stream-chat-react-native-core/lib/module/hooks/usePrunableMessageList.js

The official React Native and Expo components for Stream Chat, a service for building chat applications

Object.defineProperty(exports, "__esModule", {
  value: true
});
exports.usePrunableMessageList = usePrunableMessageList;
var _react = require("react");
var _useStableCallback = require("./useStableCallback");
function _createForOfIteratorHelperLoose(r, e) { var t = "undefined" != typeof Symbol && r[Symbol.iterator] || r["@@iterator"]; if (t) return (t = t.call(r)).next.bind(t); if (Array.isArray(r) || (t = _unsupportedIterableToArray(r)) || e && r && "number" == typeof r.length) { t && (r = t); var o = 0; return function () { return o >= r.length ? { done: !0 } : { done: !1, value: r[o++] }; }; } throw new TypeError("Invalid attempt to iterate non-iterable instance.\nIn order to be iterable, non-array objects must have a [Symbol.iterator]() method."); }
function _unsupportedIterableToArray(r, a) { if (r) { if ("string" == typeof r) return _arrayLikeToArray(r, a); var t = {}.toString.call(r).slice(8, -1); return "Object" === t && r.constructor && (t = r.constructor.name), "Map" === t || "Set" === t ? Array.from(r) : "Arguments" === t || /^(?:Ui|I)nt(?:8|16|32)(?:Clamped)?Array$/.test(t) ? _arrayLikeToArray(r, a) : void 0; } }
function _arrayLikeToArray(r, a) { (null == a || a > r.length) && (a = r.length); for (var e = 0, n = Array(a); e < a; e++) n[e] = r[e]; return n; }
var calculateSafeGap = maximumMessages => 0.2 * maximumMessages;
var isNearEnd = ({
  rangeConfig,
  maximumMessageLimit
}) => {
  var first = rangeConfig.first,
    last = rangeConfig.last,
    inverted = rangeConfig.inverted;
  var safeGap = calculateSafeGap(maximumMessageLimit);
  if (!inverted) return first <= safeGap;
  return last >= maximumMessageLimit - 1 - safeGap;
};
function usePrunableMessageList({
  setMessages: rawSetMessages,
  maximumMessageLimit
}) {
  var visibleRangeConfigRef = (0, _react.useRef)({
    first: 0,
    inverted: true,
    last: -1
  });
  var viewabilityChangedCallback = (0, _useStableCallback.useStableCallback)(({
    viewableItems,
    inverted = true
  }) => {
    if (!(viewableItems != null && viewableItems.length) || maximumMessageLimit == null) return;
    var first = Infinity;
    var last = -1;
    for (var _iterator = _createForOfIteratorHelperLoose(viewableItems), _step; !(_step = _iterator()).done;) {
      var v = _step.value;
      if (v.index == null) continue;
      if (v.index < first) first = v.index;
      if (v.index > last) last = v.index;
    }
    if (first !== Infinity) visibleRangeConfigRef.current = {
      first,
      inverted,
      last
    };
  });
  var setMessages = (0, _useStableCallback.useStableCallback)(channel => {
    var rangeConfig = visibleRangeConfigRef.current;
    if (maximumMessageLimit == null || channel.state.messages.length <= maximumMessageLimit || isNearEnd({
      maximumMessageLimit,
      rangeConfig
    })) {
      rawSetMessages(channel);
      return;
    }
    channel.state.pruneOldest(maximumMessageLimit);
    rawSetMessages(channel);
  });
  return {
    setMessages,
    viewabilityChangedCallback
  };
}
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