import { execFile, spawn, type ChildProcess, type SpawnOptions } from "node:child_process";
import { extname } from "node:path";
import { promisify } from "node:util";

import { createExternalCommandProcessEnv, type ProcessEnvRecord } from "../server/paseo-env.js";
import {
  isWindowsCommandScript,
  quoteWindowsArgument,
  quoteWindowsCommand,
} from "./windows-command.js";

const execFileAsync = promisify(execFile);

interface ExternalEnvOptions {
  baseEnv?: ProcessEnvRecord;
  envMode?: "external" | "internal";
  env?: ProcessEnvRecord;
  envOverlay?: ProcessEnvRecord;
}

export type SpawnProcessOptions = Omit<SpawnOptions, "env"> & ExternalEnvOptions;

interface ExecCommandOptions extends ExternalEnvOptions {
  cwd?: string;
  encoding?: BufferEncoding;
  killSignal?: NodeJS.Signals;
  timeout?: number;
  maxBuffer?: number;
  shell?: boolean | string;
}

interface ExecCommandResult {
  stdout: string;
  stderr: string;
}

function hasPathSeparator(value: string): boolean {
  return value.includes("/") || value.includes("\\");
}

function shouldUseWindowsShell(
  command: string,
  requestedShell?: boolean | string,
): boolean | string {
  if (isWindowsCommandScript(command)) {
    return true;
  }
  if (requestedShell !== undefined) {
    return requestedShell;
  }
  return process.platform === "win32" && !hasPathSeparator(command) && !extname(command);
}

export function spawnProcess(
  command: string,
  args: string[],
  options?: SpawnProcessOptions,
): ChildProcess {
  const { baseEnv, env, envOverlay, ...spawnOptions } = options ?? {};
  const resolvedBaseEnv = env ?? baseEnv ?? process.env;
  const isWindows = process.platform === "win32";
  const shell = shouldUseWindowsShell(command, spawnOptions.shell);

  const shouldQuoteForShell = isWindows && shell !== false;
  const resolvedCommand = shouldQuoteForShell ? quoteWindowsCommand(command) : command;
  const resolvedArgs = shouldQuoteForShell ? args.map(quoteWindowsArgument) : args;
  const childEnv =
    options?.envMode === "internal"
      ? ({ ...resolvedBaseEnv, ...envOverlay } as NodeJS.ProcessEnv)
      : createExternalCommandProcessEnv(
          command,
          resolvedBaseEnv,
          ...(envOverlay ? [envOverlay] : []),
        );

  return spawn(resolvedCommand, resolvedArgs, {
    ...spawnOptions,
    env: childEnv,
    shell,
    windowsHide: true,
  });
}

export async function execCommand(
  command: string,
  args: string[],
  options?: ExecCommandOptions,
): Promise<ExecCommandResult> {
  const { baseEnv, env, envOverlay } = options ?? {};
  const resolvedBaseEnv = env ?? baseEnv ?? process.env;
  const isWindows = process.platform === "win32";
  const shell = shouldUseWindowsShell(command, options?.shell);
  const shouldQuoteForShell = isWindows && shell !== false;
  const resolvedCommand = shouldQuoteForShell ? quoteWindowsCommand(command) : command;
  const resolvedArgs = shouldQuoteForShell ? args.map(quoteWindowsArgument) : args;
  const childEnv =
    options?.envMode === "internal"
      ? ({ ...resolvedBaseEnv, ...envOverlay } as NodeJS.ProcessEnv)
      : createExternalCommandProcessEnv(
          command,
          resolvedBaseEnv,
          ...(envOverlay ? [envOverlay] : []),
        );

  return execFileAsync(resolvedCommand, resolvedArgs, {
    cwd: options?.cwd,
    env: childEnv,
    encoding: options?.encoding ?? "utf8",
    killSignal: options?.killSignal,
    timeout: options?.timeout,
    maxBuffer: options?.maxBuffer,
    shell,
    windowsHide: true,
  }) as Promise<ExecCommandResult>;
}