(function (global, factory) {
  typeof exports === 'object' && typeof module !== 'undefined' ? factory(exports, require('vega-util'), require('vega-expression')) :
  typeof define === 'function' && define.amd ? define(['exports', 'vega-util', 'vega-expression'], factory) :
  (global = global || self, factory(global.vega = {}, global.vega, global.vega));
}(this, (function (exports, vegaUtil, vegaExpression) { 'use strict';

  const Intersect = 'intersect';
  const Union = 'union';
  const VlMulti = 'vlMulti';
  const Or = 'or';
  const And = 'and';

  var TYPE_ENUM = 'E',
      TYPE_RANGE_INC = 'R',
      TYPE_RANGE_EXC = 'R-E',
      TYPE_RANGE_LE = 'R-LE',
      TYPE_RANGE_RE = 'R-RE',
      UNIT_INDEX = 'index:unit';

  // TODO: revisit date coercion?
  function testPoint(datum, entry) {
    var fields = entry.fields,
        values = entry.values,
        n = fields.length,
        i = 0, dval, f;

    for (; i<n; ++i) {
      f = fields[i];
      f.getter = vegaUtil.field.getter || vegaUtil.field(f.field);
      dval = f.getter(datum);

      if (vegaUtil.isDate(dval)) dval = vegaUtil.toNumber(dval);
      if (vegaUtil.isDate(values[i])) values[i] = vegaUtil.toNumber(values[i]);
      if (vegaUtil.isDate(values[i][0])) values[i] = values[i].map(vegaUtil.toNumber);

      if (f.type === TYPE_ENUM) {
        // Enumerated fields can either specify individual values (single/multi selections)
        // or an array of values (interval selections).
        if(vegaUtil.isArray(values[i]) ? values[i].indexOf(dval) < 0 : dval !== values[i]) {
          return false;
        }
      } else {
        if (f.type === TYPE_RANGE_INC) {
          if (!vegaUtil.inrange(dval, values[i])) return false;
        } else if (f.type === TYPE_RANGE_RE) {
          // Discrete selection of bins test within the range [bin_start, bin_end).
          if (!vegaUtil.inrange(dval, values[i], true, false)) return false;
        } else if (f.type === TYPE_RANGE_EXC) { // 'R-E'/'R-LE' included for completeness.
          if (!vegaUtil.inrange(dval, values[i], false, false)) return false;
        } else if (f.type === TYPE_RANGE_LE) {
          if (!vegaUtil.inrange(dval, values[i], false, true)) return false;
        }
      }
    }

    return true;
  }

  /**
   * Tests if a tuple is contained within an interactive selection.
   * @param {string} name - The name of the data set representing the selection.
   *  Tuples in the dataset are of the form
   *  {unit: string, fields: array<fielddef>, values: array<*>}.
   *  Fielddef is of the form
   *  {field: string, channel: string, type: 'E' | 'R'} where
   *  'type' identifies whether tuples in the dataset enumerate
   *  values for the field, or specify a continuous range.
   * @param {object} datum - The tuple to test for inclusion.
   * @param {string} op - The set operation for combining selections.
   *   One of 'intersect' or 'union' (default).
   * @return {boolean} - True if the datum is in the selection, false otherwise.
   */
  function selectionTest(name, datum, op) {
    var data = this.context.data[name],
        entries = data ? data.values.value : [],
        unitIdx = data ? data[UNIT_INDEX] && data[UNIT_INDEX].value : undefined,
        intersect = op === Intersect,
        n = entries.length,
        i = 0,
        entry, miss, count, unit, b;

    for (; i<n; ++i) {
      entry = entries[i];

      if (unitIdx && intersect) {
        // multi selections union within the same unit and intersect across units.
        miss = miss || {};
        count = miss[unit=entry.unit] || 0;

        // if we've already matched this unit, skip.
        if (count === -1) continue;

        b = testPoint(datum, entry);
        miss[unit] = b ? -1 : ++count;

        // if we match and there are no other units return true
        // if we've missed against all tuples in this unit return false
        if (b && unitIdx.size === 1) return true;
        if (!b && count === unitIdx.get(unit).count) return false;
      } else {
        b = testPoint(datum, entry);

        // if we find a miss and we do require intersection return false
        // if we find a match and we don't require intersection return true
        if (intersect ^ b) return b;
      }
    }

    // if intersecting and we made it here, then we saw no misses
    // if not intersecting, then we saw no matches
    // if no active selections, return false
    return n && intersect;
  }

  /**
   * Resolves selection for use as a scale domain or reads via the API.
   * @param {string} name - The name of the dataset representing the selection
   * @param {string} [op='union'] - The set operation for combining selections.
   *                 One of 'intersect' or 'union' (default).
   * @returns {object} An object of selected fields and values.
   */
  function selectionResolve(name, op, isMulti) {
    var data = this.context.data[name],
      entries = data ? data.values.value : [],
      resolved = {}, multiRes = {}, types = {},
      entry, fields, values, unit, field, res, resUnit, type, union,
      n = entries.length, i = 0, j, m;

    // First union all entries within the same unit.
    for (; i < n; ++i) {
      entry = entries[i];
      unit = entry.unit;
      fields = entry.fields;
      values = entry.values;

      for (j = 0, m = fields.length; j < m; ++j) {
        field = fields[j];
        res = resolved[field.field] || (resolved[field.field] = {});
        resUnit = res[unit] || (res[unit] = []);
        types[field.field] = type = field.type.charAt(0);
        union = ops[type + '_union'];
        res[unit] = union(resUnit, vegaUtil.array(values[j]));
      }

      // If the same multi-selection is repeated over views and projected over
      // an encoding, it may operate over different fields making it especially
      // tricky to reliably resolve it. At best, we can de-dupe identical entries
      // but doing so may be more computationally expensive than it is worth.
      // Instead, for now, we simply transform our store representation into
      // a more human-friendly one.
      if (isMulti) {
        resUnit = multiRes[unit] || (multiRes[unit] = []);
        resUnit.push(vegaUtil.array(values).reduce((obj, curr, j) => (obj[fields[j].field] = curr, obj), {}));
      }
    }

    // Then resolve fields across units as per the op.
    op = op || Union;
    Object.keys(resolved).forEach(function (field) {
      resolved[field] = Object.keys(resolved[field])
        .map(unit => resolved[field][unit])
        .reduce((acc, curr) => acc === undefined ? curr : ops[types[field] + '_' + op](acc, curr));
    });

    entries = Object.keys(multiRes);
    if (isMulti && entries.length) {
      resolved[VlMulti] = op === Union
        ? {[Or]: entries.reduce((acc, k) => (acc.push.apply(acc, multiRes[k]), acc), [])}
        : {[And]: entries.map(k => ({[Or]: multiRes[k]}))};
    }

    return resolved;
  }

  var ops = {
    E_union: function(base, value) {
      if (!base.length) return value;

      var i = 0, n = value.length;
      for (; i<n; ++i) if (base.indexOf(value[i]) < 0) base.push(value[i]);
      return base;
    },

    E_intersect: function(base, value) {
      return !base.length ? value :
        base.filter(function (v) { return value.indexOf(v) >= 0; });
    },

    R_union: function(base, value) {
      var lo = vegaUtil.toNumber(value[0]), hi = vegaUtil.toNumber(value[1]);
      if (lo > hi) {
        lo = value[1];
        hi = value[0];
      }

      if (!base.length) return [lo, hi];
      if (base[0] > lo) base[0] = lo;
      if (base[1] < hi) base[1] = hi;
      return base;
    },

    R_intersect: function(base, value) {
      var lo = vegaUtil.toNumber(value[0]), hi = vegaUtil.toNumber(value[1]);
      if (lo > hi) {
        lo = value[1];
        hi = value[0];
      }

      if (!base.length) return [lo, hi];
      if (hi < base[0] || base[1] < lo) {
        return [];
      } else {
        if (base[0] < lo) base[0] = lo;
        if (base[1] > hi) base[1] = hi;
      }
      return base;
    }
  };

  const DataPrefix = ':',
        IndexPrefix = '@';

  function selectionVisitor(name, args, scope, params) {
    if (args[0].type !== vegaExpression.Literal) vegaUtil.error('First argument to selection functions must be a string literal.');

    const data = args[0].value,
          op = args.length >= 2 && vegaUtil.peek(args).value,
          field = 'unit',
          indexName = IndexPrefix + field,
          dataName = DataPrefix + data;

    // eslint-disable-next-line no-prototype-builtins
    if (op === Intersect && !vegaUtil.hasOwnProperty(params, indexName)) {
      params[indexName] = scope.getData(data).indataRef(scope, field);
    }

    // eslint-disable-next-line no-prototype-builtins
    if (!vegaUtil.hasOwnProperty(params, dataName)) {
      params[dataName] = scope.getData(data).tuplesRef();
    }
  }

  exports.selectionResolve = selectionResolve;
  exports.selectionTest = selectionTest;
  exports.selectionVisitor = selectionVisitor;

  Object.defineProperty(exports, '__esModule', { value: true });

})));