distribute

-module(distribute@election@raft_lite).
-compile([no_auto_import, nowarn_unused_vars, nowarn_unused_function, nowarn_nomatch, inline]).
-define(FILEPATH, "src/distribute/election/raft_lite.gleam").
-export([start_service/0, stop_service/0, current_term/0, am_i_leader/0, start_election/0, request_vote/2, send_heartbeat/1, get_raft_leader/0, elect/0, current_leader/0]).
-export_type([election_result/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.

-type election_result() :: {leader, binary()} | no_leader.

-file("src/distribute/election/raft_lite.gleam", 39).
?DOC(
    " Start the Raft-lite election service.\n"
    " This spawns a background process that handles election timeouts and heartbeats.\n"
).
-spec start_service() -> nil.
start_service() ->
    raft_ffi:start().

-file("src/distribute/election/raft_lite.gleam", 44).
?DOC(" Stop the Raft-lite election service.\n").
-spec stop_service() -> nil.
stop_service() ->
    raft_ffi:stop().

-file("src/distribute/election/raft_lite.gleam", 49).
?DOC(" Get the current election term.\n").
-spec current_term() -> integer().
current_term() ->
    raft_ffi:current_term().

-file("src/distribute/election/raft_lite.gleam", 54).
?DOC(" Check if this node is currently the leader.\n").
-spec am_i_leader() -> boolean().
am_i_leader() ->
    raft_ffi:am_i_leader().

-file("src/distribute/election/raft_lite.gleam", 59).
?DOC(" Trigger a new election. The node will become a candidate and request votes.\n").
-spec start_election() -> nil.
start_election() ->
    raft_ffi:start_election().

-file("src/distribute/election/raft_lite.gleam", 65).
?DOC(
    " Request a vote from a peer for the given term and candidate.\n"
    " Returns True if the vote was granted.\n"
).
-spec request_vote(integer(), binary()) -> boolean().
request_vote(Term, Candidate) ->
    raft_ffi:request_vote(Term, Candidate).

-file("src/distribute/election/raft_lite.gleam", 70).
?DOC(" Send a heartbeat as leader to maintain leadership.\n").
-spec send_heartbeat(binary()) -> nil.
send_heartbeat(Leader) ->
    raft_ffi:heartbeat(Leader).

-file("src/distribute/election/raft_lite.gleam", 76).
?DOC(
    " Get the current leader from the Raft service.\n"
    " Returns the leader node name, or empty string if no leader.\n"
).
-spec get_raft_leader() -> {ok, binary()} | {error, nil}.
get_raft_leader() ->
    Leader = raft_ffi:get_leader(),
    case Leader of
        <<""/utf8>> ->
            {error, nil};

        _ ->
            {ok, Leader}
    end.

-file("src/distribute/election/raft_lite.gleam", 98).
?DOC(
    " Elect a leader from the current alive members. The election rule is\n"
    " deterministic: choose the lexicographically largest node returned by\n"
    " `membership.alive()`. Returns `NoLeader` when there are no alive nodes.\n"
).
-spec elect() -> election_result().
elect() ->
    Alive = distribute@cluster@membership:alive(),
    case Alive of
        [] ->
            no_leader;

        [First | _] ->
            case gleam@list:max(Alive, fun gleam@string:compare/2) of
                {ok, Leader} ->
                    {leader, Leader};

                {error, _} ->
                    {leader, First}
            end
    end.

-file("src/distribute/election/raft_lite.gleam", 112).
?DOC(" Convenience: return the current leader as `Result(String, Nil)`.\n").
-spec current_leader() -> {ok, binary()} | {error, nil}.
current_leader() ->
    case elect() of
        {leader, N} ->
            {ok, N};

        no_leader ->
            {error, nil}
    end.