package hhc_ast

import (
	"git.swzry.com/zry/go-hhc-cli/hhc_common"
)

type SDTWalker struct {
	root         *SyntaxDefinitionTreeRoot
	current      SyntaxDefTreeNode
	ctx          *SDTWalkContext
	currentError hhc_common.SDTWalkError
	depthCount   uint32
	actualDepth  uint32
}

func NewSDTWalker(rootnode *SyntaxDefinitionTreeRoot) *SDTWalker {
	w := &SDTWalker{
		root:         rootnode,
		current:      rootnode,
		ctx:          &SDTWalkContext{ASTNodes: []ASTNode{}},
		currentError: nil,
		depthCount:   0,
		actualDepth:  0,
	}
	return w
}

func (w *SDTWalker) Reset() {
	w.current = w.root
	w.ctx = &SDTWalkContext{ASTNodes: []ASTNode{}}
	w.currentError = nil
	w.depthCount = 0
	w.actualDepth = 0
}

func (w *SDTWalker) NextStep(token string) bool {
	//fmt.Println("On NextStep, dc=", w.depthCount, "ad=", w.actualDepth)
	w.depthCount++
	if w.depthCount == w.actualDepth+1 {
		nc, serr := w.current.WalkNext(w.ctx, token)
		if serr != nil {
			w.currentError = serr
			return false
		}
		w.current = nc
		w.actualDepth++
		w.currentError = nil
		return true
	}
	return false
}

func (w *SDTWalker) Back() bool {
	//fmt.Println("On Back, dc=", w.depthCount, "ad=", w.actualDepth)
	if w.depthCount > 0 {
		w.depthCount--
		if w.depthCount < w.actualDepth {
			nc, serr := w.current.Fallback(w.ctx)
			if serr != nil {
				switch serr.(type) {
				case hhc_common.SDTWalkError_RootNodeCannotFallback:
					w.Reset()
					return false
				}
				w.currentError = serr
				return false
			}
			w.current = nc
			w.actualDepth--
			w.currentError = nil
			return true
		}
	}
	return false
}

func (w *SDTWalker) GetHelps(prefix string) []hhc_common.SDTHelpInfo {
	return w.current.GetHelps(prefix)
}

func (w *SDTWalker) GetContext() *SDTWalkContext {
	return w.ctx
}

func (w *SDTWalker) GetError() hhc_common.SDTWalkError {
	return w.currentError
}

func (w *SDTWalker) HasError() bool {
	return w.currentError != nil
}

func (w *SDTWalker) IsSync() bool {
	return w.actualDepth == w.actualDepth
}

func (w *SDTWalker) IsEnd() bool {
	return w.current.IsEnd()
}

func (w *SDTWalker) GetEndExecute() (bool, ExecuteFunc) {
	if w.IsEnd() {
		e := w.current.(*SDTNode_End)
		if e != nil {
			ef := e.Exec
			return true, ef
		} else {
			return false, nil
		}
	} else {
		return false, nil
	}
}