patch: implement worktree support

Implement worktree support for the patch management.

Use ":patch apply -w <commit-ish> <tag>" to create a new worktree and
apply the selected messages to it. The worktree is linked to repo in the
current project.

Internally, the worktree is stored as a new project. When this project
is deleted with ":patch delete", the underlying linked worktree is
removed as well.

":patch list" shows when a project is a worktree and to what project it
is linked to.

Worktrees enable the users to create a new copy of the repo at a given
commit and apply patches without interrupting the current work in the
base repo.

Signed-off-by: Koni Marti <koni.marti@gmail.com>
Acked-by: Robin Jarry <robin@jarry.cc>

2 files changed, 32 insertions, 8 deletions

diff --git a/lib/pama/models/models.go b/lib/pama/models/models.go
index 1c098885..9b21f0f5 100644
--- a/lib/pama/models/models.go
+++ b/lib/pama/models/models.go
@@ -20,6 +20,15 @@ type Commit struct {
 	Tag string
 }
 
+// WorktreeParent stores the name and repo location for the base project in the
+// linked worktree project.
+type WorktreeParent struct {
+	// Name is the project name from the base repo.
+	Name string
+	// Root is the root directory of the base repo.
+	Root string
+}
+
 // Project contains the data to access a revision control system and to store
 // the internal patch tracking data.
 type Project struct {
@@ -30,6 +39,9 @@ type Project struct {
 	Root string
 	// RevctrlID stores the ID for the revision control system.
 	RevctrlID string
+	// Worktree keeps the base repo information. If Worktree.Name and
+	// Worktree.Root are not zero, this project contains a linked worktree.
+	Worktree WorktreeParent
 	// Base represents the reference (base) commit.
 	Base Commit
 	// Commits contains the commits that are being tracked. The slice can
@@ -64,6 +76,12 @@ type RevisionController interface {
 	// ApplyCmd returns a string with an executable command that is used to
 	// apply patches with the :pipe command.
 	ApplyCmd() string
+	// CreateWorktree creats a worktree in path at commit.
+	CreateWorktree(path string, commit string) error
+	// DeleteWorktree removes the linked worktree stored in the path
+	// location. Note that this function should be called from the base
+	// repo.
+	DeleteWorktree(path string) error
 }
 
 // PersistentStorer is an interface to a persistent storage for Project structs.
@@ -81,6 +99,8 @@ type PersistentStorer interface {
 	Current() (Project, error)
 	// Names returns a slice of Project.Name for all stored projects.
 	Names() ([]string, error)
+	// Project returns the stored project for the provided name.
+	Project(string) (Project, error)
 	// Projects returns all stored projects.
 	Projects() ([]Project, error)
 }
diff --git a/lib/pama/models/view.go b/lib/pama/models/view.go
index 093ca6f0..6a5b6bd4 100644
--- a/lib/pama/models/view.go
+++ b/lib/pama/models/view.go
@@ -10,7 +10,7 @@ import (
 )
 
 var templateText = `
-Project    {{.Name}}    {{if .IsActive}}[active]{{end}}
+Project    {{.Name}}    {{if .IsActive}}[active]{{end}} {{if .IsWorktree}}[Linked worktree to {{.WorktreeParent}}]{{end}}
 Directory  {{.Root}}
 Base       {{with .Base.ID}}{{if ge (len .) 40}}{{printf "%-6.6s" .}}{{else}}{{.}}{{end}}{{end}}
 {{$notes := .Notes}}{{$commits := .Commits}}
@@ -37,17 +37,21 @@ type view struct {
 	// the key and the annotation is the value.
 	Notes map[string]string
 	// IsActive is true if the current project is selected.
-	IsActive bool
+	IsActive       bool
+	IsWorktree     bool
+	WorktreeParent string
 }
 
 func newView(p Project, active bool, notes map[string]string) view {
 	v := view{
-		Name:     p.Name,
-		Root:     p.Root,
-		Base:     p.Base,
-		Commits:  make(map[string][]Commit),
-		Notes:    notes,
-		IsActive: active,
+		Name:           p.Name,
+		Root:           p.Root,
+		Base:           p.Base,
+		Commits:        make(map[string][]Commit),
+		Notes:          notes,
+		IsActive:       active,
+		IsWorktree:     p.Worktree.Root != "" && p.Worktree.Name != "",
+		WorktreeParent: p.Worktree.Name,
 	}
 
 	for _, commit := range p.Commits {