/* =============================================================================
 * spreadsheet_tabs.ts  (주인 E)
 * 시트 탭 — 고르기(`ctx.showSheet`) · 더하기 · 이름 바꾸기(두 번 누르기) · 지우기 ·
 * 끌어 옮기기 · 복사. 우클릭 메뉴는 `ui_template_context_menu.ts` 재사용.
 * 이름 바꾸기 · 지우기 · 옮기기는 명령(`시트이름` · `시트지우기` · `시트옮기기` · `시트더하기`).
 * ========================================================================== */

import { createMapContextMenu, type MapContextMenuItem } from "@ui/ui_template_context_menu";
import { el, showConfirmDialog, showToast } from "@ui/ui_template_elements";
import { emptySheet } from "./spreadsheet_commands";
import { st } from "./spreadsheet_text";
import type { Sheet, Workbook } from "./spreadsheet_types";
import type { PartHandle, SpreadsheetContext } from "./spreadsheet_view_types";

import "./spreadsheet_toolbar.css";

/** 없는 `s숫자` 하나 고름. */
function nextSheetId(book: Workbook): string {
  const used = new Set(book.시트.map((s) => s.id));
  let n = 1;
  while (used.has(`s${n}`)) n++;
  return `s${n}`;
}

/** 「시트2」 · 「시트2 (2)」 처럼 안 겹치는 이름. */
function nextSheetName(book: Workbook, base: string): string {
  const used = new Set(book.시트.map((s) => s.이름));
  if (!used.has(base)) return base;
  let n = 2;
  while (used.has(`${base} (${n})`)) n++;
  return `${base} (${n})`;
}

export function mountTabs(ctx: SpreadsheetContext): PartHandle {
  const menu = createMapContextMenu("ss");
  const root = el("div", { className: "ss-tabs", children: [menu.element] });

  let dragging: string | null = null;

  function tabEl(id: string): HTMLElement | null {
    return root.querySelector<HTMLElement>(`[data-sheet-id="${CSS.escape(id)}"]`);
  }

  function render(): void {
    root.replaceChildren(menu.element, ...ctx.book.시트.map(renderTab), addButton());
  }

  function renderTab(sheet: Sheet): HTMLElement {
    const tab = el("div", {
      className: `ss-tabs__tab${sheet.id === ctx.book.활성 ? " is-active" : ""}`,
      text: sheet.이름,
      attrs: { "data-sheet-id": sheet.id },
    });
    tab.draggable = true;

    tab.addEventListener("click", () => ctx.showSheet(sheet.id));
    tab.addEventListener("dblclick", () => beginRename(sheet));
    tab.addEventListener("contextmenu", (ev) => {
      ev.preventDefault();
      const box = root.getBoundingClientRect();
      openMenu(sheet, ev.clientX - box.left, ev.clientY - box.top);
    });

    tab.addEventListener("dragstart", (ev) => {
      dragging = sheet.id;
      ev.dataTransfer?.setData("text/plain", sheet.id);
    });
    tab.addEventListener("dragover", (ev) => {
      if (!dragging || dragging === sheet.id) return;
      ev.preventDefault();
      tab.classList.add("is-dragover");
    });
    tab.addEventListener("dragleave", () => tab.classList.remove("is-dragover"));
    tab.addEventListener("drop", (ev) => {
      ev.preventDefault();
      tab.classList.remove("is-dragover");
      if (!dragging || dragging === sheet.id) return;
      const 자리 = ctx.book.시트.findIndex((s) => s.id === sheet.id);
      ctx.dispatch({ 종류: "시트옮기기", 시트: dragging, 자리 });
      dragging = null;
    });

    return tab;
  }

  function beginRename(sheet: Sheet): void {
    const tab = tabEl(sheet.id);
    if (!tab) return;
    const input = el("input", { attrs: { value: sheet.이름 } }) as HTMLInputElement;
    tab.replaceChildren(input);
    input.focus();
    input.select();
    const commit = (): void => {
      const name = input.value.trim();
      if (name && name !== sheet.이름)
        ctx.dispatch({ 종류: "시트이름", 시트: sheet.id, 이름: name });
      else render();
    };
    input.addEventListener("keydown", (ev) => {
      if (ev.key === "Enter") input.blur();
      if (ev.key === "Escape") {
        input.removeEventListener("blur", commit);
        render();
      }
    });
    input.addEventListener("blur", commit);
  }

  function openMenu(sheet: Sheet, x: number, y: number): void {
    const items: MapContextMenuItem[] = [
      [st("SheetRename"), () => beginRename(sheet)],
      [
        st("SheetDuplicate"),
        () => {
          const copy: Sheet = {
            ...structuredClone(sheet),
            id: nextSheetId(ctx.book),
            이름: nextSheetName(ctx.book, sheet.이름),
          };
          const 자리 = ctx.book.시트.findIndex((s) => s.id === sheet.id) + 1;
          ctx.dispatch({ 종류: "시트더하기", 시트: copy, 자리 });
        },
      ],
      [
        st("SheetDelete"),
        async () => {
          if (ctx.book.시트.length <= 1) {
            showToast(st("SheetDeleteLastError"), "error");
            return;
          }
          if (await showConfirmDialog(st("SheetDeleteConfirm"))) {
            ctx.dispatch({ 종류: "시트지우기", 시트: sheet.id });
          }
        },
      ],
    ];
    menu.open(x, y, items);
  }

  function addButton(): HTMLElement {
    const btn = el("button", {
      className: "ss-tabs__add",
      text: "+",
      attrs: { type: "button", title: st("SheetAdd") },
    });
    btn.addEventListener("click", () => {
      const name = nextSheetName(ctx.book, "Sheet");
      const sheet = emptySheet(nextSheetId(ctx.book), name);
      ctx.dispatch({ 종류: "시트더하기", 시트: sheet, 자리: ctx.book.시트.length });
    });
    return btn;
  }

  render();

  return {
    root,
    refresh: render,
    destroy() {
      menu.close();
      root.remove();
    },
  };
}