"use client";

import type { FocusEvent, KeyboardEvent, PropsWithChildren } from "react";
import { useId, useRef, useState } from "react";
import { Box } from "@mantine/core";
import combineClasses from "clsx";

import { useCurrentLayout } from "@homarr/boards/context";
import { useEditMode } from "@homarr/boards/edit-mode";
import { useI18n } from "@homarr/translation/client";

import type { ContainerSectionItem, SectionItem } from "~/app/[locale]/boards/_types";
import {
  getEditableGridCellAttributes,
  getLogicalItemStyle,
  getReadonlyGridItemAttributes,
} from "~/components/board/layout";
import type { GridPlacement } from "~/components/board/layout";
import { useSectionContext } from "../section-context";
import { beginGridTransaction, commitGridTransaction, previewGridMove, previewGridResize } from "./dnd";
import type { GridTransaction } from "./dnd";
import { useGridEditorRuntimeStatus } from "./grid-editor-runtime";
import type { SectionGridPlacement } from "./use-grid-layout-actions";
import { useGridLayoutActions } from "./use-grid-layout-actions";
import classes from "./section-grid.module.css";

interface FixedGridItemProps {
  item: ContainerSectionItem | SectionItem;
  minWidth?: number;
  minHeight?: number;
}

/**
 * Static SSR geometry in view mode and the stable content/keyboard handle in
 * edit mode. The focused tile owns grid-based keyboard movement while dnd-kit
 * handles pointer and touch input on the outer editor shell.
 */
export const FixedGridItem = ({
  item,
  minWidth = 1,
  minHeight = 1,
  children,
}: PropsWithChildren<FixedGridItemProps>) => {
  const [isEditMode] = useEditMode();
  const runtimeStatus = useGridEditorRuntimeStatus();
  const currentLayoutId = useCurrentLayout();
  const t = useI18n();
  const { section, items, innerSections, columnCount, maxRowCount, announce } = useSectionContext();
  const { commitSectionGrid } = useGridLayoutActions();
  const [isKeyboardEditing, setIsKeyboardEditing] = useState(false);
  const instructionsId = useId();
  const isEditorActive = isEditMode && runtimeStatus === "ready";
  const placement = toPlacement(item);
  const renderedPlacements = [...items, ...innerSections].map(toPlacement);
  const keyboardGridRef = useRef<{
    source: readonly SectionGridPlacement[];
    current: readonly SectionGridPlacement[];
  }>({
    source: renderedPlacements,
    current: renderedPlacements,
  });
  const displayName =
    item.type === "item"
      ? item.advancedOptions.title?.trim() || t(`widget.${item.kind}.name`)
      : item.options.title.trim() || t("section.container.untitled");
  const accessibleLabel = t("item.moveResize.entryLabel", {
    name: displayName,
    column: String(placement.x + 1),
    row: String(placement.y + 1),
  });
  const semantics = isEditorActive
    ? getEditableGridCellAttributes({ label: accessibleLabel, placement })
    : getReadonlyGridItemAttributes(placement);

  const setKeyboardEditing = (next: boolean) => {
    setIsKeyboardEditing(next);
    announce(
      `${accessibleLabel}: ${t(next ? "item.moveResize.keyboard.started" : "item.moveResize.keyboard.stopped")}`,
    );
  };

  const handleKeyboard = (event: KeyboardEvent<HTMLDivElement>) => {
    if (event.target !== event.currentTarget || !isEditorActive || event.altKey || event.ctrlKey || event.metaKey) {
      return;
    }
    if (event.key === "Enter" || event.key === " ") {
      event.preventDefault();
      setKeyboardEditing(!isKeyboardEditing);
      return;
    }
    if (event.key === "Escape" && isKeyboardEditing) {
      event.preventDefault();
      setKeyboardEditing(false);
      return;
    }
    if (!isKeyboardEditing || !isArrowKey(event.key)) return;

    event.preventDefault();
    if (document.body.hasAttribute("data-board-grid-interacting")) {
      setKeyboardEditing(false);
      return;
    }
    if (!arePlacementListsEqual(keyboardGridRef.current.source, renderedPlacements)) {
      keyboardGridRef.current = {
        source: renderedPlacements,
        current: renderedPlacements,
      };
    }
    const placements = keyboardGridRef.current.current;
    const current = placements.find((candidate) => candidate.id === item.id);
    if (!current) return;

    let transaction: GridTransaction<SectionGridPlacement>;
    try {
      transaction = beginGridTransaction(
        {
          grids: [
            {
              id: section.id,
              columnCount,
              maxRowCount,
              placements,
            },
          ],
        },
        { activeId: current.id, sourceGridId: section.id },
      );
    } catch {
      keyboardGridRef.current = {
        source: renderedPlacements,
        current: renderedPlacements,
      };
      setKeyboardEditing(false);
      return;
    }
    const delta = getKeyboardDelta(event.key);
    const result = event.shiftKey
      ? previewGridResize(transaction, {
          direction: "se",
          deltaColumns: delta.x,
          deltaRows: delta.y,
          minWidth,
          minHeight,
        })
      : previewGridMove(transaction, {
          targetGridId: section.id,
          x: current.x + delta.x,
          y: current.y + delta.y,
        });
    const next = result.transaction.preview.grids[0]?.placements.find((candidate) => candidate.id === item.id);
    if (!result.accepted || !next || arePlacementsEqual(current, next)) {
      announce(`${accessibleLabel}: ${t("item.moveResize.keyboard.boundary")}`);
      return;
    }

    const committed = commitGridTransaction(result.transaction).grids[0];
    if (!committed) return;
    keyboardGridRef.current = {
      ...keyboardGridRef.current,
      current: committed.placements,
    };
    commitSectionGrid({ layoutId: currentLayoutId, sectionId: section.id, placements: committed.placements });
    announce(
      `${displayName}: ${t("item.moveResize.field.xOffset.label")} ${next.x + 1}, ${t(
        "item.moveResize.field.yOffset.label",
      )} ${next.y + 1}, ${t("item.moveResize.field.width.label")} ${next.w}, ${t(
        "item.moveResize.field.height.label",
      )} ${next.h}`,
    );
  };

  const handleBlur = (event: FocusEvent<HTMLDivElement>) => {
    if (isKeyboardEditing && event.target === event.currentTarget) {
      setKeyboardEditing(false);
    }
  };

  return (
    <Box
      {...semantics}
      className={combineClasses(isEditorActive ? classes.editorEntry : classes.staticItem)}
      style={isEditorActive ? { position: "relative", width: "100%", height: "100%" } : getLogicalItemStyle(placement)}
      data-grid-item-id={isEditorActive ? undefined : item.id}
      data-grid-item-type={isEditorActive ? undefined : item.type}
      data-editor-grid-entry={isEditorActive ? "true" : undefined}
      data-type={item.type}
      data-kind={item.kind}
      data-keyboard-editing={isEditorActive ? String(isKeyboardEditing) : undefined}
      aria-describedby={isEditorActive ? instructionsId : undefined}
      aria-keyshortcuts={
        isEditorActive
          ? "Enter Space Escape ArrowLeft ArrowRight ArrowUp ArrowDown Shift+ArrowLeft Shift+ArrowRight Shift+ArrowUp Shift+ArrowDown"
          : undefined
      }
      onBlur={isEditorActive ? handleBlur : undefined}
      onKeyDown={isEditorActive ? handleKeyboard : undefined}
    >
      {children}
      {isEditorActive && (
        <span id={instructionsId} className={classes.liveRegion}>
          {t("item.moveResize.keyboard.instructions")}
        </span>
      )}
    </Box>
  );
};

const toPlacement = (item: ContainerSectionItem | SectionItem): SectionGridPlacement => ({
  id: item.id,
  type: item.type,
  x: item.xOffset,
  y: item.yOffset,
  w: item.width,
  h: item.height,
});

const isArrowKey = (key: string): key is "ArrowLeft" | "ArrowRight" | "ArrowUp" | "ArrowDown" =>
  key === "ArrowLeft" || key === "ArrowRight" || key === "ArrowUp" || key === "ArrowDown";

const getKeyboardDelta = (key: "ArrowLeft" | "ArrowRight" | "ArrowUp" | "ArrowDown") => ({
  x: key === "ArrowLeft" ? -1 : key === "ArrowRight" ? 1 : 0,
  y: key === "ArrowUp" ? -1 : key === "ArrowDown" ? 1 : 0,
});

const arePlacementsEqual = (first: GridPlacement, second: GridPlacement) =>
  first.x === second.x && first.y === second.y && first.w === second.w && first.h === second.h;

const arePlacementListsEqual = (first: readonly GridPlacement[], second: readonly GridPlacement[]) =>
  first.length === second.length &&
  first.every((placement, index) => {
    const candidate = second[index];
    return candidate?.id === placement.id && arePlacementsEqual(placement, candidate);
  });