Add interactive configuration

This adds a new --config flag and rearranges some config fields.

config/setup.go

@@ -0,0 +1,181 @@
+package config
+
+import (
+	"fmt"
+	"github.com/fatih/color"
+	"github.com/manifoldco/promptui"
+	"github.com/mitchellh/go-wordwrap"
+	"strconv"
+)
+
+func Configure() error {
+	c, err := Load()
+	if err != nil {
+		fmt.Println("No configuration yet. Creating new.")
+		c = New()
+	} else {
+		fmt.Println("Configuration loaded.")
+	}
+	title := color.New(color.Bold, color.BgGreen).PrintlnFunc()
+
+	intro := color.New(color.Bold, color.FgWhite).PrintlnFunc()
+	fmt.Println()
+	intro("  ✍ Write Freely Configuration ✍")
+	fmt.Println()
+	fmt.Println(wordwrap.WrapString("  This quick configuration process will generate the application's config file, "+FileName+".\n\n  It validates your input along the way, so you can be sure any future errors aren't caused by a bad configuration. If you'd rather configure your server manually, instead run: writefreely --create-config and edit that file.", 75))
+	fmt.Println()
+
+	title(" Server setup ")
+	fmt.Println()
+
+	prompt := promptui.Prompt{
+		Label:    "Local port",
+		Validate: validatePort,
+		Default:  fmt.Sprintf("%d", c.Server.Port),
+	}
+	port, err := prompt.Run()
+	if err != nil {
+		return err
+	}
+	c.Server.Port, _ = strconv.Atoi(port) // Ignore error, as we've already validated number
+
+	prompt = promptui.Prompt{
+		Label:    "Public-facing host",
+		Validate: validateDomain,
+		Default:  c.Server.Host,
+	}
+	c.Server.Host, err = prompt.Run()
+	if err != nil {
+		return err
+	}
+
+	fmt.Println()
+	title(" Database setup ")
+	fmt.Println()
+
+	prompt = promptui.Prompt{
+		Label:    "Username",
+		Validate: validateNonEmpty,
+		Default:  c.Database.User,
+	}
+	c.Database.User, err = prompt.Run()
+	if err != nil {
+		return err
+	}
+
+	prompt = promptui.Prompt{
+		Label:    "Password",
+		Validate: validateNonEmpty,
+		Default:  c.Database.Password,
+		Mask:     '*',
+	}
+	c.Database.Password, err = prompt.Run()
+	if err != nil {
+		return err
+	}
+
+	prompt = promptui.Prompt{
+		Label:    "Database name",
+		Validate: validateNonEmpty,
+		Default:  c.Database.Database,
+	}
+	c.Database.Database, err = prompt.Run()
+	if err != nil {
+		return err
+	}
+
+	prompt = promptui.Prompt{
+		Label:    "Host",
+		Validate: validateNonEmpty,
+		Default:  c.Database.Host,
+	}
+	c.Database.Host, err = prompt.Run()
+	if err != nil {
+		return err
+	}
+
+	prompt = promptui.Prompt{
+		Label:    "Port",
+		Validate: validatePort,
+		Default:  fmt.Sprintf("%d", c.Database.Port),
+	}
+	dbPort, err := prompt.Run()
+	if err != nil {
+		return err
+	}
+	c.Database.Port, _ = strconv.Atoi(dbPort) // Ignore error, as we've already validated number
+
+	fmt.Println()
+	title(" App setup ")
+	fmt.Println()
+
+	selPrompt := promptui.Select{
+		Label: "Site type",
+		Items: []string{"Single user", "Multiple users"},
+	}
+	_, usersType, err := selPrompt.Run()
+	if err != nil {
+		return err
+	}
+	c.App.SingleUser = usersType == "Single user"
+
+	siteNameLabel := "Instance name"
+	if c.App.SingleUser {
+		siteNameLabel = "Blog name"
+	}
+	prompt = promptui.Prompt{
+		Label:    siteNameLabel,
+		Validate: validateNonEmpty,
+		Default:  c.App.SiteName,
+	}
+	c.App.SiteName, err = prompt.Run()
+	if err != nil {
+		return err
+	}
+
+	if !c.App.SingleUser {
+		selPrompt = promptui.Select{
+			Label: "Registration",
+			Items: []string{"Open", "Closed"},
+		}
+		_, regType, err := selPrompt.Run()
+		if err != nil {
+			return err
+		}
+		c.App.OpenRegistration = regType == "Open"
+	}
+
+	selPrompt = promptui.Select{
+		Label: "Federation",
+		Items: []string{"Enabled", "Disabled"},
+	}
+	_, fedType, err := selPrompt.Run()
+	if err != nil {
+		return err
+	}
+	c.App.Federation = fedType == "Enabled"
+
+	if c.App.Federation {
+		selPrompt = promptui.Select{
+			Label: "Federation usage stats",
+			Items: []string{"Public", "Private"},
+		}
+		_, fedStatsType, err := selPrompt.Run()
+		if err != nil {
+			return err
+		}
+		c.App.PublicStats = fedStatsType == "Public"
+
+		selPrompt = promptui.Select{
+			Label: "Instance metadata privacy",
+			Items: []string{"Public", "Private"},
+		}
+		_, fedStatsType, err = selPrompt.Run()
+		if err != nil {
+			return err
+		}
+		c.App.Private = fedStatsType == "Private"
+	}
+
+	return Save(c)
+}