timestamper/src/ts_user.erl

-module(ts_user).
-export([create_table/1, new/1, update/1, lookup/1, list/2]).

-include("ts_db_records.hrl").
-include_lib("stdlib/include/qlc.hrl").

create_table(TableOpts) ->
    mnesia:create_table(ts_user,
        TableOpts ++ [{attributes, record_info(fields, ts_user)},
                      {type, ordered_set}]).

new(UR = #ts_user{}) -> 
    case mnesia:dirty_read(ts_user, UR#ts_user.username) of
        [ExistingRecord] -> {error, {record_exists, ExistingRecord}};
        [] -> mnesia:dirty_write(hash_input_record(UR))
    end.

update(UR = #ts_user{}) -> 
    case mnesia:dirty_read(ts_user, UR#ts_user.username) of
        [] -> no_record;
        [_Record] -> mnesia:dirty_write(hash_input_record(UR))
    end.

lookup(Username) ->
    case mnesia:dirty_read(ts_user, Username) of
        [] -> no_record;
        [User] -> User
    end.    

list(Start, Length) -> ts_common:list(ts_user, Start, Length).

hash_input_record(User=#ts_user{}) ->
    % generate the password salt
    Salt = generate_salt(),
    % hash the password
    HashedPwd = hash_pwd(User#ts_user.username, Salt),
    % create a new User record
    User#ts_user{pwd = HashedPwd, pwd_salt = Salt}.
    
generate_salt() ->
    "This is a worthless salt value only suitable for testing.".

hash_pwd(Password, Salt) -> do_hash(Password ++ Salt, []).

do_hash([], Hashed) -> Hashed;
do_hash([Char|Pwd], Hashed) -> do_hash(Pwd, [Char + 13 | Hashed]).