import { BBox } from "geojson";
import groupBy from "lodash-es/groupBy";
import { computed, makeObservable } from "mobx";
import binarySearch from "terriajs-cesium/Source/Core/binarySearch";
import JulianDate from "terriajs-cesium/Source/Core/JulianDate";
import TimeInterval from "terriajs-cesium/Source/Core/TimeInterval";
import filterOutUndefined from "../Core/filterOutUndefined";
import isDefined from "../Core/isDefined";
import { isJsonNumber } from "../Core/Json";
import ConstantColorMap from "../Map/ColorMap/ConstantColorMap";
import DiscreteColorMap from "../Map/ColorMap/DiscreteColorMap";
import EnumColorMap from "../Map/ColorMap/EnumColorMap";
import ConstantPointSizeMap from "../Map/SizeMap/ConstantPointSizeMap";
import PointSizeMap from "../Map/SizeMap/PointSizeMap";
import ScalePointSizeMap from "../Map/SizeMap/ScalePointSizeMap";
import TableMixin from "../ModelMixins/TableMixin";
import CommonStrata from "../Models/Definition/CommonStrata";
import createCombinedModel from "../Models/Definition/createCombinedModel";
import Model from "../Models/Definition/Model";
import TableChartStyleTraits from "../Traits/TraitsClasses/Table/ChartStyleTraits";
import TableColorStyleTraits from "../Traits/TraitsClasses/Table/ColorStyleTraits";
import { LabelSymbolTraits } from "../Traits/TraitsClasses/Table/LabelStyleTraits";
import { OutlineSymbolTraits } from "../Traits/TraitsClasses/Table/OutlineStyleTraits";
import TablePointSizeStyleTraits from "../Traits/TraitsClasses/Table/PointSizeStyleTraits";
import { PointSymbolTraits } from "../Traits/TraitsClasses/Table/PointStyleTraits";
import TableStyleTraits from "../Traits/TraitsClasses/Table/StyleTraits";
import TableTimeStyleTraits from "../Traits/TraitsClasses/Table/TimeStyleTraits";
import { TrailSymbolTraits } from "../Traits/TraitsClasses/Table/TrailStyleTraits";
import TableColorMap from "./TableColorMap";
import TableColumn from "./TableColumn";
import TableColumnType from "./TableColumnType";
import TableStyleMap from "./TableStyleMap";

const DEFAULT_FINAL_DURATION_SECONDS = 3600 * 24 - 1; // one day less a second, if there is only one date.

/**
 * A style controlling how tabular data is displayed.
 */
export default class TableStyle {
  /**
   *
   * @param tableModel TableMixin catalog member
   * @param styleNumber Index of styleTraits in tableModel (if undefined, then default style will be used)
   */
  constructor(
    readonly tableModel: TableMixin.Instance,
    readonly styleNumber?: number | undefined
  ) {
    makeObservable(this);
  }

  /** Is style ready to be used.
   * This will be false if any of dependent columns are not ready
   */
  @computed
  get ready() {
    return filterOutUndefined([
      this.longitudeColumn,
      this.latitudeColumn,
      this.regionColumn,
      this.timeColumn,
      this.endTimeColumn,
      this.xAxisColumn,
      this.colorColumn,
      this.pointSizeColumn,
      ...(this.idColumns ?? [])
    ]).every((col) => col.ready);
  }

  /**
   * Gets the ID of the style.
   */
  @computed
  get id(): string {
    return (
      this.styleTraits.id ??
      (isDefined(this.styleNumber)
        ? "Style" + this.styleNumber
        : "Default Style")
    );
  }

  @computed
  get title(): string {
    return (
      this.styleTraits.title ??
      this.tableModel.tableColumns.find((col) => col.name === this.id)?.title ??
      this.id
    );
  }

  /** Hide style from "Display Variable" selector if number of colors (EnumColorMap or DiscreteColorMap) is less than 2. As a ColorMap with a single color isn't super useful. */
  @computed
  get hidden() {
    if (isDefined(this.styleTraits.hidden)) return this.styleTraits.hidden;

    if (this.colorMap instanceof ConstantColorMap) return true;

    if (
      (this.colorMap instanceof EnumColorMap ||
        this.colorMap instanceof DiscreteColorMap) &&
      this.colorMap.colors.length < 2
    )
      return true;
  }

  /**
   * Gets the {@link TableStyleTraits} for this style. The traits are derived
   * from the default styles plus this style layered on top of the default.
   */
  @computed
  get styleTraits(): Model<TableStyleTraits> {
    if (
      isDefined(this.styleNumber) &&
      this.styleNumber < this.tableModel.styles.length
    ) {
      const result = createCombinedModel(
        this.tableModel.styles[this.styleNumber],
        this.tableModel.defaultStyle
      );
      return result;
    } else {
      return this.tableModel.defaultStyle;
    }
  }

  /** Is style "custom" - that is - has the style been created/modified by the user (either directly, or indirectly through a share link).
   */
  @computed get isCustom() {
    const colorTraits = this.colorTraits.strata.get(CommonStrata.user);
    const pointSizeTraits = this.pointSizeTraits.strata.get(CommonStrata.user);
    const styleTraits = this.styleTraits.strata.get(CommonStrata.user);

    return (
      (colorTraits?.binColors ?? [])?.length > 0 ||
      (colorTraits?.binMaximums ?? [])?.length > 0 ||
      (colorTraits?.enumColors ?? [])?.length > 0 ||
      isDefined(colorTraits?.numberOfBins) ||
      isDefined(colorTraits?.minimumValue) ||
      isDefined(colorTraits?.maximumValue) ||
      isDefined(colorTraits?.regionColor) ||
      isDefined(colorTraits?.nullColor) ||
      isDefined(colorTraits?.outlierColor) ||
      pointSizeTraits ||
      styleTraits?.point ||
      styleTraits?.outline ||
      styleTraits?.label ||
      styleTraits?.trail
    );
  }

  /**
   * Gets the {@link TableColorStyleTraits} from the {@link #styleTraits}.
   * Returns a default instance of no color traits are specified explicitly.
   */
  @computed
  get colorTraits(): Model<TableColorStyleTraits> {
    return this.styleTraits.color;
  }

  /**
   * Gets the {@link TableScaleStyleTraits} from the {@link #styleTraits}.
   * Returns a default instance of no scale traits are specified explicitly.
   */
  @computed
  get pointSizeTraits(): Model<TablePointSizeStyleTraits> {
    return this.styleTraits.pointSize;
  }

  /**
   * Gets the {@link TableChartStyleTraits} from the {@link #styleTraits}.
   * Returns a default instance of no chart traits are specified explicitly.
   */
  @computed
  get chartTraits(): Model<TableChartStyleTraits> {
    return this.styleTraits.chart;
  }

  /**
   * Gets the {@link TableTimeStyleTraits} from the {@link #styleTraits}.
   * Returns a default instance if no time traits are specified explicitly.
   */
  @computed
  get timeTraits(): Model<TableTimeStyleTraits> {
    return this.styleTraits.time;
  }

  /** Compute rectangle for point (lat/long) based table styles */
  @computed get rectangle() {
    if (this.isPoints()) {
      const bounds: BBox = [Infinity, Infinity, -Infinity, -Infinity];

      if (this.longitudeColumn && this.latitudeColumn) {
        for (let i = 0; i < this.longitudeColumn.values.length; i++) {
          const long = this.longitudeColumn.valuesAsNumbers.values[i];
          const lat = this.latitudeColumn.valuesAsNumbers.values[i];
          if (isJsonNumber(long) && isJsonNumber(lat)) {
            if (bounds[0] > long) {
              bounds[0] = long;
            }
            if (bounds[1] > lat) {
              bounds[1] = lat;
            }
            if (bounds[2] < long) {
              bounds[2] = long;
            }
            if (bounds[3] < lat) {
              bounds[3] = lat;
            }
          }
        }
      }

      // If bbox has no width or height - add crude buffer of .2 degrees
      if (bounds[0] === bounds[2]) {
        bounds[0] -= 0.1;
        bounds[2] += 0.1;
      }

      if (bounds[1] === bounds[3]) {
        bounds[1] -= 0.1;
        bounds[3] += 0.1;
      }

      if (
        bounds[0] !== Infinity &&
        bounds[1] !== Infinity &&
        bounds[2] !== -Infinity &&
        bounds[3] !== -Infinity
      )
        return {
          west: bounds[0],
          south: bounds[1],
          east: bounds[2],
          north: bounds[3]
        };
    }
  }

  /**
   * Gets the longitude column for this style, if any.
   */
  @computed
  get longitudeColumn(): TableColumn | undefined {
    return this.resolveColumn(this.styleTraits.longitudeColumn);
  }

  /**
   * Gets the latitude column for this style, if any.
   */
  @computed
  get latitudeColumn(): TableColumn | undefined {
    return this.resolveColumn(this.styleTraits.latitudeColumn);
  }

  /**
   * Gets the region column for this style, if any.
   */
  @computed
  get regionColumn(): TableColumn | undefined {
    if (this.styleTraits.regionColumn === null) return;
    return this.resolveColumn(this.styleTraits.regionColumn);
  }

  /**
   * Gets the columns that together constitute the id, eg: ["lat", "lon"] for
   * fixed features or ["id"].
   */
  @computed
  get idColumns(): TableColumn[] | undefined {
    const idColumns = filterOutUndefined(
      this.timeTraits.idColumns
        ? this.timeTraits.idColumns.map((name) => this.resolveColumn(name))
        : []
    );
    return idColumns.length > 0 ? idColumns : undefined;
  }

  /**
   * Gets the time column for this style, if any.
   */
  @computed
  get timeColumn(): TableColumn | undefined {
    return this.timeTraits.timeColumn === null
      ? undefined
      : this.resolveColumn(this.timeTraits.timeColumn);
  }

  /**
   * Gets the end time column for this style, if any.
   */
  @computed
  get endTimeColumn(): TableColumn | undefined {
    return this.resolveColumn(this.timeTraits.endTimeColumn);
  }

  /**
   * Gets the chart X-axis column for this style, if any.
   */
  @computed
  get xAxisColumn(): TableColumn | undefined {
    return this.resolveColumn(this.chartTraits.xAxisColumn);
  }

  /**
   * Gets the color column for this style, if any.
   */
  @computed
  get colorColumn(): TableColumn | undefined {
    return this.resolveColumn(this.colorTraits.colorColumn);
  }

  /**
   * Gets the scale column for this style, if any.
   */
  @computed
  get pointSizeColumn(): TableColumn | undefined {
    const col = this.resolveColumn(this.pointSizeTraits.pointSizeColumn);
    if (col?.type === TableColumnType.scalar) return col;
  }

  /**
   * Determines if this style is visualized as points on a map.
   */
  isPoints(): this is {
    readonly longitudeColumn: TableColumn;
    readonly latitudeColumn: TableColumn;
  } {
    return (
      this.longitudeColumn !== undefined && this.latitudeColumn !== undefined
    );
  }

  /**
   * Determines if this style is visualized as time varying points tracked by id
   */
  isTimeVaryingPointsWithId(): this is {
    readonly longitudeColumn: TableColumn;
    readonly latitudeColumn: TableColumn;
    readonly idColumns: TableColumn[];
    readonly timeColumn: TableColumn;
    readonly timeIntervals: (JulianDate | null)[];
  } {
    return (
      this.longitudeColumn !== undefined &&
      this.latitudeColumn !== undefined &&
      this.idColumns !== undefined &&
      this.timeColumn !== undefined &&
      this.timeIntervals !== undefined &&
      this.moreThanOneTimeInterval
    );
  }

  /**
   * Determines if this style is visualized as regions on a map.
   */
  isRegions(): this is { readonly regionColumn: TableColumn } {
    return this.regionColumn !== undefined;
  }

  /**
   * Determines if this style is visualized on a chart.
   */
  isChart(): this is {
    readonly xAxisColumn: TableColumn;
  } {
    return this.xAxisColumn !== undefined && this.chartTraits.lines.length > 0;
  }

  /** Style isSampled by default. TimeTraits.isSampled will be used if defined. If not, and color column is binary - isSampled will be false. */
  @computed get isSampled() {
    if (isDefined(this.timeTraits.isSampled)) return this.timeTraits.isSampled;
    if (isDefined(this.colorColumn) && this.colorColumn.isScalarBinary)
      return false;
    return true;
  }

  @computed get tableColorMap() {
    return new TableColorMap(
      this.tableModel.name ?? this.tableModel.uniqueId,
      this.colorColumn,
      this.colorTraits
    );
  }

  @computed get colorMap() {
    return this.tableColorMap.colorMap;
  }

  @computed get pointStyleMap() {
    return new TableStyleMap<PointSymbolTraits>(
      this.tableModel,
      this.styleTraits,
      "point"
    );
  }

  @computed get outlineStyleMap() {
    return new TableStyleMap<OutlineSymbolTraits>(
      this.tableModel,
      this.styleTraits,
      "outline"
    );
  }

  @computed get trailStyleMap() {
    return new TableStyleMap<TrailSymbolTraits>(
      this.tableModel,
      this.styleTraits,
      "trail"
    );
  }

  @computed get labelStyleMap() {
    return new TableStyleMap<LabelSymbolTraits>(
      this.tableModel,
      this.styleTraits,
      "label"
    );
  }

  @computed
  get pointSizeMap(): PointSizeMap {
    const pointSizeColumn = this.pointSizeColumn;
    const pointSizeTraits = this.pointSizeTraits;

    if (pointSizeColumn && pointSizeColumn.type === TableColumnType.scalar) {
      const maximum = pointSizeColumn.valuesAsNumbers.maximum;
      const minimum = pointSizeColumn.valuesAsNumbers.minimum;

      if (isDefined(maximum) && isDefined(minimum) && maximum !== minimum) {
        return new ScalePointSizeMap(
          minimum,
          maximum,
          pointSizeTraits.nullSize,
          pointSizeTraits.sizeFactor,
          pointSizeTraits.sizeOffset
        );
      }
    }

    // can't scale point size by values in this column, so use same point size for every value
    return new ConstantPointSizeMap(pointSizeTraits.sizeOffset);
  }

  /**
   * Returns a `TimeInterval` for each row in the table.
   */
  @computed
  get timeIntervals(): (TimeInterval | null)[] | undefined {
    const timeColumn = this.timeColumn;

    if (timeColumn === undefined) {
      return;
    }

    const lastDate = timeColumn.valuesAsJulianDates.maximum;

    const intervals: (TimeInterval | null)[] = new Array(
      timeColumn.valuesAsJulianDates.values.length
    ).fill(null);

    for (let i = 0; i < timeColumn.valuesAsJulianDates.values.length; i++) {
      const date = timeColumn.valuesAsJulianDates.values[i];

      const startDate = this.startJulianDates?.[i];
      const finishDate = this.finishJulianDates?.[i];

      if (!date || !startDate || !finishDate) continue;

      intervals[i] = new TimeInterval({
        start: startDate,
        stop: finishDate,
        isStopIncluded: JulianDate.equals(finishDate, lastDate),
        data: date
      });
    }
    return intervals;
  }

  /** Is there more than one unique time interval */
  @computed get moreThanOneTimeInterval() {
    if (this.timeIntervals) {
      // Find first non-null time interval
      const firstInterval = this.timeIntervals?.find((t) => t) as
        | TimeInterval
        | undefined;
      if (firstInterval) {
        // Does there exist an interval which is different from firstInterval (that is to say, does there exist at least two unique intervals)
        return !!this.timeIntervals?.find(
          (t) =>
            t &&
            (!firstInterval.start.equals(t.start) ||
              !firstInterval.stop.equals(t.stop))
        );
      }
    }
    return false;
  }

  /**
   * Returns a start date for each row in the table.
   * If `timeTraits.spreadStartTime` is true - the start dates will be the earliest value for all features (eg sensor IDs) - even if the time value is **after** the earliest time step. This means that at time step 0, all features will be displayed.
   */
  @computed
  private get startJulianDates(): (JulianDate | null)[] | undefined {
    const timeColumn = this.timeColumn;
    if (timeColumn === undefined) {
      return;
    }

    const firstDate = timeColumn.valuesAsJulianDates.minimum;

    if (!firstDate) return [];

    // Create a new array which will be filled by rowGroups (this will exclude dates which don't have rowGroup (eg invalid regions))
    const filteredStartDates: (JulianDate | null)[] = new Array(
      timeColumn.valuesAsJulianDates.values.length
    ).fill(null);

    for (let i = 0; i < this.rowGroups.length; i++) {
      const rowIds = this.rowGroups[i][1];

      // Copy over valid rows
      for (let j = 0; j < rowIds.length; j++) {
        filteredStartDates[rowIds[j]] =
          timeColumn.valuesAsJulianDates.values[rowIds[j]];
      }

      if (this.timeTraits.spreadStartTime) {
        // Find row ID with earliest date in this rowGroup
        const firstRowId = rowIds
          .filter((id) => filteredStartDates[id])
          .sort((idA, idB) =>
            JulianDate.compare(
              filteredStartDates[idA]!,
              filteredStartDates[idB]!
            )
          )[0];
        // Set it to earliest date in the entire column
        if (isDefined(firstRowId)) filteredStartDates[firstRowId] = firstDate;
      }
    }

    return filteredStartDates;
  }

  /**
   * Returns a finish date for each row in the table.
   */
  @computed
  private get finishJulianDates(): (JulianDate | null)[] | undefined {
    if (this.endTimeColumn) {
      return this.endTimeColumn.valuesAsJulianDates.values;
    }

    const timeColumn = this.timeColumn;
    if (timeColumn === undefined) {
      return;
    }

    const startDates = timeColumn.valuesAsJulianDates.values;
    const finishDates: (JulianDate | null)[] = new Array(
      startDates.length
    ).fill(null);

    // If displayDuration trait is set, use that to set finish date
    if (this.timeTraits.displayDuration !== undefined) {
      for (let i = 0; i < startDates.length; i++) {
        const date = startDates[i];
        if (date) {
          finishDates[i] = JulianDate.addMinutes(
            date,
            this.timeTraits.displayDuration!,
            new JulianDate()
          );
        }
      }

      return finishDates;
    }

    // Otherwise estimate a final duration value to calculate the end date for groups
    // that have only one row. Fallback to a global default if an estimate
    // cannot be found.
    for (let i = 0; i < this.rowGroups.length; i++) {
      const rowIds = this.rowGroups[i][1];
      const sortedStartDates = sortedUniqueDates(
        rowIds.map((id) => timeColumn.valuesAsJulianDates.values[id])
      );
      const finalDuration =
        estimateFinalDurationSeconds(sortedStartDates) ??
        DEFAULT_FINAL_DURATION_SECONDS;

      const startDatesForGroup = rowIds.map((id) => startDates[id]);
      const finishDatesForGroup = this.calculateFinishDatesFromStartDates(
        startDatesForGroup,
        finalDuration
      );
      for (let j = 0; j < finishDatesForGroup.length; j++) {
        finishDates[rowIds[j]] = finishDatesForGroup[j];
      }
    }

    return finishDates;
  }

  /** Columns used in rowGroups - idColumns, latitude/longitude columns or region column
   */
  @computed get groupByColumns() {
    let groupByCols = this.idColumns;

    if (!groupByCols) {
      // If points use lat long
      if (this.latitudeColumn && this.longitudeColumn) {
        groupByCols = [this.latitudeColumn, this.longitudeColumn];
        // If region - use region col
      } else if (this.regionColumn) groupByCols = [this.regionColumn];
    }

    return groupByCols ?? [];
  }

  /** Get rows grouped by id.
   */
  @computed get rowGroups() {
    const tableRowIds = this.tableModel.rowIds;

    return (
      Object.entries(
        groupBy(tableRowIds, (rowId) =>
          createRowGroupId(rowId, this.groupByColumns)
        )
      )
        // Filter out bad IDs
        .filter((value) => value[0] !== "")
    );
  }

  @computed get numberFormatOptions(): Intl.NumberFormatOptions | undefined {
    const colorColumn = this.colorColumn;
    if (colorColumn?.traits?.format)
      return colorColumn?.traits?.format as Intl.NumberFormatOptions;

    const min =
      this.tableColorMap.minimumValue ?? colorColumn?.valuesAsNumbers.minimum;
    const max =
      this.tableColorMap.maximumValue ?? colorColumn?.valuesAsNumbers.maximum;

    if (
      colorColumn &&
      colorColumn.type === TableColumnType.scalar &&
      isDefined(min) &&
      isDefined(max)
    ) {
      if (max - min === 0) return;

      // We want to show fraction digits depending on how small difference is between min and max.
      // This also takes into consideration the default number of legend items - 7
      // So we add an extra digit
      // For example:
      // - if difference is 10 - we want to show one fraction digit
      // - if difference is 1 - we want to show two fraction digits
      // - if difference is 0.1 - we want to show three fraction digits

      // log_10(20/x) achieves this (where x is difference between min and max)
      // https://www.wolframalpha.com/input/?i=log_10%2820%2Fx%29
      // We use 20 here instead of 10 to give us a more conservative value (that is, we may show an extra fraction digit even if it is not needed)
      // So when x >= 20 - we will not show any fraction digits

      // Clamp values between 0 and 5
      const fractionDigits = Math.max(
        0,
        Math.min(5, Math.ceil(Math.log10(20 / Math.abs(max - min))))
      );

      return {
        maximumFractionDigits: fractionDigits,
        minimumFractionDigits: fractionDigits
      };
    }
  }

  /**
   * Computes an and end date for each given start date. The end date for a
   * given start date is the next higher date in the input. To compute the end
   * date for the last date in the input, we estimate a duration based on the
   * average interval between dates in the input. If the input has only one
   * date, then an estimate cannot be made, in that case we use the
   * `defaultFinalDurationSeconds` to compute the end date.
   */
  private calculateFinishDatesFromStartDates(
    startDates: (JulianDate | null | undefined)[],
    defaultFinalDurationSeconds: number
  ) {
    const sortedStartDates: JulianDate[] = sortedUniqueDates(startDates);

    // Calculate last date based on if spreadFinishTime is true:
    // - If true, use the maximum date in the entire timeColumn
    // - If false, use the last date in startDates - which is the last date in the current row group
    const lastDate =
      this.timeTraits.spreadFinishTime &&
      this.timeColumn?.valuesAsJulianDates.maximum
        ? this.timeColumn.valuesAsJulianDates.maximum
        : sortedStartDates[sortedStartDates.length - 1];

    const finishDates: (JulianDate | null)[] = new Array(
      startDates.length
    ).fill(null);

    for (let i = 0; i < startDates.length; i++) {
      const date = startDates[i];
      if (!date) {
        continue;
      }

      const nextDateIndex = binarySearch(
        sortedStartDates,
        date,
        (d1: JulianDate, d2: JulianDate) => JulianDate.compare(d1, d2)
      );
      const nextDate = sortedStartDates[nextDateIndex + 1];
      if (nextDate) {
        finishDates[i] = nextDate;
      } else {
        // This is the last date in the row, so calculate a final date
        const finalDurationSeconds =
          estimateFinalDurationSeconds(sortedStartDates) ||
          defaultFinalDurationSeconds;
        finishDates[i] = addSecondsToDate(lastDate, finalDurationSeconds);
      }
    }

    return finishDates;
  }

  resolveColumn(name: string | undefined): TableColumn | undefined {
    if (name === undefined) {
      return undefined;
    }
    return this.tableModel.tableColumns.find((column) => column.name === name);
  }
}

/** Create row group ID by concatenating values for columns */
export function createRowGroupId(rowId: number, columns: TableColumn[]) {
  return columns
    .map((col) => {
      // If using region column as ID - only use valid regions
      if (col.type === TableColumnType.region) {
        return col.valuesAsRegions.regionIds[rowId];
      }
      return col.values[rowId];
    })
    .join("-");
}

/**
 * Returns an array of sorted unique dates
 */
function sortedUniqueDates(
  dates: Readonly<(JulianDate | null | undefined)[]>
): JulianDate[] {
  const nonNullDates: JulianDate[] = dates.filter((d): d is JulianDate => !!d);
  return nonNullDates
    .sort((a, b) => JulianDate.compare(a, b))
    .filter((d, i, ds) => i === 0 || !JulianDate.equals(d, ds[i - 1]));
}

function addSecondsToDate(date: JulianDate, seconds: number) {
  return JulianDate.addSeconds(date, seconds, new JulianDate());
}

function estimateFinalDurationSeconds(
  sortedDates: JulianDate[]
): number | undefined {
  const n = sortedDates.length;
  if (n > 1) {
    const finalDurationSeconds =
      JulianDate.secondsDifference(sortedDates[n - 1], sortedDates[0]) /
      (n - 1);
    return finalDurationSeconds;
  }
}