# Helper class that can save and load a `Model` into a Neo4j database.
class NeoModel

	# The model name.
	#
	# Because we use only one Neo4j instance to store all the models,
	# we need to mark their appartenance to a particular model and avoid loading all models.
	#
	# The name is used as a Neo label on each created nodes and used to load nodes from base.
	var model_name: String

	# The toolcontext used to init the `NeoModel` tool.
	var toolcontext: ToolContext

	# The Neo4j `client` used to communicate with the Neo4j instance.
	var client: Neo4jClient

	# Fill `model` using base pointed by `client`.
	fun load(model: Model): Model do
		var nodes: Array[NeoNode]

		toolcontext.info("Loading package node...", 1)
		nodes = client.nodes_with_labels([model_name, "MPackage"])
		for node in nodes do to_mpackage(model, node)
		toolcontext.info("Loading groups...", 1)
		nodes = client.nodes_with_labels([model_name, "MGroup"])
		for node in nodes do to_mgroup(model, node)
		toolcontext.info("Loading modules...", 1)
		nodes = client.nodes_with_labels([model_name, "MModule"])
		for node in nodes do to_mmodule(model, node)
		toolcontext.info("Loading classes...", 1)
		nodes = client.nodes_with_labels([model_name, "MClass"])
		for node in nodes do to_mclass(model, node)
		toolcontext.info("Loading class definitions...", 1)
		nodes = client.nodes_with_labels([model_name, "MClassDef"])
		for node in nodes do to_mclassdef(model, node)
		toolcontext.info("Loading properties...", 1)
		nodes = client.nodes_with_labels([model_name, "MProperty"])
		for node in nodes do to_mproperty(model, node)
		toolcontext.info("Loading property definitions...", 1)
		nodes = client.nodes_with_labels([model_name, "MPropDef"])
		for node in nodes do to_mpropdef(model, node)
		return model
	end

	# Save `model` in the base pointed by `client`.
	fun save(model: Model) do
		var nodes = collect_model_nodes(model)
		toolcontext.info("Save {nodes.length} nodes...", 1)
		push_all(nodes)
		var edges = collect_model_edges(model)
		toolcontext.info("Save {edges.length} edges...", 1)
		push_all(edges)
	end

	# Save `neo_entities` in base using batch mode.
	private fun push_all(neo_entities: Collection[NeoEntity]) do
		var batch = new NeoBatch(client)
		var len = neo_entities.length
		var sum = 0
		var i = 1
		for nentity in neo_entities do
			batch.save_entity(nentity)
			if i == batch_max_size then
				do_batch(batch)
				sum += batch_max_size
				toolcontext.info(" {sum * 100 / len}% done", 1)
				batch = new NeoBatch(client)
				i = 1
			else
				i += 1
			end
		end
		do_batch(batch)
	end

	# How many operation can be executed in one batch?
	private var batch_max_size = 1000

	# Execute `batch` and check for errors.
	#
	# Abort if `batch.execute` returns errors.
	private fun do_batch(batch: NeoBatch) do
		var errors = batch.execute
		if not errors.is_empty then
			print errors
			exit(1)
		end
	end

	# Collect all nodes from the current `model`.
	private fun collect_model_nodes(model: Model): Collection[NeoNode] do
		for mpackage in model.mpackages do
			mpackage.to_node(nodes, model_name)
			for mgroup in mpackage.mgroups do mgroup.to_node(nodes, model_name)
		end
		return nodes.values
	end

	# Collect all edges from the current `model`.
	#
	# Actually collect all out_edges from all nodes.
	private fun collect_model_edges(model: Model): Collection[NeoEdge] do
		var edges = new HashSet[NeoEdge]
		for node in nodes.values do edges.add_all(node.out_edges)
		return edges
	end

	# Mentities associated to nodes.
	#
	# The key is the node’s id.
	private var mentities = new HashMap[Int, MEntity]

	# Nodes associated with MEntities.
	private var nodes = new HashMap[MEntity, NeoNode]

	# Get the `MEntity` associated with `node`.
	fun to_mentity(model: Model, node: NeoNode): MEntity do
		if node.labels.has("MPackage") then return to_mpackage(model, node)
		if node.labels.has("MGroup") then return to_mgroup(model, node)
		if node.labels.has("MModule") then return to_mmodule(model, node)
		if node.labels.has("MClass") then return to_mclass(model, node)
		if node.labels.has("MClassDef") then return to_mclassdef(model, node)
		if node.labels.has("MProperty") then return to_mproperty(model, node)
		if node.labels.has("MPropDef") then return to_mpropdef(model, node)
		if node.labels.has("MType") then return to_mtype(model, node)
		if node.labels.has("MParameter") then return to_mparameter(model, node)
		abort
	end

	# Build a new `MPackage` from a `node`.
	#
	# REQUIRE `node.labels.has("MPackage")`
	private fun to_mpackage(model: Model, node: NeoNode): MPackage do
		var m = mentities.get_or_null(node.id.as(Int))
		if m isa MPackage then return m

		assert node.labels.has("MPackage")
		var location = to_location(node["location"].to_s)
		var mpackage = new MPackage(node["name"].to_s, model, location)
		mentities[node.id.as(Int)] = mpackage
		set_doc(node, mpackage)
		mpackage.root = to_mgroup(model, node.out_nodes("ROOT").first)
		return mpackage
	end

	# Build a new `MGroup` from a `node`.
	#
	# REQUIRE `node.labels.has("MGroup")`
	private fun to_mgroup(model: Model, node: NeoNode): MGroup do
		var m = mentities.get_or_null(node.id.as(Int))
		if m isa MGroup then return m

		assert node.labels.has("MGroup")
		var location = to_location(node["location"].to_s)
		var mpackage = to_mpackage(model, node.out_nodes("PROJECT").first)
		var parent: nullable MGroup = null
		var out = node.out_nodes("PARENT")
		if not out.is_empty then
			parent = to_mgroup(model, out.first)
		end
		var mgroup = new MGroup(node["name"].to_s, location, mpackage, parent)
		mentities[node.id.as(Int)] = mgroup
		set_doc(node, mgroup)
		return mgroup
	end

	# Build a new `MModule` from a `node`.
	#
	# REQUIRE `node.labels.has("MModule")`
	private fun to_mmodule(model: Model, node: NeoNode): MModule do
		var m = mentities.get_or_null(node.id.as(Int))
		if m isa MModule then return m

		assert node.labels.has("MModule")
		var ins = node.in_nodes("DECLARES")
		var mgroup: nullable MGroup = null
		if not ins.is_empty then
			mgroup = to_mgroup(model, ins.first)
		end
		var name = node["name"].to_s
		var location = to_location(node["location"].to_s)
		var mmodule = new MModule(model, mgroup, name, location)
		mentities[node.id.as(Int)] = mmodule
		set_doc(node, mmodule)
		var imported_mmodules = new Array[MModule]
		for smod in node.out_nodes("IMPORTS") do
			imported_mmodules.add to_mmodule(model, smod)
		end
		mmodule.set_imported_mmodules(imported_mmodules)
		return mmodule
	end

	# Build a new `MClass` from a `node`.
	#
	# REQUIRE `node.labels.has("MClass")`
	private fun to_mclass(model: Model, node: NeoNode): MClass do
		var m = mentities.get_or_null(node.id.as(Int))
		if m isa MClass then return m

		assert node.labels.has("MClass")
		var mmodule = to_mmodule(model, node.in_nodes("INTRODUCES").first)
		var name = node["name"].to_s
		var location = to_location(node["location"].to_s)
		var kind = to_kind(node["kind"].to_s)
		var visibility = to_visibility(node["visibility"].to_s)
		var parameter_names = new Array[String]
		if node.has_key("parameter_names") then
			for e in node["parameter_names"].as(JsonArray) do
				parameter_names.add e.to_s
			end
		end
		var mclass = new MClass(mmodule, name, location, parameter_names, kind, visibility)
		mentities[node.id.as(Int)] = mclass
		set_doc(node, mclass)
		return mclass
	end

	# Build a new `MClassDef` from a `node`.
	#
	# REQUIRE `node.labels.has("MClassDef")`
	private fun to_mclassdef(model: Model, node: NeoNode): MClassDef do
		var m = mentities.get_or_null(node.id.as(Int))
		if m isa MClassDef then return m

		assert node.labels.has("MClassDef")
		var mmodule = to_mmodule(model, node.in_nodes("DEFINES").first)
		var mtype = to_mtype(model, node.out_nodes("BOUNDTYPE").first).as(MClassType)
		var location = to_location(node["location"].to_s)
		var mclassdef = new MClassDef(mmodule, mtype, location)
		mentities[node.id.as(Int)] = mclassdef
		set_doc(node, mclassdef)
		var supertypes = new Array[MClassType]
		for sup in node.out_nodes("INHERITS") do
			supertypes.add to_mtype(model, sup).as(MClassType)
		end
		mclassdef.set_supertypes(supertypes)
		mclassdef.add_in_hierarchy
		return mclassdef
	end

	# Build a new `MProperty` from a `node`.
	#
	# REQUIRE `node.labels.has("MProperty")`
	private fun to_mproperty(model: Model, node: NeoNode): MProperty do
		var m = mentities.get_or_null(node.id.as(Int))
		if m isa MProperty then return m

		assert node.labels.has("MProperty")
		var intro_mclassdef = to_mclassdef(model, node.out_nodes("INTRO_CLASSDEF").first)
		var name = node["name"].to_s
		var location = to_location(node["location"].to_s)
		var visibility = to_visibility(node["visibility"].to_s)
		var mprop: nullable MProperty = null
		if node.labels.has("MMethod") then
			mprop = new MMethod(intro_mclassdef, name, location, visibility)
			mprop.is_init = node["is_init"].as(Bool)
		else if node.labels.has("MAttribute") then
			mprop = new MAttribute(intro_mclassdef, name, location, visibility)
		else if node.labels.has("MVirtualTypeProp") then
			mprop = new MVirtualTypeProp(intro_mclassdef, name, location, visibility)
		else if node.labels.has("MInnerClass") then
			var inner = to_mclass(model, node.out_nodes("NESTS").first)
			mprop = new MInnerClass(intro_mclassdef, name, location, visibility, inner)
		end
		if mprop == null then
			print "not yet implemented to_mproperty for {node.labels.join(",")}"
			abort
		end
		mentities[node.id.as(Int)] = mprop
		set_doc(node, mprop)
		return mprop
	end

	# Build a new `MPropDef` from a `node`.
	#
	# REQUIRE `node.labels.has("MPropDef")`
	private fun to_mpropdef(model: Model, node: NeoNode): MPropDef do
		var m = mentities.get_or_null(node.id.as(Int))
		if m isa MPropDef then return m

		assert node.labels.has("MPropDef")
		var mclassdef = to_mclassdef(model, node.in_nodes("DECLARES").first)
		var mproperty = to_mproperty(model, node.out_nodes("DEFINES").first)
		var location = to_location(node["location"].to_s)
		var mpropdef: nullable MPropDef = null
		if node.labels.has("MMethodDef") then
			mpropdef = new MMethodDef(mclassdef, mproperty.as(MMethod), location)
			mpropdef.is_abstract = node["is_abstract"].as(Bool)
			mpropdef.is_intern = node["is_intern"].as(Bool)
			mpropdef.is_extern = node["is_extern"].as(Bool)
			mentities[node.id.as(Int)] = mpropdef
			mpropdef.msignature = to_mtype(model, node.out_nodes("SIGNATURE").first).as(MSignature)
		else if node.labels.has("MAttributeDef") then
			mpropdef = new MAttributeDef(mclassdef, mproperty.as(MAttribute), location)
			mentities[node.id.as(Int)] = mpropdef
			var static_mtype = node.out_nodes("TYPE")
			if not static_mtype.is_empty then mpropdef.static_mtype = to_mtype(model, static_mtype.first)
		else if node.labels.has("MVirtualTypeDef") then
			mpropdef = new MVirtualTypeDef(mclassdef, mproperty.as(MVirtualTypeProp), location)
			mentities[node.id.as(Int)] = mpropdef
			var bound = node.out_nodes("BOUND")
			if not bound.is_empty then mpropdef.bound = to_mtype(model, bound.first)
		else if node.labels.has("MInnerClassDef") then
			var inner = to_mclassdef(model, node.out_nodes("NESTS").first)
			mpropdef = new MInnerClassDef(mclassdef,
					mproperty.as(MInnerClass), location, inner)
			mentities[node.id.as(Int)] = mpropdef
		end
		if mpropdef == null then
			print "not yet implemented to_mpropdef for {node.labels.join(",")}"
			abort
		end
		set_doc(node, mpropdef)
		return mpropdef
	end

	# Build a new `MType` from a `node`.
	#
	# REQUIRE `node.labels.has("MType")`
	private fun to_mtype(model: Model, node: NeoNode): MType do
		var m = mentities.get_or_null(node.id.as(Int))
		if m isa MType then return m

		assert node.labels.has("MType")
		if node.labels.has("MClassType") then
			var mclass = to_mclass(model, node.out_nodes("CLASS").first)
			var args = new Array[MType]
			for narg in node.out_nodes("ARGUMENT") do
				args.add to_mtype(model, narg)
			end
			var mtype = mclass.get_mtype(args)
			mentities[node.id.as(Int)] = mtype
			return mtype
		else if node.labels.has("MParameterType") then
			var mclass = to_mclass(model, node.out_nodes("CLASS").first)
			var rank = node["rank"].to_s.to_i
			var mtype = mclass.mparameters[rank]
			mentities[node.id.as(Int)] = mtype
			return  mtype
		else if node.labels.has("MNullableType") then
			var intype = to_mtype(model, node.out_nodes("TYPE").first)
			var mtype = intype.as_nullable
			mentities[node.id.as(Int)] = mtype
			return mtype
		else if node.labels.has("MVirtualType") then
			var mproperty = to_mproperty(model, node.out_nodes("PROPERTY").first)
			assert mproperty isa MVirtualTypeProp
			var mtype = mproperty.mvirtualtype
			mentities[node.id.as(Int)] = mtype
			return mtype
		else if node.labels.has("MSignature") then
			# Get all param nodes
			var mparam_nodes = new HashMap[String, MParameter]
			for pnode in node.out_nodes("PARAMETER") do
				var mparam = to_mparameter(model, pnode)
				mparam_nodes[mparam.name] = mparam
			end
			# Load params in the good order
			var mparam_names = node["parameter_names"]
			var mparameters = new Array[MParameter]
			if mparam_names isa JsonArray then
				for mparam_name in mparam_names do
					var mparam = mparam_nodes[mparam_name.to_s]
					mparameters.add mparam
				end
			end
			var return_mtype: nullable MType = null
			var ret_nodes = node.out_nodes("RETURNTYPE")
			if not ret_nodes.is_empty then
				return_mtype = to_mtype(model, ret_nodes.first)
			end
			var mtype = new MSignature(mparameters, return_mtype)
			mentities[node.id.as(Int)] = mtype
			return mtype
		else if node.labels.has("MRawType") then
			var mtype = new MRawType(model)
			var parts = node["text"]
			if parts isa JsonArray then
				for p in parts do
					mtype.parts.add(new MTypePart(model, p.to_s, null))
				end
				for pnode in node.out_nodes("LINK") do
					assert pnode.labels.has("MTypePart")
					if not pnode.out_nodes("TARGET").is_empty then
						var rank = pnode["rank"]
						var target = to_mentity(model, pnode.out_nodes("TARGET").first)
						assert rank isa Int
						mtype.parts[rank] = mtype.parts[rank].link_to(target)
					end
				end
			end
			mentities[node.id.as(Int)] = mtype
			return mtype
		end
		print "not yet implemented to_mtype for {node.labels.join(",")}"
		abort
	end

	# Build a new `MParameter` from `node`.
	#
	# REQUIRE `node.labels.has("MParameter")`
	private fun to_mparameter(model: Model, node: NeoNode): MParameter do
		var m = mentities.get_or_null(node.id.as(Int))
		if m isa MParameter then return m

		assert node.labels.has("MParameter")
		var name = node["name"].to_s
		var mtype = to_mtype(model, node.out_nodes("TYPE").first)
		var is_vararg = node["is_vararg"].as(Bool)
		var mparameter = new MParameter(name, mtype, is_vararg)
		mentities[node.id.as(Int)] = mparameter
		return mparameter
	end

	# Get a `Location` from its string representation.
	private fun to_location(loc: String): nitc::Location do
		return new nitc::Location.from_string(loc)
	end

	# Get a `MVisibility` from its string representation.
	private fun to_visibility(vis: String): MVisibility do
		if vis == intrude_visibility.to_s then
			return intrude_visibility
		else if vis == public_visibility.to_s then
			return public_visibility
		else if vis == protected_visibility.to_s then
			return protected_visibility
		else if vis == private_visibility.to_s then
			return private_visibility
		else if vis == package_visibility.to_s then
			return package_visibility
		else
			return none_visibility
		end
	end

	# Get a `MKind` from its string representation.
	private fun to_kind(kind: String): MClassKind do
		if kind == abstract_kind.to_s then
			return abstract_kind
		else if kind == concrete_kind.to_s then
			return concrete_kind
		else if kind == interface_kind.to_s then
			return interface_kind
		else if kind == enum_kind.to_s then
			return enum_kind
		else if kind == extern_kind.to_s then
			return extern_kind
		else
			return raw_kind(kind)
		end
	end

	# Extract the `MDoc` from `node` and link it to `mentity`.
	private fun set_doc(node: NeoNode, mentity: MEntity) do
		if node.has_key("mdoc") then
			var lines = new Array[String]
			for e in node["mdoc"].as(JsonArray) do
				lines.add e.to_s#.replace("\n", "\\n")
			end
			var location = to_location(node["mdoc_location"].to_s)
			var mdoc = new MDoc(location)
			mdoc.content.add_all(lines)
			mdoc.original_mentity = mentity
			mentity.mdoc = mdoc
		end
	end
end