# Check if a field is a String
#
# `min_size` and `max_size` are optional
#
# ~~~
# var validator = new ObjectValidator
# validator.add new StringField("field", required=false)
# assert validator.validate("""{}""")
#
# validator = new ObjectValidator
# validator.add new StringField("field")
# assert not validator.validate("""{}""")
# assert not validator.validate("""{ "field": 10 }""")
#
# validator = new ObjectValidator
# validator.add new StringField("field", min_size=3)
# assert validator.validate("""{ "field": "foo" }""")
# assert not validator.validate("""{ "field": "fo" }""")
# assert not validator.validate("""{ "field": "" }""")
#
# validator = new ObjectValidator
# validator.add new StringField("field", max_size=3)
# assert validator.validate("""{ "field": "foo" }""")
# assert not validator.validate("""{ "field": "fooo" }""")
#
# validator = new ObjectValidator
# validator.add new StringField("field", min_size=3, max_size=5)
# assert not validator.validate("""{ "field": "fo" }""")
# assert validator.validate("""{ "field": "foo" }""")
# assert validator.validate("""{ "field": "foooo" }""")
# assert not validator.validate("""{ "field": "fooooo" }""")
# ~~~
class StringField
	super RequiredField

	# String min size (default: not checked)
	var min_size: nullable Int

	# String max size (default: not checked)
	var max_size: nullable Int

	redef fun validate_field(v, obj) do
		if not super then return false
		var val = obj.get_or_null(field)
		if val == null then
			if required == null or required == true then
				v.validation.add_error(field, "Expected String got `null`")
				return false
			else
				return true
			end
		end
		if not val isa String then
			v.validation.add_error(field, "Expected String got `{val.class_name}`")
			return false
		end
		var min_size = self.min_size
		if min_size != null and val.length < min_size then
			v.validation.add_error(field, "Must be at least `{min_size} characters long`")
			return false
		end
		var max_size = self.max_size
		if max_size != null and val.length > max_size then
			v.validation.add_error(field, "Must be at max `{max_size} characters long`")
			return false
		end
		return true
	end
end