--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/util/jsonschema.lua	Sat Mar 06 21:07:53 2021 +0100
@@ -0,0 +1,245 @@
+local schema_t = {xml_t = {}}
+
+local type_e = schema_t.type_e
+
+local type_validators = {}
+
+local function simple_validate(schema, data)
+	if schema == "object" and type(data) == "table" then
+		return type(data) == "table" and (next(data) == nil or type((next(data, nil))) == "string")
+	elseif schema == "array" and type(data) == "table" then
+		return type(data) == "table" and (next(data) == nil or type((next(data, nil))) == "number")
+	elseif schema == "integer" then
+		return math.type(data) == schema
+	else
+		return type(data) == schema
+	end
+end
+
+type_validators.string = function(schema, data)
+
+	if type(data) == "string" then
+		if schema.maxLength and #data > schema.maxLength then
+			return false
+		end
+		if schema.minLength and #data < schema.minLength then
+			return false
+		end
+		return true
+	end
+	return false
+end
+
+type_validators.number = function(schema, data)
+	if schema.multipleOf and data % schema.multipleOf ~= 0 then
+		return false
+	end
+
+	if schema.maximum and not (data <= schema.maximum) then
+		return false
+	end
+
+	if schema.exclusiveMaximum and not (data < schema.exclusiveMaximum) then
+		return false
+	end
+
+	if schema.minimum and not (data >= schema.minimum) then
+		return false
+	end
+
+	if schema.exclusiveMinimum and not (data > schema.exclusiveMinimum) then
+		return false
+	end
+
+	return true
+end
+
+type_validators.integer = type_validators.number
+
+local function validate(schema, data)
+	if type(schema) == "string" then
+		return simple_validate(schema, data)
+	end
+	if type(schema) == "table" then
+		if schema.allOf then
+			for _, sub in ipairs(schema.allOf) do
+				if not validate(sub, data) then
+					return false
+				end
+			end
+			return true
+		end
+
+		if schema.oneOf then
+			local valid = 0
+			for _, sub in ipairs(schema.oneOf) do
+				if validate(sub, data) then
+					valid = valid + 1
+				end
+			end
+			return valid == 1
+		end
+
+		if schema.anyOf then
+			for _, sub in ipairs(schema.anyOf) do
+				if validate(sub, data) then
+					return true
+				end
+			end
+			return false
+		end
+
+		if schema["not"] then
+			if validate(schema["not"], data) then
+				return false
+			end
+		end
+
+		if schema["if"] then
+			if validate(schema["if"], data) then
+				if schema["then"] then
+					return validate(schema["then"], data)
+				end
+			else
+				if schema["else"] then
+					return validate(schema["else"], data)
+				end
+			end
+		end
+
+		if not simple_validate(schema.type, data) then
+			return false
+		end
+
+		if schema.const ~= nil and schema.const ~= data then
+			return false
+		end
+
+		if schema.enum ~= nil then
+			for _, v in ipairs(schema.enum) do
+				if v == data then
+					return true
+				end
+			end
+			return false
+		end
+
+		local validator = type_validators[schema.type]
+		if not validator then
+			return true
+		end
+
+		return validator(schema, data)
+	end
+end
+
+type_validators.table = function(schema, data)
+	if type(data) == "table" then
+
+		if schema.maxItems and #data > schema.maxItems then
+			return false
+		end
+
+		if schema.minItems and #data < schema.minItems then
+			return false
+		end
+
+		if schema.required then
+			for _, k in ipairs(schema.required) do
+				if data[k] == nil then
+					return false
+				end
+			end
+		end
+
+		if schema.properties then
+			for k, s in pairs(schema.properties) do
+				if data[k] ~= nil then
+					if not validate(s, data[k]) then
+						return false
+					end
+				end
+			end
+		end
+
+		if schema.additionalProperties then
+			for k, v in pairs(data) do
+				if type(k) == "string" then
+					if not (schema.properties and schema.properties[k]) then
+						if not validate(schema.additionalProperties, v) then
+							return false
+						end
+					end
+				end
+			end
+		elseif schema.properties then
+			for k in pairs(data) do
+				if type(k) == "string" then
+					if schema.properties[k] == nil then
+						return false
+					end
+				end
+			end
+		end
+
+		if schema.uniqueItems then
+
+			local values = {}
+			for _, v in pairs(data) do
+				if values[v] then
+					return false
+				end
+				values[v] = true
+			end
+			return true
+		end
+
+		local item_schemas = schema.items
+		if item_schemas and item_schemas[1] == nil then
+			local item_schema = item_schemas
+			for i, v in pairs(data) do
+				if type(i) == "number" then
+					if not validate(item_schema, v) then
+						return false
+					end
+				end
+			end
+		elseif item_schemas and item_schemas[1] ~= nil then
+			for i, s in ipairs(item_schemas) do
+				validate(s, data[i])
+			end
+		end
+
+		return true
+	end
+	return false
+end
+
+type_validators.object = function(schema, data)
+	if type(data) == "table" then
+		for k in pairs(data) do
+			if not (type(k) == "string") then
+				return false
+			end
+		end
+
+		return type_validators.table(schema, data)
+	end
+	return false
+end
+
+type_validators.array = function(schema, data)
+	if type(data) == "table" then
+
+		for i in pairs(data) do
+			if not (type(i) == "number") then
+				return false
+			end
+		end
+
+		return type_validators.table(schema, data)
+	end
+	return false
+end
+
+return {validate = validate; schema_t = schema_t}