---

import { IChartApi, IPrimitivePaneView, PrimitiveHoveredItem, UTCTimestamp } from 'lightweight-charts';
import { Observable } from 'rxjs';

import {
  CustomPriceAxisPaneView,
  CustomPriceAxisView,
  CustomTimeAxisPaneView,
  CustomTimeAxisView,
} from '@core/Drawings/axis';
import { SeriesDrawingBase } from '@core/Drawings/common';
import {
  getAnchorFromPoint,
  getPriceDelta as getPriceDeltaFromCoordinates,
  getXCoordinateFromTime,
  getYCoordinateFromPrice,
  isNearPoint,
  shiftTimeByPixels,
} from '@core/Drawings/helpers';
import { updateViews } from '@core/Drawings/utils';

import { getThemeStore } from '@src/theme';
import { Defaults } from '@src/types/defaults';
import { formatPrice } from '@src/utils';
import { formatDate } from '@src/utils/formatter';

import { TrendLinePaneView } from './paneView';

import {
  createDefaultSettings,
  getTrendLineSettingsTabs,
  TrendLineSettings,
  TrendLineStyle,
  TrendLineTextStyle,
} from './settings';

import type { DrawingInteraction, ISeriesDrawing } from '@core/Drawings/common';
import type { Anchor, AxisLabel, AxisSegment, Point, SeriesApi } from '@core/Drawings/types';
import type { ChartOptionsModel, SettingsTab } from '@src/types';

type TrendLineMode = 'idle' | 'drawing' | 'ready' | 'dragging-start' | 'dragging-end' | 'dragging-body';
type TimeLabelKind = 'start' | 'end';
type PriceLabelKind = 'start' | 'end';

interface TrendLineParams {
  container: HTMLElement;
  interaction: DrawingInteraction;
  formatObservable?: Observable<ChartOptionsModel>;
  removeSelf?: () => void;
  openSettings?: () => void;
}

interface TrendLineState {
  hidden: boolean;
  mode: TrendLineMode;
  startAnchor: Anchor | null;
  endAnchor: Anchor | null;
  settings: TrendLineSettings;
}

interface TrendLineGeometry {
  startPoint: Point;
  endPoint: Point;
  left: number;
  right: number;
  top: number;
  bottom: number;
}

export interface TrendLineRenderData extends TrendLineGeometry, TrendLineStyle, TrendLineTextStyle {
  showHandles: boolean;
}

const LINE_HIT_TOLERANCE = 6;
const MIN_LINE_SIZE = 4;

export class TrendLine extends SeriesDrawingBase<TrendLineSettings> implements ISeriesDrawing {
  private removeSelf?: () => void;
  private openSettings?: () => void;

  protected settings: TrendLineSettings = createDefaultSettings();
  protected mode: TrendLineMode = 'idle';

  private startAnchor: Anchor | null = null;
  private endAnchor: Anchor | null = null;

  private dragPointerId: number | null = null;
  private dragStartPoint: Point | null = null;
  private dragStateSnapshot: TrendLineState | null = null;

  private displayFormat: ChartOptionsModel = {
    dateFormat: Defaults.dateFormat,
    timeFormat: Defaults.timeFormat,
    showTime: Defaults.showTime,
  };

  private readonly paneView: TrendLinePaneView;
  private readonly timeAxisPaneView: CustomTimeAxisPaneView;
  private readonly priceAxisPaneView: CustomPriceAxisPaneView;
  private readonly startTimeAxisView: CustomTimeAxisView;
  private readonly endTimeAxisView: CustomTimeAxisView;
  private readonly startPriceAxisView: CustomPriceAxisView;
  private readonly endPriceAxisView: CustomPriceAxisView;

  constructor(
    chart: IChartApi,
    series: SeriesApi,
    { container, interaction, formatObservable, removeSelf, openSettings }: TrendLineParams,
  ) {
    super({ chart, series, container, interaction });

    this.removeSelf = removeSelf;
    this.openSettings = openSettings;

    this.paneView = new TrendLinePaneView(this);

    this.timeAxisPaneView = new CustomTimeAxisPaneView({
      getAxisSegments: () => this.getTimeAxisSegments(),
    });

    this.priceAxisPaneView = new CustomPriceAxisPaneView({
      getAxisSegments: () => this.getPriceAxisSegments(),
    });

    this.startTimeAxisView = new CustomTimeAxisView({
      getAxisLabel: (kind) => this.getTimeAxisLabel(kind),
      labelKind: 'start',
    });

    this.endTimeAxisView = new CustomTimeAxisView({
      getAxisLabel: (kind) => this.getTimeAxisLabel(kind),
      labelKind: 'end',
    });

    this.startPriceAxisView = new CustomPriceAxisView({
      getAxisLabel: (kind) => this.getPriceAxisLabel(kind),
      labelKind: 'start',
    });

    this.endPriceAxisView = new CustomPriceAxisView({
      getAxisLabel: (kind) => this.getPriceAxisLabel(kind),
      labelKind: 'end',
    });

    if (formatObservable) {
      this.subscriptions.add(
        formatObservable.subscribe((format) => {
          this.displayFormat = format;
          this.render();
        }),
      );
    }

    this.series.attachPrimitive(this);
  }

  public isCreationPending(): boolean {
    return this.mode === 'idle' || this.mode === 'drawing';
  }

  public getState(): TrendLineState {
    return {
      hidden: this.hidden,
      mode: this.mode,
      startAnchor: this.startAnchor,
      endAnchor: this.endAnchor,
      settings: { ...this.settings },
    };
  }

  public setState(state: unknown): void {
    if (!state || typeof state !== 'object') {
      return;
    }

    const nextState = state as Partial<TrendLineState>;

    if ('hidden' in nextState && typeof nextState.hidden === 'boolean') {
      this.hidden = nextState.hidden;
    }

    if ('mode' in nextState && nextState.mode) {
      this.mode = nextState.mode;
    }

    if ('startAnchor' in nextState) {
      this.startAnchor = nextState.startAnchor ?? null;
    }

    if ('endAnchor' in nextState) {
      this.endAnchor = nextState.endAnchor ?? null;
    }

    if ('settings' in nextState && nextState.settings) {
      this.settings = {
        ...createDefaultSettings(),
        ...nextState.settings,
      };
    }

    this.render();
  }

  public getSettingsTabs(): SettingsTab[] {
    return getTrendLineSettingsTabs(this.settings);
  }

  public updateAllViews(): void {
    updateViews([
      this.paneView,
      this.timeAxisPaneView,
      this.priceAxisPaneView,
      this.startTimeAxisView,
      this.endTimeAxisView,
      this.startPriceAxisView,
      this.endPriceAxisView,
    ]);
  }

  public paneViews(): readonly IPrimitivePaneView[] {
    return [this.paneView];
  }

  public timeAxisPaneViews(): readonly IPrimitivePaneView[] {
    return [this.timeAxisPaneView];
  }

  public priceAxisPaneViews(): readonly IPrimitivePaneView[] {
    return [this.priceAxisPaneView];
  }

  public timeAxisViews() {
    return [this.startTimeAxisView, this.endTimeAxisView];
  }

  public priceAxisViews() {
    return [this.startPriceAxisView, this.endPriceAxisView];
  }

  public getRenderData(): TrendLineRenderData | null {
    if (this.hidden) {
      return null;
    }

    const geometry = this.getGeometry();

    if (!geometry) {
      return null;
    }

    return {
      ...geometry,
      showHandles: this.shouldShowHandles(),
      ...this.settings,
    };
  }

  protected getHoveredItem(x: number, y: number): PrimitiveHoveredItem | null {
    if (this.hidden || this.mode === 'idle' || this.mode === 'drawing') {
      return null;
    }

    const point = { x, y };

    if (this.getPointTarget(point)) {
      return {
        cursorStyle: 'move',
        externalId: 'trend-line',
        zOrder: 'top',
      };
    }

    if (!this.isPointNearLine(point)) {
      return null;
    }

    return {
      cursorStyle: 'grab',
      externalId: 'trend-line',
      zOrder: 'top',
    };
  }

  protected getTimeAxisSegments(): AxisSegment[] {
    if (!this.isSelected() && !this.isCreationPending()) {
      return [];
    }

    const geometry = this.getGeometry();

    if (!geometry) {
      return [];
    }

    const { colors } = getThemeStore();

    return [
      {
        from: geometry.left,
        to: geometry.right,
        color: colors.axisMarkerAreaFill,
      },
    ];
  }

  protected getPriceAxisSegments(): AxisSegment[] {
    if (!this.isSelected() && !this.isCreationPending()) {
      return [];
    }

    const geometry = this.getGeometry();

    if (!geometry) {
      return [];
    }

    const { colors } = getThemeStore();

    return [
      {
        from: geometry.top,
        to: geometry.bottom,
        color: colors.axisMarkerAreaFill,
      },
    ];
  }

  protected getTimeAxisLabel(kind: string): AxisLabel | null {
    if ((!this.isSelected() && !this.isCreationPending()) || (kind !== 'start' && kind !== 'end')) {
      return null;
    }

    const coordinate = this.getTimeCoordinate(kind);
    const text = this.getTimeText(kind);

    if (coordinate === null || !text) {
      return null;
    }

    const { colors } = getThemeStore();

    return {
      coordinate,
      text,
      textColor: colors.chartPriceLineText,
      backgroundColor: colors.axisMarkerLabelFill,
    };
  }

  protected getPriceAxisLabel(kind: string): AxisLabel | null {
    if ((!this.isSelected() && !this.isCreationPending()) || (kind !== 'start' && kind !== 'end')) {
      return null;
    }

    const coordinate = this.getPriceCoordinate(kind);
    const text = this.getPriceText(kind);

    if (coordinate === null || !text) {
      return null;
    }

    const { colors } = getThemeStore();

    return {
      coordinate,
      text,
      textColor: colors.chartPriceLineText,
      backgroundColor: colors.axisMarkerLabelFill,
    };
  }

  protected handleDoubleClick = (event: MouseEvent): void => {
    if (this.hidden || this.mode === 'idle' || this.mode === 'drawing') {
      return;
    }

    const rect = this.container.getBoundingClientRect();
    const point = {
      x: event.clientX - rect.left,
      y: event.clientY - rect.top,
    };

    if (!this.getPointTarget(point) && !this.isPointNearLine(point)) {
      return;
    }

    event.preventDefault();
    event.stopPropagation();

    this.openSettings?.();
  };

  protected handlePointerDown = (event: PointerEvent): void => {
    if (this.hidden || event.button !== 0) {
      return;
    }

    const point = this.getEventPoint(event);

    if (this.mode === 'idle') {
      event.preventDefault();
      event.stopPropagation();

      this.startDrawing(point);
      return;
    }

    if (this.mode === 'drawing') {
      event.preventDefault();
      event.stopPropagation();

      this.updateDrawing(point);
      this.finishDrawing();
      return;
    }

    if (this.mode !== 'ready') {
      return;
    }

    const pointTarget = this.getPointTarget(point);
    const isNearLine = this.isPointNearLine(point);
    const isDrawingHit = pointTarget !== null || isNearLine;

    if (!this.isSelected()) {
      if (!isDrawingHit) {
        return;
      }

      event.preventDefault();
      event.stopPropagation();

      this.select();
      return;
    }

    if (pointTarget === 'start') {
      event.preventDefault();
      event.stopPropagation();

      this.startDragging('dragging-start', point, event.pointerId);
      return;
    }

    if (pointTarget === 'end') {
      event.preventDefault();
      event.stopPropagation();

      this.startDragging('dragging-end', point, event.pointerId);
      return;
    }

    if (isNearLine) {
      event.preventDefault();
      event.stopPropagation();

      this.startDragging('dragging-body', point, event.pointerId);
      return;
    }

    this.deselect();
  };

  protected handlePointerMove = (event: PointerEvent): void => {
    const point = this.getEventPoint(event);

    if (this.mode === 'drawing') {
      this.updateDrawing(point);
      return;
    }

    if (this.dragPointerId !== event.pointerId) {
      return;
    }

    if (this.mode === 'dragging-start' || this.mode === 'dragging-end') {
      event.preventDefault();
      event.stopPropagation();

      this.movePoint(point);
      this.render();
      return;
    }

    if (this.mode === 'dragging-body') {
      event.preventDefault();
      event.stopPropagation();

      this.moveBody(point);
      this.render();
    }
  };

  protected handlePointerUp = (event: PointerEvent): void => {
    if (this.dragPointerId !== event.pointerId) {
      return;
    }

    if (this.mode === 'dragging-start' || this.mode === 'dragging-end' || this.mode === 'dragging-body') {
      this.finishDragging();
    }
  };

  private startDrawing(point: Point): void {
    const anchor = this.createAnchor(point);

    if (!anchor) {
      return;
    }

    this.startAnchor = anchor;
    this.endAnchor = anchor;
    this.mode = 'drawing';

    this.render();
  }

  private updateDrawing(point: Point): void {
    const anchor = this.createAnchor(point);

    if (!anchor) {
      return;
    }

    this.endAnchor = anchor;
    this.render();
  }

  private finishDrawing(): void {
    const geometry = this.getGeometry();

    if (!geometry) {
      return;
    }

    const lineSize = Math.hypot(
      geometry.endPoint.x - geometry.startPoint.x,
      geometry.endPoint.y - geometry.startPoint.y,
    );

    if (lineSize < MIN_LINE_SIZE) {
      this.removeSelf?.();
      return;
    }

    this.mode = 'ready';
    this.resolveReady?.();

    this.render();
  }

  private startDragging(mode: TrendLineMode, point: Point, pointerId: number): void {
    this.mode = mode;

    this.dragPointerId = pointerId;
    this.dragStartPoint = point;
    this.dragStateSnapshot = this.getState();

    this.hideCrosshair();
    this.render();
  }

  private finishDragging(): void {
    this.mode = 'ready';
    this.resolveReady?.();

    this.dragPointerId = null;
    this.dragStartPoint = null;
    this.dragStateSnapshot = null;

    this.showCrosshair();
    this.render();
  }

  private movePoint(point: Point): void {
    const anchor = this.createAnchor(point);

    if (!anchor) {
      return;
    }

    if (this.mode === 'dragging-start') {
      this.startAnchor = anchor;
    }

    if (this.mode === 'dragging-end') {
      this.endAnchor = anchor;
    }
  }

  private moveBody(point: Point): void {
    const snapshot = this.dragStateSnapshot;

    if (!snapshot?.startAnchor || !snapshot.endAnchor || !this.dragStartPoint) {
      return;
    }

    const offsetX = point.x - this.dragStartPoint.x;
    const priceOffset = getPriceDeltaFromCoordinates(this.series, this.dragStartPoint.y, point.y);

    const nextStartTime = shiftTimeByPixels(this.chart, snapshot.startAnchor.time, offsetX, this.series);
    const nextEndTime = shiftTimeByPixels(this.chart, snapshot.endAnchor.time, offsetX, this.series);

    if (nextStartTime === null || nextEndTime === null) {
      return;
    }

    this.startAnchor = {
      time: nextStartTime,
      price: snapshot.startAnchor.price + priceOffset,
    };

    this.endAnchor = {
      time: nextEndTime,
      price: snapshot.endAnchor.price + priceOffset,
    };
  }

  private createAnchor(point: Point): Anchor | null {
    return getAnchorFromPoint(this.chart, this.series, point);
  }

  protected getGeometry(): TrendLineGeometry | null {
    if (!this.startAnchor || !this.endAnchor) {
      return null;
    }

    const startX = getXCoordinateFromTime(this.chart, this.startAnchor.time, this.series);
    const endX = getXCoordinateFromTime(this.chart, this.endAnchor.time, this.series);
    const startY = getYCoordinateFromPrice(this.series, this.startAnchor.price);
    const endY = getYCoordinateFromPrice(this.series, this.endAnchor.price);

    if (startX === null || endX === null || startY === null || endY === null) {
      return null;
    }

    const startPoint = {
      x: Math.round(Number(startX)),
      y: Math.round(Number(startY)),
    };

    const endPoint = {
      x: Math.round(Number(endX)),
      y: Math.round(Number(endY)),
    };

    return {
      startPoint,
      endPoint,
      left: Math.min(startPoint.x, endPoint.x),
      right: Math.max(startPoint.x, endPoint.x),
      top: Math.min(startPoint.y, endPoint.y),
      bottom: Math.max(startPoint.y, endPoint.y),
    };
  }

  private getPointTarget(point: Point): 'start' | 'end' | null {
    const geometry = this.getGeometry();

    if (!geometry) {
      return null;
    }

    if (isNearPoint(point, geometry.startPoint.x, geometry.startPoint.y, 8)) {
      return 'start';
    }

    if (isNearPoint(point, geometry.endPoint.x, geometry.endPoint.y, 8)) {
      return 'end';
    }

    return null;
  }

  private isPointNearLine(point: Point): boolean {
    const geometry = this.getGeometry();

    if (!geometry) {
      return false;
    }

    return this.getDistanceToSegment(point, geometry.startPoint, geometry.endPoint) <= LINE_HIT_TOLERANCE;
  }

  private getDistanceToSegment(point: Point, startPoint: Point, endPoint: Point): number {
    const dx = endPoint.x - startPoint.x;
    const dy = endPoint.y - startPoint.y;

    if (dx === 0 && dy === 0) {
      return Math.hypot(point.x - startPoint.x, point.y - startPoint.y);
    }

    const t = Math.max(
      0,
      Math.min(1, ((point.x - startPoint.x) * dx + (point.y - startPoint.y) * dy) / (dx * dx + dy * dy)),
    );

    const projectionX = startPoint.x + t * dx;
    const projectionY = startPoint.y + t * dy;

    return Math.hypot(point.x - projectionX, point.y - projectionY);
  }

  private getTimeCoordinate(kind: TimeLabelKind): number | null {
    const anchor = kind === 'start' ? this.startAnchor : this.endAnchor;

    if (!anchor) {
      return null;
    }

    const coordinate = getXCoordinateFromTime(this.chart, anchor.time, this.series);

    return coordinate === null ? null : Number(coordinate);
  }

  private getPriceCoordinate(kind: PriceLabelKind): number | null {
    const anchor = kind === 'start' ? this.startAnchor : this.endAnchor;

    if (!anchor) {
      return null;
    }

    const coordinate = getYCoordinateFromPrice(this.series, anchor.price);

    return coordinate === null ? null : Number(coordinate);
  }

  private getTimeText(kind: TimeLabelKind): string {
    const anchor = kind === 'start' ? this.startAnchor : this.endAnchor;

    if (!anchor || typeof anchor.time !== 'number') {
      return '';
    }

    return formatDate(
      anchor.time as UTCTimestamp,
      this.displayFormat.dateFormat,
      this.displayFormat.timeFormat,
      this.displayFormat.showTime,
    );
  }

  private getPriceText(kind: PriceLabelKind): string {
    const anchor = kind === 'start' ? this.startAnchor : this.endAnchor;

    if (!anchor) {
      return '';
    }

    return formatPrice(anchor.price) ?? '';
  }
}