package annotation

import (
	"encoding/json"
	"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[reflect.Type]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[reflect.Type]Annotation, 0)
	for name, attributes := range annotations {
		t, annotation, err := newAnnotation(name, attributes)
		if nil != err {
			return nil, err
		}
		rKVs[t] = annotation
	}

	return rKVs, nil
}

func splitAnnotation(s string) (map[string]string, error) {
	ss := make(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) {
			ss[aName] = aAttributes
		} else {
			ss[aName] = ""
		}

		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)

		if -1 == aas && -1 == aae {
			ss[aName] = ts[as+1 : len(ts)]
		} else if -1 != aas && -1 != aae {
			ss[aName] = ts[as+aas+1 : as+aas+aae+1]
		} else {
			return nil, fmt.Errorf("not valid string %s", ts)
		}

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

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

	if "" != attributes {
		_json := fmt.Sprintf("{%s}", attributes)
		if err := json.Unmarshal([]byte(_json), i); nil != err {
			return nil, nil, err
		}

	}
	return def.t, i, nil
}