# amf_controller is a semi-standalone API for Flash clients, particularly 
# Potlatch. All interaction between Potlatch (as a .SWF application) and the 
# OSM database takes place using this controller. Messages are 
# encoded in the Actionscript Message Format (AMF).
#
# Helper functions are in /lib/potlatch.
#
# Author::	editions Systeme D / Richard Fairhurst 2004-2008
# Licence::	public domain.
#
# == General structure
#
# Apart from the talk method (which distributes the requests from the
# AMF message), each method generally takes arguments in the order they were 
# sent by the Potlatch SWF. Do not assume typing has been preserved. Methods 
# all return an array to the SWF.
# 
# == Debugging
# 
# Any method that returns a status code (0 for ok) can also send:
#	return(-1,"message")		<-- just puts up a dialogue
#	return(-2,"message")		<-- also asks the user to e-mail me
# 
# To write to the Rails log, use RAILS_DEFAULT_LOGGER.info("message").
#
# == To do
# 
# - Check authentication
# - Check the right things are being written to the database!

class AmfController < ApplicationController
  require 'stringio'

  include Potlatch

  session :off
  before_filter :check_write_availability

  # Main AMF handler: processes the raw AMF string (using AMF library) and
  # calls each action (private method) accordingly.
  
  def talk
	req=StringIO.new(request.raw_post+0.chr)	# Get POST data as request
												# (cf http://www.ruby-forum.com/topic/122163)
	req.read(2)									# Skip version indicator and client ID
	results={}									# Results of each body
	renumberednodes={}							# Shared across repeated putways
	renumberedways={}							# Shared across repeated putways

	# Parse request

	headers=AMF.getint(req)					# Read number of headers

	headers.times do						# Read each header
	  name=AMF.getstring(req)				#  |
	  req.getc				   				#  | skip boolean
	  value=AMF.getvalue(req)				#  |
	  header["name"]=value					#  |
	end

	bodies=AMF.getint(req)					# Read number of bodies
	bodies.times do							# Read each body
	  message=AMF.getstring(req)			#  | get message name
	  index=AMF.getstring(req)				#  | get index in response sequence
	  bytes=AMF.getlong(req)				#  | get total size in bytes
	  args=AMF.getvalue(req)				#  | get response (probably an array)

	  case message
		when 'getpresets';			results[index]=AMF.putdata(index,getpresets())
		when 'whichways';			results[index]=AMF.putdata(index,whichways(*args))
		when 'whichways_deleted';	results[index]=AMF.putdata(index,whichways_deleted(*args))
		when 'getway';				results[index]=AMF.putdata(index,getway(args[0].to_i))
		when 'getrelation';			results[index]=AMF.putdata(index,getrelation(args[0].to_i))
		when 'getway_old';			results[index]=AMF.putdata(index,getway_old(args[0].to_i,args[1].to_i))
		when 'getway_history';		results[index]=AMF.putdata(index,getway_history(args[0].to_i))
		when 'putway';				r=putway(renumberednodes,*args)
									renumberednodes=r[3]
									if r[1] != r[2]
									  renumberedways[r[1]] = r[2]
									end
									results[index]=AMF.putdata(index,r)
		when 'putrelation';			results[index]=AMF.putdata(index,putrelation(renumberednodes, renumberedways, *args))
		when 'deleteway';			results[index]=AMF.putdata(index,deleteway(args[0],args[1].to_i))
		when 'putpoi';				results[index]=AMF.putdata(index,putpoi(*args))
		when 'getpoi';				results[index]=AMF.putdata(index,getpoi(args[0].to_i))
	  end
	end

	# Write out response

	a,b=results.length.divmod(256)
	render :content_type => "application/x-amf", :text => proc { |response, output| 
	  output.write 0.chr+0.chr+0.chr+0.chr+a.chr+b.chr
	  results.each do |k,v|
		output.write(v)
	  end
	}
  end

  private

  # Return presets (default tags, localisation etc.):
  # uses POTLATCH_PRESETS global, set up in OSM::Potlatch.

  def getpresets() #:doc:
	return POTLATCH_PRESETS
  end

  # Find all the ways, POI nodes (i.e. not part of ways), and relations
  # in a given bounding box. Nodes are returned in full; ways and relations 
  # are IDs only. 

  def whichways(xmin,ymin,xmax,ymax) #:doc:
	xmin-=0.01; ymin-=0.01
	xmax+=0.01; ymax+=0.01

	if POTLATCH_USE_SQL then
	  way_ids=sql_find_way_ids_in_area(xmin,ymin,xmax,ymax)
	  points=sql_find_pois_in_area(xmin,ymin,xmax,ymax)
	  relation_ids=sql_find_relations_in_area_and_ways(xmin,ymin,xmax,ymax,way_ids)
	else
	  # find the way ids in an area
	  nodes_in_area = Node.find_by_area(ymin, xmin, ymax, xmax, :conditions => "current_nodes.visible = 1", :include => :ways)
	  way_ids = nodes_in_area.collect { |node| node.way_ids }.flatten.uniq

	  # find the node ids in an area that aren't part of ways
	  nodes_not_used_in_area = nodes_in_area.select { |node| node.ways.empty? }
	  points = nodes_not_used_in_area.collect { |n| [n.id, n.lon, n.lat, n.tags_as_hash] }

	  # find the relations used by those nodes and ways
	  relations = nodes_in_area.collect { |node| node.containing_relations.visible }.flatten +
	              way_ids.collect { |id| Way.find(id).containing_relations.visible }.flatten
	  relation_ids = relations.collect { |relation| relation.id }.uniq
	end

	[way_ids,points,relation_ids]
  end

  # Find deleted ways in current bounding box (similar to whichways, but ways
  # with a deleted node only - not POIs or relations).

  def whichways_deleted(xmin,ymin,xmax,ymax) #:doc:
	xmin-=0.01; ymin-=0.01
	xmax+=0.01; ymax+=0.01

	nodes_in_area = Node.find_by_area(ymin, xmin, ymax,xmax, :conditions => "current_nodes.visible=0 AND current_ways.visible=0", :include => :ways_via_history )
	way_ids = nodes_in_area.collect { |node| node.ways_via_history_ids }.flatten.uniq
	[way_ids]
  end

  # Get a way including nodes and tags.
  # Returns 0 (success), a Potlatch-style array of points, and a hash of tags.

  def getway(wayid) #:doc:
	if POTLATCH_USE_SQL then
	  points=sql_get_nodes_in_way(wayid)
	  tags=sql_get_tags_in_way(wayid)
	else
	  # Ideally we would do ":include => :nodes" here but if we do that
	  # then rails only seems to return the first copy of a node when a
	  # way includes a node more than once
	  points = []
	  way = Way.find(wayid)
	  way.nodes.each do |node|
	    points << [node.lon, node.lat, node.id, nil, node.tags_as_hash]
	  end
	  tags=way.tags
	end
	[wayid,points,tags]
  end

  # Get an old version of a way, and all constituent nodes.
  #
  # For undelete (version=0), always uses the most recent version of each node, 
  # even if it's moved.  For revert (version=1+), uses the node in existence 
  # at the time, generating a new id if it's still visible and has been moved/
  # retagged.

  def getway_old(id,version) #:doc:
	if version<0
	  old_way = OldWay.find(:first, :conditions => ['visible=1 AND id=?', id], :order => 'version DESC')
	  points = old_way.get_nodes_undelete
	else
	  old_way = OldWay.find(:first, :conditions => ['id=? AND version=?', id, version])
	  points = old_way.get_nodes_revert
	end
	old_way.tags['history']="Retrieved from v#{old_way.version}"
	[0,id,points,old_way.tags,old_way.version]
  end
  
  # Find history of a way. Returns an array of previous versions.

  def getway_history(wayid) #:doc:
	history=[]
	way=Way.find(wayid)
	way.old_ways.each do |old_way|
	  if old_way.user.data_public then user=old_way.user.display_name else user='anonymous' end
	  history<<[old_way.version,old_way.timestamp.strftime("%d %b %Y, %H:%M"),old_way.visible ? 1 : 0,user]
	end
	[history]
  end

  # Get a relation with all tags and members.
  # Returns:
  # 0. relation id,
  # 1. hash of tags,
  # 2. list of members.
  
  def getrelation(relid) #:doc:
	rel = Relation.find(relid)
	[relid,rel.tags,rel.members]
  end

  # Save a relation.
  # Returns
  # 0. 0 (success),
  # 1. original relation id (unchanged),
  # 2. new relation id.

  def putrelation(renumberednodes, renumberedways, usertoken,relid,tags,members,visible) #:doc:
	uid=getuserid(usertoken)
	if !uid then return -1,"You are not logged in, so the point could not be saved." end

	relid = relid.to_i
	visible = visible.to_i

	# create a new relation, or find the existing one
	if relid <= 0
	  rel = Relation.new
	else
	  rel = Relation.find(relid)
	end

	# check the members are all positive, and correctly type
	typedmembers = []
	members.each do |m|
	  mid = m[1].to_i
	  if mid < 0
		mid = renumberednodes[mid] if m[0] == 'node'
		mid = renumberedways[mid] if m[0] == 'way'
		if mid < 0
		  return -2, "Negative ID unresolved"
		end
	  end
	  typedmembers << [m[0], mid, m[2]]
	end

	# assign new contents
	rel.members = typedmembers
	rel.tags = tags
	rel.visible = visible
	rel.user_id = uid

	# check it then save it
	# BUG: the following is commented out because it always fails on my
	#  install. I think it's a Rails bug.

	#if !rel.preconditions_ok?
	#  return -2, "Relation preconditions failed"
	#else
	  rel.save_with_history!
	#end

	[0,relid,rel.id]
  end

  # Save a way to the database, including all nodes. Any nodes in the previous
  # version and no longer used are deleted.
  # 
  # Returns:
  # 0. '0' (code for success),
  # 1. original way id (unchanged),
  # 2. new way id,
  # 3. hash of renumbered nodes (old id=>new id)

  def putway(renumberednodes,usertoken,originalway,points,attributes) #:doc:

	# -- Initialise and carry out checks
	
	uid=getuserid(usertoken)
	if !uid then return -1,"You are not logged in, so the way could not be saved." end
	originalway=originalway.to_i

	points.each do |a|
	  if a[2]==0 or a[2].nil? then return -2,"Server error - node with id 0 found in way #{originalway}." end
	  if a[1]==90 then return -2,"Server error - node with lat -90 found in way #{originalway}." end
	end

	if points.length<2 then return -2,"Server error - way is only #{points.length} points long." end

	# -- Get unique nodes

	if originalway<0
	  way=Way.new
	  uniques=[]
	else
	  way=Way.find(originalway)
	  uniques=way.unshared_node_ids
	end

	# -- Compare nodes and save changes to any that have changed

	nodes=[]

	points.each do |n|
	  lon=n[0].to_f
	  lat=n[1].to_f
	  id =n[2].to_i
	  savenode=false
	  if renumberednodes[id]
	    id=renumberednodes[id]
	  elsif id<0
		# Create new node
		node=Node.new
		savenode=true
	  else
		node=Node.find(id)
		if (!fpcomp(lat,node.lat) or !fpcomp(lon,node.lon) or \
			Tags.join(n[4])!=node.tags or node.visible==0)
		  savenode=true
		end
	  end
	  if savenode
		node.user_id=uid
	    node.lat=lat; node.lon=lon
	    node.tags=Tags.join(n[4])
	    node.visible=true
	    node.save_with_history!
		if id!=node.id
		  renumberednodes[id]=node.id
		  id=node.id
	    end
	  end
	  uniques=uniques-[id]
	  nodes.push(id)
	end

	# -- Delete any unique nodes
	
	uniques.each do |n|
	  deleteitemrelations(n,'node')
	  node=Node.find(n)
	  node.user_id=uid
	  node.visible=false
	  node.save_with_history!
	end

	# -- Save revised way

	way.tags=attributes
	way.nds=nodes
	way.user_id=uid
	way.visible=true
	way.save_with_history!

	[0,originalway,way.id,renumberednodes]
  end

  # Save POI to the database.
  # Refuses save if the node has since become part of a way.
  # Returns:
  # 0. 0 (success),
  # 1. original node id (unchanged),
  # 2. new node id.

  def putpoi(usertoken,id,lon,lat,tags,visible) #:doc:
	uid=getuserid(usertoken)
	if !uid then return -1,"You are not logged in, so the point could not be saved." end

	id=id.to_i
	visible=(visible.to_i==1)

	if (id>0) then
	  node=Node.find(id)
	  if !visible then
	    unless node.ways.empty? then return -1,"The point has since become part of a way, so you cannot save it as a POI." end
	    deleteitemrelations(id,'node')
	  end
	else
	  node=Node.new
	end

	node.user_id = uid
	node.latitude = (lat*10000000).round
	node.longitude = (lon*10000000).round
	node.tags = Tags.join(tags)
	node.visible=visible
	node.save_with_history!
	newid=node.id
	[0,id,newid]
  end

  # Read POI from database
  # (only called on revert: POIs are usually read by whichways).
  #
  # Returns array of id, long, lat, hash of tags.

  def getpoi(id) #:doc:
	n = Node.find(id)
	if n
	  return [n.id, n.lon, n.lat, n.tags_as_hash]
	else
	  return [nil,nil,nil,'']
	end
  end

  # Delete way and all constituent nodes. Also removes from any relations.
  # Returns 0 (success), unchanged way id.

  def deleteway(usertoken,way_id) #:doc:
	uid=getuserid(usertoken)
	if !uid then return -1,"You are not logged in, so the way could not be deleted." end

	# FIXME: would be good not to make two history entries when removing
	#		 two nodes from the same relation
	user = User.find(uid)
	way = Way.find(way_id)
	way.unshared_node_ids.each do |n|
	  deleteitemrelations(n,'node')
	end

	way.delete_with_relations_and_nodes_and_history(user)  
	return [0,way_id]
  end


  # ====================================================================
  # Support functions

  # Remove a node or way from all relations

  def deleteitemrelations(objid,type) #:doc:
	relationids = RelationMember.find(:all, :conditions => ['member_type=? and member_id=?', type, objid]).collect { |ws| ws.id }.uniq
	relationids.each do |relid|
	  rel=Relation.find(relid)
	  rel.members.delete_if {|x| x[0]==type and x[1]==objid}
	  rel.save_with_history!
	end
  end

  # Break out node tags into a hash
  # (should become obsolete as of API 0.6)

  def tagstring_to_hash(a) #:doc:
	tags={}
	Tags.split(a) do |k, v|
	  tags[k]=v
	end
	tags
  end

  # Authenticate token
  # (could be removed if no-one uses the username+password form)

  def getuserid(token) #:doc:
	if (token =~ /^(.+)\+(.+)$/) then
	  user = User.authenticate(:username => $1, :password => $2)
	else
	  user = User.authenticate(:token => token)
	end

	return user ? user.id : nil;
  end

  # Compare two floating-point numbers to within 0.0000001

  def fpcomp(a,b) #:doc:
	return ((a/0.0000001).round==(b/0.0000001).round)
  end


  # ====================================================================
  # Alternative SQL queries for getway/whichways

  def sql_find_way_ids_in_area(xmin,ymin,xmax,ymax)
	sql=<<-EOF
  SELECT DISTINCT current_way_nodes.id AS wayid
		FROM current_way_nodes
  INNER JOIN current_nodes ON current_nodes.id=current_way_nodes.node_id
  INNER JOIN current_ways  ON current_ways.id =current_way_nodes.id
	   WHERE current_nodes.visible=1 
		 AND current_ways.visible=1 
		 AND #{OSM.sql_for_area(ymin, xmin, ymax, xmax, "current_nodes.")}
	EOF
	return ActiveRecord::Base.connection.select_all(sql).collect { |a| a['wayid'].to_i }
  end
	
  def sql_find_pois_in_area(xmin,ymin,xmax,ymax)
	sql=<<-EOF
		  SELECT current_nodes.id,current_nodes.latitude*0.0000001 AS lat,current_nodes.longitude*0.0000001 AS lon,current_nodes.tags 
			FROM current_nodes 
 LEFT OUTER JOIN current_way_nodes cwn ON cwn.node_id=current_nodes.id 
		   WHERE current_nodes.visible=1
			 AND cwn.id IS NULL
			 AND #{OSM.sql_for_area(ymin, xmin, ymax, xmax, "current_nodes.")}
	EOF
	return ActiveRecord::Base.connection.select_all(sql).collect { |n| [n['id'].to_i,n['lon'].to_f,n['lat'].to_f,tagstring_to_hash(n['tags'])] }
  end
	
  def sql_find_relations_in_area_and_ways(xmin,ymin,xmax,ymax,way_ids)
	# ** It would be more Potlatchy to get relations for nodes within ways
	#    during 'getway', not here
	sql=<<-EOF
	  SELECT DISTINCT cr.id AS relid 
		FROM current_relations cr
  INNER JOIN current_relation_members crm ON crm.id=cr.id 
  INNER JOIN current_nodes cn ON crm.member_id=cn.id AND crm.member_type='node' 
	   WHERE #{OSM.sql_for_area(ymin, xmin, ymax, xmax, "cn.")}
	EOF
	unless way_ids.empty?
	  sql+=<<-EOF
	   UNION
	  SELECT DISTINCT cr.id AS relid
		FROM current_relations cr
  INNER JOIN current_relation_members crm ON crm.id=cr.id
	   WHERE crm.member_type='way' 
		 AND crm.member_id IN (#{way_ids.join(',')})
	  EOF
	end
	return ActiveRecord::Base.connection.select_all(sql).collect { |a| a['relid'].to_i }.uniq
  end
	
  def sql_get_nodes_in_way(wayid)
	points=[]
	sql=<<-EOF
		SELECT latitude*0.0000001 AS lat,longitude*0.0000001 AS lon,current_nodes.id,tags 
		  FROM current_way_nodes,current_nodes 
		 WHERE current_way_nodes.id=#{wayid.to_i} 
		   AND current_way_nodes.node_id=current_nodes.id 
		   AND current_nodes.visible=1
	  ORDER BY sequence_id
	  EOF
	ActiveRecord::Base.connection.select_all(sql).each do |row|
	  points << [row['lon'].to_f,row['lat'].to_f,row['id'].to_i,nil,tagstring_to_hash(row['tags'])]
	end
	points
  end
	
  def sql_get_tags_in_way(wayid)
	tags={}
	ActiveRecord::Base.connection.select_all("SELECT k,v FROM current_way_tags WHERE id=#{wayid.to_i}").each do |row|
	  tags[row['k']]=row['v']
	end
	tags
  end

end