/* =============================================================================
 * D03_PlanAnalysis_UI_DrawPanel.ts
 * D03 좌측 「그리기」 칸 몸(PLAN 599-1 · 599-4 · 요구 463-10 · 22) — [긋기] · 연도 구역 마커 · 긋기 방식 칸.
 *
 *   방식 칸 `createDrawKindFields` = 마디 고름 2 × 2(자유 · 길이 고정 · 기울기 고정 · 길이·기울기 고정) +
 *     길이 · 기울기 두 열(기울기 아래 ≈ °) — 그리기 칸 · 노드 판(598-4)이 같은 부품을 씀.
 *   연도 구역 마커 = 끌어 선 위에 놓기(`YEAR_MARK_DRAG` · 받음 = `D03_PlanAnalysis_UI_Edit` drop).
 *   설명 글 없음(요구 463-6) — 칸 오류 · ≈ ° 값만.
 * ========================================================================== */

import type { UiSize } from "@ui/ui_template_button";
import { createButton } from "@ui/ui_template_elements";
import { createInputField } from "@ui/ui_template_input";
import { createSegment } from "@ui/ui_template_segment";
import { createText } from "@ui/ui_template_text";
import { fmt, slopeDeg } from "./D03_PlanAnalysis_UI_DrawPaint";
import { YEAR_MARK_DRAG } from "./D03_PlanAnalysis_UI_Map";

/** 제약 칸 처음 값 — 길이 = 측점 간격(지식DB 설계제원_총괄) · 기울기 = 간선 20 km/h 일반지형 상한(종단선형). */
export const DRAW_DEFAULT_LENGTH_M = 20;
export const DRAW_DEFAULT_SLOPE_PCT = 9;

export type DrawConstraint = "free" | "length" | "slope" | "both";

export interface DrawKindValue {
  kind: DrawConstraint;
  lengthM: number;
  slopePct: number;
}

export const DRAW_KIND_LABELS: Record<DrawConstraint, string> = {
  free: "자유",
  length: "길이 고정",
  slope: "기울기 고정",
  both: "길이·기울기 고정",
};

export interface DrawKindFields {
  root: HTMLElement;
  get: () => DrawKindValue;
  /** 값을 바꿈(onChange 는 안 부름). */
  set: (value: Partial<DrawKindValue>) => void;
  setDisabled: (disabled: boolean) => void;
}

/** 긋기 방식 칸 — 고름 · 길이 · 기울기가 바뀔 때마다 `onChange(지금 값)`(빈 · 틀린 수는 칸 오류만). */
export function createDrawKindFields(opts: {
  value: DrawKindValue;
  onChange: (value: DrawKindValue) => void;
  size?: UiSize;
}): DrawKindFields {
  const size = opts.size ?? 24;
  let value = { ...opts.value };
  let disabled = false;
  const changed = (): void => opts.onChange({ ...value });
  const segment = createSegment({
    options: (Object.keys(DRAW_KIND_LABELS) as DrawConstraint[]).map((kind) => ({
      value: kind,
      label: DRAW_KIND_LABELS[kind],
    })),
    value: value.kind,
    size,
    columns: 2,
    ariaLabel: "긋기 방식",
    onChange: (next) => {
      value.kind = next as DrawConstraint;
      fieldsState();
      changed();
    },
  });
  segment.root.dataset.role = "draw-constraint";
  const lengthField = createInputField({
    label: "길이",
    type: "number",
    value: String(value.lengthM),
    min: 1,
    unit: "m",
    size,
    onInput: (text) => {
      const next = Number(text);
      lengthField.setError(next > 0 ? undefined : "0 보다 큰 수");
      if (!(next > 0)) return;
      value.lengthM = next;
      changed();
    },
  });
  lengthField.input.dataset.role = "draw-length";
  const slopeField = createInputField({
    label: "기울기",
    type: "number",
    value: String(value.slopePct),
    unit: "%",
    size,
    onInput: (text) => {
      const next = Number(text);
      const ok = text.trim() !== "" && Number.isFinite(next);
      slopeField.setError(ok ? undefined : "숫자");
      if (!ok) return;
      value.slopePct = next;
      degText();
      changed();
    },
  });
  slopeField.input.dataset.role = "draw-slope";
  const slopeDegText = createText("", "muted");
  slopeDegText.dataset.role = "draw-slope-deg";
  const degText = (): void => {
    slopeDegText.textContent = `≈ ${fmt(slopeDeg(Math.abs(value.slopePct)))}°`;
  };
  const slopeColumn = document.createElement("div");
  slopeColumn.append(slopeField.root, slopeDegText);
  const fields = document.createElement("div");
  fields.className = "d03-plan__draw-fields";
  fields.append(lengthField.root, slopeColumn);
  const root = document.createElement("div");
  root.className = "d03-plan__draw-kind";
  root.append(segment.root, fields);

  function fieldsState(): void {
    for (const button of segment.root.querySelectorAll("button")) button.disabled = disabled;
    lengthField.input.disabled = disabled || value.kind === "free" || value.kind === "slope";
    slopeField.input.disabled = disabled || value.kind === "free" || value.kind === "length";
  }
  degText();
  fieldsState();

  return {
    root,
    get: () => ({ ...value }),
    set(next) {
      value = { ...value, ...next };
      segment.set(value.kind);
      lengthField.input.value = String(value.lengthM);
      slopeField.input.value = String(value.slopePct);
      lengthField.setError(undefined);
      slopeField.setError(undefined);
      degText();
      fieldsState();
    },
    setDisabled(next) {
      disabled = next;
      fieldsState();
    },
  };
}

export interface DrawPanel {
  root: HTMLElement;
  /** 단추 글 · 막힘 — 긋는 중 · 고칠 수 있음 · 마커 놓을 선 있음. */
  state: (state: { drawing: boolean; editable: boolean; canMark: boolean }) => void;
}

/** 좌측 「그리기」 칸 — [긋기] · 연도 구역 마커(끌기) · 방식 칸. */
export function createDrawPanel(opts: { kind: DrawKindFields; onDraw: () => void }): DrawPanel {
  const drawButton = createButton({
    label: "긋기",
    variant: "filled",
    size: 28,
    onClick: opts.onDraw,
  });
  const markButton = createButton({
    label: "연도 구역 마커",
    variant: "ghost",
    size: 28,
    iconStart: "flag",
  });
  markButton.title = "선 위로 끌어 놓으면 구역을 나눕니다";
  markButton.dataset.role = "draw-year-mark";
  markButton.draggable = true;
  markButton.addEventListener("dragstart", (event) => {
    event.dataTransfer?.setData(YEAR_MARK_DRAG, "1");
    if (event.dataTransfer) event.dataTransfer.effectAllowed = "copy";
  });
  const row = document.createElement("div");
  row.className = "d03-plan__row";
  row.append(drawButton, markButton);
  const root = document.createElement("div");
  root.className = "d03-plan__draw";
  root.append(row, opts.kind.root);
  return {
    root,
    state({ drawing, editable, canMark }) {
      drawButton.querySelector(".ui-btn__label")!.textContent = drawing ? "긋기 끝" : "긋기";
      drawButton.disabled = !editable;
      drawButton.setAttribute("aria-pressed", String(drawing));
      markButton.disabled = !editable || drawing || !canMark;
      root.dataset.mode = drawing ? "draw" : "idle";
    },
  };
}