/**
 * Generate a deterministic summary of what a Claude Code instance is likely
 * working on, based on its working directory and git context.
 *
 * Pure git-based — no external API calls, no dependencies.
 */

export async function generateSummary(context: {
  cwd: string;
  git_root: string | null;
  git_branch?: string | null;
  recent_files?: string[];
  session_name?: string | null;
  tty?: string | null;
}): Promise<string | null> {
  const parts: string[] = [];

  // Extract project name from git root or cwd
  const dir = context.git_root || context.cwd;
  const projectName = dir.split("/").pop() || dir;

  const branch = context.git_branch || "main";

  // Branch info
  if (context.git_branch && context.git_branch !== "main" && context.git_branch !== "master") {
    parts.push(`on ${context.git_branch}`);
  }

  // Recent file activity
  if (context.recent_files && context.recent_files.length > 0) {
    const fileList = context.recent_files.slice(0, 3).join(", ");
    parts.push(`recently touched ${fileList}`);
  }

  // Build prefix: [SessionName] or [project:branch], with optional TTY for disambiguation
  const ttyTag = context.tty ? `:${context.tty.replace("/dev/", "")}` : "";
  const prefix = context.session_name
    ? `[${context.session_name}${ttyTag}]`
    : `[${projectName}:${branch}${ttyTag}]`;

  if (parts.length === 0) {
    return `${prefix} Working in ${projectName}`;
  }

  return `${prefix} ${parts.join(", ")} in ${projectName}`;
}

/**
 * Get the current git branch name for a directory.
 */
export async function getGitBranch(cwd: string): Promise<string | null> {
  try {
    const proc = Bun.spawn(["git", "rev-parse", "--abbrev-ref", "HEAD"], {
      cwd,
      stdout: "pipe",
      stderr: "ignore",
    });
    const text = await new Response(proc.stdout).text();
    const code = await proc.exited;
    if (code === 0) {
      return text.trim();
    }
  } catch {
    // not a git repo
  }
  return null;
}

/**
 * Get recently modified tracked files in the git repo.
 */
export async function getRecentFiles(
  cwd: string,
  limit = 10
): Promise<string[]> {
  try {
    // Get modified/staged files first
    const diffProc = Bun.spawn(["git", "diff", "--name-only", "HEAD"], {
      cwd,
      stdout: "pipe",
      stderr: "ignore",
    });
    const diffText = await new Response(diffProc.stdout).text();
    await diffProc.exited;

    const files = diffText
      .trim()
      .split("\n")
      .filter((f) => f.length > 0);

    if (files.length >= limit) {
      return files.slice(0, limit);
    }

    // Also get recently committed files
    const logProc = Bun.spawn(
      ["git", "log", "--oneline", "--name-only", "-5", "--format="],
      {
        cwd,
        stdout: "pipe",
        stderr: "ignore",
      }
    );
    const logText = await new Response(logProc.stdout).text();
    await logProc.exited;

    const logFiles = logText
      .trim()
      .split("\n")
      .filter((f) => f.length > 0);

    const allFiles = [...new Set([...files, ...logFiles])];
    return allFiles.slice(0, limit);
  } catch {
    return [];
  }
}