import { execSync } from "node:child_process"
import process from "node:process"

type ShellName = "bash" | "zsh" | "fish" | "powershell" | "cmd" | "sh"
type EnvVars = Record<string, string | undefined>

function getShell(): ShellName {
  const { platform, ppid, env } = process

  if (platform === "win32") {
    try {
      const command = `wmic process get ParentProcessId,Name | findstr "${ppid}"`
      const parentProcess = execSync(command, { stdio: "pipe" }).toString()

      if (parentProcess.toLowerCase().includes("powershell.exe")) {
        return "powershell"
      }
    } catch {
      return "cmd"
    }

    return "cmd"
  } else {
    const shellPath = env.SHELL
    if (shellPath) {
      if (shellPath.endsWith("zsh")) return "zsh"
      if (shellPath.endsWith("fish")) return "fish"
      if (shellPath.endsWith("bash")) return "bash"
    }

    return "sh"
  }
}

/**
 * Generates a copy-pasteable script to set multiple environment variables
 * and run a subsequent command.
 * @param {EnvVars} envVars - An object of environment variables to set.
 * @param {string} commandToRun - The command to run after setting the variables.
 * @returns {string} The formatted script string.
 */
export function generateEnvScript(
  envVars: EnvVars,
  commandToRun: string = "",
): string {
  const shell = getShell()
  const filteredEnvVars = Object.entries(envVars).filter(
    ([, value]) => value !== undefined,
  ) as Array<[string, string]>

  let commandBlock: string

  switch (shell) {
    case "powershell": {
      commandBlock = filteredEnvVars
        .map(([key, value]) => `$env:${key} = ${value}`)
        .join("; ")
      break
    }
    case "cmd": {
      commandBlock = filteredEnvVars
        .map(([key, value]) => `set ${key}=${value}`)
        .join(" & ")
      break
    }
    case "fish": {
      commandBlock = filteredEnvVars
        .map(([key, value]) => `set -gx ${key} ${value}`)
        .join("; ")
      break
    }
    default: {
      // bash, zsh, sh
      const assignments = filteredEnvVars
        .map(([key, value]) => `${key}=${value}`)
        .join(" ")
      commandBlock = filteredEnvVars.length > 0 ? `export ${assignments}` : ""
      break
    }
  }

  if (commandBlock && commandToRun) {
    const separator = shell === "cmd" ? " & " : " && "
    return `${commandBlock}${separator}${commandToRun}`
  }

  return commandBlock || commandToRun
}