package cmd

import (
	"context"
	"flag"
	"fmt"
	"regexp"
	"strings"

	"github.com/AlecAivazis/survey/v2"
	"github.com/go-git/go-git/v5"
	"github.com/go-git/go-git/v5/plumbing/object"
	"github.com/peterbourgon/ff/v3/ffcli"
	"github.com/skratchdot/open-golang/open"
)

var indexRe = regexp.MustCompile(`\(#(\d+)\)`)

func (h *Handler) Backport() *ffcli.Command {
	fs := flag.NewFlagSet("backport", flag.ContinueOnError)
	fromFlag := fs.String("from", "", "Release to backport from (ex: `main`, default: main)")
	fs.StringVar(fromFlag, "f", *fromFlag, "--from")
	toFlag := fs.String("to", "", "Release to backport to (ex: `17`, default: `latest`)")
	fs.StringVar(toFlag, "t", *toFlag, "--to")
	listFlag := fs.Bool("list", false, "Open repository to see needed backports")
	fs.BoolVar(listFlag, "l", *listFlag, "--list")
	return &ffcli.Command{
		Name:       "backport",
		FlagSet:    fs,
		ShortUsage: "backport --from [release=main] --to [release=latest]",
		ShortHelp:  "backport cherry-picks a commit and applies it to a clean branch based on `release`",
		Exec: func(ctx context.Context, _ []string) error {
			if err := h.checkInit(); err != nil {
				return err
			}

			to := *toFlag
			if to == "" {
				to = h.latestRelease()
			}

			if *listFlag {
				if err := open.Run(fmt.Sprintf("https://github.com/go-gitea/gitea/pulls?q=is%%3Apr+-label%%3Abackport%%2Fdone+label%%3Abackport%%2Fv1.%s+is%%3Amerged", to)); err != nil {
					return err
				}
				return nil
			}

			h.fetch(ctx)

			from := *fromFlag
			if from == "" {
				from = "main"
			}

			commits, err := h.repo().Log(&git.LogOptions{
				From: h.head(from),
			})
			if err != nil {
				return err
			}

			optMap := make(map[string]string)
			var opts []string
			if err := commits.ForEach(func(c *object.Commit) error {
				title := strings.Split(c.Message, "\n")[0]
				opts = append(opts, title)
				optMap[title] = c.Hash.String()
				return nil
			}); err != nil {
				return err
			}

			var resp string
			if err := survey.AskOne(&survey.Select{
				Message: "Commit to cherry-pick",
				Options: opts,
			}, &resp, survey.WithValidator(survey.Required)); err != nil {
				return err
			}

			index := optMap[resp]
			m := indexRe.FindStringSubmatch(resp)
			if m != nil {
				index = m[1]
			}

			branch := fmt.Sprintf("backport-%s-%s", to, index)
			base := fmt.Sprintf("upstream/release/v1.%s", to)
			if err := h.Branch().ParseAndRun(ctx, []string{"--base", base, branch}); err != nil {
				return err
			}

			return run(ctx, h.Config.WorkspaceBranch(branch), "git", "cherry-pick", optMap[resp])
		},
	}
}