package scaleset

import (
	"fmt"
	"net/url"
	"os"
	"strings"
)

var ErrInvalidGitHubConfigURL = fmt.Errorf("invalid config URL, should point to an enterprise, org, or repository")

type gitHubScope int

const (
	gitHubScopeUnknown gitHubScope = iota
	gitHubScopeEnterprise
	gitHubScopeOrganization
	gitHubScopeRepository
)

type gitHubConfig struct {
	configURL *url.URL
	scope     gitHubScope

	enterprise   string
	organization string
	repository   string

	isHosted bool
}

func parseGitHubConfigFromURL(in string) (*gitHubConfig, error) {
	u, err := url.Parse(strings.Trim(in, "/"))
	if err != nil {
		return nil, fmt.Errorf("failed to parse URL: %w", err)
	}

	isHosted := isHostedGitHubURL(u)

	configURL := &gitHubConfig{
		configURL: u,
		isHosted:  isHosted,
	}

	invalidURLError := fmt.Errorf("%q: %w", u.String(), ErrInvalidGitHubConfigURL)

	pathParts := strings.Split(strings.Trim(u.Path, "/"), "/")

	switch len(pathParts) {
	case 1: // Organization
		if pathParts[0] == "" {
			return nil, invalidURLError
		}

		configURL.scope = gitHubScopeOrganization
		configURL.organization = pathParts[0]

	case 2: // Repository or enterprise
		if strings.ToLower(pathParts[0]) == "enterprises" {
			configURL.scope = gitHubScopeEnterprise
			configURL.enterprise = pathParts[1]
			break
		}

		configURL.scope = gitHubScopeRepository
		configURL.organization = pathParts[0]
		configURL.repository = pathParts[1]
	default:
		return nil, invalidURLError
	}

	return configURL, nil
}

func (c *gitHubConfig) gitHubAPIURL(path string) *url.URL {
	result := &url.URL{
		Scheme: c.configURL.Scheme,
		Host:   c.configURL.Host, // default for Enterprise mode
		Path:   "/api/v3",        // default for Enterprise mode
	}

	isHosted := isHostedGitHubURL(c.configURL)

	if isHosted {
		result.Host = fmt.Sprintf("api.%s", c.configURL.Host)
		result.Path = ""

		if strings.EqualFold("www.github.com", c.configURL.Host) {
			// re-routing www.github.com to api.github.com
			result.Host = "api.github.com"
		}
	}

	result.Path += path

	return result
}

func isHostedGitHubURL(u *url.URL) bool {
	_, forceGhes := os.LookupEnv("GITHUB_ACTIONS_FORCE_GHES")
	if forceGhes {
		return false
	}

	return strings.EqualFold(u.Host, "github.com") ||
		strings.EqualFold(u.Host, "www.github.com") ||
		strings.EqualFold(u.Host, "github.localhost") ||
		strings.HasSuffix(u.Host, ".ghe.com")
}