Dropdown.coffee

`/** @jsx React.DOM */`

# Component structure:
# - DropdownButton
#  - DropdownMenu
#   - DropdownMenuItem

# refs to some utils
classSet = React.addons.classSet

# the base dropdown mixin
DropdownStateMixin =
	getInitialState: ->
		open: false
		style:
			position: 'absolute'

	componentDidMount: ->
		@setPosition()

		# handle window resize event
		$(window).on 'resize', @setPosition

	bindCloseHandler: ->
		# handle click outside event
		document.addEventListener 'click', @handleClickOutside
		document.addEventListener 'keyup', @handleKeyup

	unbindCloseHandler: ->
		document.removeEventListener 'click', @handleClickOutside
		document.removeEventListener 'keyup', @handleKeyup

	handleClickOutside: (e) ->
		@setState
			open: false
		@unbindCloseHandler()

	handleKeyup: (e) ->
		if e.keyCode is 27
			@setState
				open: false
		@unbindCloseHandler()

	handleToggle: (e) ->
		e.preventDefault()
		open = !@state.open

		@setState
			open: open

		if open is true
			@bindCloseHandler()
		else
			@unbindCloseHandler()
			
	setPosition: ->
		# ref to btn node
		$btnEl = $(@refs.button.getDOMNode())

		# props and states
		direction = @props.direction
		placement = @props.placement
		style = @state.style

		# measurements we need to calculate position
		btnWidth = $btnEl[0].offsetWidth

		if placement is 'right'
			style.right = '100%'
			style['margin-right'] = -1 * btnWidth + 'px'	
		else if placement is 'center'
			style.left = 0
			style['margin-left'] = -1 * btnWidth + 'px'	
		else
			style.left = 0

		if direction is 'up'
			style.bottom = '100%'
		else
			style.top = '100%'

		@setState
			style: style

		@adjustToViewport()

	adjustToViewport: ->
		$dropdownEl = $(@refs.menu.getDOMNode())
		dropdownMarginRight = parseInt $dropdownEl.css('margin-right')
		dropdownLeftOffset = $(@refs.button.getDOMNode()).offset().left
		dropdownWidth = $dropdownEl.width()
		style = @state.style
		winWidth = $(window).width()
		offsetDiff = 0

		# check if we've gone outside of the viewport (left)
		if dropdownLeftOffset < 0 || $dropdownEl.offset().left < 0
			offsetDiff = dropdownMarginRight - (-dropdownLeftOffset)
			if @props.placement is 'right'
				style['margin-right'] = 0
				style['left'] = 0
			else
				style['margin-left'] = 0
				style['left'] = 0

		# right
		if dropdownLeftOffset + dropdownWidth > winWidth
			offsetDiff = (dropdownLeftOffset + $dropdownEl.width()) - winWidth
			style.left = -1 * offsetDiff + 'px'

		@setState
			style: style
		
DropdownButton = React.createClass
	mixins: [DropdownStateMixin]

	render: ->	
		classes = classSet
			open: @state.open
			dropdown: true
			up: @props.direction == 'up'
			down: @props.direction == 'down'

		`<div className={classes}>
			<a href="" onClick={this.handleToggle} className="btn btn-dropdown" ref="button">
				{this.props.title} <i className="icon-caret"></i>
			</a>
			<DropdownMenu ref="menu" items={this.props.items} onSelect={this.props.onSelect} style={this.state.style} />
		</div>
		`

DropdownMenu = React.createClass
	render: ->
		`<ul className="dropdown-menu" style={this.props.style}>
			{this.props.items.map(function(item, i) {
				return (<DropdownMenuItem item={item} onSelect={this.props.onSelect} key={i} />)
			}, this)}
		</ul>
		`

DropdownMenuItem = React.createClass
	render: ->
		`<li>
		 	<a href="" onClick={this.handleClick}>{this.props.item.title}</a>
		 </li>`

	handleClick: (e) ->
		e.preventDefault()
		@props.onSelect(@props.item)

DropdownExample = React.createClass
	render: ->
		@transferPropsTo `<DropdownButton
			placement="left"
			direction="down"
			onSelect={this.handleSelect} />`
	
	handleSelect: (item) ->
		console.log 'selected', item


items = [
	{ title: 'item 1' }
	{ title: 'item 2' }
	{ title: 'item 3' }
]

React.renderComponent( `<DropdownExample items={items} title="show menu" />`, document.getElementById('content'))