From 7fe80bc1dc244d2f9d60619794a4ede45bd19450 Mon Sep 17 00:00:00 2001
From: Liang Ding <d@b3log.org>
Date: Sun, 25 Sep 2022 19:04:25 +0800
Subject: [PATCH] =?UTF-8?q?:art:=20=E5=B8=A6=E5=AD=90=E7=BA=A7=E5=8D=87?=
 =?UTF-8?q?=E9=99=8D=E6=A0=87=E9=A2=98=E5=B1=82=E7=BA=A7=20https://github.?=
 =?UTF-8?q?com/siyuan-note/siyuan/issues/2860?=
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---
 kernel/api/block.go      | 23 +++++++++++++++++
 kernel/model/blockial.go | 56 ++++++++++++++++++++++++++++++++++++++++
 2 files changed, 79 insertions(+)

diff --git a/kernel/api/block.go b/kernel/api/block.go
index 4db72e98c..8fb6288c6 100644
--- a/kernel/api/block.go
+++ b/kernel/api/block.go
@@ -31,6 +31,29 @@ import (
 	"github.com/siyuan-note/siyuan/kernel/util"
 )
 
+func getHeadingLevelTransaction(c *gin.Context) {
+	ret := gulu.Ret.NewResult()
+	defer c.JSON(http.StatusOK, ret)
+
+	arg, ok := util.JsonArg(c, ret)
+	if !ok {
+		return
+	}
+
+	id := arg["id"].(string)
+	level := int(arg["level"].(float64))
+
+	transaction, err := model.GetHeadingLevelTransaction(id, level)
+	if nil != err {
+		ret.Code = -1
+		ret.Msg = err.Error()
+		ret.Data = map[string]interface{}{"closeTimeout": 7000}
+		return
+	}
+
+	ret.Data = transaction
+}
+
 func setBlockReminder(c *gin.Context) {
 	ret := gulu.Ret.NewResult()
 	defer c.JSON(http.StatusOK, ret)
diff --git a/kernel/model/blockial.go b/kernel/model/blockial.go
index be98e505a..34cbd7aff 100644
--- a/kernel/model/blockial.go
+++ b/kernel/model/blockial.go
@@ -22,6 +22,7 @@ import (
 	"time"
 
 	"github.com/88250/gulu"
+	"github.com/88250/lute"
 	"github.com/88250/lute/ast"
 	"github.com/88250/lute/html"
 	"github.com/88250/lute/lex"
@@ -32,6 +33,61 @@ import (
 	"github.com/siyuan-note/siyuan/kernel/util"
 )
 
+func GetHeadingLevelTransaction(id string, level int) (transaction *Transaction, err error) {
+	tree, err := loadTreeByBlockID(id)
+	if nil != err {
+		return
+	}
+
+	node := treenode.GetNodeInTree(tree, id)
+	if nil == node {
+		err = errors.New(fmt.Sprintf(Conf.Language(15), id))
+		return
+	}
+
+	if ast.NodeHeading != node.Type {
+		return
+	}
+
+	hLevel := node.HeadingLevel
+	if hLevel == level {
+		return
+	}
+
+	diff := level - hLevel
+	children := treenode.HeadingChildren(node)
+	var childrenHeadings []*ast.Node
+	for _, c := range children {
+		if ast.NodeHeading == c.Type {
+			childrenHeadings = append(childrenHeadings, c)
+		}
+	}
+
+	transaction = &Transaction{}
+	luteEngine := NewLute()
+	for _, c := range childrenHeadings {
+		op := &Operation{}
+		op.ID = c.ID
+		op.Action = "update"
+		op.Data = lute.RenderNodeBlockDOM(c, luteEngine.ParseOptions, luteEngine.RenderOptions)
+		transaction.UndoOperations = append(transaction.UndoOperations, op)
+
+		c.HeadingLevel += diff
+		if 6 < c.HeadingLevel {
+			c.HeadingLevel = 6
+		} else if 1 > c.HeadingLevel {
+			c.HeadingLevel = 1
+		}
+
+		op = &Operation{}
+		op.ID = c.ID
+		op.Action = "update"
+		op.Data = lute.RenderNodeBlockDOM(c, luteEngine.ParseOptions, luteEngine.RenderOptions)
+		transaction.DoOperations = append(transaction.DoOperations, op)
+	}
+	return
+}
+
 func SetBlockReminder(id string, timed string) (err error) {
 	if !IsSubscriber() {
 		if "ios" == util.Container {