/* =============================================================================
 * D03_PlanAnalysis_UI_Map.ts
 * D03 메인 평면(PLAN 530-3) — 위성 + 도엽 등고선 + 다른 갈래(옅게) + 고른 노선 + 측점 눈금 · 이름 +
 *   지점(연도 경계) + 지점 끌기 겹.
 *
 * 셈 · 그리기는 B 부품 그대로(import 만) — 좌표 `metricToScreen` · `screenToMetric` · 맞춤
 * `computeRouteView` · 등고선 `drawPreparedLayer` · 측점 `drawStationTicks` · 집기 `stationAtScreen` ·
 * 휠 확대 · 끌어 옮기기 `bindRouteEditNavigation`. 측점 누가 = 등록 시작 누가부터(앞붙임 선
 * `leadInLine`). 지점 끌기 = 왼쪽 단추로 지점을 집으면 지도 옮기기보다 먼저 받음(끈 값은 페이지가 캐시).
 * ========================================================================== */

import { themeColor } from "@ui/ui_template_palette";
import type { VWorldMeta } from "../B04_PreProcess/B04_PreProcess_Api_Fetch";
import {
  drawStationTicks,
  type StationLabelBox,
} from "../B04_PreProcess/B04_PreProcess_UI_MapOverlays";
import {
  computeMapRect,
  computeRouteView,
  createMetricProjector,
  drawPreparedLabels,
  drawPreparedLayer,
  normalizedToScreen,
  pickLevelStep,
  routeLineColor,
  type PreparedLayer,
  type ViewState,
} from "../B04_PreProcess/B04_PreProcess_UI_MapRender";
import {
  bindRouteEditNavigation,
  stationAtScreen,
} from "../B05_Profile/B05_Profile_UI_RouteEdit_Input";
import { fitCanvas, screenToMetric } from "../B05_Profile/B05_Profile_UI_RouteEdit_View";
import { leadInLine, type Vertex } from "./logic/D03_PlanAnalysis_Plan";

/** 측점 간격(m) — B 규칙 측점과 같음. */
export const PLAN_STATION_INTERVAL_M = 20;
/** 지점 집는 반경(px). */
const NODE_HIT_PX = 12;
/** 누름으로 볼 손 떨림(px) — 넘으면 지도 옮기기. */
const CLICK_SLOP_PX = 4;
/** 위성이 없을 때 지점 둘레로 둘 가짜 도엽 여유(m). */
const FAKE_MARGIN_M = 600;

export interface PlanMapScene {
  meta: VWorldMeta | null;
  image: HTMLImageElement | null;
  contours: PreparedLayer | null;
  nodes: Vertex[];
  /** 마디마다 받은 지형 안인가 — 밖이면 빨간 고리. */
  reach: boolean[];
  /** 고르지 않은 갈래(옅게). */
  others: Vertex[][];
  /** 고른 갈래를 이은 중심선. */
  line: Vertex[];
  startM: number;
  stations: number[];
  selected: number | null;
  editable: boolean;
}

export interface PlanMapEvents {
  onDrag: (index: number, point: Vertex) => void;
  onDragEnd: (index: number) => void;
  onStation: (chainage: number) => void;
}

export interface PlanMap {
  root: HTMLElement;
  update: (patch: Partial<PlanMapScene>) => void;
  /** 지점 · 노선이 들어오게 다시 맞춤. */
  fit: () => void;
  /** 검증 창구 — 측점 누가 → 화면 px(그림 좌표). */
  stationScreen: (chainage: number) => [number, number] | null;
  dispose: () => void;
}

function fakeMeta(points: Vertex[]): VWorldMeta | null {
  if (!points.length) return null;
  const xs = points.map(([x]) => x);
  const ys = points.map(([, y]) => y);
  const x_min = Math.min(...xs) - FAKE_MARGIN_M;
  const y_min = Math.min(...ys) - FAKE_MARGIN_M;
  const x_max = Math.max(...xs) + FAKE_MARGIN_M;
  const y_max = Math.max(...ys) + FAKE_MARGIN_M;
  return {
    x_min,
    x_max,
    y_min,
    y_max,
    width_meters: x_max - x_min,
    height_meters: y_max - y_min,
    center_x: (x_min + x_max) / 2,
    center_y: (y_min + y_max) / 2,
    lon_min: 0,
    lon_max: 1,
    lat_min: 0,
    lat_max: 1,
  };
}

export function createPlanMap(events: PlanMapEvents): PlanMap {
  const root = document.createElement("div");
  root.className = "d03-plan__map";
  const canvas = document.createElement("canvas");
  root.append(canvas);
  const context = canvas.getContext("2d")!;
  let scene: PlanMapScene = {
    meta: null,
    image: null,
    contours: null,
    nodes: [],
    reach: [],
    others: [],
    line: [],
    startM: 0,
    stations: [],
    selected: null,
    editable: false,
  };
  let meta: VWorldMeta | null = null;
  let fitted = false;
  let labels: StationLabelBox[] = [];
  let view: ViewState = {
    width: 0,
    height: 0,
    scale: 1,
    offsetX: 0,
    offsetY: 0,
    mapRect: computeMapRect(null, 0, 0),
  };

  const toScreen = (point: Vertex): [number, number] =>
    createMetricProjector(meta!, view).toScreen(point[0], point[1]);

  function refit(): void {
    const all = [...scene.nodes, ...scene.line];
    meta = scene.meta ?? fakeMeta(all);
    if (!meta || !view.width || !all.length) return;
    const xs = all.map(([x]) => x);
    const ys = all.map(([, y]) => y);
    const box = {
      x_min: Math.min(...xs),
      x_max: Math.max(...xs),
      y_min: Math.min(...ys),
      y_max: Math.max(...ys),
    };
    view = {
      ...view,
      mapRect: computeMapRect(meta, view.width, view.height),
      ...computeRouteView(meta, box, view.width, view.height, 150),
    };
    fitted = true;
  }

  function polyline(points: Vertex[]): void {
    context.beginPath();
    points.forEach((point, i) => {
      const [sx, sy] = toScreen(point);
      if (i) context.lineTo(sx, sy);
      else context.moveTo(sx, sy);
    });
    context.stroke();
  }

  function draw(): void {
    context.clearRect(0, 0, view.width, view.height);
    if (!meta) return;
    const projector = createMetricProjector(meta, view);
    if (scene.image?.complete && scene.image.naturalWidth && scene.meta) {
      const [x0, y0] = normalizedToScreen(view, 0, 0);
      const [x1, y1] = normalizedToScreen(view, 1, 1);
      context.drawImage(scene.image, x0, y0, x1 - x0, y1 - y0);
    }
    if (scene.contours) {
      context.save();
      context.strokeStyle = "rgba(255, 214, 140, 0.7)";
      context.lineWidth = 0.8;
      drawPreparedLayer(
        context,
        scene.contours,
        view,
        "dot",
        pickLevelStep(scene.contours, view, 5),
      );
      context.font = "10px system-ui, sans-serif";
      context.textAlign = "center";
      context.textBaseline = "middle";
      drawPreparedLabels(context, scene.contours, view, "#fde68a", 25, 0, "rgba(0, 0, 0, 0.6)");
      context.restore();
    }
    context.save();
    context.lineCap = "round";
    context.lineJoin = "round";
    context.strokeStyle = "rgba(255, 255, 255, 0.55)";
    context.lineWidth = 1.5;
    context.setLineDash([6, 4]);
    for (const other of scene.others) if (other.length > 1) polyline(other);
    context.setLineDash([]);
    if (scene.line.length > 1) {
      context.strokeStyle = routeLineColor();
      context.lineWidth = 3;
      polyline(scene.line);
    }
    context.restore();
    labels = [];
    if (scene.line.length > 1) {
      drawStationTicks(
        context,
        leadInLine(scene.line, scene.startM).map(([x, y]) => ({ x, y })),
        {
          intervalM: PLAN_STATION_INTERVAL_M,
          pxPerMeter: projector.pxPerMeter,
          toScreen: projector.toScreen,
          chainages: scene.stations,
          onLabel: (box) => labels.push(box),
        },
      );
    }
    if (scene.selected !== null) {
      const at = stationScreen(scene.selected);
      if (at) {
        context.beginPath();
        context.arc(at[0], at[1], 7, 0, Math.PI * 2);
        context.lineWidth = 2.5;
        context.strokeStyle = themeColor("--color-primary", "#6d28d9");
        context.stroke();
      }
    }
    scene.nodes.forEach((node, i) => {
      const [sx, sy] = toScreen(node);
      const last = i === scene.nodes.length - 1;
      context.beginPath();
      context.arc(sx, sy, 7, 0, Math.PI * 2);
      context.fillStyle = i === 0 ? "#16a34a" : last ? "#dc2626" : "#2563eb";
      context.fill();
      context.lineWidth = 2;
      context.strokeStyle = scene.reach[i] === false ? "#ef4444" : "#ffffff";
      context.stroke();
      if (scene.reach[i] === false) {
        context.beginPath();
        context.arc(sx, sy, 12, 0, Math.PI * 2);
        context.setLineDash([3, 3]);
        context.stroke();
        context.setLineDash([]);
      }
    });
  }

  /** 측점 누가 → 화면 px — 앞붙임 선 위 보간(눈금과 같은 자리). */
  function stationScreen(chainage: number): [number, number] | null {
    if (!meta || scene.line.length < 2) return null;
    const line = leadInLine(scene.line, scene.startM);
    let travelled = 0;
    for (let i = 1; i < line.length; i += 1) {
      const [a, b] = [line[i - 1], line[i]];
      const span = Math.hypot(b[0] - a[0], b[1] - a[1]);
      if (travelled + span >= chainage - 1e-6) {
        const t = span ? (chainage - travelled) / span : 0;
        return toScreen([a[0] + (b[0] - a[0]) * t, a[1] + (b[1] - a[1]) * t]);
      }
      travelled += span;
    }
    return toScreen(line[line.length - 1]);
  }

  function resize(): void {
    const { width, height } = fitCanvas(canvas, context);
    if (!width || !height) return;
    view = { ...view, width, height, mapRect: computeMapRect(meta, width, height) };
    if (!fitted) refit();
    draw();
  }

  const at = (event: PointerEvent | MouseEvent): [number, number] => {
    const rect = canvas.getBoundingClientRect();
    return [event.clientX - rect.left, event.clientY - rect.top];
  };
  const nodeAt = (px: number, py: number): number => {
    let best = -1;
    let bestDistance = NODE_HIT_PX;
    scene.nodes.forEach((node, i) => {
      const [sx, sy] = toScreen(node);
      const distance = Math.hypot(sx - px, sy - py);
      if (distance < bestDistance) [best, bestDistance] = [i, distance];
    });
    return best;
  };

  // 지점 끌기 — 지도 옮기기보다 먼저 듣고 지점을 집었으면 옮기기에 안 넘김
  let dragging: { index: number; id: number } | null = null;
  let press: [number, number] | null = null;
  canvas.addEventListener("pointerdown", (event) => {
    press = [event.clientX, event.clientY];
    if (!meta || !scene.editable || event.button !== 0) return;
    const index = nodeAt(...at(event));
    if (index < 0) return;
    event.stopImmediatePropagation();
    dragging = { index, id: event.pointerId };
    canvas.setPointerCapture(event.pointerId);
    canvas.style.cursor = "grabbing";
  });
  canvas.addEventListener("pointermove", (event) => {
    if (!dragging || event.pointerId !== dragging.id || !meta) {
      if (meta && scene.editable && !dragging)
        canvas.style.cursor = nodeAt(...at(event)) >= 0 ? "grab" : "";
      return;
    }
    events.onDrag(dragging.index, screenToMetric(meta, view, ...at(event)));
  });
  const endDrag = (event: PointerEvent): void => {
    if (!dragging || event.pointerId !== dragging.id) return;
    const index = dragging.index;
    dragging = null;
    canvas.style.cursor = "";
    events.onDragEnd(index);
  };
  canvas.addEventListener("pointerup", endDrag);
  canvas.addEventListener("pointercancel", endDrag);
  bindRouteEditNavigation({
    canvas,
    getView: () => view,
    setView: (next) => (view = next),
    getMeta: () => meta,
    leftPan: true,
    draw,
  });
  // 측점 누름 — 손을 거의 안 움직인 누름만(옮기기 끝은 안 셈)
  canvas.addEventListener("click", (event) => {
    if (!press || Math.hypot(event.clientX - press[0], event.clientY - press[1]) > CLICK_SLOP_PX)
      return;
    if (!meta || scene.line.length < 2) return;
    const [px, py] = at(event);
    const hit = stationAtScreen(
      leadInLine(scene.line, scene.startM),
      toScreen,
      PLAN_STATION_INTERVAL_M,
      px,
      py,
      14,
      labels,
      scene.stations,
    );
    if (hit) events.onStation(hit.chainage);
  });

  const observer = new ResizeObserver(() => resize());
  observer.observe(root);

  return {
    root,
    update(patch) {
      const metaChanged = "meta" in patch && patch.meta !== scene.meta;
      scene = { ...scene, ...patch };
      if (metaChanged || !fitted) refit();
      draw();
    },
    fit() {
      refit();
      draw();
    },
    stationScreen,
    dispose: () => observer.disconnect(),
  };
}