using Mono.Data.SqliteClient;
using Mono.Unix;
using Gtk;
using System;
using System.Collections;

namespace FSpot.Database {
	public static class Updater {
		private static ProgressDialog dialog;
		private static Hashtable updates = new Hashtable ();
		private static MetaItem db_version;
		private static Db db;


		public static Version LatestVersion {
			get {
				if (updates == null || updates.Count == 0)
					return new Version (0, 0);
				ArrayList keys = new ArrayList (updates.Keys);
				keys.Sort ();
				return keys[keys.Count - 1] as Version;
			}
		}
		
		static Updater () {
			// Update from version 0 to 1: Remove empty Other tags
			AddUpdate (new Version ("1"), delegate () {
				string other_id = SelectSingleString ("SELECT id FROM tags WHERE name = 'Other'");

				if (other_id == null)
					return;

				// Don't do anything if there are subtags
				string tag_count = SelectSingleString (
					String.Format ("SELECT COUNT(*) FROM tags WHERE category_id = {0}", other_id));
				
				if (tag_count == null || System.Int32.Parse (tag_count) != 0)
					return;
				
				// Don't do anything if there are photos tagged with this
				string photo_count = SelectSingleString (
					String.Format ("SELECT COUNT(*) FROM photo_tags WHERE tag_id = {0}", other_id));

				if (photo_count == null || System.Int32.Parse (photo_count) != 0)
					return;

				// Finally, we know that the Other tag exists and has no children, so remove it
				ExecuteNonQuery ("DELETE FROM tags WHERE name = 'Other'");
			});

			// Update from version 1 to 2: Restore Other tags that were removed leaving dangling child tags
			AddUpdate (new Version ("2"), delegate () {
				string tag_count = SelectSingleString ("SELECT COUNT(*) FROM tags WHERE category_id != 0 AND category_id NOT IN (SELECT id FROM tags)");

				// If there are no dangling tags, then don't do anything
				if (tag_count == null || System.Int32.Parse (tag_count) == 0)
					return;

 				int id = ExecuteScalar ("INSERT INTO tags (name, category_id, is_category, icon) VALUES ('Other', 0, 1, 'stock_icon:f-spot-other.png')");

				ExecuteNonQuery (String.Format (
					"UPDATE tags SET category_id = {0} WHERE id IN "		+
					"(SELECT id FROM tags WHERE category_id != 0 AND category_id "	+
					"NOT IN (SELECT id FROM tags))",
					id));

				System.Console.WriteLine ("Other tag restored.  Sorry about that!");
			});
			
			// Update from version 2 to 3: ensure that Hidden is the only tag left which is a real tag (not category)
			AddUpdate (new Version ("3"), delegate () {
				ExecuteNonQuery ("UPDATE tags SET is_category = 1 WHERE name != 'Hidden'");
			});

			//Version 3.1, clean old (and unused) items in Export
			AddUpdate (new Version (3, 1), delegate () {
				if (TableExists ("exports"))
					ExecuteScalar ("DELETE FROM exports WHERE export_type='fspot:Folder'");
			});

			//Version 4.0, bump the version number to a integer, for backward compatibility
			AddUpdate (new Version (4, 0), delegate () {});


			//Version 5.0, add a roll_id field to photos, rename table 'imports' to 'rolls' 
			//and fix bgo 324425.
			AddUpdate (new Version (5, 0), delegate () {
				System.Console.WriteLine ("Will add a roll_id field to photos!");
				string tmp_photos = MoveTableToTemp ("photos");
				ExecuteNonQuery (
					"CREATE TABLE photos (                                     " +
					"	id                 INTEGER PRIMARY KEY NOT NULL,   " +
					"       time               INTEGER NOT NULL,	   	   " +
					"       directory_path     STRING NOT NULL,		   " +
					"       name               STRING NOT NULL,		   " +
					"       description        TEXT NOT NULL,	           " +
					"       roll_id            INTEGER NOT NULL,		   " +
					"       default_version_id INTEGER NOT NULL		   " +
					")");
				ExecuteScalar (String.Format("INSERT INTO photos SELECT id, time, directory_path, name, description, 0, default_version_id FROM {0}", tmp_photos));

				System.Console.WriteLine ("Will rename imports to rolls!");
				string tmp_rolls = MoveTableToTemp ("imports");
				ExecuteNonQuery (
					"CREATE TABLE rolls (                                     " +
					"	id                 INTEGER PRIMARY KEY NOT NULL,   " +
					"       time               INTEGER NOT NULL	   	   " +
					")");
				ExecuteScalar (String.Format("INSERT INTO rolls SELECT id, time FROM {0}", tmp_rolls));

				System.Console.WriteLine ("Cleaning weird descriptions, fixes bug #324425.");
				ExecuteNonQuery ("UPDATE photos SET description = \"\" WHERE description LIKE \"Invalid size of entry%\"");
			});				


			//Version 6.0, change tag icon f-spot-tag-other to emblem-generic
			AddUpdate (new Version (6,0),delegate () {
				ExecuteScalar ("UPDATE tags SET icon = \"stock_icon:emblem-generic\" " +
						" WHERE icon LIKE \"stock_icon:f-spot-other.png\"");
			});
			
			// Update to version 7.0
			//AddUpdate (new Version (7,0),delegate () {
			//	do update here
			//});

			
		}

		public static void Run (Db database)
		{
			db = database;
			db_version = db.Meta.DatabaseVersion;

			if (updates.Count == 0)
				return;

			Version current_version = new Version (db_version.Value);

			if (current_version == LatestVersion)
				return;
			else if (current_version > LatestVersion) {
				Console.WriteLine ("The existing database version is more recent than this version of F-Spot expects.");
				return;
			}

			Console.WriteLine ("Updating F-Spot Database");

			// Only create and show the dialog if one or more of the updates to be done is
			// marked as being slow
			bool slow = false;
			foreach (Version version in updates.Keys) {
				if (version > current_version && (updates[version] as Update).IsSlow)
					slow = true;
					break;
			}

			if (slow) {
				dialog = new ProgressDialog (Catalog.GetString ("Updating F-Spot Database"), ProgressDialog.CancelButtonType.None, 0, null);
				dialog.Message.Text = Catalog.GetString ("Please wait while your F-Spot gallery's database is updated. This may take some time.");
				dialog.Bar.Fraction = 0.0;
				dialog.Modal = false;
				dialog.SkipTaskbarHint = true;
				dialog.WindowPosition = WindowPosition.Center;
				dialog.ShowAll ();
				dialog.Present ();
				dialog.QueueDraw ();
			}

			db.BeginTransaction ();
			try {
				ArrayList keys = new ArrayList (updates.Keys);
				keys.Sort ();
				foreach (Version version in keys) {
					if (version <= current_version)
						continue;

					Pulse ();
					(updates[version] as Update).Execute (db, db_version);
				}

				db.CommitTransaction ();
			} catch (Exception e) {
				Console.WriteLine ("Rolling back database changes because of Exception");
				// There was an error, roll back the database
				db.RollbackTransaction ();

				// Pass the exception on, this is fatal
				throw e;
			}
			
			if (dialog != null)
				dialog.Destroy ();
			
			if (new Version(db_version.Value) == LatestVersion)
				Console.WriteLine ("Database updates completed successfully.");
		}
		
		private static void AddUpdate (Version version, UpdateCode code)
		{
			AddUpdate (version, code, false);
		}
		
		private static void AddUpdate (Version version, UpdateCode code, bool is_slow)
		{
			updates[version] = new Update (version, code, is_slow);
		}

		public static void Pulse ()
		{
			if (dialog != null) {
				dialog.Bar.Pulse ();
				dialog.ShowAll ();
			}
		}

		private static void ExecuteNonQuery (string statement)
		{
			db.Database.ExecuteNonQuery(statement);
		}
		
		private static int ExecuteScalar (string statement)
		{
			return db.Database.Execute(statement);
		}
		
		private static bool TableExists (string table)
		{
			return db.Database.TableExists (table);
		}

		private static string SelectSingleString (string statement)
		{
			string result = null;

			try {
				result = (string)db.Database.QuerySingle(statement);
			} catch (Exception) {}

			return result;
		}

		private static string MoveTableToTemp (string table_name)
		{
			string temp_name = table_name + "_temp";
			
			// Get the table definition for the table we are copying
			string sql = SelectSingleString (String.Format ("SELECT sql FROM sqlite_master WHERE tbl_name = '{0}' ORDER BY type DESC", table_name));

			// Change the SQL to create the temp table
			ExecuteNonQuery (sql.Replace ("CREATE TABLE " + table_name, "CREATE TEMPORARY TABLE " + temp_name));

			// Copy the data
			ExecuteScalar (String.Format ("INSERT INTO {0} SELECT * FROM {1}", temp_name, table_name));
				
			// Delete the original table
			ExecuteNonQuery ("DROP TABLE " + table_name);

			return temp_name;
		}

		private delegate void UpdateCode ();

		private class Update {
			public Version Version;
			private UpdateCode code;
			public bool IsSlow = false;
			
			public Update (Version to_version, UpdateCode code, bool slow)
			{
				this.Version = to_version;
				this.code = code;
				IsSlow = slow;
			}

			public Update (Version to_version, UpdateCode code)
			{
				this.Version = to_version;
				this.code = code;
			}

			public void Execute (Db db, MetaItem db_version)
			{
				code ();
				
				Console.WriteLine ("Updated database from version {0} to {1}",
						db_version.Value,
						Version.ToString ());


				db_version.Value = Version.ToString ();
				db.Meta.Commit (db_version);
			}
		}

		public class Version : IComparable {
			int maj = 0;
			int min = 0;

			public Version (int maj, int min)
			{
				this.maj = maj;
				this.min = min;
			}

			public Version (string version)
			{
				string [] parts = version.Split (new char [] {'.'}, 2);
				try {
					this.maj = Convert.ToInt32 (parts [0]);
				}
				catch (Exception) {
					this.maj = 0;
				}
				try {
					this.min = Convert.ToInt32 (parts [1]);
				}
				catch (Exception) {
					this.min = 0;
				}
			}

			//IComparable
			public int CompareTo (object obj) {
				if (this.GetType () == obj.GetType ())
					return Compare (this, (Version)obj);
				else
					throw new Exception ("Object must be of type Version");
			}

			public int CompareTo (Version version)
			{
				return Compare (this, version);
			}
	
			public static int Compare (Version v1, Version v2)
			{
				if (v1.maj == v2.maj)
					return v1.min.CompareTo (v2.min);
				return v1.maj.CompareTo (v2.maj);
			}

			public override string ToString ()
			{
				if (min == 0)
					return maj.ToString ();
				return maj + "." + min;
			}

			public override bool Equals (object obj)
			{
				return obj is Version && this == (Version)obj;
			}

			public override int GetHashCode ()
			{
				return maj ^ min;
			}

			public static bool operator == (Version v1, Version v2)
			{
				return v1.maj == v2.maj && v1.min == v2.min;
			}

			public static bool operator != (Version v1, Version v2)
			{
				return !(v1 == v2);
			}

			public static bool operator < (Version v1, Version v2)
			{
				return Compare (v1,v2) < 0;
			}

			public static bool operator > (Version v1, Version v2)
			{
				return Compare (v1,v2) > 0;
			}

			public static bool operator <= (Version v1, Version v2)
			{
				return !(v1 > v2);
			}

			public static bool operator >= (Version v1, Version v2)
			{
				return !(v1 < v2);
			}
		}
	} 
}