package repo

//go:generate mockgen -destination mock_repo_test.go -package repo code.gitea.io/sdk/gitea Client

import (
	"errors"
	"strings"
	"time"

	"git.polynom.me/rio/internal/constants"

	"github.com/patrickmn/go-cache"
	log "github.com/sirupsen/logrus"
)

var (
	pathCache = cache.New(1*time.Hour, 1*time.Hour)

	// Caching the existence of an user
	userCache = cache.New(24*time.Hour, 12*time.Hour)

	// Caches the existence of a Content-Security-Policy
	// Mapping: Repository key -> CSPCacheEntry
	cspCache = cache.New(24*time.Hour, 12*time.Hour)
)

type PageCacheEntry struct {
	Repository Repository
	Path       string
}

type CSPCacheEntry struct {
	CSP           string
	LastRequested time.Time
}

func makePageCacheKey(domain, path string) string {
	return domain + "/" + path
}

func makeCSPCacheKey(username, repositoryName string) string {
	return username + ":" + repositoryName
}

func lookupRepositoryAndCache(username, reponame, branchName, host, domain, path, cname string, giteaClient *GiteaClient) (*Repository, error) {
	log.Debugf("CNAME: %s", cname)
	log.Debugf("Looking up repository %s/%s", username, reponame)
	repo, err := giteaClient.getRepository(username, reponame)
	if err != nil {
		return nil, err
	}

	if !giteaClient.hasBranch(username, reponame, branchName) {
		return nil, errors.New("Specified branch does not exist")
	}

	// Check if the CNAME file matches
	if cname != "" {
		log.Debug("Checking CNAME")
		file, _, err := giteaClient.GetFile(
			username,
			reponame,
			constants.PagesBranch,
			"CNAME",
			nil,
		)
		if err != nil {
			log.Errorf(
				"Could not verify CNAME of %s/%s@%s: %v\n",
				username,
				reponame,
				constants.PagesBranch,
				err,
			)
			return nil, err
		}

		cnameContent := strings.Trim(
			string(file[:]),
			"\n",
		)

		log.Debugf("CNAME Content: %s", cnameContent)
		if cnameContent != host {
			log.Warnf("CNAME mismatch: Repo '%s', Host '%s'", cnameContent, host)
			return nil, errors.New("CNAME mismatch")
		}
	}

	// Cache data
	pathCache.Set(
		makePageCacheKey(domain, path),
		PageCacheEntry{
			repo,
			path,
		},
		cache.DefaultExpiration,
	)
	return &repo, nil
}

// host is the domain name we're accessed from. cname is the domain that host is pointing
// if, if we're accessed via a CNAME. If not, then cname is "".
func RepoFromPath(username, host, cname, path string, giteaClient *GiteaClient) (*Repository, string, error) {
	domain := host

	// Guess the repository
	key := makePageCacheKey(domain, path)
	entry, found := pathCache.Get(key)
	if found {
		pageEntry := entry.(PageCacheEntry)
		return &pageEntry.Repository, pageEntry.Path, nil
	}

	// Allow specifying the repository name in the TXT record
	reponame := ""
	if cname != "" {
		repoLookup, err := giteaClient.lookupRepoTXT(host)
		if err == nil && repoLookup != "" {
			log.Infof(
				"TXT lookup for %s resulted in choosing repository %s",
				host,
				repoLookup,
			)
			reponame = repoLookup
		}
	}

	pathParts := strings.Split(path, "/")
	log.Debugf("reponame='%s' len(pathParts)='%d'", reponame, len(pathParts))
	if reponame == "" && len(pathParts) > 1 {
		log.Debugf("Trying repository %s", pathParts[0])
		modifiedPath := strings.Join(pathParts[1:], "/")
		repo, err := lookupRepositoryAndCache(
			username,
			pathParts[0],
			constants.PagesBranch,
			host,
			domain,
			modifiedPath,
			cname,
			giteaClient,
		)
		if err == nil {
			return repo, modifiedPath, nil
		}
	}

	if reponame == "" {
		reponame = domain
	}
	log.Debugf("Trying repository %s/%s", username, reponame)
	repo, err := lookupRepositoryAndCache(
		username,
		reponame,
		constants.PagesBranch,
		host,
		domain,
		path,
		cname,
		giteaClient,
	)
	return repo, path, err
}

// Checks if the username exists as an organisation or an user on the Gitea
// instance, so that an attacker can't just request certificates for random
// usernames.
func CanRequestCertificate(username string, giteaClient *GiteaClient) bool {
	if _, found := userCache.Get(username); found {
		return true
	}

	hasUser := giteaClient.hasUser(username)
	if hasUser {
		userCache.Set(username, true, cache.DefaultExpiration)
	}
	return hasUser
}

// Checks the repository username/repository@PagesBranch for a file named CSP. If it exists,
// read it and return the value. If it does not exist, return defaultCsp.
func GetCSPForRepository(username, repositoryName, defaultCsp string, giteaClient *GiteaClient) string {
	key := makeCSPCacheKey(username, repositoryName)
	cachedCsp, found := cspCache.Get(key)
	var since time.Time
	if found {
		since = cachedCsp.(CSPCacheEntry).LastRequested
	}

	fetchedCsp, changed, err := giteaClient.GetFile(
		username,
		repositoryName,
		constants.PagesBranch,
		"CSP",
		&since,
	)
	csp := ""
	if err != nil {
		if found {
			return cachedCsp.(CSPCacheEntry).CSP
		}

		csp = defaultCsp
	} else {
		csp = string(fetchedCsp)

		if !found || changed {
			cspCache.Set(key, CSPCacheEntry{
				CSP:           csp,
				LastRequested: time.Now(),
			}, cache.DefaultExpiration)
		}
	}

	return csp
}