package gobatis

import (
	"encoding/xml"
	"io"
	"strings"
)

type ElemType string

const (
	eleTpText ElemType = "text" // 静态文本节点
	eleTpNode ElemType = "node" // 节点子节点
)

type node struct {
	Id        string
	Namespace string
	Name      string
	Attrs     map[string]xml.Attr
	Elements  []element
}

func (n *node) getAttr(attr string) string {
	res := ""
	at, ok := n.Attrs[attr]
	if ok {
		res = at.Value
	}

	return res
}

type element struct {
	ElementType ElemType
	Val         interface{}
}

func parse(r io.Reader) *node {
	parser := xml.NewDecoder(r)
	var root node
	namespace := ""

	st := NewStack()
	for {
		token, err := parser.Token()
		if err != nil {
			break
		}
		switch t := token.(type) {
		case xml.StartElement: //tag start
			elmt := xml.StartElement(t)
			name := elmt.Name.Local
			attr := elmt.Attr
			attrMap := make(map[string]xml.Attr)
			for _, val := range attr {
				attrMap[val.Name.Local] = val
			}
			node := node{
				Name:     name,
				Attrs:    attrMap,
				Elements: make([]element, 0),
			}

			id := node.getAttr("id")
			node.Id = id

			if namespace == "" {
				namespace = node.getAttr("namespace")
			}

			st.Push(node)

		case xml.EndElement: //tag end
			if st.Len() > 0 {
				//cur node
				n := st.Pop().(node)

				// set namespace
				if namespace != "" {
					n.Namespace = namespace + "."
				}

				if st.Len() > 0 { //if the root node then append to element
					e := element{
						ElementType: eleTpNode,
						Val:         n,
					}

					pn := st.Pop().(node)
					els := pn.Elements
					els = append(els, e)
					pn.Elements = els
					st.Push(pn)
				} else { //else root = n
					root = n
				}
			}
		case xml.CharData: //tag content
			if st.Len() > 0 {
				n := st.Pop().(node)

				bytes := xml.CharData(t)
				content := strings.TrimSpace(string(bytes))
				if content != "" {
					e := element{
						ElementType: eleTpText,
						Val:         content,
					}
					els := n.Elements
					els = append(els, e)
					n.Elements = els
				}

				st.Push(n)
			}

		case xml.Comment:
		case xml.ProcInst:
		case xml.Directive:
		default:
		}
	}

	if st.Len() != 0 {
		panic("Parse xml error, there is tag no close, please check your xml config!")
	}

	return &root
}