package main

import (
	"errors"
	"fmt"
	"os"
	"regexp"
	"strings"

	"code.gitea.io/sdk/gitea"
	"github.com/cqroot/prompt"
	"github.com/cqroot/prompt/input"
	"github.com/cqroot/prompt/multichoose"
	"github.com/google/go-github/github"
	"golang.org/x/exp/slices"
)

// getGithubUsername prompts the user for their Github username.
// The username is returned as a string.
func getGithubUsername() string {
	result, err := prompt.New().Ask("Github username").Input("johndoe69")
	checkErr(err)
	return result
}

// getGithubToken prompts the user for their Github token.
// The token is returned as a string.
func getGithubToken() string {
	result, err := prompt.New().Ask("Github personal access token").
		Input("", input.WithEchoMode(input.EchoPassword))
	checkErr(err)
	return result
}

// getGiteaHost prompts the user for the host of their Gitea instance.
// The host is returned as a string.
func getGiteaHost() string {
	result, err := prompt.New().Ask("Gitea host").Input("https://gitea.com")
	checkErr(err)
	return result
}

// getGiteaUser prompts the user for their Gitea username. This is where the
// repositories will be migrated to.
// The username is returned as a string.
func getGiteaUser() string {
	result, err := prompt.New().Ask("Gitea username").Input("johndoe69")
	checkErr(err)
	return result
}

// getGiteaToken prompts the user for their Gitea application token.
// The token is returned as a string.
func getGiteaToken() string {
	result, err := prompt.New().Ask("Gitea application token").
		Input("", input.WithEchoMode(input.EchoPassword))
	checkErr(err)
	return result
}

// getRepos first prompts users to choose how they want to select repositories.
// They will have the option of fetching a list from github and selecting from that,
// entering a list of repositories manually, providing a path to a file containing
// a list of repositories, or selecting filters which will be used to fetch a list
// of repositories from github.
// Once the user has selected how they want to select repositories, they will be
// prompted to select repositories based on their chosen method.
// The selected repositories are returned as a list of strings.
func getRepos(client *github.Client, user string, organization bool) []string {
	result, err := prompt.New().Ask("How do you want to select repositories?").
		Choose([]string{"Fetch from Github", "Enter manually", "File path", "Filters"})
	checkErr(err)

	var repos []string
	switch result {
	case "Fetch from Github":
		repos = getReposFromGithub(client)
	case "Enter manually":
		repos = getReposManually()
	case "File path":
		repos = getReposFromFile()
	case "Filters":
		repos = getReposByType(client, user, organization)
	}

	should_continue, err := prompt.New().Ask(fmt.Sprintf("You have selected %d repositories. Continue?", len(repos))).
		Choose([]string{"Yes", "No"})
	checkErr(err)

	if should_continue == "No" {
		os.Exit(0)
	}

	return repos
}

// getReposFromGithub first asks the user for the name of the organization,
// or user, whose repositories they want to migrate.
// It then fetches a list of repositories from github, and prompts the user
// to select which repositories they want to migrate.
// The selected repositories are returned as a list of strings.
func getReposFromGithub(client *github.Client) []string {
	result, err := prompt.New().Ask("Select repositories from:").
		Choose([]string{"Organization", "User"})
	checkErr(err)

	var repo_names []string
	switch result {
	case "Organization":
		result, err := prompt.New().Ask("Organization name").Input("acme")
		checkErr(err)
		repos := fetchReposForUser(client, result, true)
		repo_names = append(repo_names, repos...)
	case "User":
		result, err := prompt.New().Ask("User name").Input("johndoe69")
		checkErr(err)
		repos := fetchReposForUser(client, result, false)
		repo_names = append(repo_names, repos...)
	}

	selected, err := prompt.New().Ask("Select repositories:").
		MultiChoose(repo_names, multichoose.WithTheme(ThemeScroll))
	checkErr(err)

	return selected
}

// getReposManually prompts the user to enter a list of repositories manually.
// The list of repositories is returned as a list of strings.
func getReposManually() []string {
	result, err := prompt.New().Ask("Enter repositories manually").
		Input("acme/repo1, acme/repo2, johndoe69/repo3")
	checkErr(err)

	repos := regexp.MustCompile(`\s*,\s*`).Split(result, -1)
	for i, repo := range repos {
		repos[i] = regexp.MustCompile(`^https?://(www.)?github.com/`).ReplaceAllString(repo, "")
	}
	return repos
}

// getReposFromFile prompts the user to enter a path to a file containing a repository
// on each line. It then reads the file and returns the list of repositories as a list
// of strings.
func getReposFromFile() []string {
	result, err := prompt.New().Ask("Enter path to file containing repositories (one on each line)").
		Input("./repos.txt")
	checkErr(err)

	data, err := os.ReadFile(result)
	checkErr(err)

	// Convert the bytes into a string
	str := string(data)
	repos := regexp.MustCompile(`\s*\n\s*`).Split(str, -1)

	for i, repo := range repos {
		repos[i] = regexp.MustCompile(`^https?://(www.)?github.com/`).ReplaceAllString(repo, "")
	}
	return repos
}

// getReposByType prompts the user to select the types of repositories they want to migrate.
// The selected repositories are returned as a list of strings.
func getReposByType(client *github.Client, user string, organization bool) []string {
	types, err := prompt.New().Ask("Select visibility:").
		MultiChoose([]string{"All", "Public", "Private", "Forks", "Sources", "Member"})
	checkErr(err)

	repos := fetchReposByType(client, user, organization, types)
	return repos
}

// getRepoVisibility prompts the user to select the visibility of the migrated repositories.
// The selected visibility is returned as a string.
func getRepoVisibility() string {
	result, err := prompt.New().Ask("Select visibility:").
		Choose([]string{"Maintain", "Public", "Private"})
	checkErr(err)

	return result
}

// getShouldMirror prompts the user to select whether they want to mirror the
// repositories, or migrate them as a one-time copy.
// The user's selection is returned as a boolean.
func getShouldMirror() bool {
	result, err := prompt.New().Ask("Mirror repositories").
		Choose([]string{"Yes", "No"})
	checkErr(err)

	if result == "Yes" {
		return true
	}
	return false
}

// getItemsToMigrate prompts the user to select which items they want to migrate.
// The user's selection is returned as a list of strings.
func getItemsToMigrate() []string {
	result, err := prompt.New().Ask("Select items to migrate:").
		MultiChoose([]string{"Issues", "Wiki", "Labels", "Pull Requests", "Milestones", "Releases"})
	checkErr(err)

	return result
}

// getPushMirrorToGithub prompts the user to select whether they want to push
// changes to the mirror on Gitea to the original repository on Github.
// The user's selection is returned as a boolean.
func getPushMirrorToGithub() bool {
	result, err := prompt.New().Ask("Would you like to mirror pushes to github?").
		Choose([]string{"Yes", "No"})
	checkErr(err)

	if result == "Yes" {
		return true
	}
	return false
}

// getUseGithubIssueTracker prompts the user to select whether they want to use
// the github issue tracker, or migrate issues. This option is only available if
// issues are not being migrated.
// The user's selection is returned as a boolean.
func getUseGithubIssueTracker() bool {
	result, err := prompt.New().Ask("Use Github issue tracker").
		Choose([]string{"Yes", "No"})
	checkErr(err)

	if result == "Yes" {
		return true
	}
	return false
}

type MigrationOptions struct {
	github_client            *github.Client
	gitea_client             *gitea.Client
	github_user              string
	github_token             string
	gitea_user               string
	repos                    []string
	visibility_map           map[string]string
	visibility               string
	should_mirror            bool
	use_github_issue_tracker bool
	push_mirror_to_github    bool
	items_to_migrate         []string
}

// executeMigration executes the migration process.
// The migration process is executed with the given options.
// If an error occurs during the migration process, it is returned.
func executeMigration(options *MigrationOptions) error {
	repos := options.repos
	gitea_client := options.gitea_client
	var errs error

	for _, repo := range repos {
		fmt.Printf("Migrating %s...\n", repo)
		repo_address := fmt.Sprintf("https://github.com/%s", repo)
		repo_parts := strings.Split(repo, "/")
		repo_name := repo_parts[1]
		visibility := "public"
		if options.visibility == "Maintain" {
			visibility = options.visibility_map[repo]
		}

		new_repo, _, err := gitea_client.MigrateRepo(gitea.MigrateRepoOption{
			RepoOwner:    options.gitea_user,
			RepoName:     repo_name,
			CloneAddr:    repo_address,
			Service:      gitea.GitServiceGithub,
			AuthUsername: options.github_user,
			AuthToken:    options.github_token,
			Mirror:       options.should_mirror,
			Private:      visibility == "private",
			Wiki:         slices.Contains(options.items_to_migrate, "Wiki"),
			Milestones:   slices.Contains(options.items_to_migrate, "Milestones"),
			Labels:       slices.Contains(options.items_to_migrate, "Labels"),
			PullRequests: slices.Contains(options.items_to_migrate, "Pull Requests"),
			Releases:     slices.Contains(options.items_to_migrate, "Releases"),
			Issues:       slices.Contains(options.items_to_migrate, "Issues"),
		})

		if err != nil {
			errs = errors.Join(errs, err)
			continue
		}

		if options.use_github_issue_tracker {
			hasIssues := true
			_, _, err := gitea_client.EditRepo(new_repo.Owner.UserName, new_repo.Name, gitea.EditRepoOption{
				HasIssues: &hasIssues,
				ExternalTracker: &gitea.ExternalTracker{
					ExternalTrackerURL:    repo_address + "/issues",
					ExternalTrackerFormat: "https://github.com/{user}/{repo}/issues/{index}",
					ExternalTrackerStyle:  "numeric",
				},
			})

			if err != nil {
				errs = errors.Join(errs, err)
				continue
			}
		}
	}

	return errs
}

// Github to Gitea migration tool.
// This tool will migrate selected repositories from Github to Gitea,
// based on user input. This process is entirely interactive.
// The tool will ask for the following:
// - Github username
// - Github password/token
// - Gitea username
// - Gitea application token
// - Repositories to migrate, or filters to select repositories to migrate
// - Whether repos should be mirrored, or migrated as a one-time copy
// - Whether to migrate issues, use the github issue tracker, or neither
// - How to set visibility of the migrated repos
// - Whether to migrate wiki pages, labels, pull requests, milestones, and releases
func main() {
	fmt.Println("Welcome to the Github to Gitea migration tool!")

	githubUsername := getGithubUsername()
	githubToken := getGithubToken()
	githubClient := authenticateGithub(githubUsername, githubToken)

	giteaHost := getGiteaHost()
	giteaUser := getGiteaUser()
	giteaToken := getGiteaToken()
	giteaClient := authenticateGitea(giteaHost, giteaUser, giteaToken)

	repos := getRepos(githubClient, "watzon", false)
	repo_visibility := getRepoVisibility()

	var visibility_map map[string]string
	if repo_visibility == "Maintain" {
		visibility_map = buildRepoVisibilityMap(githubClient, repos)
	}

	should_mirror := getShouldMirror()
	to_migrate := getItemsToMigrate()

	push_mirror_to_github := false
	// TODO: Waiting on https://gitea.com/gitea/go-sdk/issues/635
	// if !should_mirror {
	// 	push_mirror_to_github = getPushMirrorToGithub()
	// }

	use_github_issue_tracker := false
	if !slices.Contains(to_migrate, "Issues") {
		use_github_issue_tracker = getUseGithubIssueTracker()
	}

	err := executeMigration(&MigrationOptions{
		github_client:            githubClient,
		gitea_client:             giteaClient,
		github_user:              githubUsername,
		github_token:             githubToken,
		gitea_user:               giteaUser,
		repos:                    repos,
		visibility_map:           visibility_map,
		visibility:               repo_visibility,
		should_mirror:            should_mirror,
		use_github_issue_tracker: use_github_issue_tracker,
		items_to_migrate:         to_migrate,
		push_mirror_to_github:    push_mirror_to_github,
	})

	if err != nil {
		fmt.Println("Error", err)
	} else {
		fmt.Println("Migration completed successfully!")
	}
}