package github

import (
	"crypto/tls"
	"encoding/base32"
	"fmt"
	"io/ioutil"
	"net/http"
	"net/url"
	"strings"

	"github.com/drone/drone/shared/oauth2"
	"github.com/google/go-github/github"
	"github.com/gorilla/securecookie"
)

// NewClient is a helper function that returns a new GitHub
// client using the provided OAuth token.
func NewClient(uri, token string, skipVerify bool) *github.Client {
	t := &oauth2.Transport{
		Token: &oauth2.Token{AccessToken: token},
	}

	// this is for GitHub enterprise users that are using
	// self-signed certificates.
	if skipVerify {
		t.Transport = &http.Transport{
			Proxy:           http.ProxyFromEnvironment,
			TLSClientConfig: &tls.Config{InsecureSkipVerify: true},
		}
	}

	c := github.NewClient(t.Client())
	c.BaseURL, _ = url.Parse(uri)
	return c
}

// GetUserEmail is a heper function that retrieves the currently
// authenticated user from GitHub + Email address.
func GetUserEmail(client *github.Client) (*github.User, error) {
	user, _, err := client.Users.Get("")
	if err != nil {
		return nil, err
	}

	emails, _, err := client.Users.ListEmails(nil)
	if err != nil {
		return nil, err
	}

	for _, email := range emails {
		if *email.Primary && *email.Verified {
			user.Email = email.Email
			return user, nil
		}
	}

	// WARNING, HACK
	// for out-of-date github enterprise editions the primary
	// and verified fields won't exist.
	if !strings.HasPrefix(*user.URL, DefaultAPI) && len(emails) != 0 {
		user.Email = emails[0].Email
		return user, nil
	}

	return nil, fmt.Errorf("No verified Email address for GitHub account")
}

// GetRepo is a helper function that returns a named repo
func GetRepo(client *github.Client, owner, repo string) (*github.Repository, error) {
	r, _, err := client.Repositories.Get(owner, repo)
	return r, err
}

// GetUserRepos is a helper function that returns a list of
// all user repositories. Paginated results are aggregated into
// a single list.
func GetUserRepos(client *github.Client) ([]github.Repository, error) {
	var repos []github.Repository
	var opts = github.RepositoryListOptions{}
	opts.PerPage = 100
	opts.Page = 1

	// loop through user repository list
	for opts.Page > 0 {
		list, resp, err := client.Repositories.List("", &opts)
		if err != nil {
			return nil, err
		}
		repos = append(repos, list...)

		// increment the next page to retrieve
		opts.Page = resp.NextPage
	}

	return repos, nil
}

// GetOrgs is a helper function that returns a list of
// all orgs that a user belongs to.
func GetOrgs(client *github.Client) ([]github.Organization, error) {
	var orgs []github.Organization
	var opts = github.ListOptions{}
	opts.Page = 1

	for opts.Page > 0 {
		list, resp, err := client.Organizations.List("", &opts)
		if err != nil {
			return nil, err
		}
		orgs = append(orgs, list...)

		// increment the next page to retrieve
		opts.Page = resp.NextPage
	}
	return orgs, nil
}

// GetHook is a heper function that retrieves a hook by
// hostname. To do this, it will retrieve a list of all hooks
// and iterate through the list.
func GetHook(client *github.Client, owner, name, url string) (*github.Hook, error) {
	hooks, _, err := client.Repositories.ListHooks(owner, name, nil)
	if err != nil {
		return nil, err
	}
	for _, hook := range hooks {
		hookurl, ok := hook.Config["url"].(string)
		if !ok {
			continue
		}
		if strings.HasPrefix(hookurl, url) {
			return &hook, nil
		}
	}
	return nil, nil
}

func DeleteHook(client *github.Client, owner, name, url string) error {
	hook, err := GetHook(client, owner, name, url)
	if err != nil {
		return err
	}
	if hook == nil {
		return nil
	}
	_, err = client.Repositories.DeleteHook(owner, name, *hook.ID)
	return err
}

// CreateHook is a heper function that creates a post-commit hook
// for the specified repository.
func CreateHook(client *github.Client, owner, name, url string) (*github.Hook, error) {
	var hook = new(github.Hook)
	hook.Name = github.String("web")
	hook.Events = []string{"push", "pull_request", "deployment"}
	hook.Config = map[string]interface{}{}
	hook.Config["url"] = url
	hook.Config["content_type"] = "form"
	created, _, err := client.Repositories.CreateHook(owner, name, hook)
	return created, err
}

// CreateUpdateHook is a heper function that creates a post-commit hook
// for the specified repository if it does not already exist, otherwise
// it updates the existing hook
func CreateUpdateHook(client *github.Client, owner, name, url string) (*github.Hook, error) {
	var hook, _ = GetHook(client, owner, name, url)
	if hook != nil {
		hook.Name = github.String("web")
		hook.Events = []string{"push", "pull_request"}
		hook.Config = map[string]interface{}{}
		hook.Config["url"] = url
		hook.Config["content_type"] = "form"
		var updated, _, err = client.Repositories.EditHook(owner, name, *hook.ID, hook)
		return updated, err
	}

	return CreateHook(client, owner, name, url)
}

// GetFile is a heper function that retrieves a file from
// GitHub and returns its contents in byte array format.
func GetFile(client *github.Client, owner, name, path, ref string) ([]byte, error) {
	var opts = new(github.RepositoryContentGetOptions)
	opts.Ref = ref
	content, _, _, err := client.Repositories.GetContents(owner, name, path, opts)
	if err != nil {
		return nil, err
	}
	return content.Decode()
}

// GetRandom is a helper function that generates a 32-bit random
// key, base32 encoded as a string value.
func GetRandom() string {
	return base32.StdEncoding.EncodeToString(securecookie.GenerateRandomKey(32))
}

// GetPayload is a helper function that will parse the JSON payload. It will
// first check for a `payload` parameter in a POST, but can fallback to a
// raw JSON body as well.
func GetPayload(req *http.Request) []byte {
	var payload = req.FormValue("payload")
	if len(payload) == 0 {
		defer req.Body.Close()
		raw, _ := ioutil.ReadAll(req.Body)
		return raw
	}
	return []byte(payload)
}