import { runProcess, getMtaCommand } from "./process-utils";

type SemVer = {
  major: number;
  minor: number;
  patch: number;
};

let MTA_COMMAND_FLAGS = ["-v"];
// This version number should be synchronized with the version in the README.md and package.json
const MIN_MTA_VERSION: SemVer = {
  major: 1,
  minor: 0,
  patch: 0,
};
let minMtaVersion = MIN_MTA_VERSION;
export const MIN_CLOUD_MTA_VERSION = `${MIN_MTA_VERSION.major}.${MIN_MTA_VERSION.minor}.${MIN_MTA_VERSION.patch}`;

export function setMtaCommandParamsForTests(testParams: {
  flags?: string[];
  minVersion?: SemVer;
}): void {
  // These values should be synchronized with those above
  MTA_COMMAND_FLAGS = testParams.flags ?? ["-v"];
  minMtaVersion = testParams.minVersion ?? MIN_MTA_VERSION;
}

const messages = {
  CLOUD_MTA_NOT_INSTALLED:
    "Cloud MTA is not installed in your environment. Go to https://github.com/SAP/cloud-mta to install the tool and try again.",
  CLOUD_MTA_UNKNOWN_VERSION:
    "Could not determine which Cloud MTA version is installed in your system. Go to https://github.com/SAP/cloud-mta to install the tool and try again.",
  CLOUD_MTA_VERSION_MISMATCH: `The Cloud MTA version is lower than the minimal supported version (${MIN_CLOUD_MTA_VERSION}). Go to https://github.com/SAP/cloud-mta to install the tool and try again.`,
};

export class CloudMtaNotInstalledError extends Error {}
export class CloudMtaVersionMismatchError extends Error {}

export function createCloudMtaNotInstalledError(): CloudMtaNotInstalledError {
  return new CloudMtaNotInstalledError(messages.CLOUD_MTA_NOT_INSTALLED);
}

export async function ensureCloudMtaInstalled(): Promise<void> {
  return ensureCloudMtaInstalledInPath(await getMtaCommand());
}

export async function ensureCloudMtaInstalledInPath(
  mtaPath: string
): Promise<void> {
  let output: string;
  try {
    output = await runProcess(mtaPath, MTA_COMMAND_FLAGS);
  } catch (e) {
    if (e.code === "ENOENT") {
      throw createCloudMtaNotInstalledError();
    }
    throw new CloudMtaVersionMismatchError(messages.CLOUD_MTA_UNKNOWN_VERSION);
  }

  const versionMatch = /(\d+)\.(\d+)\.(\d+)/.exec(output);
  if (versionMatch === null) {
    throw new CloudMtaVersionMismatchError(messages.CLOUD_MTA_UNKNOWN_VERSION);
  } else {
    const version = {
      major: Number(versionMatch[1]),
      minor: Number(versionMatch[2]),
      patch: Number(versionMatch[3]),
    };
    if (isVersionLower(version, minMtaVersion)) {
      throw new CloudMtaVersionMismatchError(
        messages.CLOUD_MTA_VERSION_MISMATCH
      );
    }
  }
}

export function isCloudMtaNotInstalledError(err: Error): boolean {
  return err instanceof CloudMtaNotInstalledError;
}

function isVersionLower(first: SemVer, second: SemVer): boolean {
  return (
    first.major < second.major ||
    (first.major === second.major && first.minor < second.minor) ||
    (first.major === second.major &&
      first.minor === second.minor &&
      first.patch < second.patch)
  );
}