Git statistics in Activity tab (#4724)

* Initial implementation for git statistics in Activity tab

* Create top user by commit count endpoint

* Add UI and update src-d/go-git dependency

* Add coloring

* Fix typo

* Move git activity stats data extraction to git module

* Fix message

* Add git code stats test

modules/git/repo_stats.go

@@ -0,0 +1,108 @@
+// Copyright 2019 The Gitea Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package git
+
+import (
+	"bufio"
+	"bytes"
+	"fmt"
+	"strconv"
+	"strings"
+	"time"
+)
+
+// CodeActivityStats represents git statistics data
+type CodeActivityStats struct {
+	AuthorCount              int64
+	CommitCount              int64
+	ChangedFiles             int64
+	Additions                int64
+	Deletions                int64
+	CommitCountInAllBranches int64
+	Authors                  map[string]int64
+}
+
+// GetCodeActivityStats returns code statistics for acitivity page
+func (repo *Repository) GetCodeActivityStats(fromTime time.Time, branch string) (*CodeActivityStats, error) {
+	stats := &CodeActivityStats{}
+
+	since := fromTime.Format(time.RFC3339)
+
+	stdout, err := NewCommand("rev-list", "--count", "--no-merges", "--branches=*", "--date=iso", fmt.Sprintf("--since='%s'", since)).RunInDirBytes(repo.Path)
+	if err != nil {
+		return nil, err
+	}
+
+	c, err := strconv.ParseInt(strings.TrimSpace(string(stdout)), 10, 64)
+	if err != nil {
+		return nil, err
+	}
+	stats.CommitCountInAllBranches = c
+
+	args := []string{"log", "--numstat", "--no-merges", "--pretty=format:---%n%h%n%an%n%ae%n", "--date=iso", fmt.Sprintf("--since='%s'", since)}
+	if len(branch) == 0 {
+		args = append(args, "--branches=*")
+	} else {
+		args = append(args, "--first-parent", branch)
+	}
+
+	stdout, err = NewCommand(args...).RunInDirBytes(repo.Path)
+	if err != nil {
+		return nil, err
+	}
+
+	scanner := bufio.NewScanner(bytes.NewReader(stdout))
+	scanner.Split(bufio.ScanLines)
+	stats.CommitCount = 0
+	stats.Additions = 0
+	stats.Deletions = 0
+	authors := make(map[string]int64)
+	files := make(map[string]bool)
+	p := 0
+	for scanner.Scan() {
+		l := strings.TrimSpace(scanner.Text())
+		if l == "---" {
+			p = 1
+		} else if p == 0 {
+			continue
+		} else {
+			p++
+		}
+		if p > 4 && len(l) == 0 {
+			continue
+		}
+		switch p {
+		case 1: // Separator
+		case 2: // Commit sha-1
+			stats.CommitCount++
+		case 3: // Author
+		case 4: // E-mail
+			email := strings.ToLower(l)
+			i := authors[email]
+			authors[email] = i + 1
+		default: // Changed file
+			if parts := strings.Fields(l); len(parts) >= 3 {
+				if parts[0] != "-" {
+					if c, err := strconv.ParseInt(strings.TrimSpace(parts[0]), 10, 64); err == nil {
+						stats.Additions += c
+					}
+				}
+				if parts[1] != "-" {
+					if c, err := strconv.ParseInt(strings.TrimSpace(parts[1]), 10, 64); err == nil {
+						stats.Deletions += c
+					}
+				}
+				if _, ok := files[parts[2]]; !ok {
+					files[parts[2]] = true
+				}
+			}
+		}
+	}
+	stats.AuthorCount = int64(len(authors))
+	stats.ChangedFiles = int64(len(files))
+	stats.Authors = authors
+
+	return stats, nil
+}