package cmd

import (
	"context"
	"errors"
	"flag"
	"fmt"
	"os"
	"os/exec"
	"os/user"
	"regexp"
	"strings"

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

	"github.com/go-git/go-git/v5"
	"github.com/go-git/go-git/v5/plumbing"
	"github.com/peterbourgon/ff/v3/ffcli"
	"github.com/rs/zerolog/log"
)

var Version = "x.y.z"

type Handler struct {
	Config *config.Config
}

func New() (*ffcli.Command, error) {
	cfg, err := config.Load()
	if err != nil {
		return nil, err
	}

	handler := Handler{
		Config: cfg,
	}

	fs := flag.NewFlagSet("git-ea", flag.ContinueOnError)
	versionFlag := fs.Bool("version", false, "Print git-ea version")
	fs.BoolVar(versionFlag, "v", *versionFlag, "--version")

	c := &ffcli.Command{
		Name:       "git-ea",
		FlagSet:    fs,
		ShortUsage: "git-ea <cmd>",
		ShortHelp:  "git-ea is the base command",
		Subcommands: []*ffcli.Command{
			handler.Cleanup(),
			handler.Backport(),
			handler.Branch(),
			handler.Frontport(),
			handler.IDE(),
			handler.Init(),
			handler.Post(),
			handler.PR(),
		},
	}
	c.Exec = func(_ context.Context, _ []string) error {
		if *versionFlag {
			log.Info().Msgf("git-ea v%s", Version)
			return nil
		}

		dir := cfg.Base
		if fs.NArg() > 0 {
			if strings.EqualFold(fs.Arg(0), "help") {
				fmt.Println(ffcli.DefaultUsageFunc(c))
				return nil
			}
			dir = cfg.WorkspaceBranch(fs.Arg(0))
		}

		fmt.Println(dir)
		return nil
	}
	return c, nil
}

func (h *Handler) checkInit() error {
	if !h.Config.IsInit() {
		return errors.New("git-ea must be initialized first with `git ea init` in an appropriate directory")
	}
	return nil
}

func (h *Handler) run(ctx context.Context, cmd string, args ...string) error {
	return run(ctx, h.Config.Base, cmd, args...)
}

func run(ctx context.Context, dir, cmd string, args ...string) error {
	c := exec.CommandContext(ctx, cmd, args...)
	c.Dir = dir
	c.Stdout = os.Stdout
	c.Stderr = os.Stderr
	c.Stdin = os.Stdin
	return c.Run()
}

func (h *Handler) fetch(ctx context.Context) {
	if err := run(ctx, h.Config.Base, "git", "fetch", "upstream"); err != nil {
		log.Err(err).Msg("")
	}
}

func (h *Handler) repo() *git.Repository {
	repo, err := git.PlainOpen(h.Config.Base)
	if err != nil {
		log.Fatal().Err(err).Msg("cannot open git repository")
	}
	return repo
}

func (h *Handler) worktree() *git.Worktree {
	tree, err := h.repo().Worktree()
	if err != nil {
		log.Fatal().Err(err).Msg("cannot get git worktree")
	}
	return tree
}

func (h *Handler) head(name string) plumbing.Hash {
	ref, err := h.repo().Reference(plumbing.NewRemoteReferenceName("upstream", name), false)
	if err != nil {
		log.Fatal().Err(err).Msgf("cannot get remote upstream %s HEAD", name)
	}
	return ref.Hash()
}

var releaseRe = regexp.MustCompile(`release/v1\.(\d+)`)

func (h *Handler) latestRelease() string {
	cmd := exec.Command("git", "ls-remote", "upstream", "release/*")
	cmd.Dir = h.Config.Base
	out, err := cmd.Output()
	if err != nil {
		log.Fatal().Err(err).Msg("could not get latest release")
	}
	matches := releaseRe.FindAllStringSubmatch(string(out), -1)

	var latest string
	for _, match := range matches {
		m := match[1]
		if len(m) < 3 {
			m = strings.Repeat("0", 3-len(m)) + m
		}
		if m > latest {
			latest = m
		}
	}

	return strings.TrimLeft(latest, "0")
}

func currentUser() string {
	u, err := user.Current()
	if err != nil {
		return ""
	}
	return u.Username
}