[CHORE] Drop go-git support

See https://codeberg.org/forgejo/discussions/issues/164 for the
rationale and discussion of this change.

Everything related to the `go-git` dependency is dropped (Only a single
instance is left in a test file to test for an XSS, it requires crafting
an commit that Git itself refuses to craft). `_gogit` files have
been removed entirely, `go:build: !gogit` is removed, `XXX_nogogit.go` files
either have been renamed or had their code being merged into the
`XXX.go` file.

modules/git/commit_info.go

@@ -3,9 +3,173 @@
 
 package git
 
+import (
+	"context"
+	"fmt"
+	"io"
+	"path"
+	"sort"
+
+	"code.gitea.io/gitea/modules/log"
+)
+
 // CommitInfo describes the first commit with the provided entry
 type CommitInfo struct {
 	Entry         *TreeEntry
 	Commit        *Commit
 	SubModuleFile *SubModuleFile
 }
+
+// GetCommitsInfo gets information of all commits that are corresponding to these entries
+func (tes Entries) GetCommitsInfo(ctx context.Context, commit *Commit, treePath string) ([]CommitInfo, *Commit, error) {
+	entryPaths := make([]string, len(tes)+1)
+	// Get the commit for the treePath itself
+	entryPaths[0] = ""
+	for i, entry := range tes {
+		entryPaths[i+1] = entry.Name()
+	}
+
+	var err error
+
+	var revs map[string]*Commit
+	if commit.repo.LastCommitCache != nil {
+		var unHitPaths []string
+		revs, unHitPaths, err = getLastCommitForPathsByCache(commit.ID.String(), treePath, entryPaths, commit.repo.LastCommitCache)
+		if err != nil {
+			return nil, nil, err
+		}
+		if len(unHitPaths) > 0 {
+			sort.Strings(unHitPaths)
+			commits, err := GetLastCommitForPaths(ctx, commit, treePath, unHitPaths)
+			if err != nil {
+				return nil, nil, err
+			}
+
+			for pth, found := range commits {
+				revs[pth] = found
+			}
+		}
+	} else {
+		sort.Strings(entryPaths)
+		revs, err = GetLastCommitForPaths(ctx, commit, treePath, entryPaths)
+	}
+	if err != nil {
+		return nil, nil, err
+	}
+
+	commitsInfo := make([]CommitInfo, len(tes))
+	for i, entry := range tes {
+		commitsInfo[i] = CommitInfo{
+			Entry: entry,
+		}
+
+		// Check if we have found a commit for this entry in time
+		if entryCommit, ok := revs[entry.Name()]; ok {
+			commitsInfo[i].Commit = entryCommit
+		} else {
+			log.Debug("missing commit for %s", entry.Name())
+		}
+
+		// If the entry if a submodule add a submodule file for this
+		if entry.IsSubModule() {
+			subModuleURL := ""
+			var fullPath string
+			if len(treePath) > 0 {
+				fullPath = treePath + "/" + entry.Name()
+			} else {
+				fullPath = entry.Name()
+			}
+			if subModule, err := commit.GetSubModule(fullPath); err != nil {
+				return nil, nil, err
+			} else if subModule != nil {
+				subModuleURL = subModule.URL
+			}
+			subModuleFile := NewSubModuleFile(commitsInfo[i].Commit, subModuleURL, entry.ID.String())
+			commitsInfo[i].SubModuleFile = subModuleFile
+		}
+	}
+
+	// Retrieve the commit for the treePath itself (see above). We basically
+	// get it for free during the tree traversal and it's used for listing
+	// pages to display information about newest commit for a given path.
+	var treeCommit *Commit
+	var ok bool
+	if treePath == "" {
+		treeCommit = commit
+	} else if treeCommit, ok = revs[""]; ok {
+		treeCommit.repo = commit.repo
+	}
+	return commitsInfo, treeCommit, nil
+}
+
+func getLastCommitForPathsByCache(commitID, treePath string, paths []string, cache *LastCommitCache) (map[string]*Commit, []string, error) {
+	var unHitEntryPaths []string
+	results := make(map[string]*Commit)
+	for _, p := range paths {
+		lastCommit, err := cache.Get(commitID, path.Join(treePath, p))
+		if err != nil {
+			return nil, nil, err
+		}
+		if lastCommit != nil {
+			results[p] = lastCommit
+			continue
+		}
+
+		unHitEntryPaths = append(unHitEntryPaths, p)
+	}
+
+	return results, unHitEntryPaths, nil
+}
+
+// GetLastCommitForPaths returns last commit information
+func GetLastCommitForPaths(ctx context.Context, commit *Commit, treePath string, paths []string) (map[string]*Commit, error) {
+	// We read backwards from the commit to obtain all of the commits
+	revs, err := WalkGitLog(ctx, commit.repo, commit, treePath, paths...)
+	if err != nil {
+		return nil, err
+	}
+
+	batchStdinWriter, batchReader, cancel := commit.repo.CatFileBatch(ctx)
+	defer cancel()
+
+	commitsMap := map[string]*Commit{}
+	commitsMap[commit.ID.String()] = commit
+
+	commitCommits := map[string]*Commit{}
+	for path, commitID := range revs {
+		c, ok := commitsMap[commitID]
+		if ok {
+			commitCommits[path] = c
+			continue
+		}
+
+		if len(commitID) == 0 {
+			continue
+		}
+
+		_, err := batchStdinWriter.Write([]byte(commitID + "\n"))
+		if err != nil {
+			return nil, err
+		}
+		_, typ, size, err := ReadBatchLine(batchReader)
+		if err != nil {
+			return nil, err
+		}
+		if typ != "commit" {
+			if err := DiscardFull(batchReader, size+1); err != nil {
+				return nil, err
+			}
+			return nil, fmt.Errorf("unexpected type: %s for commit id: %s", typ, commitID)
+		}
+		c, err = CommitFromReader(commit.repo, MustIDFromString(commitID), io.LimitReader(batchReader, size))
+		if err != nil {
+			return nil, err
+		}
+		if _, err := batchReader.Discard(1); err != nil {
+			return nil, err
+		}
+		commitCommits[path] = c
+	}
+
+	return commitCommits, nil
+}