Continuing work on the API.

The id_counter module now includes the record directly in the source.
Fixed many typos and small syntax errors.
Added ts_api:dispatch_user/2 to handle different HTTP methods.
Added method placeholder stubs to ts_api.
Implemented ts_api:list_entries/3.
Added ts_user record and ts_user module.
Implemented ts_entry:list/4, the more generic guts of the other list functions.
Created ts_entry:list_asc/3 and ts_entry:list_desc/3.
Fixed ts_json:encode_datetime/1.

src/ts_entry.erl

@@ -1,5 +1,5 @@
 -module(ts_entry).
--export([create_table/1, new/1, update/1, lookup/3, list/3]).
+-export([create_table/1, new/1, update/1, lookup/3, list_asc/3, list_desc/3]).
 
 -include("ts_db_records.hrl").
 -include_lib("stdlib/include/qlc.hrl").
@@ -7,10 +7,10 @@
 create_table(TableOpts) ->
     mnesia:create_table(ts_entry,
         TableOpts ++ [{attributes, record_info(fields, ts_entry)},
-                      {type, ordered_set}, {index, timestamp}]).
+                      {type, ordered_set}, {index, [timestamp]}]).
 
-new(ER = #ts_entry()) ->
-    {atmoic, NewRow) = mnesia:transaction(fun() ->
+new(ER = #ts_entry{}) ->
+    {atmoic, NewRow} = mnesia:transaction(fun() ->
         {Username, TimelineId, _} = ER#ts_entry.ref,
         NextId = id_counter:next_counter(ts_entry_id),
         NewRow = ER#ts_entry{ref = {Username, TimelineId, NextId}},
@@ -18,7 +18,7 @@ new(ER = #ts_entry()) ->
         NewRow end),
     {ok, NewRow}.
 
-update(ER = #ts_entry()) ->
+update(ER = #ts_entry{}) ->
     
     % look for existing record
     case mnesia:dirty_read(ts_entry, ER#ts_entry.ref) of
@@ -34,30 +34,60 @@ lookup(Username, TimelineId, EntryId) ->
         [Entry] -> Entry
     end.
 
-list({Username, Timeline}, Start, Length)
+list({Username, Timeline}, Start, Length, OrderFun)
 when is_integer(Start) and is_integer(Length) ->
-    ts_common:list(
-        qlc:q([E || E <- mnesia:table(ts_entry),
-                    E#ts_entry.ref =:= {Username, Timeline, _}]_,
-            Start, Length).
-
-list({Username, Timeline}, StartDateTime, EndDateTime) ->
 
     {atomic, Entries} = mnesia:transaction(fun() ->
+        % match the username and timeline
+        MatchHead = #ts_entry{ref = {Username, Timeline, '_'}, _='_'},
 
-        StartSeconds = calendar:datetime_to_gregorian_seconds(StartDateTime),
-        EndSeconds = calendar:datetime_to_gregorian_seconds(EndDateTime),
-
-        % create the query that will select these records
-        Q = qlc:q([E || E <- mnesia:table(ts_entry),
-                        E#ts_entry.timestamp >= StartSeconds,
-                        E#ts_entry.timestamp < EndSeconds]),
-
-        % sort by timestamp
-        SortedQ = qlc:sort(Q, {order, fun(A, B) ->
-            A#ts_entry.timestamp > B#ts_entry.timestamp end}),
-
-        % return
-        qlc:e(SortedQ)
+        % select all records that match
+        mnesia:select(ts_entry, [{MatchHead, [], ['$_']}]
     end),
-    Entries.
+
+    % sort
+    SortedEntries = lists:sort(OrderFun, Entries),
+
+    % return only the range selected.
+    % TODO: can we do this without selecting all entries?
+    lists:sublist(SortedEntries, Start, Length);
+
+list({Username, Timeline}, StartDateTime, EndDateTime, OrderFun) ->
+
+    % compute the seconds from datetimes
+    StartSeconds = calendar:datetime_to_gregorian_seconds(StartDateTime),
+    EndSeconds = calendar:datetime_to_gregorian_seconds(EndDateTime),
+
+    % select all entries from the timeline that are within the time range
+    {atomic, Entries} = mnesia:transaction(fun() ->
+
+        % match the username and timeline id
+        MatchHead = #ts_entry{ref = {Username, Timeline, '_'}, timestamp='$1', _='_'},
+
+        % guards for the time range
+        StartGuard = {'>=', '$1', StartSeconds},
+        EndGuard = {'<', '$1', EndSeconds},
+
+        mnesia:select(ts_entry, [{MatchHead, [StartGuard, EndGuard], ['$_']}])
+    end,
+
+    % sort
+    lists:sort(OrderFun, Entries).
+
+list_asc(TimelineRef, Start, Length)
+when is_integer(Start) and is_integer(Length) ->
+    list(TimelineRef, Start, Length, fun timestamp_asc/2);
+
+list_asc(TimelineRef, StartDateTime, EndDateTime) ->
+    list(TimelineRef, StartDateTime, EndDateTime, fun timestamp_asc/2).
+
+list_desc(TimelineRef, Start, Length)
+when is_integer(Start) and is_integer(Length) ->
+    list(TimelineRef, Start, Length, fun timestamp_desc/2);
+
+list_desc(TimelineRef, StartDateTime, EndDateTime) ->
+    list(TimelineRef, StartDateTime, EndDateTime, fun timestamp_desc/2).
+
+timestamp_asc(E1, E2) -> E1#ts_entry.timestamp > E2#ts_entry.timestamp.
+
+timestamp_desc(E1, E2) -> E1#ts_entry.timestamp < E2#ts_entry.timestamp.