git log without os exec

git_log.go

package main

import (
	"fmt"
	"sort"
	"strconv"
	"time"

	"github.com/go-git/go-git/v5"
	"github.com/go-git/go-git/v5/plumbing/object"
)

// CommitRef represents a commit hash and the date it was committed
type CommitRef struct {
	DateTime time.Time `json:"datetime"`
	Commit   string    `json:"commit"`
}

// GetFirstCommitEachWeek returns a slice of commit hashes,
// containing the first commit hash for each week of the given year.
func GetFirstCommitEachWeek(year string) ([]CommitRef, error) {
	// Open the repository
	repo, err := git.PlainOpen("........")
	if err != nil {
		return nil, fmt.Errorf("error opening repository: %v", err)
	}

	// Parse the year
	yearInt, err := strconv.Atoi(year)
	if err != nil {
		return nil, fmt.Errorf("invalid year: %v", err)
	}

	// Construct date range for given year
	since := time.Date(yearInt, 1, 1, 0, 0, 0, 0, time.UTC)
	until := time.Date(yearInt+1, 1, 1, 0, 0, 0, 0, time.UTC)

	// Get the HEAD reference
	ref, err := repo.Head()
	if err != nil {
		return nil, fmt.Errorf("error getting HEAD: %v", err)
	}

	// Create a new LogOptions
	logOptions := &git.LogOptions{
		From:  ref.Hash(),
		Order: git.LogOrderCommitterTime,
		Since: &since,
		Until: &until,
	}

	// Get the commit iterator
	iter, err := repo.Log(logOptions)
	if err != nil {
		return nil, fmt.Errorf("error creating log iterator: %v", err)
	}

	commits := make(map[int]CommitRef)

	// Iterate through the commits
	err = iter.ForEach(func(c *object.Commit) error {
		_, week := c.Committer.When.ISOWeek()
		if _, ok := commits[week]; !ok {
			commits[week] = CommitRef{
				DateTime: c.Committer.When,
				Commit:   c.Hash.String(),
			}
		}
		return nil
	})

	if err != nil {
		return nil, fmt.Errorf("error iterating through commits: %v", err)
	}

	result := make([]CommitRef, 0, len(commits))
	for _, commit := range commits {
		result = append(result, commit)
	}

	sort.Slice(result, func(i, j int) bool {
		return result[i].DateTime.Before(result[j].DateTime)
	})

	return result, nil
}

func main() {
	year := "2024"
	commits, err := GetFirstCommitEachWeek(year)
	if err != nil {
		fmt.Printf("Error: %v\n", err)
		return
	}

	for _, commit := range commits {
		fmt.Printf("%v: %v\n", commit.DateTime.Format("2006-01-02"), commit.Commit)
	}
}