package gitlab

import (
	"bufio"
	"fmt"
	"net/url"
	"os"
	"path"
	"regexp"
	"sort"
	"strconv"
	"strings"
	"time"

	text "github.com/MichaelMure/go-term-text"
	"github.com/pkg/errors"
	"github.com/xanzy/go-gitlab"

	"github.com/MichaelMure/git-bug/bridge/core"
	"github.com/MichaelMure/git-bug/bridge/core/auth"
	"github.com/MichaelMure/git-bug/cache"
	"github.com/MichaelMure/git-bug/input"
	"github.com/MichaelMure/git-bug/repository"
	"github.com/MichaelMure/git-bug/util/colors"
)

var (
	ErrBadProjectURL = errors.New("bad project url")
)

func (g *Gitlab) Configure(repo *cache.RepoCache, params core.BridgeParams) (core.Configuration, error) {
	if params.Project != "" {
		fmt.Println("warning: --project is ineffective for a gitlab bridge")
	}
	if params.Owner != "" {
		fmt.Println("warning: --owner is ineffective for a gitlab bridge")
	}
	if params.Login != "" {
		fmt.Println("warning: --login is ineffective for a gitlab bridge")
	}

	conf := make(core.Configuration)
	var err error
	var baseUrl string

	switch {
	case params.BaseURL != "":
		baseUrl = params.BaseURL
	default:
		baseUrl, err = promptBaseUrlOptions()
		if err != nil {
			return nil, errors.Wrap(err, "base url prompt")
		}
	}

	var url string

	// get project url
	switch {
	case params.URL != "":
		url = params.URL
	default:
		// terminal prompt
		url, err = promptURL(repo, baseUrl)
		if err != nil {
			return nil, errors.Wrap(err, "url prompt")
		}
	}

	if !strings.HasPrefix(url, params.BaseURL) {
		return nil, fmt.Errorf("base URL (%s) doesn't match the project URL (%s)", params.BaseURL, url)
	}

	var cred auth.Credential

	switch {
	case params.CredPrefix != "":
		cred, err = auth.LoadWithPrefix(repo, params.CredPrefix)
		if err != nil {
			return nil, err
		}
	case params.TokenRaw != "":
		token := auth.NewToken(params.TokenRaw, target)
		login, err := getLoginFromToken(baseUrl, token)
		if err != nil {
			return nil, err
		}
		token.SetMetadata(auth.MetaKeyLogin, login)
		cred = token
	default:
		cred, err = promptTokenOptions(repo, baseUrl)
		if err != nil {
			return nil, err
		}
	}

	token, ok := cred.(*auth.Token)
	if !ok {
		return nil, fmt.Errorf("the Gitlab bridge only handle token credentials")
	}

	// validate project url and get its ID
	id, err := validateProjectURL(baseUrl, url, token)
	if err != nil {
		return nil, errors.Wrap(err, "project validation")
	}

	conf[core.ConfigKeyTarget] = target
	conf[keyProjectID] = strconv.Itoa(id)
	conf[keyGitlabBaseUrl] = baseUrl

	err = g.ValidateConfig(conf)
	if err != nil {
		return nil, err
	}

	// don't forget to store the now known valid token
	if !auth.IdExist(repo, cred.ID()) {
		err = auth.Store(repo, cred)
		if err != nil {
			return nil, err
		}
	}

	return conf, nil
}

func (g *Gitlab) ValidateConfig(conf core.Configuration) error {
	if v, ok := conf[core.ConfigKeyTarget]; !ok {
		return fmt.Errorf("missing %s key", core.ConfigKeyTarget)
	} else if v != target {
		return fmt.Errorf("unexpected target name: %v", v)
	}
	if _, ok := conf[keyGitlabBaseUrl]; !ok {
		return fmt.Errorf("missing %s key", keyGitlabBaseUrl)
	}
	if _, ok := conf[keyProjectID]; !ok {
		return fmt.Errorf("missing %s key", keyProjectID)
	}

	return nil
}

func promptBaseUrlOptions() (string, error) {
	index, err := input.PromptChoice("Gitlab base url", []string{
		"https://gitlab.com",
		"enter your own base url",
	})

	if err != nil {
		return "", err
	}

	if index == 0 {
		return defaultBaseURL, nil
	} else {
		return promptBaseUrl()
	}
}

func promptBaseUrl() (string, error) {
	validator := func(name string, value string) (string, error) {
		u, err := url.Parse(value)
		if err != nil {
			return err.Error(), nil
		}
		if u.Scheme == "" {
			return "missing scheme", nil
		}
		if u.Host == "" {
			return "missing host", nil
		}
		return "", nil
	}

	return input.Prompt("Base url", "url", input.Required, validator)
}

func promptTokenOptions(repo repository.RepoConfig, baseUrl string) (auth.Credential, error) {
	for {
		creds, err := auth.List(repo, auth.WithTarget(target), auth.WithKind(auth.KindToken))
		if err != nil {
			return nil, err
		}

		// if we don't have existing token, fast-track to the token prompt
		if len(creds) == 0 {
			return promptToken(baseUrl)
		}

		fmt.Println()
		fmt.Println("[1]: enter my token")

		fmt.Println()
		fmt.Println("Existing tokens for Gitlab:")

		sort.Sort(auth.ById(creds))
		for i, cred := range creds {
			token := cred.(*auth.Token)
			fmt.Printf("[%d]: %s => %s (%s)\n",
				i+2,
				colors.Cyan(token.ID().Human()),
				colors.Red(text.TruncateMax(token.Value, 10)),
				token.CreateTime().Format(time.RFC822),
			)
		}

		fmt.Println()
		fmt.Print("Select option: ")

		line, err := bufio.NewReader(os.Stdin).ReadString('\n')
		fmt.Println()
		if err != nil {
			return nil, err
		}

		line = strings.TrimSpace(line)
		index, err := strconv.Atoi(line)
		if err != nil || index < 1 || index > len(creds)+1 {
			fmt.Println("invalid input")
			continue
		}

		switch index {
		case 1:
			return promptToken(baseUrl)
		default:
			return creds[index-2], nil
		}
	}
}

func promptToken(baseUrl string) (*auth.Token, error) {
	fmt.Printf("You can generate a new token by visiting %s.\n", path.Join(baseUrl, "profile/personal_access_tokens"))
	fmt.Println("Choose 'Create personal access token' and set the necessary access scope for your repository.")
	fmt.Println()
	fmt.Println("'api' access scope: to be able to make api calls")
	fmt.Println()

	re, err := regexp.Compile(`^[a-zA-Z0-9\-\_]{20}$`)
	if err != nil {
		panic("regexp compile:" + err.Error())
	}

	var login string

	validator := func(name string, value string) (complaint string, err error) {
		if !re.MatchString(value) {
			return "token has incorrect format", nil
		}
		login, err = getLoginFromToken(baseUrl, auth.NewToken(value, target))
		if err != nil {
			return fmt.Sprintf("token is invalid: %v", err), nil
		}
		return "", nil
	}

	rawToken, err := input.Prompt("Enter token", "token", input.Required, validator)
	if err != nil {
		return nil, err
	}

	token := auth.NewToken(rawToken, target)
	token.SetMetadata(auth.MetaKeyLogin, login)

	return token, nil
}

func promptURL(repo repository.RepoCommon, baseUrl string) (string, error) {
	// remote suggestions
	remotes, err := repo.GetRemotes()
	if err != nil {
		return "", errors.Wrap(err, "getting remotes")
	}

	validRemotes := getValidGitlabRemoteURLs(baseUrl, remotes)
	if len(validRemotes) > 0 {
		for {
			fmt.Println("\nDetected projects:")

			// print valid remote gitlab urls
			for i, remote := range validRemotes {
				fmt.Printf("[%d]: %v\n", i+1, remote)
			}

			fmt.Printf("\n[0]: Another project\n\n")
			fmt.Printf("Select option: ")

			line, err := bufio.NewReader(os.Stdin).ReadString('\n')
			if err != nil {
				return "", err
			}

			line = strings.TrimSpace(line)

			index, err := strconv.Atoi(line)
			if err != nil || index < 0 || index > len(validRemotes) {
				fmt.Println("invalid input")
				continue
			}

			// if user want to enter another project url break this loop
			if index == 0 {
				break
			}

			return validRemotes[index-1], nil
		}
	}

	// manually enter gitlab url
	for {
		fmt.Print("Gitlab project URL: ")

		line, err := bufio.NewReader(os.Stdin).ReadString('\n')
		if err != nil {
			return "", err
		}

		url := strings.TrimSpace(line)
		if url == "" {
			fmt.Println("URL is empty")
			continue
		}

		return url, nil
	}
}

func getProjectPath(baseUrl, projectUrl string) (string, error) {
	cleanUrl := strings.TrimSuffix(projectUrl, ".git")
	cleanUrl = strings.Replace(cleanUrl, "git@", "https://", 1)
	objectUrl, err := url.Parse(cleanUrl)
	if err != nil {
		return "", ErrBadProjectURL
	}

	objectBaseUrl, err := url.Parse(baseUrl)
	if err != nil {
		return "", ErrBadProjectURL
	}

	if objectUrl.Hostname() != objectBaseUrl.Hostname() {
		return "", fmt.Errorf("base url and project url hostnames doesn't match")
	}
	return objectUrl.Path[1:], nil
}

func getValidGitlabRemoteURLs(baseUrl string, remotes map[string]string) []string {
	urls := make([]string, 0, len(remotes))
	for _, u := range remotes {
		path, err := getProjectPath(baseUrl, u)
		if err != nil {
			continue
		}

		urls = append(urls, fmt.Sprintf("%s/%s", baseUrl, path))
	}

	return urls
}

func validateProjectURL(baseUrl, url string, token *auth.Token) (int, error) {
	projectPath, err := getProjectPath(baseUrl, url)
	if err != nil {
		return 0, err
	}

	client, err := buildClient(baseUrl, token)
	if err != nil {
		return 0, err
	}

	project, _, err := client.Projects.GetProject(projectPath, &gitlab.GetProjectOptions{})
	if err != nil {
		return 0, errors.Wrap(err, "wrong token scope ou non-existent project")
	}

	return project.ID, nil
}

func getLoginFromToken(baseUrl string, token *auth.Token) (string, error) {
	client, err := buildClient(baseUrl, token)
	if err != nil {
		return "", err
	}

	user, _, err := client.Users.CurrentUser()
	if err != nil {
		return "", err
	}
	if user.Username == "" {
		return "", fmt.Errorf("gitlab say username is empty")
	}

	return user.Username, nil
}