POC for generating API endpoints using code generation

Note: This PR is messy as it includes some refactoring of content from
the 'fastly' package into new 'errors' and 'decodebody' packages;
those will be split out into their own PRs before this is ready for
review.

This PR is a proof-of-concept for generating API endpoints using the
Jennifer code-generation module. It generates endpoints for Brotli
compression and NGWAF as examples. For NGWAF, it includes
configuration-during-enablement for the 'workspace_id'.

.gitignore

@@ -25,7 +25,6 @@ _testmain.go
 *.prof
 
 bin/
-pkg/
 RELEASE_CHANGELOG.md
 
 .envrc

Makefile

@@ -26,14 +26,9 @@ FASTLY_API_KEY ?=
 # Enables support for tools such as https://github.com/rakyll/gotest
 TEST_COMMAND ?= $(GO) test
 
-all: mod-download dev-dependencies tidy fmt fiximports test vet staticcheck semgrep ## Runs all of the required cleaning and verification targets.
+all: mod-download dev-dependencies tidy generate fmt fiximports test vet staticcheck semgrep ## Runs all of the required cleaning and verification targets.
 .PHONY: all
 
-tidy: ## Cleans the Go module.
-	@echo "==> Tidying module"
-	@$(GO) mod tidy
-.PHONY: tidy
-
 mod-download: ## Downloads the Go module.
 	@echo "==> Downloading Go module"
 	@$(GO) mod download
@@ -46,11 +41,47 @@ dev-dependencies: ## Downloads the necessary dev dependencies.
 	@if [[ "$$(uname)" == 'Darwin' ]]; then brew install semgrep; fi
 .PHONY: dev-dependencies
 
+tidy: ## Cleans the Go module.
+	@echo "==> Tidying module"
+	@$(GO) mod tidy
+.PHONY: tidy
+
+generate: ## Builds and runs generators, to generate code for API endpoints and tests.
+	@echo "==> Building generators"
+	@$(GO) build -o generators ./internal/generators/...
+	@echo "==> Generating code from templates"
+	@PATH=${PATH}:$(shell pwd)/generators $(GO) generate -v ./internal/templates/...
+
+fmt: ## Properly formats Go files and orders dependencies.
+	@echo "==> Running gofmt"
+	@gofmt -s -w ${GOFILES}
+.PHONY: fmt
+
+fiximports: ## Properly formats and orders imports.
+	@echo "==> Fixing imports"
+	@goimports -w {fastly,tools}
+.PHONY: fiximports
+
 test: ## Runs the test suite with VCR mocks enabled.
 	@echo "==> Testing ${NAME}"
 	@$(TEST_COMMAND) -timeout=30s -parallel=20 -tags="${GOTAGS}" ${GOPKGS} ${TESTARGS}
 .PHONY: test
 
+vet: ## Identifies common errors.
+	@echo "==> Running go vet"
+	@$(GO) vet ./...
+.PHONY: vet
+
+staticcheck: ## Runs the staticcheck linter.
+	@echo "==> Running staticcheck"
+	@staticcheck -version
+	@staticcheck ./...
+.PHONY: staticcheck
+
+semgrep: ## Run semgrep checker.
+	if command -v semgrep &> /dev/null; then semgrep ci --config auto --exclude-rule generic.secrets.security.detected-private-key.detected-private-key $(SEMGREP_ARGS); fi
+.PHONY: semgrep
+
 test-race: ## Runs the test suite with the -race flag to identify race conditions, if they exist.
 	@echo "==> Testing ${NAME} (race)"
 	@$(TEST_COMMAND) -timeout=60s -race -tags="${GOTAGS}" ${GOPKGS} ${TESTARGS}
@@ -85,35 +116,9 @@ check-mod: ## A check which lists extraneous dependencies, if they exist.
 	@$(shell pwd)/scripts/check-mod.sh
 .PHONY: check-mod
 
-fiximports: ## Properly formats and orders imports.
-	@echo "==> Fixing imports"
-	@goimports -w {fastly,tools}
-.PHONY: fiximports
-
-fmt: ## Properly formats Go files and orders dependencies.
-	@echo "==> Running gofmt"
-	@gofmt -s -w ${GOFILES}
-.PHONY: fmt
-
-vet: ## Identifies common errors.
-	@echo "==> Running go vet"
-	@$(GO) vet ./...
-.PHONY: vet
-
-staticcheck: ## Runs the staticcheck linter.
-	@echo "==> Running staticcheck"
-	@staticcheck -version
-	@staticcheck ./...
-.PHONY: staticcheck
-
 nilaway: ## Run nilaway
 	@nilaway ./...
 
-# Run semgrep checker.
-.PHONY: semgrep
-semgrep:
-	if command -v semgrep &> /dev/null; then semgrep ci --config auto --exclude-rule generic.secrets.security.detected-private-key.detected-private-key $(SEMGREP_ARGS); fi
-
 .PHONY: help
 help: ## Prints this help menu.
 	@grep -E '^[a-zA-Z_-]+:.*?## .*$$' $(MAKEFILE_LIST) | sort | awk 'BEGIN {FS = ":.*?## "}; {printf "\033[36m%-30s\033[0m %s\n", $$1, $$2}'

fastly/client.go

@@ -12,17 +12,16 @@ import (
 	"net/url"
 	"os"
 	"path/filepath"
-	"reflect"
 	"runtime"
 	"strconv"
 	"strings"
 	"sync"
 	"time"
 
+	"github.com/fastly/go-fastly/v9/pkg/decodebody"
 	"github.com/google/go-querystring/query"
 	"github.com/google/jsonapi"
 	"github.com/hashicorp/go-cleanhttp"
-	"github.com/mitchellh/mapstructure"
 )
 
 // APIKeyEnvVar is the name of the environment variable where the Fastly API
@@ -653,95 +652,12 @@ func checkResp(resp *http.Response, err error) (*http.Response, error) {
 
 // decodeBodyMap is used to decode an HTTP response body into a mapstructure struct.
 func decodeBodyMap(body io.Reader, out any) error {
-	var parsed any
-	dec := json.NewDecoder(body)
-	if err := dec.Decode(&parsed); err != nil {
-		return err
-	}
-
-	return decodeMap(parsed, out)
+	return decodebody.DecodeBodyMap(body, out)
 }
 
 // decodeMap decodes an `in` struct or map to a mapstructure tagged `out`.
 // It applies the decoder defaults used throughout go-fastly.
 // Note that this uses opposite argument order from Go's copy().
 func decodeMap(in, out any) error {
-	decoder, err := mapstructure.NewDecoder(&mapstructure.DecoderConfig{
-		DecodeHook: mapstructure.ComposeDecodeHookFunc(
-			mapToHTTPHeaderHookFunc(),
-			stringToTimeHookFunc(),
-		),
-		WeaklyTypedInput: true,
-		Result:           out,
-	})
-	if err != nil {
-		return err
-	}
-	return decoder.Decode(in)
-}
-
-// mapToHTTPHeaderHookFunc returns a function that converts maps into an
-// http.Header value.
-func mapToHTTPHeaderHookFunc() mapstructure.DecodeHookFunc {
-	return func(
-		f reflect.Type,
-		t reflect.Type,
-		data any,
-	) (any, error) {
-		if f.Kind() != reflect.Map {
-			return data, nil
-		}
-		if t != reflect.TypeOf(new(http.Header)) {
-			return data, nil
-		}
-
-		typed, ok := data.(map[string]any)
-		if !ok {
-			return nil, fmt.Errorf("cannot convert %T to http.Header", data)
-		}
-
-		n := map[string][]string{}
-		for k, v := range typed {
-			switch tv := v.(type) {
-			case string:
-				n[k] = []string{tv}
-			case []string:
-				n[k] = tv
-			case int, int8, int16, int32, int64:
-				n[k] = []string{fmt.Sprintf("%d", tv)}
-			case float32, float64:
-				n[k] = []string{fmt.Sprintf("%f", tv)}
-			default:
-				return nil, fmt.Errorf("cannot convert %T to http.Header", v)
-			}
-		}
-
-		return n, nil
-	}
-}
-
-// stringToTimeHookFunc returns a function that converts strings to a time.Time
-// value.
-func stringToTimeHookFunc() mapstructure.DecodeHookFunc {
-	return func(
-		f reflect.Type,
-		t reflect.Type,
-		data any,
-	) (any, error) {
-		if f.Kind() != reflect.String {
-			return data, nil
-		}
-		if t != reflect.TypeOf(time.Now()) {
-			return data, nil
-		}
-
-		// Convert it by parsing
-		v, err := time.Parse(time.RFC3339, data.(string))
-		if err != nil {
-			// DictionaryInfo#get uses it's own special time format for now.
-			v, _ := data.(string) // type assert to avoid runtime panic (v will have zero value for its type)
-			return time.Parse("2006-01-02 15:04:05", v)
-		}
-		return v, err
-	}
+	return decodebody.DecodeMap(in, out)
 }