appview: implement repo fork

appview/db/db.go

···
 		return err
 	})
 
+	runMigration(db, "add-source-to-repos", func(tx *sql.Tx) error {
+		_, err := tx.Exec(`
+			alter table repos add column source text;
+		`)
+		return err
+	})
+
 	return &DB{db}, nil
 }
 

appview/db/repos.go

···
 import (
 	"database/sql"
 	"time"
+
+	"github.com/bluesky-social/indigo/atproto/syntax"
 )
 
 type Repo struct {
···
 
 	// optionally, populate this when querying for reverse mappings
 	RepoStats *RepoStats
+
+	// optional
+	Source string
 }
 
 func GetAllRepos(e Execer, limit int) ([]Repo, error) {
 	var repos []Repo
 
 	rows, err := e.Query(
-		`select did, name, knot, rkey, description, created 
+		`select did, name, knot, rkey, description, created, source
 		from repos
 		order by created desc
 		limit ?
···
 	for rows.Next() {
 		var repo Repo
 		err := scanRepo(
-			rows, &repo.Did, &repo.Name, &repo.Knot, &repo.Rkey, &repo.Description, &repo.Created,
+			rows, &repo.Did, &repo.Name, &repo.Knot, &repo.Rkey, &repo.Description, &repo.Created, &repo.Source,
 		)
 		if err != nil {
 			return nil, err
···
 			r.rkey,
 			r.description,
 			r.created,
-			count(s.id) as star_count
+			count(s.id) as star_count,
+			r.source
 		from
 			repos r
 		left join
···
 
 func AddRepo(e Execer, repo *Repo) error {
 	_, err := e.Exec(
-		`insert into repos 
-		(did, name, knot, rkey, at_uri, description)
-		values (?, ?, ?, ?, ?, ?)`,
-		repo.Did, repo.Name, repo.Knot, repo.Rkey, repo.AtUri, repo.Description,
+		`insert into repos
+		(did, name, knot, rkey, at_uri, description, source)
+		values (?, ?, ?, ?, ?, ?, ?)`,
+		repo.Did, repo.Name, repo.Knot, repo.Rkey, repo.AtUri, repo.Description, repo.Source,
 	)
 	return err
 }
···
 func RemoveRepo(e Execer, did, name, rkey string) error {
 	_, err := e.Exec(`delete from repos where did = ? and name = ? and rkey = ?`, did, name, rkey)
 	return err
+}
+
+func GetRepoSource(e Execer, repoAt syntax.ATURI) (string, error) {
+	var source string
+	err := e.QueryRow(`select source from repos where at_uri = ?`, repoAt).Scan(&source)
+	if err != nil {
+		return "", err
+	}
+	return source, nil
 }
 
 func AddCollaborator(e Execer, collaborator, repoOwnerDid, repoName, repoKnot string) error {
···
 	PullCount  PullCount
 }
 
-func scanRepo(rows *sql.Rows, did, name, knot, rkey, description *string, created *time.Time) error {
+func scanRepo(rows *sql.Rows, did, name, knot, rkey, description *string, created *time.Time, source *string) error {
 	var createdAt string
 	var nullableDescription sql.NullString
-	if err := rows.Scan(did, name, knot, rkey, &nullableDescription, &createdAt); err != nil {
+	var nullableSource sql.NullString
+	if err := rows.Scan(did, name, knot, rkey, &nullableDescription, &createdAt, &nullableSource); err != nil {
 		return err
 	}
 
···
 		*created = time.Now()
 	} else {
 		*created = createdAtTime
+	}
+
+	if nullableSource.Valid {
+		*source = nullableSource.String
+	} else {
+		*source = ""
 	}
 
 	return nil

appview/db/timeline.go

···
 	*Repo
 	*Follow
 	*Star
+
 	EventAt time.Time
+
+	// optional: populate only if Repo is a fork
+	Source *Repo
 }
 
 // TODO: this gathers heterogenous events from different sources and aggregates
···
 	}
 
 	for _, repo := range repos {
+		if repo.Source != "" {
+			sourceRepo, err := GetRepoByAtUri(e, repo.Source)
+			if err != nil {
+				return nil, err
+			}
+
+			events = append(events, TimelineEvent{
+				Repo:    &repo,
+				EventAt: repo.Created,
+				Source:  sourceRepo,
+			})
+		}
+
 		events = append(events, TimelineEvent{
 			Repo:    &repo,
 			EventAt: repo.Created,

appview/pages/pages.go

···
 	return p.execute("repo/new", w, params)
 }
 
+type ForkRepoParams struct {
+	LoggedInUser *auth.User
+	Knots        []string
+	RepoInfo     RepoInfo
+}
+
+func (p *Pages) ForkRepo(w io.Writer, params ForkRepoParams) error {
+	return p.execute("repo/fork", w, params)
+}
+
 type ProfilePageParams struct {
 	LoggedInUser       *auth.User
 	UserDid            string
···
 }
 
 type RepoInfo struct {
-	Name        string
-	OwnerDid    string
-	OwnerHandle string
-	Description string
-	Knot        string
-	RepoAt      syntax.ATURI
-	IsStarred   bool
-	Stats       db.RepoStats
-	Roles       RolesInRepo
+	Name         string
+	OwnerDid     string
+	OwnerHandle  string
+	Description  string
+	Knot         string
+	RepoAt       syntax.ATURI
+	IsStarred    bool
+	Stats        db.RepoStats
+	Roles        RolesInRepo
+	Source       *db.Repo
+	SourceHandle string
 }
 
 type RolesInRepo struct {

appview/pages/templates/layouts/repobase.html

···
 
 {{ define "content" }}
     <section id="repo-header" class="mb-4 py-2 px-6 dark:text-white">
+      {{ if .RepoInfo.Source }}
+      <p class="text-sm">
+      <div class="flex items-center">
+          {{ i "git-fork" "w-3 h-3 mr-1"}}
+          forked from
+          {{ $sourceOwner := didOrHandle .RepoInfo.Source.Did .RepoInfo.SourceHandle  }}
+          <a class="ml-1 underline" href="/{{ $sourceOwner }}/{{ .RepoInfo.Source.Name }}">{{ $sourceOwner }}/{{ .RepoInfo.Source.Name }}</a>
+      </div>
+      </p>
+      {{ end }}
       <p class="text-lg">
         <a href="/{{ .RepoInfo.OwnerWithAt }}">{{ .RepoInfo.OwnerWithAt }}</a>
         <span class="select-none">/</span>

appview/pages/templates/repo/fork.html

···
+{{ define "title" }}fork · {{ .RepoInfo.FullName }}{{ end }}
+
+{{ define "content" }}
+<div class="p-6">
+  <p class="text-xl font-bold dark:text-white">Fork {{ .RepoInfo.FullName }}</p>
+</div>
+<div class="p-6 bg-white dark:bg-gray-800 drop-shadow-sm rounded">
+  <form hx-post="/{{ .RepoInfo.FullName }}/fork" class="space-y-12" hx-swap="none">
+    <fieldset class="space-y-3">
+      <legend class="dark:text-white">Select a knot to fork into</legend>
+      <div class="space-y-2">
+        <div class="flex flex-col">
+        {{ range .Knots }}
+          <div class="flex items-center">
+            <input
+                type="radio"
+                name="knot"
+                value="{{ . }}"
+                class="mr-2"
+                id="domain-{{ . }}"
+                />
+            <span class="dark:text-white">{{ . }}</span>
+          </div>
+        {{ else }}
+        <p class="dark:text-white">No knots available.</p>
+        {{ end }}
+        </div>
+      </div>
+      <p class="text-sm text-gray-500 dark:text-gray-400">A knot hosts repository data. <a href="/knots" class="underline">Learn how to register your own knot.</a></p>
+    </fieldset>
+
+    <div class="space-y-2">
+      <button type="submit" class="btn">fork repo</button>
+      <div id="repo" class="error"></div>
+    </div>
+  </form>
+</div>
+{{ end }}

appview/pages/templates/repo/settings.html

···
 {{ define "title" }}settings · {{ .RepoInfo.FullName }}{{ end }}
 {{ define "repoContent" }}
-    <header class="font-bold text-sm mb-4 uppercase dark:text-white">Collaborators</header>
+    <header class="font-bold text-sm mb-4 uppercase dark:text-white">
+        Collaborators
+    </header>
 
     <div id="collaborator-list" class="flex flex-col gap-2 mb-2">
         {{ range .Collaborators }}
···
     </div>
 
     {{ if .IsCollaboratorInviteAllowed }}
-        <h3 class="dark:text-white">add collaborator</h3>
         <form hx-put="/{{ $.RepoInfo.FullName }}/settings/collaborator">
-            <label for="collaborator" class="dark:text-white">did or handle:</label>
-            <input type="text" id="collaborator" name="collaborator" required class="dark:bg-gray-700 dark:text-white" />
-            <button class="btn my-2 dark:text-white dark:hover:bg-gray-700" type="text">add collaborator</button>
+            <label for="collaborator" class="dark:text-white"
+                >add collaborator</label
+            >
+            <input
+                type="text"
+                id="collaborator"
+                name="collaborator"
+                required
+                class="dark:bg-gray-700 dark:text-white"
+                placeholder="enter did or handle"
+            />
+            <button
+                class="btn my-2 dark:text-white dark:hover:bg-gray-700"
+                type="text"
+            >
+                add
+            </button>
         </form>
     {{ end }}
 

appview/pages/templates/timeline.html

···
         <div class="flex items-center">
           <p class="text-gray-600 dark:text-gray-300">
           <a href="/{{ $userHandle }}" class="no-underline hover:underline">{{ $userHandle | truncateAt30 }}</a>
+          {{ if .Source }}
+          forked
+          <a href="/{{ $userHandle }}/{{ .Repo.Name }}" class="no-underline hover:underline">{{ .Repo.Name }}</a>
+          from
+          <a href="/{{ index $.DidHandleMap .Source.Did }}/{{ .Source.Name }}" class="no-underline hover:underline">{{ index $.DidHandleMap .Source.Did }}/{{ .Source.Name }}</a>
+          {{ else }}
           created
           <a href="/{{ $userHandle }}/{{ .Repo.Name }}" class="no-underline hover:underline">{{ .Repo.Name }}</a>
+          {{ end }}
           <time class="text-gray-700 dark:text-gray-400 text-xs">{{ .Repo.Created | timeFmt }}</time>
           </p>
         </div>

appview/state/repo.go

···
 
 import (
 	"context"
+	"database/sql"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"io"
 	"log"
-	"math/rand/v2"
+	mathrand "math/rand/v2"
 	"net/http"
 	"path"
 	"slices"
···
 	if err != nil {
 		log.Println("failed to get issue count for ", f.RepoAt)
 	}
+	source, err := db.GetRepoSource(s.db, f.RepoAt)
+	if errors.Is(err, sql.ErrNoRows) {
+		source = ""
+	} else if err != nil {
+		log.Println("failed to get repo source for ", f.RepoAt)
+	}
+
+	var sourceRepo *db.Repo
+	if source != "" {
+		sourceRepo, err = db.GetRepoByAtUri(s.db, source)
+		if err != nil {
+			log.Println("failed to get repo by at uri", err)
+		}
+	}
 
 	knot := f.Knot
 	if knot == "knot1.tangled.sh" {
 		knot = "tangled.sh"
+	}
+
+	var sourceHandle *identity.Identity
+	if sourceRepo != nil {
+		sourceHandle, err = s.resolver.ResolveIdent(context.Background(), sourceRepo.Did)
+		if err != nil {
+			log.Println("failed to resolve source repo", err)
+		}
 	}
 
 	return pages.RepoInfo{
···
 			IssueCount: issueCount,
 			PullCount:  pullCount,
 		},
+		Source:       sourceRepo,
+		SourceHandle: sourceHandle.Handle.String(),
 	}
 }
 
···
 			return
 		}
 
-		commentId := rand.IntN(1000000)
+		commentId := mathrand.IntN(1000000)
 		rkey := s.TID()
 
 		err := db.NewIssueComment(s.db, &db.Comment{
···
 		}
 
 		s.pages.HxLocation(w, fmt.Sprintf("/%s/issues/%d", f.OwnerSlashRepo(), issueId))
+		return
+	}
+}
+
+func (s *State) ForkRepo(w http.ResponseWriter, r *http.Request) {
+	user := s.auth.GetUser(r)
+	f, err := fullyResolvedRepo(r)
+	if err != nil {
+		log.Printf("failed to resolve source repo: %v", err)
+		return
+	}
+
+	switch r.Method {
+	case http.MethodGet:
+		user := s.auth.GetUser(r)
+		knots, err := s.enforcer.GetDomainsForUser(user.Did)
+		if err != nil {
+			s.pages.Notice(w, "repo", "Invalid user account.")
+			return
+		}
+
+		s.pages.ForkRepo(w, pages.ForkRepoParams{
+			LoggedInUser: user,
+			Knots:        knots,
+			RepoInfo:     f.RepoInfo(s, user),
+		})
+
+	case http.MethodPost:
+
+		knot := r.FormValue("knot")
+		if knot == "" {
+			s.pages.Notice(w, "repo", "Invalid form submission—missing knot domain.")
+			return
+		}
+
+		ok, err := s.enforcer.E.Enforce(user.Did, knot, knot, "repo:create")
+		if err != nil || !ok {
+			s.pages.Notice(w, "repo", "You do not have permission to create a repo in this knot.")
+			return
+		}
+
+		forkName := fmt.Sprintf("%s", f.RepoName)
+
+		existingRepo, err := db.GetRepo(s.db, user.Did, f.RepoName)
+		if err == nil && existingRepo != nil {
+			forkName = fmt.Sprintf("%s-%s", forkName, randomString(3))
+		}
+
+		secret, err := db.GetRegistrationKey(s.db, knot)
+		if err != nil {
+			s.pages.Notice(w, "repo", fmt.Sprintf("No registration key found for knot %s.", knot))
+			return
+		}
+
+		client, err := NewSignedClient(knot, secret, s.config.Dev)
+		if err != nil {
+			s.pages.Notice(w, "repo", "Failed to connect to knot server.")
+			return
+		}
+
+		var uri string
+		if s.config.Dev {
+			uri = "http"
+		} else {
+			uri = "https"
+		}
+		sourceUrl := fmt.Sprintf("%s://%s/%s/%s", uri, knot, f.OwnerDid(), f.RepoName)
+		sourceAt := f.RepoAt.String()
+
+		rkey := s.TID()
+		repo := &db.Repo{
+			Did:    user.Did,
+			Name:   forkName,
+			Knot:   knot,
+			Rkey:   rkey,
+			Source: sourceAt,
+		}
+
+		tx, err := s.db.BeginTx(r.Context(), nil)
+		if err != nil {
+			log.Println(err)
+			s.pages.Notice(w, "repo", "Failed to save repository information.")
+			return
+		}
+		defer func() {
+			tx.Rollback()
+			err = s.enforcer.E.LoadPolicy()
+			if err != nil {
+				log.Println("failed to rollback policies")
+			}
+		}()
+
+		resp, err := client.ForkRepo(user.Did, sourceUrl, forkName)
+		if err != nil {
+			s.pages.Notice(w, "repo", "Failed to create repository on knot server.")
+			return
+		}
+
+		switch resp.StatusCode {
+		case http.StatusConflict:
+			s.pages.Notice(w, "repo", "A repository with that name already exists.")
+			return
+		case http.StatusInternalServerError:
+			s.pages.Notice(w, "repo", "Failed to create repository on knot. Try again later.")
+		case http.StatusNoContent:
+			// continue
+		}
+
+		xrpcClient, _ := s.auth.AuthorizedClient(r)
+
+		addedAt := time.Now().Format(time.RFC3339)
+		atresp, err := comatproto.RepoPutRecord(r.Context(), xrpcClient, &comatproto.RepoPutRecord_Input{
+			Collection: tangled.RepoNSID,
+			Repo:       user.Did,
+			Rkey:       rkey,
+			Record: &lexutil.LexiconTypeDecoder{
+				Val: &tangled.Repo{
+					Knot:    repo.Knot,
+					Name:    repo.Name,
+					AddedAt: &addedAt,
+					Owner:   user.Did,
+					Source:  &sourceAt,
+				}},
+		})
+		if err != nil {
+			log.Printf("failed to create record: %s", err)
+			s.pages.Notice(w, "repo", "Failed to announce repository creation.")
+			return
+		}
+		log.Println("created repo record: ", atresp.Uri)
+
+		repo.AtUri = atresp.Uri
+		err = db.AddRepo(tx, repo)
+		if err != nil {
+			log.Println(err)
+			s.pages.Notice(w, "repo", "Failed to save repository information.")
+			return
+		}
+
+		// acls
+		p, _ := securejoin.SecureJoin(user.Did, forkName)
+		err = s.enforcer.AddRepo(user.Did, knot, p)
+		if err != nil {
+			log.Println(err)
+			s.pages.Notice(w, "repo", "Failed to set up repository permissions.")
+			return
+		}
+
+		err = tx.Commit()
+		if err != nil {
+			log.Println("failed to commit changes", err)
+			http.Error(w, err.Error(), http.StatusInternalServerError)
+			return
+		}
+
+		err = s.enforcer.E.SavePolicy()
+		if err != nil {
+			log.Println("failed to update ACLs", err)
+			http.Error(w, err.Error(), http.StatusInternalServerError)
+			return
+		}
+
+		s.pages.HxLocation(w, fmt.Sprintf("/@%s/%s", user.Handle, forkName))
 		return
 	}
 }

appview/state/repo_util.go

···
 
 import (
 	"context"
+	"crypto/rand"
 	"fmt"
 	"log"
+	"math/big"
 	"net/http"
 
 	"github.com/bluesky-social/indigo/atproto/identity"
···
 	}
 
 	return emailToDidOrHandle
+}
+
+func randomString(n int) string {
+	const letters = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
+	result := make([]byte, n)
+
+	for i := 0; i < n; i++ {
+		n, _ := rand.Int(rand.Reader, big.NewInt(int64(len(letters))))
+		result[i] = letters[n.Int64()]
+	}
+
+	return string(result)
 }

appview/state/router.go

···
 				})
 			})
 
+			r.Route("/fork", func(r chi.Router) {
+				r.Use(AuthMiddleware(s))
+				r.Get("/", s.ForkRepo)
+				r.Post("/", s.ForkRepo)
+			})
+
 			r.Route("/pulls", func(r chi.Router) {
 				r.Get("/", s.RepoPulls)
 				r.With(AuthMiddleware(s)).Route("/new", func(r chi.Router) {

appview/state/signer.go

···
 	return s.client.Do(req)
 }
 
+func (s *SignedClient) ForkRepo(ownerDid, source, name string) (*http.Response, error) {
+	const (
+		Method   = "POST"
+		Endpoint = "/repo/fork"
+	)
+
+	body, _ := json.Marshal(map[string]any{
+		"did":    ownerDid,
+		"source": source,
+		"name":   name,
+	})
+
+	req, err := s.newRequest(Method, Endpoint, body)
+	if err != nil {
+		return nil, err
+	}
+
+	return s.client.Do(req)
+}
+
 func (s *SignedClient) RemoveRepo(did, repoName string) (*http.Response, error) {
 	const (
 		Method   = "DELETE"

appview/state/state.go

···
 	for _, ev := range timeline {
 		if ev.Repo != nil {
 			didsToResolve = append(didsToResolve, ev.Repo.Did)
+			if ev.Source != nil {
+				didsToResolve = append(didsToResolve, ev.Source.Did)
+			}
 		}
 		if ev.Follow != nil {
 			didsToResolve = append(didsToResolve, ev.Follow.UserDid, ev.Follow.SubjectDid)

knotserver/git/fork.go

···
+package git
+
+import (
+	"fmt"
+
+	"github.com/go-git/go-git/v5"
+)
+
+func Fork(repoPath, source string) error {
+	_, err := git.PlainClone(repoPath, true, &git.CloneOptions{
+		URL:          source,
+		Depth:        1,
+		SingleBranch: false,
+	})
+
+	if err != nil {
+		return fmt.Errorf("failed to bare clone repository: %w", err)
+	}
+	return nil
+}

knotserver/handler.go

···
 		r.Use(h.VerifySignature)
 		r.Put("/new", h.NewRepo)
 		r.Delete("/", h.RemoveRepo)
+		r.Post("/fork", h.RepoFork)
 	})
 
 	r.Route("/member", func(r chi.Router) {

knotserver/routes.go

···
 	w.WriteHeader(http.StatusNoContent)
 }
 
+func (h *Handle) RepoFork(w http.ResponseWriter, r *http.Request) {
+	l := h.l.With("handler", "RepoFork")
+
+	data := struct {
+		Did    string `json:"did"`
+		Source string `json:"source"`
+		Name   string `json:"name,omitempty"`
+	}{}
+
+	if err := json.NewDecoder(r.Body).Decode(&data); err != nil {
+		writeError(w, "invalid request body", http.StatusBadRequest)
+		return
+	}
+
+	did := data.Did
+	source := data.Source
+
+	if did == "" || source == "" {
+		l.Error("invalid request body, empty did or name")
+		w.WriteHeader(http.StatusBadRequest)
+		return
+	}
+
+	var name string
+	if data.Name != "" {
+		name = data.Name
+	} else {
+		name = filepath.Base(source)
+	}
+
+	relativeRepoPath := filepath.Join(did, name)
+	repoPath, _ := securejoin.SecureJoin(h.c.Repo.ScanPath, relativeRepoPath)
+
+	err := git.Fork(repoPath, source)
+	if err != nil {
+		l.Error("forking repo", "error", err.Error())
+		writeError(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+
+	w.WriteHeader(http.StatusNoContent)
+}
+
 func (h *Handle) RemoveRepo(w http.ResponseWriter, r *http.Request) {
 	l := h.l.With("handler", "RemoveRepo")
 

lexicons/repo.json

···
             "format": "datetime",
             "minLength": 1,
             "maxLength": 140
+          },
+          "source": {
+            "type": "string",
+            "format": "uri",
+            "description": "source of the repo"
           }
         }
       }