WIP on a unified edit

This allows a unified edit functionality that supports the following:

**`t e 25 due tom`**

* Edits the due date
* Leaves subject, projects and contexts unchanged

**`t e 25 take out the trash with @bob`

* Updates the subject, projects and contexts
* Leaves the due date unchanged

**`t e 25 take out the trash with @bob due tom`

* Updates the subject, projects and contexts
* Updates the due date

**What's missing**

* Tests that exercise this functionality

3 files changed, 35 insertions, 54 deletions

diff --git a/todo.go b/todo.go
index d091cd3..130fd55 100644
--- a/todo.go
+++ b/todo.go
@@ -140,10 +140,8 @@ func routeInput(command string, input string) {
 		app.UnarchiveTodo(input)
 	case "ac":
 		app.ArchiveCompleted()
-	case "e", "edit", "ed", "edit-date":
-		app.EditTodoDue(input)
-	case "es", "edit-subject":
-		app.EditTodoSubject(input)
+	case "e", "edit":
+		app.EditTodo(input)
 	case "ex", "expand":
 		app.ExpandTodo(input)
 	case "gc":
diff --git a/todolist/app.go b/todolist/app.go
index 12cc39d..9fefd8e 100644
--- a/todolist/app.go
+++ b/todolist/app.go
@@ -3,8 +3,8 @@ package todolist
 import (
 	"fmt"
 	"regexp"
+	"strconv"
 	"strings"
-	"time"
 )
 
 type App struct {
@@ -91,38 +91,18 @@ func (a *App) UnarchiveTodo(input string) {
 	fmt.Println("Todo unarchived.")
 }
 
-func (a *App) EditTodoSubject(input string) {
+func (a *App) EditTodo(input string) {
 	a.Load()
-
-	p := Parser{input}
-	_, id, subject := p.Parse()
+	id, _ := a.getId(input)
 	if id == -1 {
 		return
 	}
+	parser := &Parser{}
 
-	_, todo := a.getId(input)
-	if todo == nil {
-		return
-	}
-
-	todo.Subject = subject
-	todo.Projects = p.Projects(subject)
-	todo.Contexts = p.Contexts(subject)
-
-	a.Save()
-	fmt.Println("Todo subject updated.")
-}
-
-func (a *App) EditTodoDue(input string) {
-	a.Load()
-	id, todo := a.getId(input)
-	if id == -1 {
-		return
+	if (parser.ParseEditTodo(a.TodoList.FindById(id), input)) {
+		a.Save()
+		fmt.Println("Todo updated.")
 	}
-	parser := &Parser{}
-	todo.Due = parser.Due(input, time.Now())
-	a.Save()
-	fmt.Println("Todo due date updated.")
 }
 
 func (a *App) ExpandTodo(input string) {
@@ -195,13 +175,22 @@ func (a *App) UnprioritizeTodo(input string) {
 }
 
 func (a *App) getId(input string) (int, *Todo) {
-	_, id, _ := Parser{input}.Parse()
-	todo := a.TodoList.FindById(id)
-	if todo == nil {
-		fmt.Println("No such id.")
+	re, _ := regexp.Compile("\\d+")
+	if re.MatchString(input) {
+		id, _ := strconv.Atoi(re.FindString(input))
+		todo := a.TodoList.FindById(id)
+		if todo == nil {
+			fmt.Println("No such id.")
+			return -1, nil
+
+		}
+		return id, todo
+
+	} else {
+		fmt.Println("Invalid id.")
 		return -1, nil
+
 	}
-	return id, todo
 }
 
 func (a *App) getGroups(input string, todos []*Todo) *GroupedTodos {
diff --git a/todolist/parser.go b/todolist/parser.go
index 3598e12..91f9b6e 100644
--- a/todolist/parser.go
+++ b/todolist/parser.go
@@ -9,9 +9,7 @@ import (
 	"time"
 )
 
-type Parser struct {
-	input string
-}
+type Parser struct {}
 
 func (p *Parser) ParseNewTodo(input string) *Todo {
 	r, _ := regexp.Compile(`^(add|a)(\\ |) `)
@@ -30,29 +28,25 @@ func (p *Parser) ParseNewTodo(input string) *Todo {
 	return todo
 }
 
-// Parse accepts user input and splits it into subcommand, the todo id to
-// work on and the subject for the subcommand function.
-func (p Parser) Parse() (subcommand string, id int, subject string) {
+func (p *Parser) ParseEditTodo(todo *Todo, input string) bool {
 	r := regexp.MustCompile(`(\w+)\s+(\d+)(\s+(.*))?`)
-	matches := r.FindStringSubmatch(p.input)
+	matches := r.FindStringSubmatch(input)
 	if len(matches) < 3 {
 		fmt.Println("Could match command or id")
-		return "", -1, ""
+		return false
 	}
 
-	subcommand = matches[1]
+	subjectOnly := matches[3]
 
-	// because of the regexp match, this can never fail
-	id, err := strconv.Atoi(matches[2])
-	if err != nil {
-		panic(err)
+	if p.Subject(subjectOnly) != "" {
+		todo.Subject = p.Subject(subjectOnly)
+		todo.Projects = p.Projects(subjectOnly)
+		todo.Contexts = p.Contexts(subjectOnly)
 	}
-
-	if len(matches) == 5 {
-		subject = matches[4]
+	if p.hasDue(subjectOnly) {
+		todo.Due = p.Due(subjectOnly, time.Now())
 	}
-
-	return
+	return true
 }
 
 func (p *Parser) Subject(input string) string {