import type { CommandSpec } from './command.ts';

// What can go wrong, and the exit code each kind of failure leaves.
//
// Agents branch on exit codes, so they are few and stable:
//
//   0  done
//   1  anything else that went wrong (a server error, a file that is not there)
//   2  the command line was wrong: an unknown option, a missing argument
//   3  not signed in, or the session cannot be used and needs a new login
//   4  the thing named does not exist: an unknown handle, a deleted post
//   5  the server said to slow down, for longer than is worth waiting
//   6  a question needed answering and there was no terminal to ask on
//
// With --json, every failure is also printed on stdout as
// {"error": {"code", "message", "status"?, "exit"}}, so a caller that reads only
// stdout still learns what happened.

export const EXIT = {
    ok: 0,
    error: 1,
    usage: 2,
    auth: 3,
    notFound: 4,
    rateLimited: 5,
    needsInput: 6,
} as const;

export class CliError extends Error {
    exit: number;
    code: string;
    constructor(message: string, code = 'Error', exit: number = EXIT.error) {
        super(message);
        this.code = code;
        this.exit = exit;
    }
}

export class UsageError extends CliError {
    /** The command the mistake was made in, so its help can be pointed at. */
    path: CommandSpec[];
    constructor(message: string, path: CommandSpec[] = []) {
        super(message, 'UsageError', EXIT.usage);
        this.path = path;
    }
}

export class AuthError extends CliError {
    constructor(message: string, code = 'AuthRequired') {
        super(message, code, EXIT.auth);
    }
}

export class NotFoundError extends CliError {
    constructor(message: string, code = 'NotFound') {
        super(message, code, EXIT.notFound);
    }
}

export class NeedsInputError extends CliError {
    constructor(message: string) {
        super(message, 'NeedsInput', EXIT.needsInput);
    }
}

/** An error an XRPC service answered with. */
export class XrpcError extends CliError {
    status: number;
    nsid: string;
    constructor(nsid: string, status: number, code: string, message: string) {
        super(message, code, exitFor(status, code));
        this.status = status;
        this.nsid = nsid;
    }
}

function exitFor(status: number, code: string): number {
    if (status === 401 || /^(AuthRequired|AuthMissing|ExpiredToken|InvalidToken|invalid_token|AccountTakedown|AccountDeactivated)$/.test(code)) return EXIT.auth;
    if (status === 404 || /NotFound$|^(UnknownFeed|UnknownList|InvalidUri)$/.test(code)) return EXIT.notFound;
    if (status === 429) return EXIT.rateLimited;
    return EXIT.error;
}