export function get ( key ) {
	return key ? this._state[ key ] : this._state;
}

export function fire ( eventName, data ) {
	var handlers = eventName in this._handlers && this._handlers[ eventName ].slice();
	if ( !handlers ) return;

	for ( var i = 0; i < handlers.length; i += 1 ) {
		handlers[i].call( this, data );
	}
}

export function observe ( key, callback, options ) {
	var group = ( options && options.defer ) ? this._observers.post : this._observers.pre;

	( group[ key ] || ( group[ key ] = [] ) ).push( callback );

	if ( !options || options.init !== false ) {
		callback.__calling = true;
		callback.call( this, this._state[ key ] );
		callback.__calling = false;
	}

	return {
		cancel: function () {
			var index = group[ key ].indexOf( callback );
			if ( ~index ) group[ key ].splice( index, 1 );
		}
	};
}

export function observeDev ( key, callback, options ) {
	var c = ( key = '' + key ).search( /[^\w]/ );
	if ( c > -1 ) {
		var message = "The first argument to component.observe(...) must be the name of a top-level property";
		if ( c > 0 ) message += ", i.e. '" + key.slice( 0, c ) + "' rather than '" + key + "'";

		throw new Error( message );
	}

	return observe.call( this, key, callback, options );
}

export function on ( eventName, handler ) {
	if ( eventName === 'teardown' ) return this.on( 'destroy', handler );

	var handlers = this._handlers[ eventName ] || ( this._handlers[ eventName ] = [] );
	handlers.push( handler );

	return {
		cancel: function () {
			var index = handlers.indexOf( handler );
			if ( ~index ) handlers.splice( index, 1 );
		}
	};
}

export function onDev ( eventName, handler ) {
	if ( eventName === 'teardown' ) {
		console.warn( "Use component.on('destroy', ...) instead of component.on('teardown', ...) which has been deprecated and will be unsupported in Svelte 2" );
		return this.on( 'destroy', handler );
	}

	return on.call( this, eventName, handler );
}

export function set ( newState ) {
	this._set( newState );
	( this._root || this )._flush();
}

export function _flush () {
	if ( !this._renderHooks ) return;

	while ( this._renderHooks.length ) {
		var hook = this._renderHooks.pop();
		hook.fn.call( hook.context );
	}
}

export var proto = {
	get: get,
	fire: fire,
	observe: observe,
	on: on,
	set: set,
	_flush: _flush
};

export var protoDev = {
	get: get,
	fire: fire,
	observe: observeDev,
	on: onDev,
	set: set,
	_flush: _flush
};