4 files changed, 135 insertions, 0 deletions
diff --git a/src/metadata/MediaMetadata.vala b/src/metadata/MediaMetadata.vala
new file mode 100644
index 0000000..a329cb1
--- /dev/null
+++ b/src/metadata/MediaMetadata.vala
@@ -0,0 +1,15 @@
+/* Copyright 2016 Software Freedom Conservancy Inc.
+ *
+ * This software is licensed under the GNU Lesser General Public License
+ * (version 2.1 or later).  See the COPYING file in this distribution.
+ */
+
+public abstract class MediaMetadata {
+    public abstract void read_from_file(File file) throws Error;
+
+    public abstract MetadataDateTime? get_creation_date_time();
+
+    public abstract string? get_title();
+
+    public abstract string? get_comment();
+}
diff --git a/src/metadata/MetadataDateTime.vala b/src/metadata/MetadataDateTime.vala
new file mode 100644
index 0000000..9dae99b
--- /dev/null
+++ b/src/metadata/MetadataDateTime.vala
@@ -0,0 +1,78 @@
+public errordomain MetadataDateTimeError {
+    INVALID_FORMAT,
+    UNSUPPORTED_FORMAT
+}
+
+public class MetadataDateTime {
+
+    private DateTime timestamp;
+
+    public MetadataDateTime(DateTime timestamp) {
+        this.timestamp = timestamp;
+    }
+
+    public MetadataDateTime.from_exif(string label) throws MetadataDateTimeError {
+        if (!from_exif_date_time(label, out timestamp))
+            throw new MetadataDateTimeError.INVALID_FORMAT("%s is not EXIF format date/time", label);
+    }
+
+    public MetadataDateTime.from_iptc(string date, string time) throws MetadataDateTimeError {
+        // TODO: Support IPTC date/time format
+        throw new MetadataDateTimeError.UNSUPPORTED_FORMAT("IPTC date/time format not currently supported");
+    }
+
+    public MetadataDateTime.from_xmp(string label) throws MetadataDateTimeError {
+        var dt = new DateTime.from_iso8601(label, null);
+        if (dt == null)
+            throw new MetadataDateTimeError.INVALID_FORMAT("%s is not XMP format date/time", label);
+
+        timestamp = dt;
+    }
+
+    public DateTime? get_timestamp() {
+        return timestamp;
+    }
+
+    public string get_exif_label() {
+        return to_exif_date_time(timestamp);
+    }
+
+    // TODO: get_iptc_date() and get_iptc_time()
+
+    public string get_xmp_label() {
+        return timestamp.format_iso8601();
+    }
+
+    public static bool from_exif_date_time(string date_time, out DateTime? timestamp) {
+        timestamp = null;
+
+        Time tm = Time();
+
+        // Check standard EXIF format
+        if (date_time.scanf("%d:%d:%d %d:%d:%d",
+                            &tm.year, &tm.month, &tm.day, &tm.hour, &tm.minute, &tm.second) != 6) {
+            // Fallback in a more generic format
+            string tmp = date_time.dup();
+            tmp.canon("0123456789", ' ');
+            if (tmp.scanf("%4d%2d%2d%2d%2d%2d",
+                          &tm.year, &tm.month, &tm.day, &tm.hour, &tm.minute,&tm.second) != 6)
+                return false;
+        }
+
+        // watch for bogosity
+        if (tm.year <= 1900 || tm.month <= 0 || tm.day < 0 || tm.hour < 0 || tm.minute < 0 || tm.second < 0)
+            return false;
+
+        timestamp = new DateTime.local(tm.year, tm.month, tm.day, tm.hour, tm.minute, tm.second);
+
+        return true;
+    }
+
+    public static string to_exif_date_time(DateTime timestamp) {
+        return timestamp.to_local().format("%Y:%m:%d %H:%M:%S");
+    }
+
+    public string to_string() {
+        return to_exif_date_time(timestamp);
+    }
+}
diff --git a/src/metadata/MetadataRational.vala b/src/metadata/MetadataRational.vala
new file mode 100644
index 0000000..ec3ac17
--- /dev/null
+++ b/src/metadata/MetadataRational.vala
@@ -0,0 +1,26 @@
+public struct MetadataRational {
+    public int numerator;
+    public int denominator;
+
+    public MetadataRational.invalid() {
+        this.numerator = -1;
+        this.denominator = -1;
+    }
+
+    public MetadataRational(int numerator, int denominator) {
+        this.numerator = numerator;
+        this.denominator = denominator;
+    }
+
+    private bool is_component_valid(int component) {
+        return (component >= 0) && (component <= 1000000);
+    }
+
+    public bool is_valid() {
+        return (is_component_valid(numerator) && is_component_valid(denominator));
+    }
+
+    public string to_string() {
+        return (is_valid()) ? ("%d/%d".printf(numerator, denominator)) : "";
+    }
+}
diff --git a/src/metadata/meson.build b/src/metadata/meson.build
new file mode 100644
index 0000000..7f322ca
--- /dev/null
+++ b/src/metadata/meson.build
@@ -0,0 +1,16 @@
+libmetadata = static_library(
+    'metadata',
+    [
+        'MediaMetadata.vala',
+        'MetadataDateTime.vala',
+        'MetadataRational.vala'
+    ],
+    dependencies : [
+        gio
+    ]
+)
+
+metadata = declare_dependency(
+    include_directories : include_directories('.'),
+    link_with : libmetadata
+)