package main

import (
	"context"
	"crypto/sha256"
	"encoding/hex"
	"io"
	"net/http"
	"os"
	"path/filepath"
	"strings"

	"github.com/google/go-github/v45/github"
	"github.com/sagernet/sing-box/common/geosite"
	"github.com/sagernet/sing/common"
	E "github.com/sagernet/sing/common/exceptions"
	"github.com/sirupsen/logrus"
	"github.com/v2fly/v2ray-core/v5/app/router/routercommon"
	"google.golang.org/protobuf/proto"
)

var githubClient *github.Client

func init() {
	accessToken, loaded := os.LookupEnv("ACCESS_TOKEN")
	if !loaded {
		githubClient = github.NewClient(nil)
		return
	}
	transport := &github.BasicAuthTransport{
		Username: accessToken,
	}
	githubClient = github.NewClient(transport.Client())
}

func fetch(from string) (*github.RepositoryRelease, error) {
	names := strings.SplitN(from, "/", 2)
	latestRelease, _, err := githubClient.Repositories.GetLatestRelease(context.Background(), names[0], names[1])
	if err != nil {
		return nil, err
	}
	return latestRelease, err
}

func get(downloadURL *string) ([]byte, error) {
	logrus.Info("download ", *downloadURL)
	response, err := http.Get(*downloadURL)
	if err != nil {
		return nil, err
	}
	defer response.Body.Close()
	return io.ReadAll(response.Body)
}

func download(release *github.RepositoryRelease) ([]byte, error) {
	geositeAsset := common.Find(release.Assets, func(it *github.ReleaseAsset) bool {
		return *it.Name == "dlc.dat"
	})
	geositeChecksumAsset := common.Find(release.Assets, func(it *github.ReleaseAsset) bool {
		return *it.Name == "dlc.dat.sha256sum"
	})
	if geositeAsset == nil {
		return nil, E.New("geosite asset not found in upstream release ", release.Name)
	}
	if geositeChecksumAsset == nil {
		return nil, E.New("geosite asset not found in upstream release ", release.Name)
	}
	data, err := get(geositeAsset.BrowserDownloadURL)
	if err != nil {
		return nil, err
	}
	remoteChecksum, err := get(geositeChecksumAsset.BrowserDownloadURL)
	if err != nil {
		return nil, err
	}
	checksum := sha256.Sum256(data)
	if hex.EncodeToString(checksum[:]) != string(remoteChecksum[:64]) {
		return nil, E.New("checksum mismatch")
	}
	return data, nil
}

func parse(vGeositeData []byte) (map[string][]geosite.Item, error) {
	vGeositeList := routercommon.GeoSiteList{}
	err := proto.Unmarshal(vGeositeData, &vGeositeList)
	if err != nil {
		return nil, err
	}
	domainMap := make(map[string][]geosite.Item)
	for _, vGeositeEntry := range vGeositeList.Entry {
		domains := make([]geosite.Item, 0, len(vGeositeEntry.Domain)*2)
		for _, domain := range vGeositeEntry.Domain {
			switch domain.Type {
			case routercommon.Domain_Plain:
				domains = append(domains, geosite.Item{
					Type:  geosite.RuleTypeDomainKeyword,
					Value: domain.Value,
				})
			case routercommon.Domain_Regex:
				domains = append(domains, geosite.Item{
					Type:  geosite.RuleTypeDomainRegex,
					Value: domain.Value,
				})
			case routercommon.Domain_RootDomain:
				if strings.Contains(domain.Value, ".") {
					domains = append(domains, geosite.Item{
						Type:  geosite.RuleTypeDomain,
						Value: domain.Value,
					})
				}
				domains = append(domains, geosite.Item{
					Type:  geosite.RuleTypeDomainSuffix,
					Value: "." + domain.Value,
				})
			case routercommon.Domain_Full:
				domains = append(domains, geosite.Item{
					Type:  geosite.RuleTypeDomain,
					Value: domain.Value,
				})
			}
		}
		domainMap[strings.ToLower(vGeositeEntry.CountryCode)] = common.Uniq(domains)
	}
	return domainMap, nil
}

func generate(release *github.RepositoryRelease, output string) error {
	outputFile, err := os.Create(output)
	if err != nil {
		return err
	}
	defer outputFile.Close()
	vData, err := download(release)
	if err != nil {
		return err
	}
	domainMap, err := parse(vData)
	if err != nil {
		return err
	}
	outputPath, _ := filepath.Abs(output)
	os.Stderr.WriteString("write " + outputPath + "\n")
	return geosite.Write(outputFile, domainMap)
}

func setActionOutput(name string, content string) {
	os.Stdout.WriteString("::set-output name=" + name + "::" + content + "\n")
}

func release(source string, destination string, output string) error {
	sourceRelease, err := fetch(source)
	if err != nil {
		return err
	}
	destinationRelease, err := fetch(destination)
	if err != nil {
		logrus.Warn("missing destination latest release")
	} else {
		if os.Getenv("NO_SKIP") != "true" && strings.Contains(*destinationRelease.Name, *sourceRelease.Name) {
			logrus.Info("already latest")
			setActionOutput("skip", "true")
			return nil
		}
	}
	err = generate(sourceRelease, output)
	if err != nil {
		return err
	}
	setActionOutput("tag", *sourceRelease.Name)
	return nil
}

func main() {
	err := release("v2fly/domain-list-community", "sagernet/sing-geosite", "geosite.db")
	if err != nil {
		logrus.Fatal(err)
	}
}