package distros

import (
	"errors"
	"fmt"
	"net/http"
	"regexp"
	"strconv"

	"github.com/rs/zerolog/log"
	"golang.org/x/net/html"
	"libguestfs.org/guestfs"

	"git.csclub.uwaterloo.ca/cloud/cloudbuild/pkg/config"
)

type FedoraTemplateManager struct {
	TemplateManager
}

// NewFedoraTemplateManager returns a FedoraTemplateManager with the given
// config values.
func NewFedoraTemplateManager(cfg *config.Config) *FedoraTemplateManager {
	logger := log.With().Str("distro", "fedora").Logger()
	fedoraTemplateManager := FedoraTemplateManager{
		TemplateManager{
			cfg:    cfg,
			logger: &logger,
			impl:   nil,
		},
	}
	fedoraTemplateManager.TemplateManager.impl = &fedoraTemplateManager
	return &fedoraTemplateManager
}

var numberSlashPattern *regexp.Regexp = regexp.MustCompile("^\\d+/$")

func isHyperlink(node *html.Node) bool {
	return node.Type == html.ElementNode && node.Data == "a" &&
		node.FirstChild != nil && node.FirstChild.Type == html.TextNode
}

func getMatchingLinkFromHtml(node *html.Node, pattern *regexp.Regexp) string {
	if isHyperlink(node) {
		text := node.FirstChild.Data
		return pattern.FindString(text)
	}
	for c := node.FirstChild; c != nil; c = c.NextSibling {
		result := getMatchingLinkFromHtml(c, pattern)
		if result != "" {
			return result
		}
	}
	return ""
}

func getMaxVersionFromHtml(node *html.Node, maxVersion *int64) {
	if isHyperlink(node) {
		text := node.FirstChild.Data
		if numberSlashPattern.FindString(text) != "" {
			version, _ := strconv.ParseInt(text[:len(text)-1], 10, 64)
			if version > *maxVersion {
				*maxVersion = version
			}
		}
		return
	}
	for c := node.FirstChild; c != nil; c = c.NextSibling {
		getMaxVersionFromHtml(c, maxVersion)
	}
}

func (mgr *FedoraTemplateManager) GetLatestVersion() (version string, codename string, err error) {
	resp, err := http.Get("https://mirror.csclub.uwaterloo.ca/fedora/linux/releases/")
	if err != nil {
		return
	}
	defer resp.Body.Close()
	node, err := html.Parse(resp.Body)
	if err != nil {
		return
	}
	var intVersion int64
	getMaxVersionFromHtml(node, &intVersion)
	if intVersion == 0 {
		err = errors.New("Could not determine latest Fedora version from HTML")
	} else {
		version = strconv.FormatInt(intVersion, 10)
		// Fedora doesn't have codenames, only numbered versions
		codename = version
	}
	return
}

func (mgr *FedoraTemplateManager) DownloadTemplate(version, codename string) (path string, err error) {
	pattern := regexp.MustCompile(fmt.Sprintf("^Fedora-Cloud-Base-%s-\\d+(\\.\\d+)?\\.x86_64\\.qcow2$", version))
	imagesUrl := fmt.Sprintf("https://mirror.csclub.uwaterloo.ca/fedora/linux/releases/%s/Cloud/x86_64/images/", version)
	resp, err := http.Get(imagesUrl)
	if err != nil {
		return
	}
	defer resp.Body.Close()
	node, err := html.Parse(resp.Body)
	if err != nil {
		return
	}
	filename := getMatchingLinkFromHtml(node, pattern)
	if filename == "" {
		err = errors.New("Could not find hyperlink for Fedora Cloud image")
		return
	}
	url := imagesUrl + filename
	return mgr.DownloadTemplateGeneric(filename, url)
}

func (mgr *FedoraTemplateManager) UsesNetworkManager() bool {
	return true
}

func (mgr *FedoraTemplateManager) addCloudInitSnippet(handle *guestfs.Guestfs) error {
	path := "/etc/cloud/cloud.cfg.d/99_csclub.cfg"
	mgr.logger.Debug().Msg("Writing to " + path)
	return handle.Write(path, getResource("fedora-cloud-init"))
}

func (mgr *FedoraTemplateManager) HasSELinuxEnabled() bool {
	return true
}

func (mgr *FedoraTemplateManager) CommandToUpdatePackageCache() []string {
	return fedoraCommandToUpdatePackageCache()
}

var fedoraYumRepoBaseUrlPattern *regexp.Regexp = regexp.MustCompile(
	"^(?P<scheme>https?://)[A-Za-z0-9./-]+(?P<path>/fedora/linux/[A-Za-z0-9./$-]+)$",
)

func (mgr *FedoraTemplateManager) transformFedoraYumRepoBaseUrl(url string) string {
	submatches := fedoraYumRepoBaseUrlPattern.FindStringSubmatch(url)
	if submatches != nil {
		scheme, path := submatches[1], submatches[2]
		url = scheme + mgr.cfg.MirrorHost + path
	}
	return url
}

func (mgr *FedoraTemplateManager) PerformDistroSpecificModifications(handle *guestfs.Guestfs) (err error) {
	if err = mgr.setChronyOptions(handle, "/etc/chrony.conf"); err != nil {
		return
	}
	if err = mgr.setNetworkManagerOptions(handle); err != nil {
		return
	}
	if err = mgr.addCloudInitSnippet(handle); err != nil {
		return
	}
	if err = mgr.replaceYumMirrorUrls(handle, mgr.transformFedoraYumRepoBaseUrl); err != nil {
		return
	}
	if err = mgr.dnfRemoveUnnecessaryPackages(handle); err != nil {
		return
	}
	if err = mgr.setJournaldConf(handle); err != nil {
		return
	}
	return
}