/* =============================================================================
 * spreadsheet_mouse.ts  (주인 D)
 * 마우스 — 칸 · 범위 끌기 · Shift 늘림 · 행열 머리 · 모서리(전체) · 식 편집 중 참조 가리키기 ·
 * 채우기 핸들 끌기(늘림 · 안으로 끌면 지움) · 두 번 누르기(칸 편집 · 핸들이면 옆 열 끝까지 아래로) ·
 * 우클릭 자리(고름 밖이면 그 칸을 고름 — 메뉴는 E).
 * 머리 끝(폭 · 높이 끌기)은 C 몫 — 여기서 건드리지 않음.
 * ========================================================================== */

import { autofitColumn } from "./spreadsheet_autofit";
import { fillCells } from "./spreadsheet_fill";
import {
  hasValue,
  inRange,
  LAST_C,
  LAST_R,
  selectAll,
  selectCell,
  selectCols,
  selectRows,
  selectSpan,
} from "./spreadsheet_selection";
import { boxStyle, slotOf, type Editor } from "./spreadsheet_editor";
import type { CellAddress, CellRange } from "./spreadsheet_types";
import type { HitResult, Selection, SpreadsheetContext } from "./spreadsheet_view_types";

/** 채우기 끌기 목표 — 늘림(fill) · 안으로 줄임(clear = 지울 부분) */
export function fillTarget(
  src: CellRange,
  p: CellAddress,
): { target: CellRange; clear: CellRange | null } {
  if (inRange(src, p.r, p.c)) {
    const up = src.r1 - p.r;
    const left = src.c1 - p.c;
    if (up === 0 && left === 0) return { target: src, clear: null };
    if (up >= left) return { target: { ...src, r1: p.r }, clear: { ...src, r0: p.r + 1 } };
    return { target: { ...src, c1: p.c }, clear: { ...src, c0: p.c + 1 } };
  }
  const down = p.r - src.r1;
  const upOut = src.r0 - p.r;
  const right = p.c - src.c1;
  const leftOut = src.c0 - p.c;
  const best = Math.max(down, upOut, right, leftOut);
  if (best === down) return { target: { ...src, r1: p.r }, clear: null };
  if (best === upOut) return { target: { ...src, r0: p.r }, clear: null };
  if (best === right) return { target: { ...src, c1: p.c }, clear: null };
  return { target: { ...src, c0: p.c }, clear: null };
}

/** 2단계 잇기 자리 — 부른 쪽(spreadsheet.ts)이 채움 */
export interface MouseHooks {
  /** 칸 끌어 고르기가 끝남(서식 붓 바르기) */
  selected?(): void;
  /** 누르지 않고 움직일 때 가리킨 것(메모 풍선) — 격자 밖이면 null */
  hover?(hit: HitResult | null): void;
}

export function attachMouse(
  ctx: SpreadsheetContext,
  ed: Editor,
  hooks: MouseHooks = {},
): () => void {
  const root = ctx.grid.root;
  const preview = document.createElement("div");
  preview.className = "ss-fill-preview";
  let stopDrag: (() => void) | null = null;

  /** 끌기 — 누른 채 움직이면 `onMove(칸)` · 떼면 `onUp` · 격자 밖이면 가장자리 칸(스크롤 따라감) */
  function drag(onMove: (p: HitResult) => void, onUp?: () => void): void {
    const move = (e: MouseEvent): void => {
      const box = root.getBoundingClientRect();
      const x = Math.min(box.right - 2, Math.max(box.left + 2, e.clientX));
      const y = Math.min(box.bottom - 2, Math.max(box.top + 2, e.clientY));
      const hit = ctx.grid.hitTest(x, y);
      if (!hit || hit.r < 0 || hit.c < 0) return;
      onMove(hit);
      if (x !== e.clientX || y !== e.clientY) ctx.grid.reveal(hit.r, hit.c);
    };
    const up = (): void => {
      stopDrag?.();
      onUp?.();
    };
    stopDrag = () => {
      window.removeEventListener("mousemove", move);
      window.removeEventListener("mouseup", up);
      stopDrag = null;
    };
    window.addEventListener("mousemove", move);
    window.addEventListener("mouseup", up);
  }

  const inSelection = (r: number, c: number): boolean =>
    ctx.selection.범위.some((g) => inRange(g, r, c));

  function showPreview(g: CellRange | null): void {
    if (!g) return preview.remove();
    const a = slotOf(ctx, g.r0, g.c0);
    const b = slotOf(ctx, Math.min(g.r1, LAST_R), Math.min(g.c1, LAST_C));
    if (preview.parentElement !== a.layer) a.layer.append(preview);
    boxStyle(preview, {
      x: a.box.x,
      y: a.box.y,
      w: b.box.x + b.box.w - a.box.x,
      h: b.box.y + b.box.h - a.box.y,
    });
  }

  function fillDrag(): void {
    const sheet = ctx.sheet();
    const src = ctx.selection.범위[0];
    let result = { target: src, clear: null as CellRange | null };
    drag(
      (p) => {
        result = fillTarget(src, p);
        showPreview(result.clear ?? result.target);
      },
      () => {
        showPreview(null);
        applyFill(sheet.id, src, result.target, result.clear);
      },
    );
  }

  function applyFill(
    sheet: string,
    src: CellRange,
    target: CellRange,
    clear: CellRange | null,
  ): void {
    const at = ctx.selection.활성;
    const sel = (g: CellRange): Selection => ({
      시트: sheet,
      범위: [g],
      활성: at,
      기준: { ...at },
    });
    if (clear) {
      ctx.dispatch({ 종류: "내용지움", 시트: sheet, 범위: [clear] });
      ctx.select(sel(target));
      return;
    }
    if (
      target.r0 === src.r0 &&
      target.r1 === src.r1 &&
      target.c0 === src.c0 &&
      target.c1 === src.c1
    )
      return;
    ctx.dispatch({ 종류: "칸", 시트: sheet, 칸: fillCells(ctx.book, sheet, src, target) });
    ctx.select(sel(target));
  }

  /** 핸들 두 번 누르기 — 왼쪽(없으면 오른쪽) 열 값이 이어진 끝까지 아래로 */
  function fillDown(): void {
    const sheet = ctx.sheet();
    const src = ctx.selection.범위[0];
    const side = [src.c0 - 1, src.c1 + 1].find(
      (c) => c >= 0 && c <= LAST_C && hasValue(sheet, src.r1 + 1, c),
    );
    if (side === undefined) return;
    let r = src.r1 + 1;
    while (r < LAST_R && hasValue(sheet, r + 1, side)) r++;
    applyFill(sheet.id, src, { ...src, r1: r }, null);
  }

  function onDown(e: MouseEvent): void {
    if (e.target === ed.ta) return; // 편집 칸 안 — 글자 자리 옮김
    const hit = ctx.grid.hitTest(e.clientX, e.clientY);
    if (!hit || hit.kind === "colEdge" || hit.kind === "rowEdge") return;
    const sheet = ctx.sheet();
    if (e.button === 2) {
      if (ed.editing() || (hit.kind === "cell" && inSelection(hit.r, hit.c))) return;
      if (hit.kind === "cell") ctx.select(selectCell(sheet, hit.r, hit.c));
      else if (hit.kind === "rowHead" && !inSelection(hit.r, ctx.selection.활성.c))
        ctx.select(selectRows(sheet, hit.r, hit.r));
      else if (hit.kind === "colHead" && !inSelection(ctx.selection.활성.r, hit.c))
        ctx.select(selectCols(sheet, hit.c, hit.c));
      return;
    }
    if (e.button !== 0) return;
    e.preventDefault(); // 초점은 편집기 · 수식 입력줄에 둠
    if (ed.editing()) {
      if (hit.kind === "cell" && ed.pointable()) {
        const at = { r: hit.r, c: hit.c };
        ed.point(selectCell(sheet, hit.r, hit.c));
        drag((p) => ed.point(selectSpan(sheet, at, { r: p.r, c: p.c })));
        return;
      }
      ed.commit();
    }
    ed.focus();
    if (ctx.readOnly && hit.kind === "fillHandle") hit.kind = "cell";
    switch (hit.kind) {
      case "fillHandle":
        return fillDrag();
      case "corner":
        return ctx.select(selectAll(sheet));
      case "rowHead": {
        const a = e.shiftKey ? ctx.selection.기준.r : hit.r;
        ctx.select(selectRows(sheet, a, hit.r, a));
        return drag((p) => ctx.select(selectRows(sheet, a, p.r, a)));
      }
      case "colHead": {
        const a = e.shiftKey ? ctx.selection.기준.c : hit.c;
        ctx.select(selectCols(sheet, a, hit.c, a));
        return drag((p) => ctx.select(selectCols(sheet, a, p.c, a)));
      }
      case "cell": {
        const first = e.shiftKey
          ? selectSpan(sheet, ctx.selection.기준, hit)
          : selectCell(sheet, hit.r, hit.c);
        ctx.select(first);
        const anchor = first.기준;
        let last = `${hit.r},${hit.c}`;
        return drag(
          (p) => {
            if (`${p.r},${p.c}` === last) return;
            last = `${p.r},${p.c}`;
            ctx.select(selectSpan(sheet, anchor, p));
          },
          () => hooks.selected?.(),
        );
      }
    }
  }

  function onDbl(e: MouseEvent): void {
    if (e.target === ed.ta || ctx.readOnly) return;
    const hit = ctx.grid.hitTest(e.clientX, e.clientY);
    if (!hit) return;
    if (hit.kind === "fillHandle") return fillDown();
    if (hit.kind === "colEdge") {
      // 고른 열 전체의 경계면 고른 열 모두(엑셀)
      const g = ctx.selection.범위[0];
      const whole = g.r0 === 0 && g.r1 === LAST_R && inRange(g, 0, hit.c);
      for (let c = whole ? g.c0 : hit.c; c <= (whole ? g.c1 : hit.c); c++) autofitColumn(ctx, c);
      return;
    }
    if (hit.kind === "cell" && !ed.editing()) ed.begin();
  }

  const onHover = (e: MouseEvent): void => {
    if (!stopDrag && !e.buttons) hooks.hover?.(ctx.grid.hitTest(e.clientX, e.clientY));
  };
  const onLeave = (): void => hooks.hover?.(null);

  root.addEventListener("mousedown", onDown);
  root.addEventListener("dblclick", onDbl);
  root.addEventListener("mousemove", onHover);
  root.addEventListener("mouseleave", onLeave);
  return () => {
    root.removeEventListener("mousemove", onHover);
    root.removeEventListener("mouseleave", onLeave);
    stopDrag?.();
    preview.remove();
    root.removeEventListener("mousedown", onDown);
    root.removeEventListener("dblclick", onDbl);
  };
}