var Gun = require('./index');
Gun.chain.on = function(tag, arg, eas, as){ // don't rewrite!
	var gun = this, cat = gun._, root = cat.root, act, off, id, tmp;
	if(typeof tag === 'string'){
		if(!arg){ return cat.on(tag) }
		act = cat.on(tag, arg, eas || cat, as);
		if(eas && eas.$){
			(eas.subs || (eas.subs = [])).push(act);
		}
		return gun;
	}
	var opt = arg;
	(opt = (true === opt)? {change: true} : opt || {}).not = 1; opt.on = 1;
	//opt.at = cat;
	//opt.ok = tag;
	//opt.last = {};
	var wait = {}; // can we assign this to the at instead, like in once?
	gun.get(tag, opt);
	/*gun.get(function on(data,key,msg,eve){ var $ = this;
		if(tmp = root.hatch){ // quick hack!
			if(wait[$._.id]){ return } wait[$._.id] = 1;
			tmp.push(function(){on.call($, data,key,msg,eve)});
			return;
		}; wait = {}; // end quick hack.
		tag.call($, data,key,msg,eve);
	}, opt); // TODO: PERF! Event listener leak!!!?*/
	/*
	function one(msg, eve){
		if(one.stun){ return }
		var at = msg.$._, data = at.put, tmp;
		if(tmp = at.link){ data = root.$.get(tmp)._.put }
		if(opt.not===u && u === data){ return }
		if(opt.stun===u && (tmp = root.stun) && (tmp = tmp[at.id] || tmp[at.back.id]) && !tmp.end){ // Remember! If you port this into `.get(cb` make sure you allow stun:0 skip option for `.put(`.
			tmp[id] = function(){one(msg,eve)};
			return;
		}
		//tmp = one.wait || (one.wait = {}); console.log(tmp[at.id] === ''); if(tmp[at.id] !== ''){ tmp[at.id] = tmp[at.id] || setTimeout(function(){tmp[at.id]='';one(msg,eve)},1); return } delete tmp[at.id];
		// call:
		if(opt.as){
			opt.ok.call(opt.as, msg, eve || one);
		} else {
			opt.ok.call(at.$, data, msg.get || at.get, msg, eve || one);
		}
	};
	one.at = cat;
	(cat.act||(cat.act={}))[id = String.random(7)] = one;
	one.off = function(){ one.stun = 1; if(!cat.act){ return } delete cat.act[id] }
	cat.on('out', {get: {}});*/
	return gun;
}
// Rules:
// 1. If cached, should be fast, but not read while write.
// 2. Should not retrigger other listeners, should get triggered even if nothing found.
// 3. If the same callback passed to many different once chains, each should resolve - an unsubscribe from the same callback should not effect the state of the other resolving chains, if you do want to cancel them all early you should mutate the callback itself with a flag & check for it at top of callback
Gun.chain.once = function(cb, opt){ opt = opt || {}; // avoid rewriting
	if(!cb){ return none(this,opt) }
	var gun = this, cat = gun._, root = cat.root, data = cat.put, id = String.random(7), one, tmp;
	gun.get(function(data,key,msg,eve){
		var $ = this, at = $._, one = (at.one||(at.one={}));
		if(eve.stun){ return } if('' === one[id]){ return }
		if(true === (tmp = Gun.valid(data))){ once(); return }
		if('string' == typeof tmp){ return } // TODO: BUG? Will this always load?
		clearTimeout((cat.one||'')[id]); // clear "not found" since they only get set on cat.
		clearTimeout(one[id]); one[id] = setTimeout(once, opt.wait||99); // TODO: Bug? This doesn't handle plural chains.
		function once(){
			if(!at.has && !at.soul){ at = {put: data, get: key} } // handles non-core messages.
			if(u === (tmp = at.put)){ tmp = ((msg.$$||'')._||'').put }
			if('string' == typeof Gun.valid(tmp)){ tmp = root.$.get(tmp)._.put; if(tmp === u){return} }
			if(eve.stun){ return } if('' === one[id]){ return } one[id] = '';
			if(cat.soul || cat.has){ eve.off() } // TODO: Plural chains? // else { ?.off() } // better than one check?
			cb.call($, tmp, at.get);
		};
	}, {on: 1});
	return gun;
}
function none(gun,opt,chain){
	Gun.log.once("valonce", "Chainable val is experimental, its behavior and API may change moving forward. Please play with it and report bugs and ideas on how to improve it.");
	(chain = gun.chain())._.nix = gun.once(function(data, key){ chain._.on('in', this._) });
	chain._.lex = gun._.lex; // TODO: Better approach in future? This is quick for now.
	return chain;
}

Gun.chain.off = function(){
	// make off more aggressive. Warning, it might backfire!
	var gun = this, at = gun._, tmp;
	var cat = at.back;
	if(!cat){ return }
	at.ack = 0; // so can resubscribe.
	if(tmp = cat.next){
		if(tmp[at.get]){
			delete tmp[at.get];
		} else {

		}
	}
	// TODO: delete cat.one[map.id]?
	if(tmp = cat.ask){
		delete tmp[at.get];
	}
	if(tmp = cat.put){
		delete tmp[at.get];
	}
	if(tmp = at.soul){
		delete cat.root.graph[tmp];
	}
	if(tmp = at.map){
		Object.keys(tmp).forEach(function(i,at){ at = tmp[i]; //obj_map(tmp, function(at){
			if(at.link){
				cat.root.$.get(at.link).off();
			}
		});
	}
	if(tmp = at.next){
		Object.keys(tmp).forEach(function(i,neat){ neat = tmp[i]; //obj_map(tmp, function(neat){
			neat.$.off();
		});
	}
	at.on('off', {});
	return gun;
}
var empty = {}, noop = function(){}, u;