feat: add 7.x source code

pkg/gotenberg/modules.go

@@ -0,0 +1,135 @@
+package gotenberg
+
+import (
+	"context"
+	"fmt"
+	"sort"
+	"sync"
+
+	flag "github.com/spf13/pflag"
+)
+
+// Module is a sort of plugin which adds new functionalities to the application
+// or other modules.
+//
+//	type YourModule struct {
+//		property string
+//	}
+//
+//	func (YourModule) Descriptor() gotenberg.ModuleDescriptor {
+//		return gotenberg.ModuleDescriptor{
+//			ID: "your_module",
+//			FlagSet: func() *flag.FlagSet {
+//				fs := flag.NewFlagSet("your_module", flag.ExitOnError)
+//				fs.String("your_module-property", "default value", "flag description")
+//
+//				return fs
+//			}(),
+//			New: func() gotenberg.Module { return new(YourModule) },
+//		}
+//	}
+type Module interface {
+	Descriptor() ModuleDescriptor
+}
+
+// ModuleDescriptor describes your module for the application.
+type ModuleDescriptor struct {
+	// ID is the unique name (snake case) of the module.
+	// Required.
+	ID string
+
+	// FlagSet is the definition of the flags of the module.
+	// Optional.
+	FlagSet *flag.FlagSet
+
+	// New returns a new and empty instance of the module's type.
+	// Required.
+	New func() Module
+}
+
+// Provisioner is a module interface for modules which have to be initialized
+// according to flags, environment variables, the context, etc.
+type Provisioner interface {
+	Provision(*Context) error
+}
+
+// Validator is a module interface for modules which have to be validated after
+// provisioning.
+type Validator interface {
+	Validate() error
+}
+
+// App is a module interface for modules which can be started or stopped by the
+// application.
+type App interface {
+	Start() error
+	// StartupMessage returns a custom message to display on startup. If it
+	// returns an empty string, a default startup message is used instead.
+	StartupMessage() string
+	Stop(ctx context.Context) error
+}
+
+// MustRegisterModule registers a module.
+//
+// To register a module, create an init() method in the module main go file:
+//
+//	func init() {
+//		gotenberg.MustRegisterModule(YourModule{})
+//	}
+//
+// Then, in the main command (github.com/gotenberg/gotenberg/v7/cmd/gotenberg),
+// import the module:
+//
+//	imports (
+//		// Gotenberg modules.
+//		_ "your_module_path"
+//	)
+func MustRegisterModule(mod Module) {
+	desc := mod.Descriptor()
+
+	if desc.ID == "" {
+		panic("module with an empty ID cannot be registered")
+	}
+
+	if desc.New == nil {
+		panic("module New function cannot be nil")
+	}
+
+	if val := desc.New(); val == nil {
+		panic("module New function cannot return a nil instance")
+	}
+
+	descriptorsMu.Lock()
+	defer descriptorsMu.Unlock()
+
+	if _, ok := descriptors[desc.ID]; ok {
+		panic(fmt.Sprintf("module %s is already registered", desc.ID))
+	}
+
+	descriptors[desc.ID] = desc
+}
+
+// GetModuleDescriptors returns the descriptors of all registered modules.
+func GetModuleDescriptors() []ModuleDescriptor {
+	descriptorsMu.RLock()
+	defer descriptorsMu.RUnlock()
+
+	mods := make([]ModuleDescriptor, len(descriptors))
+	i := 0
+
+	for _, desc := range descriptors {
+		mods[i] = desc
+		i++
+	}
+
+	sort.Slice(mods, func(i, j int) bool {
+		return mods[i].ID < mods[j].ID
+	})
+
+	return mods
+}
+
+var (
+	descriptors   = make(map[string]ModuleDescriptor)
+	descriptorsMu sync.RWMutex
+)