package annotation

import (
	"fmt"
	"reflect"
	"strings"
)

const (
	AnnotationTag                         = "annotation"
	AnnotationMetaTag                     = "@annotation"
	AnnotationChar                        = "@"
	AnnotationStartChar                   = "("
	AnnotationEndChar                     = ")"
	AnnotationSpliter                     = ";"
	AnnotationAttributeSpliter            = ","
	AnnotationAttributeStartChar          = "'"
	AnnotationAttributeEndChar            = "'"
	AnnotationKeyValueSpliter             = "="
	AnnotationAttributeArrayStartChar     = "["
	AnnotationAttributeArrayEndChar       = "]"
	AnnotationAttributeArrayItemSpliter   = ","
	AnnotationAttributeMapStartChar       = "{"
	AnnotationAttributeMapEndChar         = "}"
	AnnotationAttributeMapKeyValueSpliter = ":"
	AnnotationAttributeMapItemSpliter     = ","
)

type Annotation interface {
}

// // @Inject(name? string)
// // @Resource(name? string)
// func ParseAnnotation(tag reflect.StructTag) (map[string]Annotation, error) {
// 	s := strings.Trim(tag.Get(AnnotationTag), " ")
// 	if "" == s {
// 		return nil, nil
// 	}

// 	annotations := strings.Split(s, AnnotationSpliter)
// 	if nil == annotations || 0 == len(annotations) {
// 		return nil, nil
// 	}

// 	rKVs := make(map[string]Annotation, 0)
// 	for _, a := range annotations {
// 		a = strings.Trim(a, " ")
// 		if "" == a {
// 			continue
// 		}
// 		aName, attributes, err := parseAnnotationItem(a)
// 		if nil != err {
// 			return nil, err
// 		}
// 		if "" == aName {
// 			continue
// 		}
// 		annotation, err := newAnnotation(aName, attributes)
// 		if nil != err {
// 			return nil, err
// 		}
// 		rKVs[aName] = annotation
// 	}

// 	return rKVs, nil
// }

// @Inject(name? string)
// @Resource(name? string)
func ParseAnnotation(tag reflect.StructTag) (map[string]Annotation, error) {
	s := strings.Trim(tag.Get(AnnotationTag), " ")
	if "" == s {
		return nil, nil
	}

	annotations, err := splitAnnotation(s)
	if nil != err {
		return nil, err
	}

	if nil == annotations || 0 == len(annotations) {
		return nil, nil
	}

	rKVs := make(map[string]Annotation, 0)
	for name, attributes := range annotations {
		annotation, err := newAnnotation(name, attributes)
		if nil != err {
			return nil, err
		}
		rKVs[name] = annotation
	}

	return rKVs, nil
}

func splitAnnotation(s string) (map[string]map[string]string, error) {
	ss := make(map[string]map[string]string, 0)
	ts := s
	for {
		as := strings.Index(ts, AnnotationChar)
		if -1 == as {
			break
		}
		aas := strings.Index(ts, AnnotationStartChar)
		aae := strings.Index(ts, AnnotationEndChar)

		aName := ts[as:aas]
		aAttributes := ts[aas+1 : aae]

		if 0 < len(aAttributes) {
			attributes, err := splitAnnotationAttribute(aAttributes)
			if nil != err {
				return nil, err
			}
			ss[aName] = attributes
		} else {
			ss[aName] = nil
		}

		if len(ts) <= (aae + 1) {
			break
		}
		ts = ts[aae+1:]
	}

	return ss, nil
}

func splitAnnotationAttribute(s string) (map[string]string, error) {
	ss := make(map[string]string, 0)
	ts := s
	for {
		as := strings.Index(ts, AnnotationKeyValueSpliter)
		if -1 == as {
			break
		}
		aName := ts[:as]

		aas := strings.Index(ts[as:], AnnotationAttributeStartChar)
		aae := strings.Index(ts[as+aas+1:], AnnotationAttributeEndChar)

		ss[aName] = ts[as+aas+1 : as+aas+aae+1]

		asi := strings.Index(ts[as+aae:], AnnotationAttributeSpliter)
		if -1 == asi {
			break
		}
		if len(ts) <= (as + aae + asi + 1) {
			break
		}
		ts = strings.TrimSpace(ts[as+aae+asi+1:])
	}

	return ss, nil
}

func newAnnotation(name string, attributes map[string]string) (Annotation, error) {
	def, ok := annotationRegistry[name]
	if !ok {
		return nil, fmt.Errorf("There is no annotation[%s]", name)
	}

	v := reflect.New(def.rt)
	i := v.Interface().(Annotation)

	if nil != attributes {
		setMetaAttributes(def, v.Elem(), attributes)
	}
	return i, nil
}

// func parseAnnotationItem(a string) (name string, attributes map[string]string, err error) {
// 	s := strings.Trim(a, " ")
// 	if "" == s {
// 		return
// 	}

// 	i := strings.Index(s, AnnotationChar)
// 	if -1 == i {
// 		err = fmt.Errorf("Syntax error: annotation must be started %s", AnnotationChar)
// 		return
// 	}

// 	aStart := strings.Index(s, AnnotationStartChar)
// 	if -1 == aStart {
// 		// This is pure annotation ex)@Resource
// 		name = s
// 		return
// 	}

// 	name = s[:aStart]

// 	aEnd := strings.Index(s, AnnotationEndChar)
// 	if -1 == aEnd {
// 		// This is syntax error ex)@Resource(
// 		err = fmt.Errorf("Syntax error: annotation must be ended %s", AnnotationEndChar)
// 		return
// 	}

// 	if 1 >= aEnd-aStart {
// 		return
// 	}

// 	attr := s[aStart+1 : aEnd]
// 	attr = strings.Trim(attr, " ")

// 	if "" == attr {
// 		return
// 	}

// 	attrs, pErr := parseAttributeString(s[aStart+1 : aEnd])
// 	if nil != pErr {
// 		err = pErr
// 		return
// 	}

// 	attributes = attrs

// 	return
// }

// func parseAttributeString(s string) (map[string]string, error) {
// 	attr := strings.Trim(s, " ")
// 	if "" == attr {
// 		return nil, nil
// 	}

// 	kvs := strings.Split(attr, AnnotationAttributeSpliter)
// 	if nil == kvs || 0 == len(kvs) {
// 		return nil, nil
// 	}

// 	rKVs := make(map[string]string)
// 	for i := 0; i < len(kvs); i++ {
// 		s := strings.Trim(kvs[i], " ")
// 		if "" == s {
// 			continue
// 		}
// 		kv := strings.Split(s, AnnotationKeyValueSpliter)
// 		k := strings.Trim(kv[0], " ")
// 		v := strings.Trim(kv[1], " ")
// 		rKVs[k] = v
// 	}

// 	return rKVs, nil
// }