Split commit message panel into commit summary and commit description panel

When we use the one panel for the entire commit message, its tricky to have a keybinding both for adding a newline and submitting.
By having two panels: one for the summary line and one for the description, we allow for 'enter' to submit the message when done from the summary panel,
and 'enter' to add a newline when done from the description panel. Alt-enter, for those who can use that key combo, also works for submitting the message
from the description panel. For those who can't use that key combo, and don't want to remap the keybinding, they can hit tab to go back to the summary panel
and then 'enter' to submit the message.

We have some awkwardness in that both contexts (i.e. panels) need to appear and disappear in tandem and we don't have a great way of handling that concept,
so we just push both contexts one after the other, and likewise remove both contexts when we escape.

pkg/gui/controllers/helpers/commits_helper.go

@@ -0,0 +1,153 @@
+package helpers
+
+import (
+	"strings"
+
+	"github.com/jesseduffield/lazygit/pkg/gui/types"
+)
+
+type ICommitsHelper interface {
+	UpdateCommitPanelView(message string)
+}
+
+type CommitsHelper struct {
+	c *HelperCommon
+
+	getCommitSummary     func() string
+	setCommitSummary     func(string)
+	getCommitDescription func() string
+	setCommitDescription func(string)
+}
+
+var _ ICommitsHelper = &CommitsHelper{}
+
+func NewCommitsHelper(
+	c *HelperCommon,
+	getCommitSummary func() string,
+	setCommitSummary func(string),
+	getCommitDescription func() string,
+	setCommitDescription func(string),
+) *CommitsHelper {
+	return &CommitsHelper{
+		c:                    c,
+		getCommitSummary:     getCommitSummary,
+		setCommitSummary:     setCommitSummary,
+		getCommitDescription: getCommitDescription,
+		setCommitDescription: setCommitDescription,
+	}
+}
+
+func (self *CommitsHelper) SplitCommitMessageAndDescription(message string) (string, string) {
+	for _, separator := range []string{"\n\n", "\n\r\n\r", "\n", "\n\r"} {
+		msg, description, found := strings.Cut(message, separator)
+		if found {
+			return msg, description
+		}
+	}
+	return message, ""
+}
+
+func (self *CommitsHelper) SetMessageAndDescriptionInView(message string) {
+	summary, description := self.SplitCommitMessageAndDescription(message)
+
+	self.setCommitSummary(summary)
+	self.setCommitDescription(description)
+	self.c.Contexts().CommitMessage.RenderCommitLength()
+}
+
+func (self *CommitsHelper) joinCommitMessageAndDescription() string {
+	if len(self.getCommitDescription()) == 0 {
+		return self.getCommitSummary()
+	}
+	return self.getCommitSummary() + "\n" + self.getCommitDescription()
+}
+
+func (self *CommitsHelper) UpdateCommitPanelView(message string) {
+	// first try the passed in message, if not fallback to context -> view in that order
+	if message != "" {
+		self.SetMessageAndDescriptionInView(message)
+		return
+	}
+	message = self.c.Contexts().CommitMessage.GetPreservedMessage()
+	if message != "" {
+		self.SetMessageAndDescriptionInView(message)
+	} else {
+		self.SetMessageAndDescriptionInView(self.getCommitSummary())
+	}
+}
+
+type OpenCommitMessagePanelOpts struct {
+	CommitIndex     int
+	Title           string
+	PreserveMessage bool
+	OnConfirm       func(string) error
+	InitialMessage  string
+}
+
+func (self *CommitsHelper) OpenCommitMessagePanel(opts *OpenCommitMessagePanelOpts) error {
+	self.c.Contexts().CommitMessage.SetPanelState(
+		opts.CommitIndex,
+		opts.Title,
+		opts.PreserveMessage,
+		opts.OnConfirm,
+	)
+
+	self.UpdateCommitPanelView(opts.InitialMessage)
+
+	return self.pushCommitMessageContexts()
+}
+
+func (self *CommitsHelper) OnCommitSuccess() {
+	// if we have a preserved message we want to clear it on success
+	if self.c.Contexts().CommitMessage.GetPreserveMessage() {
+		self.c.Contexts().CommitMessage.SetPreservedMessage("")
+	}
+	self.SetMessageAndDescriptionInView("")
+}
+
+func (self *CommitsHelper) HandleCommitConfirm() error {
+	fullMessage := self.joinCommitMessageAndDescription()
+
+	if fullMessage == "" {
+		return self.c.ErrorMsg(self.c.Tr.CommitWithoutMessageErr)
+	}
+
+	err := self.c.Contexts().CommitMessage.OnConfirm(fullMessage)
+	if err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func (self *CommitsHelper) CloseCommitMessagePanel() error {
+	if self.c.Contexts().CommitMessage.GetPreserveMessage() {
+		message := self.joinCommitMessageAndDescription()
+
+		self.c.Contexts().CommitMessage.SetPreservedMessage(message)
+	} else {
+		self.SetMessageAndDescriptionInView("")
+	}
+	return self.EscapeCommitsPanel()
+}
+
+func (self *CommitsHelper) EscapeCommitsPanel() error {
+	return self.c.RemoveContexts(self.commitMessageContexts())
+}
+
+func (self *CommitsHelper) pushCommitMessageContexts() error {
+	for _, context := range self.commitMessageContexts() {
+		if err := self.c.PushContext(context); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+func (self *CommitsHelper) commitMessageContexts() []types.Context {
+	return []types.Context{
+		self.c.Contexts().CommitDescription,
+		self.c.Contexts().CommitMessage,
+	}
+}