import type { ExtensionAPI } from "@earendil-works/pi-coding-agent";

export interface GitRunOptions {
  cwd?: string;
  signal?: AbortSignal;
  timeout?: number;
  acceptedExitCodes?: readonly number[];
}

export interface GitRunResult {
  stdout: string;
  stderr: string;
  code: number;
  killed: boolean;
}

const MAX_GIT_ERROR_CHARS = 4_000;
/* oxlint-disable no-control-regex -- 这些正则的目的就是识别并清除控制字符 */
const ANSI_CSI_SEQUENCE = /\u001B\[[0-?]*[ -/]*[@-~]/g;
const ANSI_OSC_SEQUENCE = /\u001B\][^\u0007]*(?:\u0007|\u001B\\)/g;
const UNSAFE_CONTROL_CHARACTERS = /[\u0000-\u0008\u000B\u000C\u000E-\u001F\u007F]/g;
/* oxlint-enable no-control-regex */

/** 清理终端控制序列并统一换行，避免 Git 或 hook 输出污染 TUI。 */
function sanitizeGitOutput(output: string): string {
  return output
    .replace(ANSI_OSC_SEQUENCE, "")
    .replace(ANSI_CSI_SEQUENCE, "")
    .replaceAll("\r\n", "\n")
    .replaceAll("\r", "\n")
    .replace(UNSAFE_CONTROL_CHARACTERS, "")
    .trim();
}

/** 按 Unicode 码点保留首尾并限制错误详情总长度。 */
function truncateGitOutput(output: string, maxChars: number): string {
  const characters = Array.from(output);
  if (characters.length <= maxChars) {
    return output;
  }

  let notice = "\n...[Git output truncated]...\n";
  let available = Math.max(0, maxChars - Array.from(notice).length);
  let omitted = characters.length - available;
  notice = `\n...[${omitted} code points omitted]...\n`;
  available = Math.max(0, maxChars - Array.from(notice).length);
  omitted = characters.length - available;
  notice = `\n...[${omitted} code points omitted]...\n`;

  const finalAvailable = Math.max(0, maxChars - Array.from(notice).length);
  const headLength = Math.ceil(finalAvailable / 2);
  const tailLength = Math.floor(finalAvailable / 2);
  return `${characters.slice(0, headLength).join("")}${notice}${characters.slice(-tailLength).join("")}`;
}

/** 生成有界、保留首尾且适合展示给用户的 Git 错误详情。 */
export function formatGitError(result: GitRunResult): string {
  const stderr = sanitizeGitOutput(result.stderr);
  const stdout = sanitizeGitOutput(result.stdout);
  const sections = [stderr ? `stderr:\n${stderr}` : "", stdout ? `stdout:\n${stdout}` : ""].filter(
    Boolean,
  );
  const detail = sections.join("\n");
  return detail ? truncateGitOutput(detail, MAX_GIT_ERROR_CHARS) : `exit code ${result.code}`;
}

/** 通过 Pi 的参数化执行接口调用 Git。 */
export class GitClient {
  private readonly pi: Pick<ExtensionAPI, "exec">;

  /** 保存扩展 API，确保所有 Git 命令都通过 pi.exec 执行。 */
  constructor(pi: Pick<ExtensionAPI, "exec">) {
    this.pi = pi;
  }

  /** 执行 Git 子命令，并校验允许的退出码。 */
  async run(args: string[], options: GitRunOptions = {}): Promise<GitRunResult> {
    const result = await this.pi.exec("git", args, {
      cwd: options.cwd,
      signal: options.signal,
      timeout: options.timeout ?? 15_000,
    });
    const acceptedExitCodes = options.acceptedExitCodes ?? [0];

    if (result.killed) {
      throw new Error(
        `Git command git ${args[0] ?? ""} was cancelled or timed out: ${formatGitError(result)}`,
      );
    }
    if (!acceptedExitCodes.includes(result.code)) {
      throw new Error(`Git command git ${args[0] ?? ""} failed: ${formatGitError(result)}`);
    }

    return result;
  }
}