/* =============================================================================
 * D03_PlanAnalysis_UI_SlopeBands.ts
 * D03 급경사 범위 옵션(PLAN 603 · 요구 466 · 467 · 468) — 범례 급경사 줄 ⚙ → 모달
 *   (범위 줄 = 아래 % · 위 % · 색 · 지움 · 칸 옆 ° 환산 · [범위 추가] · [기본값] · [적용] · 빈 값 · 겹침 막음).
 *   기억 = 화면 취향(`aislo:pref:d03.slope-bands` · 계정에 붙음 · 프로젝트 무관).
 *   칠하기 = 서버 값 그림(회색 · 칸 = 기울기 % 내림) → 범위 색 그림(서버 왕복 없음 · CLAUDE.md 5장).
 *   범위 · 비율 셈 = `logic/D03_PlanAnalysis_SlopeBands.ts` · 부르는 곳 = `D03_PlanAnalysis_UI_Layers.ts`.
 * ========================================================================== */

import { createButton, createIconButton } from "@ui/ui_template_button";
import { createInputField, createSelectField } from "@ui/ui_template_input";
import { createLegend } from "@ui/ui_template_flow_legend";
import { openModal } from "@ui/ui_template_modal";
import { themeColor } from "@ui/ui_template_palette";
import { createText } from "@ui/ui_template_text";
import { readByKey, writeByKey } from "../A00_Common/b_page_state";
import { loadImage } from "./D03_PlanAnalysis_UI_LayerDefs";
import {
  DEFAULT_SLOPE_BANDS,
  SLOPE_COLORS,
  SLOPE_MAX_BANDS,
  SLOPE_MAX_PCT,
  bandOf,
  checkBands,
  parseBands,
  pctToDeg,
  type SlopeBand,
} from "./logic/D03_PlanAnalysis_SlopeBands";

const PREF_KEY = "aislo:pref:d03.slope-bands";
/** 칠한 칸 투명도(겹 투명도 0.55 는 따로). */
const ALPHA = 150;

export const readSlopeBands = (): SlopeBand[] => parseBands(readByKey(PREF_KEY));
export const writeSlopeBands = (bands: SlopeBand[]): void =>
  writeByKey(PREF_KEY, JSON.stringify(bands));

/** 값 그림 → 칸 값(빨강 자리 = 회색 값). */
export function slopeValues(image: HTMLImageElement): ImageData {
  const canvas = document.createElement("canvas");
  canvas.width = image.naturalWidth;
  canvas.height = image.naturalHeight;
  const context = canvas.getContext("2d", { willReadFrequently: true })!;
  context.drawImage(image, 0, 0);
  return context.getImageData(0, 0, canvas.width, canvas.height);
}

/** 범위대로 칠한 그림(주소 = blob · 다 쓰면 부르는 쪽이 `URL.revokeObjectURL`). */
export async function paintSlope(
  values: ImageData,
  bands: SlopeBand[],
): Promise<{ url: string; image: HTMLImageElement }> {
  const rgb = bands.map((band) => hexRgb(themeColor(band.color, "#facc15")));
  const lut = new Uint32Array(256);
  const view = new DataView(lut.buffer);
  for (let v = 0; v < 256; v++) {
    const i = bandOf(v, bands);
    if (i >= 0) view.setUint32(v * 4, ((rgb[i] << 8) | ALPHA) >>> 0, false);
  }
  const out = new ImageData(values.width, values.height);
  const src = values.data;
  const dst = new Uint32Array(out.data.buffer);
  for (let p = 0; p < dst.length; p++) dst[p] = lut[src[p * 4]];
  const canvas = document.createElement("canvas");
  canvas.width = values.width;
  canvas.height = values.height;
  canvas.getContext("2d")!.putImageData(out, 0, 0);
  const blob = await new Promise<Blob>((done, fail) =>
    canvas.toBlob(
      (got) => (got ? done(got) : fail(new Error("그림을 만들지 못했습니다"))),
      "image/png",
    ),
  );
  const url = URL.createObjectURL(blob);
  return { url, image: await loadImage(url) };
}

/** `#rrggbb` → 0xrrggbb(못 읽으면 노랑). */
function hexRgb(color: string): number {
  const hex = /^#?([0-9a-f]{6})$/i.exec(color.trim())?.[1];
  return hex ? parseInt(hex, 16) : 0xfacc15;
}

/** 범례 급경사 줄 ⚙. */
export const slopeGear = (onClick: () => void): HTMLButtonElement => {
  const button = createIconButton({
    icon: "settings",
    title: "급경사 범위 바꾸기(기울기 %)",
    size: 20,
    onClick,
  });
  button.dataset.role = "slope-bands";
  return button;
};

const degText = (value: string): string => {
  const pct = Number(value);
  return value.trim() && Number.isFinite(pct) ? `≈ ${pctToDeg(pct).toFixed(1)}°` : "—";
};

/** 옵션 모달 — [적용] = 막을 것 없으면 `onApply` 후 닫음. */
export function openSlopeBands(current: SlopeBand[], onApply: (bands: SlopeBand[]) => void): void {
  let rows: Array<{ root: HTMLElement; read: () => SlopeBand }> = [];
  const list = document.createElement("div");
  const error = createText("", "error");
  error.hidden = true;
  const addButton = createButton({
    label: "범위 추가",
    variant: "ghost",
    size: 28,
    iconStart: "plus",
    onClick: () => {
      const last = rows.at(-1)?.read();
      const low = last && Number.isFinite(last.high) ? Math.min(last.high, SLOPE_MAX_PCT - 1) : 0;
      const color = SLOPE_COLORS[rows.length % SLOPE_COLORS.length].color;
      add({ low, high: SLOPE_MAX_PCT, color });
    },
  });
  addButton.dataset.role = "slope-band-add";

  function refresh(): void {
    addButton.disabled = rows.length >= SLOPE_MAX_BANDS;
    error.hidden = true;
  }

  function add(band: SlopeBand): void {
    const field = (label: string, value: number) => {
      const got = createInputField({
        label,
        type: "number",
        unit: "%",
        min: 0,
        max: SLOPE_MAX_PCT,
        size: 28,
        value: Number.isFinite(value) ? String(value) : "",
      });
      const deg = createText(degText(got.input.value), "muted");
      got.input.addEventListener("input", () => {
        deg.textContent = degText(got.input.value);
        refresh();
      });
      got.root.append(deg);
      return got;
    };
    const low = field("아래", band.low);
    const high = field("위", band.high);
    const color = createSelectField({
      label: "색",
      size: 28,
      options: SLOPE_COLORS.map((c) => ({ value: c.color, text: c.name })),
      value: band.color,
    });
    const chip = createLegend([{ label: "", color: `var(${band.color})` }]);
    color.select.addEventListener("change", () =>
      chip
        .querySelector<HTMLElement>(".ui-legend__mark")!
        .style.setProperty("--legend-color", `var(${color.select.value})`),
    );
    const root = document.createElement("div");
    root.className = "d03-plan__row";
    root.dataset.role = "slope-band";
    const entry = {
      root,
      read: (): SlopeBand => ({
        low: low.input.value.trim() === "" ? NaN : Number(low.input.value),
        high: high.input.value.trim() === "" ? NaN : Number(high.input.value),
        color: color.select.value,
      }),
    };
    const remove = createIconButton({
      icon: "trash",
      title: "이 범위 지움",
      size: 28,
      onClick: () => {
        rows = rows.filter((row) => row !== entry);
        root.remove();
        refresh();
      },
    });
    root.append(low.root, high.root, color.root, chip, remove);
    rows.push(entry);
    list.append(root);
    refresh();
  }

  function fill(bands: SlopeBand[]): void {
    rows = [];
    list.replaceChildren();
    bands.forEach(add);
  }

  openModal({
    title: "급경사 범위(기울기 %)",
    closeLabel: "닫기",
    width: "40rem",
    mount: (body, close, actions) => {
      fill(current);
      const reset = createButton({
        label: "기본값",
        variant: "ghost",
        size: 28,
        onClick: () => fill(DEFAULT_SLOPE_BANDS),
      });
      reset.dataset.role = "slope-band-default";
      const apply = createButton({
        label: "적용",
        size: 28,
        onClick: () => {
          const bands = rows.map((row) => row.read());
          const why = checkBands(bands);
          if (why) {
            error.lastChild!.textContent = why;
            error.hidden = false;
            return;
          }
          onApply(bands.sort((a, b) => a.low - b.low));
          close();
        },
      });
      apply.dataset.role = "slope-band-apply";
      actions.append(apply);
      const foot = document.createElement("div");
      foot.className = "d03-plan__row";
      foot.append(addButton, reset);
      body.append(
        createText(
          `0~${SLOPE_MAX_PCT} % · 아래 포함 · 위 뺌 · 겹치면 안 됨 · 기본 = 15 · 35 · 40°(지식DB)`,
          "hint",
        ),
        list,
        foot,
        error,
      );
    },
  });
}