package di

import (
	"fmt"
	"log"
	"reflect"
	"strings"

	oa "git.loafle.net/overflow/annotation-go"
	"git.loafle.net/overflow/di-go/annotation"
	our "git.loafle.net/overflow/util-go/reflect"
)

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

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

func New(parent Registry) Registry {
	r := &InstanceRegistry{
		parent:           parent,
		definitionByType: make(map[reflect.Type]*TypeDefinition, 0),
		definitionByName: make(map[string]*TypeDefinition, 0),
		instanceByType:   make(map[reflect.Type]interface{}, 0),
		instanceByName:   make(map[string]interface{}, 0),
	}
	if nil == r.parent {
		r.parent = AppRegistry
	}
	return r
}

var AppRegistry = &InstanceRegistry{
	parent:           nil,
	definitionByType: make(map[reflect.Type]*TypeDefinition, 0),
	definitionByName: make(map[string]*TypeDefinition, 0),
	instanceByType:   make(map[reflect.Type]interface{}, 0),
	instanceByName:   make(map[string]interface{}, 0),
}

type InstanceRegistry struct {
	parent           Registry
	definitionByType map[reflect.Type]*TypeDefinition
	definitionByName map[string]*TypeDefinition
	instanceByType   map[reflect.Type]interface{}
	instanceByName   map[string]interface{}
}

func RegisterType(t reflect.Type) {
	AppRegistry.RegisterType(t)
}
func (r *InstanceRegistry) RegisterType(t reflect.Type) {
	if nil == t {
		log.Panicf("t[reflect.Type] is nil")
	}
	if !our.IsTypeKind(t, reflect.Struct, true) {
		log.Panicf("t[reflect.Type] must be specified but is %v", t)
	}

	td, err := r.buildDefinition(t)
	if nil != err {
		log.Panicf("DI: %v", err)
	}

	if _, ok := r.definitionByType[td.Type]; ok {
		log.Panicf("The type[%s] of Component is exist already", td.FullName)
	}
	r.definitionByType[td.Type] = td

	name := td.TypeName

	a, err := oa.GetTypeAnnotation(td.Type, annotation.InjectableAnnotationType)
	if nil != err {
		log.Panicf("%v", err)
	}
	if nil != a {
		ia := a.(*annotation.InjectableAnnotation)
		if "" != strings.Trim(ia.Name, " ") {
			name = ia.Name
		}
	}

	if eTD, ok := r.definitionByName[name]; ok {
		log.Panicf("The name[%s] of Component is exist already type[%s]", name, eTD.FullName)
	}
	r.definitionByName[name] = td
}

func RegisterResource(name string, resource interface{}) error {
	return AppRegistry.RegisterResource(name, resource)
}
func (r *InstanceRegistry) RegisterResource(name string, resource interface{}) error {
	if _, ok := r.instanceByName[name]; ok {
		return fmt.Errorf("Resource[%s] is already exist", name)
	}
	r.instanceByName[name] = resource

	return nil
}

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

	rt, pkgName, tName := our.GetTypeInfo(t)
	td := &TypeDefinition{}
	td.FullName = FullName(pkgName, tName)
	td.PkgName = pkgName
	td.TypeName = tName
	td.Type = t
	td.RealType = rt

	return td, nil
}

// GetInstance returns instance of type
// t must be pointer of struct
func GetInstance(t reflect.Type) (interface{}, error) {
	return AppRegistry.GetInstance(t)
}
func (r *InstanceRegistry) GetInstance(t reflect.Type) (instance interface{}, err error) {
	if nil == t {
		return nil, fmt.Errorf("t[reflect.Type] is nil")
	}

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

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

	var (
		td   *TypeDefinition
		comV interface{}
		ok   bool
	)

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

	if comV, ok = r.instanceByType[td.RealType]; ok {
		return comV, nil
	}

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

	instance = v.Interface()
	r.instanceByType[td.RealType] = instance
	err = nil
	defer func() {
		if nil != err {
			instance = nil
			delete(r.instanceByType, td.RealType)
		}
	}()

	var (
		fV interface{}
	)

	ass, err := oa.GetAllFieldAnnotations(td.Type)
	if nil != err {
		return nil, fmt.Errorf("%v", err)
	}
	if nil != ass {
		for n, as := range ass {
			f := rv.FieldByName(n)

			if !f.IsValid() {
				err = fmt.Errorf("Field[%s] is not valid", n)
				return
			}
			if !f.CanSet() {
				err = fmt.Errorf("Field[%s] can not set", n)
				return
			}

			_, ok = as[annotation.InjectAnnotationType]
			if ok {
				if fV, err = r.GetInstance(f.Type()); nil != err {
					return
				}
			}

			if nil != err {
				return
			}
			f.Set(reflect.ValueOf(fV))
		}
	}

	return
}

func GetInstanceByName(name string) (interface{}, error) {
	return AppRegistry.GetInstanceByName(name)
}
func (r *InstanceRegistry) GetInstanceByName(name string) (interface{}, error) {
	v, ok := r.instanceByName[name]
	if ok {
		return v, nil
	}
	return nil, fmt.Errorf("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 AppRegistry.GetInstances(ts)
}
func (r *InstanceRegistry) GetInstances(ts []reflect.Type) ([]interface{}, error) {
	var (
		i   interface{}
		err error
	)
	instances := make([]interface{}, 0)
	for _, t := range ts {
		if i, err = r.GetInstance(t); nil != err {
			return nil, err
		}
		instances = append(instances, i)
	}

	return instances, nil
}

func GetInstancesByAnnotationType(at reflect.Type) ([]interface{}, error) {
	return AppRegistry.GetInstancesByAnnotationType(at)
}
func (r *InstanceRegistry) GetInstancesByAnnotationType(at reflect.Type) ([]interface{}, error) {
	var (
		a   oa.Annotation
		i   interface{}
		err error
	)
	instances := make([]interface{}, 0)

	for _, td := range r.definitionByType {
		a, err = oa.GetTypeAnnotation(td.Type, at)
		if nil != err {
			return nil, err
		}
		if nil != a {
			i, err = r.GetInstance(td.Type)
			if nil != err {
				return nil, err
			}
			instances = append(instances, i)
		}
	}

	return instances, nil
}