di/registry/registry.go

package registry

import (
	"fmt"
	"reflect"
	"runtime"
	"strings"

	cda "git.loafle.net/commons_go/di/annotation"
	cdia "git.loafle.net/commons_go/di/injection/annotation"
	cur "git.loafle.net/commons_go/util/reflect"
)

func init() {
	registry = newRegistry()
}

var registry ComponentRegistry

type ComponentRegistry interface {
	RegisterType(t reflect.Type) error
	RegisterResource(name string, resource interface{}) error

	GetInstance(t reflect.Type) (interface{}, error)
	GetInstances(ts []reflect.Type) ([]interface{}, error)
	GetInstanceByName(name string) (interface{}, error)
	GetInstancesByAnnotationName(n string) ([]interface{}, error)
}

func newRegistry() ComponentRegistry {
	r := &defaultComponentRegistry{}
	r.definitionByType = make(map[reflect.Type]*TypeDefinition, 0)
	r.definitionByName = make(map[string]*TypeDefinition, 0)
	r.instanceByType = make(map[reflect.Type]interface{}, 0)
	r.resourceByName = make(map[string]interface{}, 0)

	return r
}

type defaultComponentRegistry struct {
	definitionByType map[reflect.Type]*TypeDefinition
	definitionByName map[string]*TypeDefinition
	instanceByType   map[reflect.Type]interface{}
	resourceByName   map[string]interface{}
}

func RegisterType(t reflect.Type) error {
	pc, _, _, ok := runtime.Caller(1)
	details := runtime.FuncForPC(pc)
	if ok && details != nil {
		return fmt.Errorf("called from %s", details.Name())
	}

	return registry.RegisterType(t)
}
func (cr *defaultComponentRegistry) RegisterType(t reflect.Type) error {
	if nil == t {
		return fmt.Errorf("DI: t[reflect.Type] is nil")
	}
	if !cur.IsTypeKind(t, reflect.Struct, true) {
		return fmt.Errorf("DI: t[reflect.Type] must be specified but is %v", t)
	}

	td, err := cr.buildDefinition(t)
	if nil != err {
		return fmt.Errorf("DI: %v", err)
	}

	if _, ok := cr.definitionByType[td.RealType]; ok {
		return fmt.Errorf("DI: The type[%s] of Component is exist already", td.FullName)
	}
	cr.definitionByType[td.RealType] = td

	name := td.TypeName

	if a := td.GetAnnotationByType(reflect.TypeOf((*cdia.Component)(nil)), true); nil != a {
		ca := a.(*cdia.Component)
		if "" != strings.Trim(ca.Name, " ") {
			name = ca.Name
		}
	}

	if eTD, ok := cr.definitionByName[name]; ok {
		return fmt.Errorf("DI: The name[%s] of Component is exist already type[%s]", name, eTD.FullName)
	}
	cr.definitionByName[name] = td

	return nil
}

func RegisterResource(name string, resource interface{}) error {
	return registry.RegisterResource(name, resource)
}
func (cr *defaultComponentRegistry) RegisterResource(name string, resource interface{}) error {
	if _, ok := cr.resourceByName[name]; ok {
		return fmt.Errorf("DI: Resource[%s] is already exist", name)
	}
	cr.resourceByName[name] = resource

	return nil
}

// GetInstance returns instance of type
// t must be pointer of struct
func GetInstance(t reflect.Type) (interface{}, error) {
	return registry.GetInstance(t)
}
func (cr *defaultComponentRegistry) GetInstance(t reflect.Type) (interface{}, error) {
	if nil == t {
		return nil, fmt.Errorf("DI: t[reflect.Type] is nil")
	}

	if reflect.Ptr != t.Kind() {
		return nil, fmt.Errorf("DI: t[reflect.Type] must be pointer of struct")
	}

	if reflect.Struct != t.Elem().Kind() {
		return nil, fmt.Errorf("DI: t[reflect.Type] must be pointer of struct")
	}

	var err error

	rt, _, _ := cur.GetTypeInfo(t)
	td, ok := cr.definitionByType[rt]
	if !ok {
		td, err = cr.buildDefinition(t)
		if nil != err {
			return nil, fmt.Errorf("DI: %v", err)
		}
	}

	comV, ok := cr.instanceByType[td.RealType]
	if ok {
		return comV, nil
	}

	v := reflect.New(rt)
	rv := v.Elem()

	var annotation cda.Annotation
	var fV interface{}

	for _, fd := range td.Fields {
		f := rv.FieldByName(fd.FieldName)

		if !f.IsValid() {
			return nil, fmt.Errorf("DI: Field[%s] is not valid", fd.FieldName)
		}
		if !f.CanSet() {
			return nil, fmt.Errorf("DI: Field[%s] can not set", fd.FieldName)
		}

		if annotation = fd.GetAnnotationByType(reflect.TypeOf((*cdia.Inject)(nil)), false); nil != annotation {
			fV, err = cr.GetInstance(fd.Type)
			if nil != err {
				return nil, err
			}
		}

		if annotation = fd.GetAnnotationByType(reflect.TypeOf((*cdia.Resource)(nil)), false); nil != annotation {
			n := annotation.(*cdia.Resource).Name
			if "" == n {
				n = fd.FieldName
			}
			fV, err = cr.GetInstanceByName(n)
			if nil != err {
				return nil, err
			}
		}

		if nil != err {
			return nil, fmt.Errorf("DI: %v", err)
		}
		f.Set(reflect.ValueOf(fV))
	}

	cr.instanceByType[td.RealType] = v.Interface()

	return v.Interface(), nil
}

func GetInstanceByName(name string) (interface{}, error) {
	return registry.GetInstanceByName(name)
}
func (cr *defaultComponentRegistry) GetInstanceByName(name string) (interface{}, error) {
	v, ok := cr.resourceByName[name]
	if ok {
		return v, nil
	}
	return nil, fmt.Errorf("DI: Resource[%s] is not exist", name)
}

// GetInstances returns instance of annotated
// n must be name of registered annotation
func GetInstances(ts []reflect.Type) ([]interface{}, error) {
	return registry.GetInstances(ts)
}
func (cr *defaultComponentRegistry) GetInstances(ts []reflect.Type) ([]interface{}, error) {
	var (
		i   interface{}
		err error
	)
	instances := make([]interface{}, 0)
	for _, t := range ts {
		i, err = cr.GetInstance(t)
		if nil != err {
			return nil, err
		}
		instances = append(instances, i)
	}

	return instances, nil
}

// GetInstancesByAnnotationName returns instance of annotated
// n must be name of registered annotation
func GetInstancesByAnnotationName(n string) ([]interface{}, error) {
	return registry.GetInstancesByAnnotationName(n)
}
func (cr *defaultComponentRegistry) GetInstancesByAnnotationName(n string) ([]interface{}, error) {
	var (
		i   interface{}
		err error
	)
	instances := make([]interface{}, 0)

	for _, td := range cr.definitionByType {
		if nil != td.GetAnnotation(n) {
			i, err = cr.GetInstance(td.Type)
			if nil != err {
				return nil, err
			}
			instances = append(instances, i)
		}
	}

	return instances, nil
}

func (cr *defaultComponentRegistry) buildDefinition(t reflect.Type) (*TypeDefinition, error) {
	if nil == t {
		return nil, fmt.Errorf("t[reflect.Type] is nil")
	}

	rt, pkgName, tName := cur.GetTypeInfo(t)
	td := &TypeDefinition{}
	td.FullName = FullName(pkgName, tName)
	td.PkgName = pkgName
	td.TypeName = tName
	td.Type = t
	td.RealType = rt
	td.Fields = make([]*FieldDefinition, 0)

	parseFields(rt, td)

	return td, nil
}

func parseFields(t reflect.Type, td *TypeDefinition) {
	// fields := make([]*FieldDefinition, 0)
	rt, _, _ := cur.GetTypeInfo(t)
	if reflect.Struct != rt.Kind() {
		return
	}

	for i := 0; i < rt.NumField(); i++ {
		f := rt.Field(i)

		if f.Anonymous {
			if parseAnonymousField(f, td) {
				continue
			}
			parseFields(f.Type, td)
		} else {
			as, err := cda.ParseAnnotation(f.Tag)
			if nil != err {
				return
			}
			if nil != as && 0 < len(as) {
				fRT, fPkgName, fTName := cur.GetTypeInfo(f.Type)

				fd := &FieldDefinition{
					FieldName:   f.Name,
					PkgName:     fPkgName,
					TypeName:    fTName,
					Type:        f.Type,
					RealType:    fRT,
					Annotations: as,
				}
				td.Fields = append(td.Fields, fd)
			}
		}
	}
}

func parseAnonymousField(f reflect.StructField, td *TypeDefinition) bool {
	ct := reflect.TypeOf((*cda.TypeAnnotation)(nil)).Elem()

	if f.Type != ct {
		return false
	}

	as, err := cda.ParseAnnotation(f.Tag)
	if nil != err {
		return false
	}

	if nil != as && 0 < len(as) {
		td.TypeAnnotations = as
		return true
	}

	return false
}