'use strict';

function _interopDefault (ex) { return (ex && (typeof ex === 'object') && 'default' in ex) ? ex['default'] : ex; }

var makeShadow = _interopDefault(require('shadow-callbag'));

/**

• tallbag-merge

• ---

• Tallbag factory that merges data from multiple tallbag sources. Works well
• with listenable sources, and while it may work for some pullable sources,
• it is only designed for listenable sources.
• npm install tallbag-merge
• Example:

• const interval = require('callbag-interval');

• const forEach = require('callbag-for-each');

• const merge = require('tallbag-merge');

• const source = merge(interval(100), interval(350));

• forEach(x => console.log(x))(source); // 0

•                                       // 1

•                                       // 2

•                                       // 0

•                                       // 3

•                                       // 4

•                                       // 5

•                                       // ...

*/

function merge(...sources) { return (start, sink) => { if (start !== 0) return; const n = sources.length; const sourceShadows = new Array(n); const sourceTalkbacks = new Array(n); let shadow; let startCount = 0; let endCount = 0; let ended = false; const talkback = (t, d) => { if (t === 2) ended = true; for (let i = 0; i < n; i++) sourceTalkbacks[i] && sourceTalkbacks[i](t, d); }; for (let i = 0; i < n; i++) { if (ended) return; sources[i](0, (t, d, s) => { if (t === 0) { sourceShadows[i] = s; sourceTalkbacks[i] = d; if (++startCount === 1) { shadow = makeShadow('merge', sourceShadows); sink(0, talkback, shadow); } }

    if (t === 1) {
      shadow(1, d);
      sink(1, d);
    }

    if (t === 2) {
      if (!!d) {
        ended = true;
        for (let j = 0; j < n; j++) {
          if (j !== i) sourceTalkbacks[j] && sourceTalkbacks[j](2);
        }
        sink(2, d);
      } else {
        sourceTalkbacks[i] = void 0;
        if (++endCount === n) sink(2);
      }
    }
  });
}

}; }

module.exports = merge;