import type { CliDeps } from "./deps.js";
import { runSubprocess } from "./subprocess.js";

export interface RemoteRepo {
  host: string;
  owner: string;
  name: string;
}

function parseRepoPath(rawPath: string): { owner: string; name: string } | null {
  const path = rawPath.replace(/^\/+/, "").replace(/\/+$/, "").replace(/\.git$/, "");
  const segments = path.split("/");
  if (segments.length !== 2 || !segments[0] || !segments[1]) {
    return null;
  }
  return { owner: segments[0], name: segments[1] };
}

export function parseRemoteUrl(url: string): RemoteRepo | null {
  const trimmed = url.trim();
  if (/^(https?|ssh):\/\//.test(trimmed)) {
    let parsed: URL;
    try {
      parsed = new URL(trimmed);
    } catch {
      return null;
    }
    const repo = parseRepoPath(parsed.pathname);
    if (!repo || !parsed.hostname) {
      return null;
    }
    return { host: parsed.hostname, ...repo };
  }
  // scp-like SSH form: [user@]host:owner/name[.git]
  const scp = /^(?:[^@/\s]+@)?([^:/\s]+):(.+)$/.exec(trimmed);
  if (scp) {
    const repo = parseRepoPath(scp[2]!);
    if (!repo) {
      return null;
    }
    return { host: scp[1]!, ...repo };
  }
  return null;
}

/**
 * The branch currently checked out, or null when git cannot name one — it is
 * absent, this is not a repository, or HEAD is detached. Every null case is
 * repaired the same way, by the caller naming the branch explicitly, so they
 * are not distinguished here.
 */
export async function currentBranch(deps: CliDeps): Promise<string | null> {
  const result = await runSubprocess("git", ["rev-parse", "--abbrev-ref", "HEAD"], {
    cwd: deps.cwd,
    env: deps.env,
  });
  if (result.enoent || result.code !== 0) {
    return null;
  }
  const branch = result.stdout.trim();
  // A detached HEAD abbreviates to the literal "HEAD", which is no branch.
  return branch && branch !== "HEAD" ? branch : null;
}

export async function detectRemote(deps: CliDeps): Promise<RemoteRepo | null> {
  const result = await runSubprocess("git", ["remote", "get-url", "origin"], {
    cwd: deps.cwd,
    env: deps.env,
  });
  if (result.enoent || result.code !== 0) {
    return null;
  }
  return parseRemoteUrl(result.stdout);
}