/* =============================================================================
 * D03_PlanAnalysis_UI_DrawPaint.ts
 * D03 손 긋기 겹 그림 · 집기(PLAN 562-3 · 580) — `D03_PlanAnalysis_UI_Draw`(긋기) ·
 *   `D03_PlanAnalysis_UI_Edit`(고르기 · 고치기)가 같이 씀. 그림 = 선 · 측점 · 구간 글 · 꺾임점 · 마크 · 연도 ·
 *   시점 · 종점 · 미리보기(거리 · 가상 종단 기울기 % · °) · 집기 = 화면 px 둘레 선 위 자리.
 * ========================================================================== */

import { drawStationTicks } from "../B04_PreProcess/B04_PreProcess_UI_MapOverlays";
import {
  distanceAlong,
  groundSlopePct,
  lineLength,
  pointAtDistance,
  segmentLength,
  stationChainages,
  type HeightAt,
} from "./logic/D03_PlanAnalysis_Draw";
import type { PlanNetwork, Vertex } from "./logic/D03_PlanAnalysis_Plan";
import { planColors, PLAN_STATION_INTERVAL_M, type ScreenMap } from "./D03_PlanAnalysis_UI_Map";
import type { DrawPreview } from "./D03_PlanAnalysis_UI_Draw";

/** 시점 · 종점 · 꺾임점에 붙는 반경(px). */
export const SNAP_PX = 12;
/** 선 위 누름으로 볼 반경(px). */
export const LINE_HIT_PX = 8;
/** 구간 길이 라벨을 보일 화면 길이(px). */
const LABEL_MIN_PX = 70;

export const fmt = (value: number): string => value.toFixed(1);
const signed = (value: number): string => `${value >= 0 ? "+" : ""}${value.toFixed(1)}`;
/** 기울기 % → 각(°) — 가상 종단 기울기를 두 단위로. */
export const slopeDeg = (pct: number): number => (Math.atan(pct / 100) * 180) / Math.PI;
const slopeText = (pct: number): string => `${signed(pct)} % (${signed(slopeDeg(pct))}°)`;
/** 화면 px 거리(작업 좌표계 점 ↔ 마우스). */
export const screenGap = (map: ScreenMap, point: Vertex, px: number, py: number): number => {
  const [sx, sy] = map.toScreen(point);
  return Math.hypot(sx - px, sy - py);
};

/** 화면 px 둘레 선 위 자리 — 가장 가까운 선 · 누가 · 꺾임점(가까우면) · 구간 · `skip` 선 빼고. */
export function lineAt(
  network: PlanNetwork,
  px: number,
  py: number,
  map: ScreenMap,
  skip: number | null = null,
): { line: number; atM: number; point: Vertex; vertex: number | null; segment: number } | null {
  const cursor = map.toMetric(px, py);
  let best: ReturnType<typeof lineAt> = null;
  let bestPx = LINE_HIT_PX;
  network.lines.forEach((line, index) => {
    if (line.vertices.length < 2 || index === skip) return;
    // 붙는 반경 안 꺾임점 중 가장 가까운 것
    let vertex = -1;
    let vertexPx = SNAP_PX;
    line.vertices.forEach((v, i) => {
      const [vx, vy] = map.toScreen(v);
      const d = Math.hypot(vx - px, vy - py);
      if (d <= vertexPx) [vertex, vertexPx] = [i, d];
    });
    const atM =
      vertex >= 0
        ? lineLength(line.vertices.slice(0, vertex + 1))
        : distanceAlong(line.vertices, cursor);
    const point = vertex >= 0 ? line.vertices[vertex] : pointAtDistance(line.vertices, atM);
    const [sx, sy] = map.toScreen(point);
    const gap = vertex >= 0 ? 0 : Math.hypot(sx - px, sy - py);
    if (gap > bestPx || (best && gap === bestPx)) return;
    // 누가가 든 구간(꺾임점 끼울 자리)
    let segment = 0;
    for (let walked = 0; segment < line.vertices.length - 2; segment += 1) {
      walked += segmentLength(line.vertices[segment], line.vertices[segment + 1]);
      if (walked >= atM) break;
    }
    best = { line: index, atM, point, vertex: vertex >= 0 ? vertex : null, segment };
    bestPx = gap;
  });
  return best;
}

/** 그은 선 · 측점 · 구간 글 · 꺾임점 · 마크 · 연도 · (extra = 미리보기) · 시점(초록) · 종점(빨강).
 *  `active` = 그리는 선(굵은 보라). */
export function paintNetwork(
  context: CanvasRenderingContext2D,
  map: ScreenMap,
  network: PlanNetwork,
  base: { starts: Vertex[]; ends: Vertex[] },
  active: number | null,
  z: HeightAt,
  extra: () => void,
): void {
  const { starts, ends } = base;
  const colors = planColors();
  context.lineCap = "round";
  context.lineJoin = "round";
  network.lines.forEach((line, index) => {
    if (line.vertices.length < 2) return;
    context.strokeStyle = index === active ? colors.active : colors.line;
    context.lineWidth = line.branch ? 2.5 : 3;
    context.beginPath();
    line.vertices.forEach((v, i) => {
      const [sx, sy] = map.toScreen(v);
      if (i) context.lineTo(sx, sy);
      else context.moveTo(sx, sy);
    });
    context.stroke();
    if (map.stations)
      drawStationTicks(
        context,
        line.vertices.map(([x, y]) => ({ x, y })),
        {
          intervalM: PLAN_STATION_INTERVAL_M,
          pxPerMeter: map.pxPerMeter,
          toScreen: (x, y) => map.toScreen([x, y]),
          uprightRad: map.uprightRad,
          chainages: stationChainages(lineLength(line.vertices), PLAN_STATION_INTERVAL_M),
        },
      );
    if (map.slopes) segmentLabels(context, map, line.vertices, z);
  });
  // 꺾임점
  context.fillStyle = "#ffffff";
  for (const line of network.lines)
    for (const v of line.vertices.slice(1)) {
      const [sx, sy] = map.toScreen(v);
      context.beginPath();
      context.arc(sx, sy, 3, 0, Math.PI * 2);
      context.fill();
    }
  drawPieces(context, map, network);
  extra();
  // 시점(초록) · 종점(빨강)
  for (const [points, fill] of [
    [starts, "#16a34a"],
    [ends, "#dc2626"],
  ] as const)
    for (const point of points) {
      const [sx, sy] = map.toScreen(point);
      context.beginPath();
      context.arc(sx, sy, 7, 0, Math.PI * 2);
      context.fillStyle = fill;
      context.fill();
      context.lineWidth = 2;
      context.strokeStyle = "#ffffff";
      context.stroke();
    }
}

function segmentLabels(
  context: CanvasRenderingContext2D,
  map: ScreenMap,
  vertices: Vertex[],
  z: HeightAt,
): void {
  for (let i = 1; i < vertices.length; i += 1) {
    const [a, b] = [map.toScreen(vertices[i - 1]), map.toScreen(vertices[i])];
    if (Math.hypot(b[0] - a[0], b[1] - a[1]) < LABEL_MIN_PX) continue;
    const slope = groundSlopePct(vertices[i - 1], vertices[i], z);
    const text = `${fmt(segmentLength(vertices[i - 1], vertices[i]))} m · ${slope === null ? "—" : `${signed(slope)} %`}`;
    planLabel(context, map, (a[0] + b[0]) / 2, (a[1] + b[1]) / 2 - 12, text, "11px");
  }
}

function drawPieces(context: CanvasRenderingContext2D, map: ScreenMap, network: PlanNetwork): void {
  const colors = planColors();
  network.pieces.forEach((piece) => {
    const vertices = network.lines.find((line) => line.id === piece.line)?.vertices;
    if (!vertices || vertices.length < 2) return;
    if (piece.from_m > 0) {
      const [sx, sy] = map.toScreen(pointAtDistance(vertices, piece.from_m));
      context.beginPath();
      context.moveTo(sx, sy - 8);
      context.lineTo(sx + 6, sy);
      context.lineTo(sx, sy + 8);
      context.lineTo(sx - 6, sy);
      context.closePath();
      context.fillStyle = colors.active;
      context.fill();
      context.lineWidth = 1.5;
      context.strokeStyle = "#ffffff";
      context.stroke();
    }
    const [mx, my] = map.toScreen(pointAtDistance(vertices, (piece.from_m + piece.to_m) / 2));
    planLabel(context, map, mx, my + 16, `${piece.year}년`, "bold 12px");
  });
}

/** 미리보기 — 점선 · 둘 다(양각기) 원 · 후보 · 글(거리 · 가상 종단 기울기 % · °). */
export function paintPreview(
  context: CanvasRenderingContext2D,
  map: ScreenMap,
  from: Vertex,
  preview: DrawPreview,
  compass: { lengthM: number; candidates: Vertex[] } | null,
): void {
  const colors = planColors();
  const [ax, ay] = map.toScreen(from);
  const [bx, by] = map.toScreen(preview.point);
  if (compass) {
    context.strokeStyle = colors.active;
    context.lineWidth = 1;
    context.setLineDash([3, 4]);
    context.beginPath();
    context.arc(ax, ay, compass.lengthM * map.pxPerMeter, 0, Math.PI * 2);
    context.stroke();
    context.fillStyle = colors.active;
    for (const c of compass.candidates) {
      const [cx, cy] = map.toScreen(c);
      context.beginPath();
      context.arc(cx, cy, 3, 0, Math.PI * 2);
      context.fill();
    }
  }
  context.strokeStyle = preview.blocked ? colors.warn : colors.active;
  context.lineWidth = 2;
  context.setLineDash([6, 4]);
  context.beginPath();
  context.moveTo(ax, ay);
  context.lineTo(bx, by);
  context.stroke();
  context.setLineDash([]);
  context.beginPath();
  context.arc(bx, by, 5, 0, Math.PI * 2);
  context.stroke();
  const value =
    `${fmt(preview.lengthM)} m · ` +
    (preview.slopePct === null ? "지형 밖" : slopeText(preview.slopePct));
  planLabel(
    context,
    map,
    bx + 14,
    by - 14,
    preview.note ? `${value} · ${preview.note}` : value,
    "12px",
    "left",
  );
}

export function planLabel(
  context: CanvasRenderingContext2D,
  map: ScreenMap,
  x: number,
  y: number,
  text: string,
  font: string,
  align: CanvasTextAlign = "center",
): void {
  map.upright(context, x, y, () => {
    context.font = `${font} system-ui, sans-serif`;
    context.textAlign = align;
    context.textBaseline = "middle";
    context.lineWidth = 3;
    context.strokeStyle = planColors().halo;
    context.strokeText(text, x, y);
    context.fillStyle = "#ffffff";
    context.fillText(text, x, y);
  });
}