import {
  FIRMWARE_TOOL_REQUIREMENTS,
  type FirmwareEngineName,
} from "../contracts/firmware/firmwareToolRequirements.js";

interface ReleaseNumber {
  readonly major: number;
  readonly minor: number;
  readonly token: string;
}

const TOKEN = /^(\d+)\.(\d+)\.(\d+)([-+][0-9A-Za-z.-]+)?$/u;

const parseToken = (token: string): ReleaseNumber | undefined => {
  const match = TOKEN.exec(token);
  if (match === null) return undefined;
  const major = Number(match[1]);
  const minor = Number(match[2]);
  const patch = Number(match[3]);
  if (![major, minor, patch].every((part) => Number.isSafeInteger(part)))
    return undefined;
  return { major, minor, token };
};

/** Admission of one observed `--version` banner. */
export type FirmwareVersionAdmission =
  | { readonly status: "verified"; readonly version: string }
  | {
      readonly status: "compatible";
      readonly version: string;
      readonly limitation: string;
    }
  | { readonly status: "unsupported"; readonly message: string }
  | { readonly status: "unresolved"; readonly message: string };

/**
 * Classify a `--version` banner against the audited release line.
 * Binwalk prints `binwalk <version>`; Unblob prints the version alone.
 */
export const admitFirmwareVersion = (
  engine: FirmwareEngineName,
  banner: string,
): FirmwareVersionAdmission => {
  const token = versionToken(engine, banner);
  const parsed = token === undefined ? undefined : parseToken(token);
  const verified = FIRMWARE_TOOL_REQUIREMENTS[engine];
  const accepted = `accepted releases are ${verified.requirement}`;
  if (parsed === undefined)
    return {
      status: "unresolved",
      message: `Unsupported tool version ${banner.length === 0 ? "missing" : banner}; ${accepted}.`,
    };
  if (parsed.major !== verified.major || parsed.minor !== verified.minor)
    return {
      status: "unsupported",
      message: `Unsupported tool version ${banner}; ${accepted}.`,
    };
  if (parsed.token === verified.version)
    return { status: "verified", version: parsed.token };
  return {
    status: "compatible",
    version: parsed.token,
    limitation: `This session uses ${verified.name} ${parsed.token}. The report parser is verified against ${verified.version}; other ${verified.line} builds are accepted and the observed version is reported.`,
  };
};

const versionToken = (
  engine: FirmwareEngineName,
  banner: string,
): string | undefined => {
  switch (engine) {
    case "binwalk":
      return banner.startsWith("binwalk ")
        ? banner.slice("binwalk ".length)
        : undefined;
    case "unblob":
      return banner;
    default: {
      const unreachable: never = engine;
      return unreachable;
    }
  }
};