modifyast.go

package main

import (
	"bytes"

	"github.com/gomarkdown/markdown/ast"
)

func modifyAst(doc ast.Node) ast.Node {
	doclinkPrefixBytes := []byte("[[")
	doclinkSuffixBytes := []byte("]]")
	doclinkPrefixBytesLen := len(doclinkPrefixBytes)
	ast.WalkFunc(doc, func(node ast.Node, entering bool) ast.WalkStatus {
		if entering {
			leaf := node.AsLeaf()
			if leaf != nil {
				for {
					doclinkPrefixIndex := bytes.Index(leaf.Literal, doclinkPrefixBytes)
					if doclinkPrefixIndex == -1 {
						return ast.GoToNext
					}
					doclinkSuffixIndex := bytes.Index(leaf.Literal[doclinkPrefixIndex:], doclinkSuffixBytes)
					if doclinkSuffixIndex == -1 {
						return ast.GoToNext
					}

					if doclinkPrefixIndex > doclinkSuffixIndex {
						return ast.GoToNext
					}

					if doclinkPrefixIndex != 0 {
						newnode := &ast.Text{}
						newnode.Literal = leaf.Literal[:doclinkPrefixIndex]
						leaf.Literal = leaf.Literal[doclinkPrefixIndex:]
						index := 0
						parent := node.GetParent().AsContainer()
						for i, v := range parent.Children {
							if v == node {
								index = i
								break
							}
						}

						insertNewNode(newnode, parent, index)
						// debug
						// fmt.Println("--")
						// for _, v := range parent.Children {
						// 	vv := v.AsLeaf()
						// 	if vv != nil {
						// 		fmt.Println(string(vv.Literal))
						// 	}
						// }
						continue
					}

					insideDoclink := leaf.Literal[doclinkPrefixIndex+doclinkPrefixBytesLen : doclinkSuffixIndex]

					leaf.Literal = leaf.Literal[doclinkSuffixIndex+doclinkPrefixBytesLen:]

					parent := node.GetParent().AsContainer()
					index := 0
					for i, v := range parent.Children {
						if v == node {
							index = i
							break
						}
					}
					newnode := &DocLink{
						URL:    string(insideDoclink),
						Inline: true,
					}
					insertNewNode(newnode, parent, index)

					// debug
					// fmt.Println("--")
					// for _, v := range parent.Children {
					// 	vv := v.AsLeaf()
					// 	if vv != nil {
					// 		fmt.Println(string(vv.Literal))
					// 	}
					// }
				}

			}
		}
		return ast.GoToNext
	})
	return doc
}

func insertNewNode(newnode ast.Node, parentn ast.Node, at int) {
	newnode.SetParent(parentn)
	parent := parentn.AsContainer()
	pc := parent.Children
	tmp := append([]ast.Node{}, pc[at:]...)
	pc = append(pc[0:at], newnode)
	pc = append(pc, tmp...)
	parent.SetChildren(pc)
}