feat: allow Makefile to install swagger if missing

Author: redhatrises

Makefile

@@ -8,8 +8,8 @@ build:
 
 clean-generate: remove-generated generate
 
-generate: specs/swagger-stripped-oauth.json
-	swagger generate client --skip-validation -f $^ -t falcon
+generate: swagger-cli specs/swagger-stripped-oauth.json
+	$(SWAGGER) generate client --skip-validation -f $^ -t falcon
 
 .PHONY: build generate remove-generated
 
@@ -27,3 +27,37 @@ specs/swagger-patched.json: specs/swagger.json ./specs/transformation.jq
 specs/swagger.json:
 	@echo "Sorry swagger.json needs to be obtained manually at this moment"
 	@exit 1
+
+##@ Dependencies
+
+## Location to install dependencies to
+LOCALBIN ?= $(shell pwd)/bin
+$(LOCALBIN):
+	mkdir -p $(LOCALBIN)
+
+## Tool Binaries
+SWAGGER = $(LOCALBIN)/swagger
+
+## Tool Versions
+SWAGGER_VERSION ?= v0.31.0
+
+.PHONY: swagger-cli
+swagger-cli: $(SWAGGER) ## Download swagger locally if necessary.
+$(SWAGGER): $(LOCALBIN)
+	$(call go-install-tool,$(SWAGGER),github.com/go-swagger/go-swagger/cmd/swagger,$(SWAGGER_VERSION))
+
+# go-install-tool will 'go install' any package with custom target and name of binary, if it doesn't exist
+# $1 - target path with name of binary
+# $2 - package url which can be installed
+# $3 - specific version of package
+define go-install-tool
+@[ -f "$(1)-$(3)" ] || { \
+set -e; \
+package=$(2)@$(3) ;\
+echo "Downloading $${package}" ;\
+rm -f $(1) || true ;\
+GOBIN=$(LOCALBIN) go install $${package} ;\
+mv $(1) $(1)-$(3) ;\
+} ;\
+ln -sf $(1)-$(3) $(1)
+endef