feat: add PR diff, PR review, and structured error handling commands

cmd/pr_diff.go

@@ -0,0 +1,271 @@
+package cmd
+
+import (
+	"fmt"
+	"os"
+	"strconv"
+	"strings"
+
+	"codeberg.org/romaintb/fgj/internal/api"
+	"codeberg.org/romaintb/fgj/internal/config"
+	"github.com/spf13/cobra"
+	"golang.org/x/term"
+)
+
+var prDiffCmd = &cobra.Command{
+	Use:   "diff <number>",
+	Short: "Show the diff for a pull request",
+	Long:  "Fetch and display the diff for a pull request.",
+	Example: `  # View the diff for PR #123
+  fgj pr diff 123
+
+  # Colorized diff output
+  fgj pr diff 123 --color always
+
+  # Show only changed file names
+  fgj pr diff 123 --name-only
+
+  # Show diffstat summary
+  fgj pr diff 123 --stat`,
+	Args: cobra.ExactArgs(1),
+	RunE: runPRDiff,
+}
+
+func init() {
+	prCmd.AddCommand(prDiffCmd)
+
+	prDiffCmd.Flags().StringP("repo", "R", "", "Repository in owner/name format")
+	prDiffCmd.Flags().String("color", "auto", "Colorize the diff output: auto, always, never")
+	prDiffCmd.Flags().Bool("name-only", false, "Show only changed file names")
+	prDiffCmd.Flags().Bool("stat", false, "Show diffstat summary")
+}
+
+func runPRDiff(cmd *cobra.Command, args []string) error {
+	repo, _ := cmd.Flags().GetString("repo")
+	colorMode, _ := cmd.Flags().GetString("color")
+	nameOnly, _ := cmd.Flags().GetBool("name-only")
+	stat, _ := cmd.Flags().GetBool("stat")
+
+	prNumber, err := strconv.ParseInt(args[0], 10, 64)
+	if err != nil {
+		return fmt.Errorf("invalid pull request number: %w", err)
+	}
+
+	owner, name, err := parseRepo(repo)
+	if err != nil {
+		return err
+	}
+
+	cfg, err := config.Load()
+	if err != nil {
+		return err
+	}
+
+	client, err := api.NewClientFromConfig(cfg, "", getDetectedHost())
+	if err != nil {
+		return err
+	}
+
+	diffURL := fmt.Sprintf("https://%s/api/v1/repos/%s/%s/pulls/%d.diff",
+		client.Hostname(), owner, name, prNumber)
+
+	diff, err := client.GetRawLog(diffURL)
+	if err != nil {
+		return fmt.Errorf("failed to get pull request diff: %w", err)
+	}
+
+	if nameOnly {
+		return printNameOnly(diff)
+	}
+
+	if stat {
+		return printDiffStat(diff)
+	}
+
+	useColor := shouldColorize(colorMode)
+	if useColor {
+		return printColorizedDiff(diff)
+	}
+
+	fmt.Print(diff)
+	return nil
+}
+
+// shouldColorize determines whether to colorize output based on the color flag.
+func shouldColorize(mode string) bool {
+	switch strings.ToLower(mode) {
+	case "always":
+		return true
+	case "never":
+		return false
+	default: // "auto"
+		return term.IsTerminal(int(os.Stdout.Fd()))
+	}
+}
+
+// printNameOnly extracts and prints changed file names from the diff.
+func printNameOnly(diff string) error {
+	seen := make(map[string]bool)
+	for _, line := range strings.Split(diff, "\n") {
+		if strings.HasPrefix(line, "+++ b/") {
+			name := strings.TrimPrefix(line, "+++ b/")
+			if name != "" && !seen[name] {
+				seen[name] = true
+				fmt.Println(name)
+			}
+		}
+	}
+	return nil
+}
+
+// fileStat holds per-file diff statistics.
+type fileStat struct {
+	name       string
+	additions  int
+	deletions  int
+}
+
+// printDiffStat parses the diff and prints a diffstat summary.
+func printDiffStat(diff string) error {
+	var stats []fileStat
+	var current *fileStat
+	inHeader := true
+
+	for _, line := range strings.Split(diff, "\n") {
+		if strings.HasPrefix(line, "diff --git ") {
+			if current != nil {
+				stats = append(stats, *current)
+			}
+			current = &fileStat{}
+			inHeader = true
+			continue
+		}
+		if current == nil {
+			continue
+		}
+		if strings.HasPrefix(line, "+++ b/") {
+			current.name = strings.TrimPrefix(line, "+++ b/")
+			continue
+		}
+		if strings.HasPrefix(line, "@@") {
+			inHeader = false
+			continue
+		}
+		if inHeader {
+			continue
+		}
+		if strings.HasPrefix(line, "+") {
+			current.additions++
+		} else if strings.HasPrefix(line, "-") {
+			current.deletions++
+		}
+	}
+	if current != nil && current.name != "" {
+		stats = append(stats, *current)
+	}
+
+	if len(stats) == 0 {
+		fmt.Println("0 files changed")
+		return nil
+	}
+
+	// Find the longest file name for alignment
+	maxNameLen := 0
+	maxChanges := 0
+	for _, s := range stats {
+		if len(s.name) > maxNameLen {
+			maxNameLen = len(s.name)
+		}
+		total := s.additions + s.deletions
+		if total > maxChanges {
+			maxChanges = total
+		}
+	}
+
+	// Cap the bar width
+	barWidth := maxChanges
+	if barWidth > 50 {
+		barWidth = 50
+	}
+
+	totalAdditions := 0
+	totalDeletions := 0
+
+	for _, s := range stats {
+		total := s.additions + s.deletions
+		totalAdditions += s.additions
+		totalDeletions += s.deletions
+
+		var bar string
+		if maxChanges > 0 {
+			scaledAdd := s.additions
+			scaledDel := s.deletions
+			if maxChanges > 50 {
+				scaledAdd = s.additions * 50 / maxChanges
+				scaledDel = s.deletions * 50 / maxChanges
+				if s.additions > 0 && scaledAdd == 0 {
+					scaledAdd = 1
+				}
+				if s.deletions > 0 && scaledDel == 0 {
+					scaledDel = 1
+				}
+			}
+			bar = strings.Repeat("+", scaledAdd) + strings.Repeat("-", scaledDel)
+		}
+
+		fmt.Printf(" %-*s | %4d %s\n", maxNameLen, s.name, total, bar)
+	}
+
+	fmt.Printf(" %d file", len(stats))
+	if len(stats) != 1 {
+		fmt.Print("s")
+	}
+	fmt.Printf(" changed, %d insertion", totalAdditions)
+	if totalAdditions != 1 {
+		fmt.Print("s")
+	}
+	fmt.Printf("(+), %d deletion", totalDeletions)
+	if totalDeletions != 1 {
+		fmt.Print("s")
+	}
+	fmt.Println("(-)")
+
+	return nil
+}
+
+// ANSI color codes for diff output.
+const (
+	colorReset = "\033[0m"
+	colorRed   = "\033[31m"
+	colorGreen = "\033[32m"
+	colorCyan  = "\033[36m"
+	colorBold  = "\033[1m"
+)
+
+// printColorizedDiff prints the diff with ANSI color codes.
+func printColorizedDiff(diff string) error {
+	for _, line := range strings.Split(diff, "\n") {
+		switch {
+		case strings.HasPrefix(line, "diff --git "):
+			fmt.Println(colorBold + line + colorReset)
+		case strings.HasPrefix(line, "index "),
+			strings.HasPrefix(line, "--- "),
+			strings.HasPrefix(line, "+++ "),
+			strings.HasPrefix(line, "new file"),
+			strings.HasPrefix(line, "deleted file"),
+			strings.HasPrefix(line, "similarity index"),
+			strings.HasPrefix(line, "rename from"),
+			strings.HasPrefix(line, "rename to"):
+			fmt.Println(colorBold + line + colorReset)
+		case strings.HasPrefix(line, "@@"):
+			fmt.Println(colorCyan + line + colorReset)
+		case strings.HasPrefix(line, "+"):
+			fmt.Println(colorGreen + line + colorReset)
+		case strings.HasPrefix(line, "-"):
+			fmt.Println(colorRed + line + colorReset)
+		default:
+			fmt.Println(line)
+		}
+	}
+	return nil
+}