{ok, LisAddr} = inet:getaddr(Host, inet), 

  {ok, LisAddr} = inet:getaddr(Host, inet),

  {ok, Db} = sqlite3:open(cabal),
  init_tables(Db),

  Db = db:start_link(),

% sql helpers
%%%%%%%%%%%%%
init_tables(Db) ->
  ColId = {id, integer, [{primary_key, [asc, autoincrement]}]},
  Tables = #{
    channels => [ColId, {name, text, not_null}],
    users => [ColId, {pubkey, blob, not_null}, {name, text, not_null}],
    posts => [ColId, {pubkey, blob, not_null}, {type, integer, not_null}]
  },
  case tables_exist(Db, maps:keys(Tables)) of 
    missing -> 
      CreateTable = fun(T, Cols) -> 
        ok = sqlite3:create_table(Db, T, Cols),
        io:format("Created table: ~p~n", [T])
      end,
      maps:foreach(CreateTable, Tables);
    ok ->
      ok
  end.
tables_exist(Db, [T | Rest]) ->
  case lists:member(T, sqlite3:list_tables(Db)) of
      true -> tables_exist(Db, Rest);
      false -> missing
  end;
tables_exist(_, []) -> ok.
drop_table_if_exists(Db, Table) ->
  case lists:member(Table, sqlite3:list_tables(Db)) of
      true -> sqlite3:drop_table(Db, Table);
      false -> ok
  end.
rows(SqlExecReply) ->
  case SqlExecReply of
      [{columns, _Columns}, {rows, Rows}] -> Rows;
      {error, Code, Reason} -> {error, Code, Reason}
  end.

-module(db).
-behavior(gen_server).
-export([start_link/1]).
% gen_server things
-export([init/1, handle_call/3, handle_cast/2, handle_info/2, code_change/3, terminate/2]).
%% server things
init(Args) ->
    process_flag(trap_exit, true),
    [{dbpath, Path}, _] = Args,
    open_db(Path).
open_db(Path) ->
    {ok, Db} = sqlite3:open(Path),
    ok = init_tables(Db),
    {ok, [{sql, Db}, {dbPath, Path}]}.
start_link(DbPath) ->
    gen_server:start_link({local, cabaldb}, ?MODULE, [{dbpath, DbPath}], []).
handle_call({addchannel, Name}, _From, State = [{sql, Db}, _]) ->
    io:format("INSERTing channel: ~p~n", [Name]),
    sqlite3:write(Db, channels, [{name, Name}]),
    {reply, ok, State};
handle_call(listchannels, _From, State = [{sql, Db}, _]) ->
    [_, {rows, Rows}] = sqlite3:read_all(Db, channels),
    Chans = lists:map(fun({_Id, Name}) ->
      binary_to_list(Name)
    end, Rows),
    {reply, {ok, Chans}, State}.
handle_cast(Msg, State) ->
    io:format("Unexpected async call: ~p~n", [Msg]),
    {noreply, State}.
handle_info(Msg, State) ->
    io:format("Unexpected message: ~p~n", [Msg]),
    {noreply, State}.
terminate(normal, _State = [{sql, Db, _}]) ->
    sqlite3:close(Db),
    ok.
code_change(_OldVsn, State, _Extra) ->
    % let's re-open the Db, just in case the driver changed.
    [{sql, Db}, {dbPath, Path}] = State,
    sqlite3:close(Db),
    open_db(Path).
%% private helpers
init_tables(Db) ->
  ColId = {id, integer, [{primary_key, [asc, autoincrement]}]},
  Tables = #{
    channels => [ColId, {name, text, not_null}],
    users => [ColId, {pubkey, blob, not_null}, {name, text, not_null}],
    posts => [ColId, {pubkey, blob, not_null}, {type, integer, not_null}]
  },
  case tables_exist(Db, maps:keys(Tables)) of
    missing ->
      CreateTable = fun(T, Cols) ->
        ok = sqlite3:create_table(Db, T, Cols),
        io:format("Created table: ~p~n", [T])
      end,
      maps:foreach(CreateTable, Tables);
    ok ->
      ok
  end.
tables_exist(Db, [T | Rest]) ->
    case lists:member(T, sqlite3:list_tables(Db)) of
        true -> tables_exist(Db, Rest);
        false -> missing
    end;
tables_exist(_, []) ->
    ok.