feat: scaffolding new revert wizard to revert back to a specific commit

README.md

@@ -34,6 +34,7 @@ Watcher TUI that shows changed files on the left and a side-by-side diff on the
 - `<`/`>` or `H`/`L`: adjust left pane width
 - `c`: open commit flow (overlay)
 - `q`: quit
+- `V`: open revert wizard (revert to a specified commit `git revert <commit_hash>..HEAD`)
 
 The top bar shows `Changes | <file>` with a horizontal rule below. The bottom bar shows `h: help` on the left and the last `refreshed` time on the right. Requires `git` in PATH. Binary files are listed but not rendered as text diffs yet.
 

internal/gitx/gitx.go

@@ -8,6 +8,7 @@ import (
 	"path/filepath"
 	"sort"
 	"strings"
+	"time"
 )
 
 // FileChange represents a changed file in the repo.
@@ -20,6 +21,20 @@ type FileChange struct {
 	Deleted   bool
 }
 
+// CommitInfo represents single git commit
+type CommitInfo struct {
+	ID              string
+	AbbreviatedHash string
+	Message         string
+	AuthorEmail     string
+	AuthorName      string
+	AuthorDate      time.Time
+	CommitterName   string
+	CommitterEmail  string
+	CommitterDate   string
+	Body            string
+}
+
 // RepoRoot resolves the git repository root from a given path (or current dir).
 func RepoRoot(path string) (string, error) {
 	if path == "" {
@@ -439,3 +454,103 @@ func CurrentBranch(repoRoot string) (string, error) {
 	}
 	return strings.TrimSpace(string(b)), nil
 }
+
+// ListCommits returns a slice of commits in reverse chronological order (latest first).
+// The `from` and `to` parameters define a range of commits to fetch. This prevents
+// loading thousands of commits at once, which could consume excessive memory.
+// Example: ListCommits("/path/to/repo", 0, 50) retrieves the latest 50 commits.
+func ListCommits(repoRoot string, from int, to int) ([]CommitInfo, error) {
+	if from < 0 || to < 0 || to < from {
+		return nil, fmt.Errorf("invalid range: from=%d, to=%d", from, to)
+	}
+
+	const sep = "<--END-->"
+	format := strings.Join([]string{
+		"%H",  // full hash
+		"%s",  // subject line
+		"%ae", // author email
+		"%an", // author name
+		"%ad", // author date
+		"%cn", // committer name
+		"%ce", // committer email
+		"%cd", // committer date
+		"%b",  // body (commit description)
+		"%h",  // abbreviated hash
+	}, "%n") + "%n" + sep
+
+	count := to - from
+
+	args := []string{
+		"-C", repoRoot,
+		"log",
+		"--date=iso-strict",
+		"--skip", fmt.Sprint(from),
+		"-n", fmt.Sprint(count),
+		"--pretty=format:" + format,
+	}
+
+	cmd := exec.Command("git", args...)
+	out, err := cmd.Output()
+	if err != nil {
+		return nil, fmt.Errorf("list commits failed: %w", err)
+	}
+
+	rawCommits := strings.Split(string(out), sep)
+	var commits []CommitInfo
+
+	for _, raw := range rawCommits {
+		lines := strings.Split(strings.TrimSpace(raw), "\n")
+		if len(lines) < 10 {
+			continue
+		}
+
+		authorDate, _ := time.Parse(time.RFC3339, strings.TrimSpace(lines[4]))
+
+		commits = append(commits, CommitInfo{
+			ID:              lines[0],
+			Message:         lines[1],
+			AuthorEmail:     lines[2],
+			AuthorName:      lines[3],
+			AuthorDate:      authorDate,
+			CommitterName:   lines[5],
+			CommitterEmail:  lines[6],
+			CommitterDate:   lines[7],
+			Body:            strings.TrimSpace(strings.Join(lines[8:len(lines)-1], "\n")),
+			AbbreviatedHash: strings.TrimSpace(lines[len(lines)-1]),
+		})
+	}
+
+	return commits, nil
+}
+
+// RevertBack reverts all commits made after the specified commit hash (exclusive).
+// Internally, it runs `git revert --no-edit <hash>..HEAD` to undo subsequent changes.
+// Note: This creates new "revert" commits instead of rewriting history.
+func RevertBack(repoRoot string, hash string) error {
+	if hash == "" {
+		return fmt.Errorf("hash cannot be empty")
+	}
+
+	args := []string{
+		"-C", repoRoot,
+		"revert",
+		"--no-edit",
+		hash + "..HEAD",
+	}
+	cmd := exec.Command("git", args...)
+
+	b, err := cmd.Output()
+
+	if err != nil {
+		return fmt.Errorf("git revert %s..HEAD: %w :%s", hash, err, string(b))
+	}
+
+	return nil
+}
+
+// RevertPreview shows a what would change if the repository were reverted
+// back to the specified commit. This runs a `git diff HEAD <hash>` internally to
+// preview the potential modifications before actually reverting.
+func RevertPreview(repoRoot, hash string) ([]string, error) {
+	return listNames(repoRoot, []string{"diff", "HEAD", hash})
+}

internal/tui/program.go

@@ -113,6 +113,16 @@ type model struct {
 	searchQuery   string
 	searchMatches []int
 	searchIndex   int
+
+	// revert wizard
+	showRevert bool
+	revertStep int // 0: list commits, 1: preview, 2: confirm
+	rwCommits  []gitx.CommitInfo
+	rwSelected int
+	rwPreview  []string // preview of what will be changed
+	reverting  bool
+	revertErr  string
+	revertDone bool
 }
 
 // messages
@@ -176,7 +186,9 @@ func (m model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 		if m.showPull {
 			return m.handlePullKeys(msg)
 		}
-
+		if m.showRevert {
+			return m.handleRevertKeys(msg)
+		}
 		key := msg.String()
 
 		if isNumericKey(key) {
@@ -214,6 +226,10 @@ func (m model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 			// Open reset/clean wizard
 			m.openResetCleanWizard()
 			return m, m.recalcViewport()
+		case "V":
+			// Open revert wizard
+			m.openRevertWizard()
+			return m, m.recalcViewport()
 		case "/":
 			(&m).openSearch()
 			return m, m.recalcViewport()
@@ -657,6 +673,16 @@ func (m model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 		m.uncommitDone = true
 		m.showUncommit = false
 		return m, tea.Batch(loadFiles(m.repoRoot, m.diffMode), loadLastCommit(m.repoRoot), m.recalcViewport())
+	case revertResultMessage:
+		m.reverting = false
+		if msg.err != nil {
+			m.revertErr = msg.err.Error()
+			m.revertDone = false
+			return m, tea.Batch(loadFiles(m.repoRoot, m.diffMode), loadLastCommit(m.repoRoot), m.recalcViewport())
+		}
+		m.revertErr = ""
+		m.revertDone = true
+		m.showRevert = false
 	}
 	return m, nil
 }
@@ -722,6 +748,9 @@ func (m model) View() string {
 	if m.showPull {
 		overlay = append(overlay, m.pullOverlayLines(m.width)...)
 	}
+	if m.showRevert {
+		overlay = append(overlay, m.revertOverlayLines(m.width)...)
+	}
 	if m.searchActive {
 		overlay = append(overlay, m.searchOverlayLines(m.width)...)
 	}
@@ -1137,6 +1166,7 @@ func (m model) helpOverlayLines(width int) []string {
 		"u              Uncommit (open wizard)",
 		"R              Reset/Clean (open wizard)",
 		"c              Commit & push (open wizard)",
+		"V              Revert (open wizard)",
 		"s              Toggle side-by-side / inline",
 		"t              Toggle HEAD / staged diffs",
 		"w              Toggle line wrap (diff)",
@@ -2849,3 +2879,153 @@ func isMovementKey(key string) bool {
 func isNumericKey(key string) bool {
 	return key <= "9" && key >= "0"
 }
+
+// Revert Wizard
+
+// handle revert wizard keys
+func (m model) handleRevertKeys(key tea.KeyMsg) (tea.Model, tea.Cmd) {
+	switch m.revertStep {
+	case 0: // list commits
+		switch key.String() {
+		case "esc":
+			m.showRevert = false
+			return m, m.recalcViewport()
+		case "enter":
+			m.revertStep = 1
+			// load preview
+			m.loadRevertPreview()
+			return m, m.recalcViewport()
+		case "j", "down":
+			if len(m.rwCommits) > 0 && m.rwSelected < len(m.rwCommits)-1 {
+				m.rwSelected++
+			}
+			return m, nil
+		case "k", "up":
+			if m.rwSelected > 0 {
+				m.rwSelected--
+			}
+			return m, nil
+		}
+	case 1: // preview
+		switch key.String() {
+		case "esc":
+			m.showRevert = false
+			return m, m.recalcViewport()
+		case "b":
+			m.revertStep = 0
+			return m, m.recalcViewport()
+		case "enter":
+			m.revertStep = 2
+			m.revertDone = false
+			m.revertErr = ""
+			m.reverting = false
+			return m, m.recalcViewport()
+		}
+	case 2: // confirm/progress
+		switch key.String() {
+		case "esc":
+			// can't cancel mid-revert, but if not running: exit
+			if !m.reverting {
+				m.showRevert = false
+				return m, m.recalcViewport()
+			}
+			return m, nil
+		case "b":
+			if !m.reverting && !m.revertDone {
+				m.revertStep = 1
+				return m, m.recalcViewport()
+			}
+			return m, nil
+		case "y", "enter":
+			if !m.reverting && !m.revertDone {
+				m.revertErr = ""
+				m.reverting = true
+				return m, runRevertBack(m.repoRoot, m.rwCommits[m.rwSelected].ID)
+			}
+			return m, nil
+		}
+	}
+	return m, nil
+}
+
+func (m model) revertOverlayLines(width int) []string {
+	if !m.showRevert {
+		return nil
+	}
+	lines := make([]string, 0, 64)
+	lines = append(lines, strings.Repeat("─", width))
+	switch m.revertStep {
+	case 0:
+		title := lipgloss.NewStyle().Bold(true).Render("Revert — Select commmit (enter: continue, esc: cancel)")
+		lines = append(lines, title)
+		if len(m.rwCommits) == 0 {
+			lines = append(lines, lipgloss.NewStyle().Faint(true).Render("No commits to revert to."))
+			return lines
+		}
+		for i, c := range m.rwCommits {
+			cur := "  "
+			if i == m.rwSelected {
+				cur = "> "
+			}
+			mark := "[ ]"
+			if i == m.rwSelected {
+				mark = "[x]"
+			}
+			lines = append(lines, fmt.Sprintf("%s%s %s %s", cur, mark, c.AbbreviatedHash, c.Message))
+		}
+	case 1:
+		title := lipgloss.NewStyle().Bold(true).Render("Revert — Preview (enter: continue, b: back, esc: cancel)")
+		lines = append(lines, title)
+		lines = append(lines, lipgloss.NewStyle().Bold(true).Foreground(lipgloss.Color("220")).Render("The following changes will be done:"))
+		lines = append(lines, m.rwPreview...)
+	case 2:
+		title := lipgloss.NewStyle().Bold(true).Render("Revert - Confirm (y/enter: execute, b: back, esc: cancel)")
+		lines = append(lines, title)
+		lines = append(lines, lipgloss.NewStyle().Bold(true).Foreground(lipgloss.Color("220")).Render(fmt.Sprintf("Please Confirm:")))
+		if m.reverting {
+			lines = append(lines, lipgloss.NewStyle().Foreground(lipgloss.Color("63")).Render("Reverting..."))
+		}
+		if m.revertErr != "" {
+			lines = append(lines, lipgloss.NewStyle().Foreground(lipgloss.Color("196")).Render("Error: ")+m.revertErr)
+		}
+	}
+	return lines
+}
+
+func (m *model) openRevertWizard() {
+	m.showRevert = true
+	// TODO: move to constant
+	commits, err := gitx.ListCommits(m.repoRoot, 0, 20)
+	if err != nil {
+		m.revertErr = err.Error()
+	}
+	m.rwCommits = commits
+	m.revertStep = 0
+	m.rwSelected = 0
+	m.revertErr = ""
+	m.revertDone = false
+	m.reverting = false
+}
+
+func (m *model) loadRevertPreview() {
+	preview, err := gitx.RevertPreview(m.repoRoot, m.rwCommits[m.rwSelected].ID)
+	if err != nil {
+		m.revertErr = err.Error()
+		m.revertStep = 2
+		return
+	}
+	m.rwPreview = preview
+}
+
+type revertResultMessage struct {
+	err error
+}
+
+func runRevertBack(repoRoot string, hash string) tea.Cmd {
+	return func() tea.Msg {
+		err := gitx.RevertBack(repoRoot, hash)
+		return revertResultMessage{
+			err: err,
+		}
+	}
+}