package cmd

import (
	"bytes"
	"context"
	"flag"
	"fmt"
	"os"
	"strings"

	"go.jolheiser.com/git-ea/blog"

	"github.com/AlecAivazis/survey/v2"
	"github.com/peterbourgon/ff/v3/ffcli"
)

func (h *Handler) Post() *ffcli.Command {
	fs := flag.NewFlagSet("post", flag.ContinueOnError)
	authorFlag := fs.String("author", "", "Post author")
	fs.StringVar(authorFlag, "a", *authorFlag, "--author")
	milestoneFlag := fs.String("milestone", "", "Post milestone")
	fs.StringVar(milestoneFlag, "m", *milestoneFlag, "--milestone")
	changelogFlag := fs.String("changelog", "", "Post changelog (no header)")
	fs.StringVar(changelogFlag, "c", *changelogFlag, "--changelog")
	outputFlag := fs.String("output", "content/post/release-of-${milestone}.md", "Output file")
	fs.StringVar(outputFlag, "o", *outputFlag, "--output")
	return &ffcli.Command{
		Name:       "post",
		FlagSet:    fs,
		ShortUsage: "post",
		ShortHelp:  "post creates a new blog release post",
		Exec: func(ctx context.Context, args []string) error {
			author := *authorFlag
			if author == "" {
				if err := survey.AskOne(&survey.Input{
					Message: "Blog post author",
					Default: currentUser(),
				}, &author, survey.WithValidator(survey.Required)); err != nil {
					return err
				}
			}

			milestone := *milestoneFlag
			if milestone == "" {
				var defMilestone blog.Release
				r, err := blog.LatestRelease()
				if err == nil {
					defMilestone = r
				}
				if err := survey.AskOne(&survey.Input{
					Message: "Release milestone",
					Default: strings.TrimPrefix(defMilestone.Name, "v"),
					Help:    fmt.Sprintf("Default was published on %s", defMilestone.PublishedAt.Format("01/02/2006")),
				}, &milestone, survey.WithValidator(survey.Required)); err != nil {
					return err
				}
			}

			changelog := *changelogFlag
			if changelog == "" {
				if err := blog.OpenChangelogPullRequest(milestone); err != nil {
					fmt.Println(err)
				}
				if err := survey.AskOne(&survey.Editor{
					Message:  "Blog post changelog",
					FileName: "*.md",
				}, &changelog, survey.WithValidator(survey.Required)); err != nil {
					return err
				}
			}

			post, err := blog.FormatRelease(author, milestone, changelog)
			if err != nil {
				return err
			}

			complete, err := blog.FormatPR(bytes.NewReader(post))
			if err != nil {
				return err
			}

			output := os.Expand(*outputFlag, func(s string) string {
				switch s {
				case "milestone":
					return milestone
				default:
					return s
				}
			})

			fi, err := os.Create(output)
			if err != nil {
				return err
			}
			defer fi.Close()

			if _, err := fi.Write(complete); err != nil {
				fmt.Println(err)
			}
			fmt.Printf("Blog post created at %q\n", output)
			return nil
		},
	}
}