%%%-------------------------------------------------------------------
%%% @doc Clerk — vote collection, opinion storage.
%%%
%%% Architecture §3.2:
%%% The clerk collects votes, stores opinions (both majority
%%% and minority), and maintains the decision record.
%%%
%%% Opinions are stored as append-only — consistent with
%%% L3 write protocol. Minority opinions are NEVER deleted.
%%% @end
%%%-------------------------------------------------------------------
-module(clerk).

-behaviour(gen_server).

-include("sanhedrin.hrl").

%% API
-export([start_link/0,
         store_decision/2,
         store_opinion/1,
         get_decision/1,
         get_opinions/1,
         get_minority_opinions/1,
         count_decisions/0,
         count_opinions/0]).

%% gen_server callbacks
-export([init/1, handle_call/3, handle_cast/2, handle_info/2]).

-define(SERVER, ?MODULE).

-record(state, {
    decisions = #{} :: map(),      %% case_ref => #decision{}
    opinions  = []  :: [#opinion{}] %% Append-only list
}).

%%====================================================================
%% API
%%====================================================================

start_link() ->
    gen_server:start_link({local, ?SERVER}, ?MODULE, [], []).

%% @doc Store a deliberation decision.
-spec store_decision(binary(), #decision{}) -> ok.
store_decision(CaseRef, Decision) ->
    gen_server:cast(?SERVER, {store_decision, CaseRef, Decision}).

%% @doc Store an individual opinion (majority or minority).
%% Opinions are NEVER deleted. Both tablets are in the aron.
-spec store_opinion(#opinion{}) -> ok.
store_opinion(Opinion) ->
    gen_server:cast(?SERVER, {store_opinion, Opinion}).

%% @doc Retrieve a decision by case reference.
-spec get_decision(binary()) -> {ok, #decision{}} | {error, not_found}.
get_decision(CaseRef) ->
    gen_server:call(?SERVER, {get_decision, CaseRef}).

%% @doc Retrieve all opinions for a case reference.
-spec get_opinions(binary()) -> [#opinion{}].
get_opinions(CaseRef) ->
    gen_server:call(?SERVER, {get_opinions, CaseRef}).

%% @doc Retrieve only minority opinions for a case reference.
-spec get_minority_opinions(binary()) -> [#opinion{}].
get_minority_opinions(CaseRef) ->
    gen_server:call(?SERVER, {get_minority_opinions, CaseRef}).

%% @doc Count total stored decisions.
-spec count_decisions() -> non_neg_integer().
count_decisions() ->
    gen_server:call(?SERVER, count_decisions).

%% @doc Count total stored opinions.
-spec count_opinions() -> non_neg_integer().
count_opinions() ->
    gen_server:call(?SERVER, count_opinions).

%%====================================================================
%% gen_server callbacks
%%====================================================================

init([]) ->
    {ok, #state{}}.

handle_call({get_decision, CaseRef}, _From, State) ->
    case maps:find(CaseRef, State#state.decisions) of
        {ok, Decision} -> {reply, {ok, Decision}, State};
        error -> {reply, {error, not_found}, State}
    end;

handle_call({get_opinions, CaseRef}, _From, State) ->
    Opinions = [O || O <- State#state.opinions,
                     O#opinion.case_ref == CaseRef],
    {reply, Opinions, State};

handle_call({get_minority_opinions, CaseRef}, _From, State) ->
    Opinions = [O || O <- State#state.opinions,
                     O#opinion.case_ref == CaseRef,
                     O#opinion.is_majority == false],
    {reply, Opinions, State};

handle_call(count_decisions, _From, State) ->
    {reply, maps:size(State#state.decisions), State};

handle_call(count_opinions, _From, State) ->
    {reply, length(State#state.opinions), State};

handle_call(_Request, _From, State) ->
    {reply, {error, unknown_request}, State}.

handle_cast({store_decision, CaseRef, Decision}, State) ->
    NewDecisions = maps:put(CaseRef, Decision, State#state.decisions),
    {noreply, State#state{decisions = NewDecisions}};

handle_cast({store_opinion, Opinion}, State) ->
    %% Append-only — opinions are never removed
    NewOpinions = [Opinion | State#state.opinions],
    {noreply, State#state{opinions = NewOpinions}};

handle_cast(_Msg, State) ->
    {noreply, State}.

handle_info(_Info, State) ->
    {noreply, State}.