gftp

-module(gftp@result).
-compile([no_auto_import, nowarn_unused_vars, nowarn_unused_function, nowarn_nomatch, inline]).
-define(FILEPATH, "src/gftp/result.gleam").
-export([describe_error/1]).
-export_type([ftp_error/0]).

-if(?OTP_RELEASE >= 27).
-define(MODULEDOC(Str), -moduledoc(Str)).
-define(DOC(Str), -doc(Str)).
-else.
-define(MODULEDOC(Str), -compile([])).
-define(DOC(Str), -compile([])).
-endif.

?MODULEDOC(
    " Error types and result aliases for gftp operations.\n"
    "\n"
    " All gftp functions return `FtpResult(a)` which is `Result(a, FtpError)`.\n"
    "\n"
    " ```gleam\n"
    " import gftp\n"
    " import gftp/result\n"
    "\n"
    " case gftp.cwd(client, \"/nonexistent\") {\n"
    "   Ok(_) -> // success\n"
    "   Error(err) -> {\n"
    "     let msg = result.describe_error(err)\n"
    "     // \"Unexpected response: [requested action not taken; file unavailable] ...\"\n"
    "   }\n"
    " }\n"
    " ```\n"
).

-type ftp_error() :: {connection_error, mug:connect_error()} |
    {unexpected_response, gftp@response:response()} |
    bad_response |
    {tls, kafein:error()} |
    {socket, mug:error()} |
    data_transfer_in_progress.

-file("src/gftp/result.gleam", 43).
-spec connection_error_to_string(mug:connect_error()) -> binary().
connection_error_to_string(E) ->
    case E of
        {connect_failed_ipv4, E@1} ->
            mug:describe_error(E@1);

        {connect_failed_ipv6, E@2} ->
            mug:describe_error(E@2);

        {connect_failed_both, E@3, _} ->
            mug:describe_error(E@3)
    end.

-file("src/gftp/result.gleam", 58).
?DOC(
    " Convert an `FtpError` to a human-readable string.\n"
    "\n"
    " ```gleam\n"
    " let msg = result.describe_error(err)\n"
    " // e.g. \"Connection error: Connection refused\"\n"
    " // e.g. \"Unexpected response: [user not logged in] Login required\"\n"
    " ```\n"
).
-spec describe_error(ftp_error()) -> binary().
describe_error(Err) ->
    case Err of
        {connection_error, E} ->
            <<"Connection error: "/utf8,
                (connection_error_to_string(E))/binary>>;

        {unexpected_response, R} ->
            <<"Unexpected response: "/utf8, (gftp@response:describe(R))/binary>>;

        bad_response ->
            <<"Bad response syntax"/utf8>>;

        {socket, E@1} ->
            <<"Socket error: "/utf8, (mug:describe_error(E@1))/binary>>;

        {tls, E@2} ->
            <<"TLS error"/utf8, (case E@2 of
                    closed ->
                        <<": connection closed"/utf8>>;

                    timeout ->
                        <<": timeout reached"/utf8>>;

                    {other, _} ->
                        <<": an error occurred during TLS operation"/utf8>>;

                    {posix_error, E@3} ->
                        <<": "/utf8, (mug:describe_error(E@3))/binary>>;

                    {cipher_suite_not_recognized, E@4} ->
                        <<": cipher suite not recognized: "/utf8, E@4/binary>>;

                    {tls_alert, _, Description} ->
                        <<": TLS alert: "/utf8, Description/binary>>
                end)/binary>>;

        data_transfer_in_progress ->
            <<"Data transfer in progress: close the data channel before issuing control commands"/utf8>>
    end.