import arcpy
from arcpy import env # for setting overall extent

layerDict = {} # dictionary of name (key) and layer (value) for all map layers in the folder

def GetExtentOfAllLayers(extents):
	# takes a list of extents and finds the overall minimum bounding rectangle (MBR)
	# This works, but can't be used as I wanted to set full extent for data frame
	# initialize overall MBR values
	XMin = 180.0 # init min values with max possible value
	XMax = -180.0 # init max values with min possible value
	YMin = 90.0
	YMax = -90.0
	# for each extent, see if the extent exceeds previous overall extent
	for e in extents:
		if e.XMin < XMin:
			XMin = e.XMin
		if e.XMax > XMax:
			XMax = e.XMax
		if e.YMin < YMin:
			YMin = e.YMin
		if e.YMax > YMax:
			YMax = e.YMax
	# instantiate and return an arcpy.Extent object with final MBR values
	return arcpy.Extent(XMin, YMin, XMax, YMax, None, None, None, None)	
def ZoomToLayer(layerName):
	mxd = arcpy.mapping.MapDocument("CURRENT")
	df = arcpy.mapping.ListDataFrames(mxd, '')[0]
	lyr = layerDict[layerName] # this code searches for a name as a dictionary key (faster)
	df.extent = lyr.getExtent()
	#Refresh Table of Contents
	arcpy.RefreshTOC()
	#Refresh Active View
	arcpy.RefreshActiveView()
def DeleteAllLayers():
	# Delete all layers
	# this is just a demo--real method would ask for confirmation
	mxd = arcpy.mapping.MapDocument("CURRENT")
	df = arcpy.mapping.ListDataFrames(mxd, '')[0]
	for i in arcpy.mapping.ListLayers(mxd , ""):
		print "Deleting layer", i
		arcpy.mapping.RemoveLayer(df , i)
		arcpy.RefreshTOC()
		arcpy.RefreshActiveView()

def BringToTop(layerName):
	mxd = arcpy.mapping.MapDocument("CURRENT")
	df = arcpy.mapping.ListDataFrames(mxd, '')[0]
	topLayer = arcpy.mapping.ListLayers(mxd , "")[0]
	for lyr in arcpy.mapping.ListLayers(mxd , ""):
		if lyr.name == layerName:
			arcpy.mapping.MoveLayer(df, topLayer, lyr, 'BEFORE')
	# Following is correct approach but broken:
	# 		print lyr.name, ' is a layer == ', isinstance(lyr, arcpy.mapping.Layer)
	# lyr = layerDict[layerName] # this code searches for a name as a dictionary key (faster)
	# print 'layer name: ', lyr.name
	# arcpy.mapping.MoveLayer(df, topLayer, lyr, 'BEFORE')
def LoadAllMyShapefiles(mypath):
	# Set the workspace for the ListFeatureClass function
	env.workspace = mypath
	# Use the ListFeatureClasses function to return a list of 
	#  all shapefiles.
	fcList = arcpy.ListFeatureClasses()
	print 'the workspace ' + env.workspace + ' contains ' + str(len(fcList)) + ' shapefiles.'
	# get the current map document and first dataframe
	mxd = arcpy.mapping.MapDocument("CURRENT")
	df = arcpy.mapping.ListDataFrames(mxd, '')[0]
	for fc in fcList: # for each shapefile found in the folder...
		fcStr = str(fc) # convert the unicode string fc to a regular string
		fcStrBase = fcStr.split('.') # split shapefilename into 2 pieces separated by . char
		pathToFC = env.workspace + '/' + fc # create a complete path that includes the shapefile
		newlayer = arcpy.mapping.Layer(pathToFC) # create a layer from the path
		layerDict[fcStrBase[0]] = newlayer # use shapefile base name as key in dictionary
		arcpy.mapping.AddLayer(df,newlayer,"BOTTOM") # add the layer to the dataframe
		
	#Refresh Table of Contents
	arcpy.RefreshTOC()
	#Refresh Active View
	arcpy.RefreshActiveView()
	print layerDict