Refactor the formatter to an interface and rename it

This change refactors the formatter to be an interface called Printer.
`NewApp` will use the functionality of `ScreenPrinter`,  which is what I
refactored the old `Formatter` class into.

There is a new class the implements the `Printer` interface called
`MemoryPrinter`, which will simply store the `groups` as they were
passed to it.  This will allow tests in `app_test.go` to become much
more powerful, since `App` no longer needs to be tightly coupled to
printing to the screen.

1 files changed, 131 insertions, 0 deletions

diff --git a/todolist/screen_printer.go b/todolist/screen_printer.go
new file mode 100644
index 0000000..eab0c39
--- /dev/null
+++ b/todolist/screen_printer.go
@@ -0,0 +1,131 @@
+package todolist
+
+import (
+	"fmt"
+	"os"
+	"regexp"
+	"sort"
+	"strconv"
+	"strings"
+	"text/tabwriter"
+	"time"
+
+	"github.com/fatih/color"
+)
+
+type ScreenPrinter struct {
+	Writer *tabwriter.Writer
+}
+
+func NewScreenPrinter() *ScreenPrinter {
+	w := new(tabwriter.Writer)
+	w.Init(os.Stdout, 0, 8, 0, '\t', 0)
+	formatter := &ScreenPrinter{Writer: w}
+	return formatter
+}
+
+func (f *ScreenPrinter) Print(groupedTodos *GroupedTodos, printNotes bool) {
+	cyan := color.New(color.FgCyan).SprintFunc()
+
+	var keys []string
+	for key := range groupedTodos.Groups {
+		keys = append(keys, key)
+	}
+	sort.Strings(keys)
+
+	for _, key := range keys {
+		fmt.Fprintf(f.Writer, "\n %s\n", cyan(key))
+		for _, todo := range groupedTodos.Groups[key] {
+			f.printTodo(todo)
+			if printNotes {
+				for nid, note := range todo.Notes {
+					fmt.Fprintf(f.Writer, "   %s\t%s\t\n",
+						cyan(strconv.Itoa(nid)), note)
+				}
+			}
+		}
+	}
+	f.Writer.Flush()
+}
+
+func (f *ScreenPrinter) printTodo(todo *Todo) {
+	yellow := color.New(color.FgYellow)
+	if todo.IsPriority {
+		yellow.Add(color.Bold, color.Italic)
+	}
+	fmt.Fprintf(f.Writer, " %s\t%s\t%s\t%s\t\n",
+		yellow.SprintFunc()(strconv.Itoa(todo.Id)),
+		f.formatCompleted(todo.Completed),
+		f.formatDue(todo.Due, todo.IsPriority),
+		f.formatSubject(todo.Subject, todo.IsPriority))
+}
+
+func (f *ScreenPrinter) formatDue(due string, isPriority bool) string {
+	blue := color.New(color.FgBlue)
+	red := color.New(color.FgRed)
+
+	if isPriority {
+		blue.Add(color.Bold, color.Italic)
+		red.Add(color.Bold, color.Italic)
+	}
+
+	if due == "" {
+		return blue.SprintFunc()(" ")
+	}
+	dueTime, err := time.Parse("2006-01-02", due)
+
+	if err != nil {
+		fmt.Println(err)
+		fmt.Println("This may due to the corruption of .todos.json file.")
+		os.Exit(-1)
+	}
+
+	if isToday(dueTime) {
+		return blue.SprintFunc()("today")
+	} else if isTomorrow(dueTime) {
+		return blue.SprintFunc()("tomorrow")
+	} else if isPastDue(dueTime) {
+		return red.SprintFunc()(dueTime.Format("Mon Jan 2"))
+	} else {
+		return blue.SprintFunc()(dueTime.Format("Mon Jan 2"))
+	}
+}
+
+func (f *ScreenPrinter) formatSubject(subject string, isPriority bool) string {
+
+	red := color.New(color.FgRed)
+	magenta := color.New(color.FgMagenta)
+	white := color.New(color.FgWhite)
+
+	if isPriority {
+		red.Add(color.Bold, color.Italic)
+		magenta.Add(color.Bold, color.Italic)
+		white.Add(color.Bold, color.Italic)
+	}
+
+	splitted := strings.Split(subject, " ")
+	projectRegex, _ := regexp.Compile(`\+[\p{L}\d_]+`)
+	contextRegex, _ := regexp.Compile(`\@[\p{L}\d_]+`)
+
+	coloredWords := []string{}
+
+	for _, word := range splitted {
+		if projectRegex.MatchString(word) {
+			coloredWords = append(coloredWords, magenta.SprintFunc()(word))
+		} else if contextRegex.MatchString(word) {
+			coloredWords = append(coloredWords, red.SprintFunc()(word))
+		} else {
+			coloredWords = append(coloredWords, white.SprintFunc()(word))
+		}
+	}
+	return strings.Join(coloredWords, " ")
+
+}
+
+func (f *ScreenPrinter) formatCompleted(completed bool) string {
+	if completed {
+		return "[x]"
+	} else {
+		return "[ ]"
+	}
+}