package gitlab

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

	"github.com/pkg/errors"
	"github.com/xanzy/go-gitlab"

	"github.com/MichaelMure/git-bug/bridge/core"
	"github.com/MichaelMure/git-bug/entity"
	"github.com/MichaelMure/git-bug/repository"
)

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

func (g *Gitlab) Configure(repo repository.RepoCommon, 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")
	}

	conf := make(core.Configuration)
	var err error
	var url string
	var token string
	var tokenId entity.Id
	var tokenObj *core.Token

	if (params.Token != "" || params.TokenStdin) && params.URL == "" {
		return nil, fmt.Errorf("you must provide a project URL to configure this bridge with a token")
	}

	// get project url
	if params.URL != "" {
		url = params.URL

	} else {
		// remote suggestions
		remotes, err := repo.GetRemotes()
		if err != nil {
			return nil, errors.Wrap(err, "getting remotes")
		}

		// terminal prompt
		url, err = promptURL(remotes)
		if err != nil {
			return nil, errors.Wrap(err, "url prompt")
		}
	}

	// get user token
	if params.Token != "" {
		token = params.Token
	} else if params.TokenStdin {
		reader := bufio.NewReader(os.Stdin)
		token, err = reader.ReadString('\n')
		if err != nil {
			return nil, fmt.Errorf("reading from stdin: %v", err)
		}
		token = strings.TrimSpace(token)
	} else if params.TokenId != "" {
		tokenId = entity.Id(params.TokenId)
	} else {
		tokenObj, err = promptTokenOptions(repo)
		if err != nil {
			return nil, errors.Wrap(err, "token prompt")
		}
	}

	if token != "" {
		tokenObj, err = core.LoadOrCreateToken(repo, target, token)
		if err != nil {
			return nil, err
		}
	} else if tokenId != "" {
		tokenObj, err = core.LoadToken(repo, entity.Id(tokenId))
		if err != nil {
			return nil, err
		}
		if tokenObj.Target != target {
			return nil, fmt.Errorf("token target is incompatible %s", tokenObj.Target)
		}
	}

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

	conf[keyProjectID] = strconv.Itoa(id)
	conf[core.ConfigKeyTokenId] = tokenObj.ID().String()
	conf[core.ConfigKeyTarget] = target

	err = g.ValidateConfig(conf)
	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[keyToken]; !ok {
		return fmt.Errorf("missing %s key", keyToken)
	}

	if _, ok := conf[keyProjectID]; !ok {
		return fmt.Errorf("missing %s key", keyProjectID)
	}

	return nil
}

func promptTokenOptions(repo repository.RepoCommon) (*core.Token, error) {
	for {
		tokens, err := core.LoadTokensWithTarget(repo, target)
		if err != nil {
			return nil, err
		}

		fmt.Println()
		fmt.Println("[1]: user provided token")

		if len(tokens) > 0 {
			fmt.Println("known tokens for Gitlab:")
			for i, token := range tokens {
				if token.Target == target {
					fmt.Printf("[%d]: %s\n", i+2, token.ID())
				}
			}
		}
		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(tokens)+1 {
			fmt.Println("invalid input")
			continue
		}

		var token string
		switch index {
		case 1:
			token, err = promptToken()
			if err != nil {
				return nil, err
			}
		default:
			return tokens[index-2], nil
		}

		return core.LoadOrCreateToken(repo, target, token)
	}
}

func promptToken() (string, error) {
	fmt.Println("You can generate a new token by visiting https://gitlab.com/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())
	}

	for {
		fmt.Print("Enter token: ")

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

		token := strings.TrimSpace(line)
		if re.MatchString(token) {
			return token, nil
		}

		fmt.Println("token format is invalid")
	}
}

func promptURL(remotes map[string]string) (string, error) {
	validRemotes := getValidGitlabRemoteURLs(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 line == "" {
			fmt.Println("URL is empty")
			continue
		}

		return url, nil
	}
}

func getProjectPath(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
	}

	return objectUrl.Path[1:], nil
}

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

		urls = append(urls, fmt.Sprintf("%s%s", "gitlab.com", path))
	}

	return urls
}

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

	client := buildClient(token)

	project, _, err := client.Projects.GetProject(projectPath, &gitlab.GetProjectOptions{})
	if err != nil {
		return 0, err
	}

	return project.ID, nil
}