+S to save immediately
  useSaveShortcut(
    state.hasUnsavedChanges,
    state.isSaving,
    state.savePlan,
    state.draftContent,
    state.plan?.title,
  );

  if (state.isLoading) {
    return (
      <div className="flex h-full items-center justify-center text-muted-foreground">
        <IconLoader2 className="h-5 w-5 animate-spin mr-2" />
        <span className="text-sm">Loading plan...</span>
      </div>
    );
  }

  if (!taskId) {
    return (
      <div className="flex h-full items-center justify-center text-muted-foreground">
        <span className="text-sm">No task selected</span>
      </div>
    );
  }

  return <PlanPanelContent taskId={taskId} state={state} />;
});

function PlanPanelContent({
  taskId,
  state,
}: {
  taskId: string;
  state: ReturnType<typeof useTaskPlanPanelState>;
}) {
  const { editorWrapperRef, editorInstanceRef, editorInstance, selectionState } = state;
  const { textSelection, setTextSelection } = selectionState;
  // Ctrl+F in-document find (registers a keydown listener on the editor wrapper)
  const planSearch = usePlanFindShortcut(editorWrapperRef, editorInstance);
  return (
    <PanelRoot data-testid="plan-panel">
      <PlanPanelHeader
        taskId={taskId}
        revisions={state.revisions}
        isLoadingRevisions={state.isLoadingRevisions}
        isSaving={state.isSaving}
        onOpenRevisions={state.loadRevisions}
        onRevert={state.revertTo}
        loadRevisionContent={state.loadRevisionContent}
        previewRevisionId={state.previewRevisionId}
        setPreviewRevision={state.setPreviewRevision}
        comparePair={state.comparePair}
        toggleCompareSelection={state.toggleCompareSelection}
        clearComparePair={state.clearComparePair}
      />
      <PanelBody
        padding={false}
        scroll={false}
        className={cn(
          "relative transition-colors cursor-text",
          state.isAgentBusy && "bg-background",
        )}
        ref={editorWrapperRef}
        onClick={state.handleEmptyStateClick}
        data-panel-kind="plan"
      >
        <PlanEditor
          key={`${taskId}-${state.editorKey}`}
          value={state.draftContent}
          onChange={state.setDraftContent}
          placeholder="Start typing your plan..."
          onSelectionChange={state.activeSessionId ? setTextSelection : undefined}
          comments={state.commentHighlights}
          onCommentClick={selectionState.handleCommentHighlightClick}
          onCommentDeleted={state.handleCommentDeleted}
          onEditorReady={state.handleEditorReady}
        />
        <PlanEmptyState
          isLoading={state.isLoading}
          draftContent={state.draftContent}
          isEditorFocused={state.isEditorFocused}
          isAgentCreatingPlan={state.isAgentCreatingPlan}
          onClick={state.handleEmptyStateClick}
        />
        {planSearch.isOpen && (
          <PanelSearchBar
            value={planSearch.query}
            onChange={planSearch.setQuery}
            onNext={planSearch.findNext}
            onPrev={planSearch.findPrev}
            onClose={planSearch.close}
            matchInfo={planSearch.matchInfo}
          />
        )}
      </PanelBody>

      <PlanSelectionPopoverWrapper
        textSelection={textSelection}
        activeSessionId={state.activeSessionId}
        taskId={taskId}
        commentState={state.commentState}
        editorRef={editorInstanceRef}
        onClose={selectionState.handleSelectionClose}
      />
    </PanelRoot>
  );
}

function removeCommentMark(editor: Editor | null, commentId: string) {
  if (!editor) return;
  const markType = editor.state.schema.marks.commentMark;
  if (!markType) return;
  const { tr } = editor.state;
  tr.removeMark(0, editor.state.doc.content.size, markType.create({ commentId }));
  editor.view.dispatch(tr);
}

/** Conditional selection popover for adding/editing comments */
function PlanSelectionPopoverWrapper({
  textSelection,
  activeSessionId,
  taskId,
  commentState,
  editorRef,
  onClose,
}: {
  textSelection: TextSelection | null;
  activeSessionId: string | null | undefined;
  taskId: string | null;
  commentState: ReturnType<typeof usePlanComments>;
  editorRef: React.RefObject<Editor | null>;
  onClose: () => void;
}) {
  const { runComment } = useRunComment({
    sessionId: activeSessionId ?? null,
    taskId,
  });

  const addCommentAndApplyMark = useCallback(
    (comment: string, selectedText: string) => {
      const from = textSelection?.from;
      const to = textSelection?.to;
      const id = commentState.handleAddComment(comment, selectedText, from, to);
      const editor = editorRef.current;
      if (id && editor && from != null && to != null) {
        editor
          .chain()
          .setTextSelection({ from, to })
          .setMark("commentMark", { commentId: id })
          .run();
      }
      return id;
    },
    [commentState, textSelection, editorRef],
  );

  const handleAdd = useCallback(
    (comment: string, selectedText: string) => {
      addCommentAndApplyMark(comment, selectedText);
    },
    [addCommentAndApplyMark],
  );

  const handleAddAndRun = useCallback(
    (comment: string, selectedText: string) => {
      const id = addCommentAndApplyMark(comment, selectedText);
      if (!id || !activeSessionId) return;
      const newComment: PlanComment = {
        id,
        sessionId: activeSessionId,
        source: "plan",
        text: comment,
        selectedText,
        from: textSelection?.from,
        to: textSelection?.to,
        createdAt: new Date().toISOString(),
        status: "pending",
      };
      runComment(newComment).catch((err) => console.error("Failed to run plan comment:", err));
    },
    [addCommentAndApplyMark, activeSessionId, runComment, textSelection],
  );

  if (!textSelection || !activeSessionId) return null;
  const editingComment = commentState.editingCommentId
    ? commentState.comments.find((c) => c.id === commentState.editingCommentId)?.text
    : undefined;
  const onDelete = commentState.editingCommentId
    ? () => {
        const id = commentState.editingCommentId!;
        removeCommentMark(editorRef.current, id);
        commentState.handleDeleteComment(id);
      }
    : undefined;
  return (
    <PlanSelectionPopover
      selectedText={textSelection.text}
      position={textSelection.position}
      onAdd={handleAdd}
      onAddAndRun={editingComment ? undefined : handleAddAndRun}
      onClose={onClose}
      editingComment={editingComment}
      onDelete={onDelete}
    />
  );
}

/** Draft content, editor key, focus tracking, and auto-save */
function usePlanDraft(
  plan: { content?: string; title?: string } | null | undefined,
  isSaving: boolean,
  savePlan: (content: string, title?: string) => Promise<unknown>,
  editorWrapperRef: React.RefObject<HTMLDivElement | null>,
) {
  const [draftContent, setDraftContent] = useState(plan?.content ?? "");
  const draftContentRef = useRef(draftContent);
  const [editorKey, setEditorKey] = useState(0);
  const lastPlanContentRef = useRef<string | undefined>(undefined);
  const isExternalUpdateRef = useRef(false);
  const [isEditorFocused, setIsEditorFocused] = useState(false);
  const autoSaveTimerRef = useRef<ReturnType<typeof setTimeout> | null>(null);

  const handleEmptyStateClick = useCallback(() => {
    const el = editorWrapperRef.current?.querySelector(".ProseMirror");
    if (el) (el as HTMLElement).focus();
  }, [editorWrapperRef]);

  // Track focus state
  useEffect(() => {
    const checkFocus = () => {
      const wrapper = editorWrapperRef.current;
      if (!wrapper) return;
      setIsEditorFocused(wrapper.contains(document.activeElement));
    };
    document.addEventListener("focusin", checkFocus);
    document.addEventListener("focusout", checkFocus);
    checkFocus();
    return () => {
      document.removeEventListener("focusin", checkFocus);
      document.removeEventListener("focusout", checkFocus);
    };
  }, [editorWrapperRef]);

  useEffect(() => {
    draftContentRef.current = draftContent;
  }, [draftContent]);

  // Sync from external plan updates
  useEffect(() => {
    const prevContent = lastPlanContentRef.current;
    const newContent = plan?.content;
    lastPlanContentRef.current = newContent;
    if (newContent !== prevContent) {
      const resolved = newContent ?? "";
      if (resolved === draftContentRef.current) return;
      isExternalUpdateRef.current = true;
      // eslint-disable-next-line react-hooks/set-state-in-effect -- syncing external plan data to local editor state
      setDraftContent(resolved);
      setEditorKey((k) => k + 1);
    }
  }, [plan?.content]);

  // Auto-save with debounce
  useEffect(() => {
    if (isExternalUpdateRef.current) {
      isExternalUpdateRef.current = false;
      return;
    }
    const hasChanges = plan ? draftContent !== plan.content : draftContent.length > 0;
    if (!hasChanges || isSaving) return;
    if (autoSaveTimerRef.current) clearTimeout(autoSaveTimerRef.current);
    autoSaveTimerRef.current = setTimeout(() => {
      autoSaveTimerRef.current = null;
      savePlan(draftContent, plan?.title);
    }, AUTO_SAVE_DELAY);
    return () => {
      if (autoSaveTimerRef.current) {
        clearTimeout(autoSaveTimerRef.current);
        autoSaveTimerRef.current = null;
      }
    };
  }, [draftContent, plan, isSaving, savePlan]);

  const hasUnsavedChanges = plan ? draftContent !== plan.content : draftContent.length > 0;
  return {
    draftContent,
    setDraftContent,
    editorKey,
    isEditorFocused,
    handleEmptyStateClick,
    hasUnsavedChanges,
  };
}

/** Text selection state for comment popover */
function usePlanSelection(
  activeSessionId: string | null | undefined,
  commentState: ReturnType<typeof usePlanComments>,
) {
  const [textSelection, setTextSelection] = useState<TextSelection | null>(null);

  const handleCommentHighlightClick = useCallback(
    (id: string, position: { x: number; y: number }) => {
      const comment = commentState.comments.find((c) => c.id === id);
      if (comment) {
        commentState.setEditingCommentId(id);
        setTextSelection({
          text: comment.selectedText,
          from: comment.from,
          to: comment.to,
          position,
        });
      }
    },
    [commentState],
  );

  const handleSelectionClose = useCallback(() => {
    setTextSelection(null);
    commentState.setEditingCommentId(null);
    window.getSelection()?.removeAllRanges();
  }, [commentState]);

  return { textSelection, setTextSelection, handleCommentHighlightClick, handleSelectionClose };
}

/** Ctrl+S save shortcut */
function useSaveShortcut(
  hasUnsavedChanges: boolean,
  isSaving: boolean,
  savePlan: (content: string, title?: string) => Promise<unknown>,
  draftContent: string,
  title?: string,
) {
  useEffect(() => {
    const handleKeyDown = (e: KeyboardEvent) => {
      if ((e.ctrlKey || e.metaKey) && e.key === "s") {
        e.preventDefault();
        if (hasUnsavedChanges && !isSaving) savePlan(draftContent, title);
      }
    };
    window.addEventListener("keydown", handleKeyDown);
    return () => window.removeEventListener("keydown", handleKeyDown);
  }, [hasUnsavedChanges, isSaving, savePlan, draftContent, title]);
}

/** Rich empty state - shows when no content and editor not focused */
function PlanEmptyState({
  isLoading,
  draftContent,
  isEditorFocused,
  isAgentCreatingPlan,
  onClick,
}: {
  isLoading: boolean;
  draftContent: string;
  isEditorFocused: boolean;
  isAgentCreatingPlan: boolean;
  onClick: () => void;
}) {
  if (isLoading || draftContent.trim() !== "" || isEditorFocused || isAgentCreatingPlan)
    return null;
  return (
    <div
      className="absolute inset-0 flex items-center justify-center pointer-events-none"
      onClick={onClick}
    >
      <div className="flex flex-col items-center gap-6 max-w-md px-6">
        <div className="flex items-center justify-center w-12 h-12 rounded-xl bg-muted/50">
          <IconFileText className="h-6 w-6 text-muted-foreground" />
        </div>
        <div className="text-center">
          <h3 className="text-sm font-medium text-foreground mb-1">Plan your implementation</h3>
          <p className="text-xs text-muted-foreground">
            A shared document for you and the agent to collaborate on the approach
          </p>
        </div>
        <div className="flex flex-col gap-3 w-full">
          <div className="flex items-start gap-3">
            <IconRobot className="h-4 w-4 text-muted-foreground mt-0.5 shrink-0" />
            <p className="text-xs text-muted-foreground">
              The agent can write and update the plan as it works
            </p>
          </div>
          <div className="flex items-start gap-3">
            <IconMessage className="h-4 w-4 text-muted-foreground mt-0.5 shrink-0" />
            <p className="text-xs text-muted-foreground">
              Select text and press{" "}
              <kbd className="px-1.5 py-0.5 rounded bg-muted text-muted-foreground font-mono text-[10px]">
                &#8984;&#8679;C
              </kbd>{" "}
              to comment
            </p>
          </div>
        </div>
        <div className="flex items-center gap-2 text-xs text-muted-foreground/70">
          <IconClick className="h-3.5 w-3.5" />
          <span>Click anywhere to start writing</span>
        </div>
      </div>
    </div>
  );
}

type PlanPanelHeaderProps = {
  taskId: string;
  revisions: TaskPlanRevision[];
  isLoadingRevisions: boolean;
  isSaving: boolean;
  onOpenRevisions: () => void;
  onRevert: (id: string) => Promise<TaskPlanRevision | null>;
  loadRevisionContent: (revisionId: string) => Promise<string>;
  previewRevisionId: string | null;
  setPreviewRevision: (revisionId: string | null) => void;
  comparePair: [string | null, string | null];
  toggleCompareSelection: (revisionId: string) => void;
  clearComparePair: () => void;
};

// Header bar lives only to host the rewind button. The plan's title (default
// "Plan") is already shown by the dockview/mobile tab above the panel, so we
// don't repeat it here.
function PlanPanelHeader({
  taskId,
  revisions,
  isLoadingRevisions,
  isSaving,
  onOpenRevisions,
  onRevert,
  loadRevisionContent,
  previewRevisionId,
  setPreviewRevision,
  comparePair,
  toggleCompareSelection,
  clearComparePair,
}: PlanPanelHeaderProps) {
  return (
    <PanelHeaderBarSplit
      left={null}
      right={
        <TaskPlanRevisions
          taskId={taskId}
          revisions={revisions}
          isLoading={isLoadingRevisions}
          isSaving={isSaving}
          onOpen={onOpenRevisions}
          onRevert={onRevert}
          loadRevisionContent={loadRevisionContent}
          previewRevisionId={previewRevisionId}
          setPreviewRevision={setPreviewRevision}
          comparePair={comparePair}
          toggleCompareSelection={toggleCompareSelection}
          clearComparePair={clearComparePair}
        />
      }
    />
  );
}