Create magician cmd flow to to handle arbitrary commands (#15669)

Author: ScottSuarez

.ci/magician/cmd/parse_comment.go

@@ -0,0 +1,132 @@
+package cmd
+
+import (
+	"fmt"
+	"os"
+	"regexp"
+	"strings"
+
+	"magician/github"
+
+	"github.com/spf13/cobra"
+)
+
+// This regex captures the entire line starting with @modular-magician
+// Example: "@modular-magician reassign-reviewer user1" or "@modular-magician assign review @user2"
+var magicianInvocationRegex = regexp.MustCompile(`@modular-magician\s+([^\n\r]+)`)
+
+// Command patterns for reassign-reviewer with flexible syntax
+// Supports: assign-reviewer, reassign-reviewer, assign reviewer, reassign review, etc.
+// Captures only valid GitHub usernames: [a-zA-Z0-9-_]
+var reassignReviewerRegex = regexp.MustCompile(`^(?:re)?assign[- ]?review(?:er)?\s*@?([a-zA-Z0-9-_]*)`)
+
+var parseCommentCmd = &cobra.Command{
+	Use:   "parse-comment PR_NUMBER COMMENT_AUTHOR",
+	Short: "Parses a comment from the COMMENT_BODY env var to execute magician commands",
+	Long: `This command parses GitHub PR comments for @modular-magician invocations.
+	
+	It supports flexible command syntax including:
+	- Commands with hyphens: reassign-reviewer
+	- Commands with spaces: reassign reviewer
+	- Optional prefixes and suffixes: assign-review, reassign-reviewer
+	- Optional @ prefix for usernames
+	
+	The command expects the comment body to be provided in the COMMENT_BODY environment variable and also requires:
+	1. PR_NUMBER - The pull request number
+	2. COMMENT_AUTHOR - The GitHub username who made the comment`,
+	Args: cobra.ExactArgs(2),
+	RunE: func(cmd *cobra.Command, args []string) error {
+		prNumber := args[0]
+		author := args[1]
+
+		githubToken, ok := os.LookupEnv("GITHUB_TOKEN")
+		if !ok {
+			return fmt.Errorf("did not provide GITHUB_TOKEN environment variable")
+		}
+		gh := github.NewClient(githubToken)
+
+		if gh.GetUserType(author) != github.CoreContributorUserType {
+			return fmt.Errorf("comment author %s is not a core contributor", author)
+		}
+
+		comment, ok := os.LookupEnv("COMMENT_BODY")
+		if !ok {
+			return fmt.Errorf("did not provide COMMENT_BODY environment variable")
+		}
+		if comment == "" {
+			fmt.Println("COMMENT_BODY is empty. Ignoring.")
+			return nil
+		}
+
+		return execParseComment(prNumber, comment, gh)
+	},
+}
+
+// execParseComment is the main router that finds and executes the first command
+func execParseComment(prNumber, comment string, gh GithubClient) error {
+	// Find the first @modular-magician invocation in the comment
+	match := magicianInvocationRegex.FindStringSubmatch(comment)
+
+	if match == nil {
+		fmt.Println("No @modular-magician invocation found. Ignoring comment.")
+		return nil
+	}
+
+	if len(match) < 2 {
+		fmt.Printf("Invalid match structure. Ignoring.\n")
+		return nil
+	}
+
+	commandLine := strings.TrimSpace(match[1])
+	if commandLine == "" {
+		fmt.Printf("Empty command after @modular-magician. Ignoring.\n")
+		return nil
+	}
+
+	fmt.Printf("Processing command: %q\n", commandLine)
+
+	// Route to appropriate handler based on command pattern
+	return routeCommand(prNumber, commandLine, gh)
+}
+
+// routeCommand determines which command handler to call based on the command pattern
+func routeCommand(prNumber, commandLine string, gh GithubClient) error {
+	// Check for reassign-reviewer command variants
+	if matches := reassignReviewerRegex.FindStringSubmatch(commandLine); matches != nil {
+		reviewer := strings.TrimSpace(matches[1])
+		return handleReassignReviewer(prNumber, reviewer, gh)
+	}
+
+	// Add more command patterns here as needed
+	// Example for future commands:
+	// if matches := cherryPickRegex.FindStringSubmatch(commandLine); matches != nil {
+	//     return handleCherryPick(prNumber, matches[1:], gh)
+	// }
+
+	fmt.Printf("Unknown command format: %q\n", commandLine)
+	return nil
+}
+
+// handleReassignReviewer processes the reassign-reviewer command
+func handleReassignReviewer(prNumber, reviewer string, _ GithubClient) error {
+	// The regex already extracted just the username without @
+	// and only allows valid GitHub username characters [a-zA-Z0-9-_]
+
+	fmt.Printf("Reassigning reviewer for PR #%s", prNumber)
+	if reviewer != "" {
+		fmt.Printf(" to @%s", reviewer)
+	} else {
+		fmt.Printf(" (selecting random reviewer)")
+	}
+	fmt.Println()
+
+	fmt.Printf("[DEBUG] - placeholder call - prNumber: %s, reviewer %s\n", prNumber, reviewer)
+	return nil
+
+	// Call the existing reassign reviewer logic
+	// return execReassignReviewer(prNumber, reviewer, gh)
+}
+
+func init() {
+	rootCmd.AddCommand(parseCommentCmd)
+}