Lua solution for week 103, part 2

2 files changed, 82 insertions, 0 deletions

diff --git a/challenge-103/abigail/README.md b/challenge-103/abigail/README.md
index 0f05539ef8..03b5dc3a3c 100644
--- a/challenge-103/abigail/README.md
+++ b/challenge-103/abigail/README.md
@@ -123,6 +123,7 @@ Output:
 ~~~~
 
 ### Solutions
+* [Lua](lua/ch-1.lua)
 * [Perl](perl/ch-2.pl)
 
 ### Blog
diff --git a/challenge-103/abigail/lua/ch-2.lua b/challenge-103/abigail/lua/ch-2.lua
new file mode 100644
index 0000000000..dc39dc3e8a
--- /dev/null
+++ b/challenge-103/abigail/lua/ch-2.lua
@@ -0,0 +1,81 @@
+#!/opt/local/bin/lua
+
+--
+-- See ../README.md
+--
+
+--
+-- Run as: lua ch-2.lua < input-file
+--
+
+--
+-- We're reading a start time, the current time, and a file name
+-- from STDIN, separated by white space. The file contains the
+-- tracks played.
+--
+
+for line in io . lines () do
+    local _, _, start_time, current_time, file_name =
+                line : find ("(%d+)%s+(%d+)%s+(%S+)")
+
+    --
+    -- Time difference in milliseconds
+    --
+    local time_diff  = (current_time - start_time) * 1000
+
+    local tracks     = {}
+    local total_time = 0
+
+    --
+    -- Read in the media file; store the results in the
+    -- table tracks.
+    --
+    for track in io . lines (file_name) do
+        local _, _, play_time, title = track : find ("(%d+),(.*)")
+        local record = {}
+        record [0] = play_time
+        record [1] = title
+        total_time = total_time + play_time
+        table . insert (tracks, record)
+    end
+
+    --
+    -- We're not interested in playing full loops.
+    --
+    time_diff = time_diff % total_time
+
+    --
+    -- Find the current track playing. If time_diff is less than the
+    -- play time of the track, this is the track currently playing. If
+    -- so, print the track name (with quotes, as given in the example --
+    -- although they don't belong there, as they're from the CSV encoding;
+    -- for that reason, we won't deescape anything else either). Otherwise
+    -- (track length is shorter than time_diff), we subtrack the length
+    -- of the track from time_diff, and continue checking the next track.
+    --
+    for _, track in ipairs (tracks) do
+        if   time_diff - track [0] < 0
+        then time_diff     =  math . floor  (time_diff / 1000)
+             local hours   =  math . floor  (time_diff / 3600)
+             local minutes =  math . floor ((time_diff % 3600) / 60)
+             local seconds =                 time_diff         % 60
+        
+             --
+             -- Format a time string
+             --
+             local time
+             if   hours > 0
+             then time = string .
+                         format ("%02d:%02d:%02d", hours, minutes, seconds)
+             else time = string .
+                         format (     "%02d:%02d",        minutes, seconds)
+             end
+             print (track [1])
+             print (time)
+             break
+        else time_diff = time_diff - track [0]
+        end
+    end
+end
+
+