// Copyright (C) 2009-2011 Novell, Inc.
// Copyright (C) 2009 Julien Rebetez
// Copyright (C) 2009 Igor Vatavuk
//
// This program is free software; you can redistribute it and/or
// modify it under the terms of the GNU General Public License
// as published by the Free Software Foundation; either version 2
// of the License, or (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.

using System;
using System.Collections.Generic;
using System.Linq;

using Gtk;
using Gdk;

using PdfSharp.Pdf;

using PdfMod.Pdf;
using PdfMod.Pdf.Actions;

namespace PdfMod.Gui
{
    public enum PageSelectionMode {
        None,
        Evens,
        Odds,
        Matching,
        Inverse,
        All
    }

    public class DocumentIconView : Gtk.IconView, IDisposable
    {
        public const int MIN_WIDTH = 128;
        public const int MAX_WIDTH = 2054;

        enum Target {
            UriSrc,
            UriDest,
            MoveInternal,
            MoveExternal
        }

        static readonly TargetEntry uri_src_target = new TargetEntry ("text/uri-list", 0, (uint)Target.UriSrc);
        static readonly TargetEntry uri_dest_target = new TargetEntry ("text/uri-list", TargetFlags.OtherApp, (uint)Target.UriDest);
        static readonly TargetEntry move_internal_target = new TargetEntry ("pdfmod/page-list", TargetFlags.Widget, (uint)Target.MoveInternal);
        static readonly TargetEntry move_external_target = new TargetEntry ("pdfmod/page-list-external", 0, (uint)Target.MoveExternal);

        Client app;
        Document document;
        PageListStore store;
        PageCell page_renderer;
        PageSelectionMode page_selection_mode = PageSelectionMode.None;
        bool highlighted;

        public PageListStore Store { get { return store; } }
        public bool CanZoomIn { get; private set; }
        public bool CanZoomOut { get; private set; }

        public IEnumerable<Page> SelectedPages {
            get {
                var pages = new List<Page> ();
                foreach (var path in SelectedItems) {
                    TreeIter iter;
                    store.GetIter (out iter, path);
                    pages.Add (store.GetValue (iter, PageListStore.PageColumn) as Page);
                }
                pages.Sort ((a, b) => { return a.Index < b.Index ? -1 : 1; });
                return pages;
            }
        }

        public event System.Action ZoomChanged;

        public DocumentIconView (Client app) : base ()
        {
            this.app = app;

            TooltipColumn = PageListStore.TooltipColumn;
            SelectionMode = SelectionMode.Multiple;
            ColumnSpacing = RowSpacing = Margin;
            Model = store = new PageListStore ();
            Reorderable = false;
            Spacing = 0;
            Orientation = Orientation.Vertical;

            // Properties not bound in Gtk#
            SetProperty ("item-padding", new GLib.Value ((int)0));

            CanZoomIn = CanZoomOut = true;

            page_renderer = new PageCell (this);
            PackStart (page_renderer, false);
            AddAttribute (page_renderer, "page", PageListStore.PageColumn);

            // TODO enable uri-list as drag source target for drag-out-of-pdfmod-to-extract feature
            EnableModelDragSource (Gdk.ModifierType.None, new TargetEntry [] { move_internal_target, move_external_target, uri_src_target }, Gdk.DragAction.Default | Gdk.DragAction.Move);
            EnableModelDragDest (new TargetEntry [] { move_internal_target, move_external_target, uri_dest_target }, Gdk.DragAction.Default | Gdk.DragAction.Move);

            SizeAllocated += HandleSizeAllocated;
            PopupMenu += HandlePopupMenu;
            ButtonPressEvent += HandleButtonPressEvent;
            SelectionChanged += HandleSelectionChanged;
            DragDataReceived += HandleDragDataReceived;
            DragDataGet += HandleDragDataGet;
            DragBegin += HandleDragBegin;
            DragLeave += HandleDragLeave;
        }

        public override void Dispose ()
        {
            page_renderer.Dispose ();
            base.Dispose ();
        }

        #region Gtk.Widget event handlers/overrides

        protected override bool OnScrollEvent (Gdk.EventScroll evnt)
        {
            if ((evnt.State & Gdk.ModifierType.ControlMask) != 0) {
                Zoom (evnt.Direction == ScrollDirection.Down ? -20 : 20);
                return true;
            } else {
                return base.OnScrollEvent (evnt);
            }
        }

        void HandleSizeAllocated (object o, EventArgs args)
        {
            if (!zoom_manually_set) {
                ZoomFit ();
            }
        }

        void HandleSelectionChanged (object o, EventArgs args)
        {
            if (!refreshing_selection) {
                page_selection_mode = PageSelectionMode.None;
            }
        }

        void HandleButtonPressEvent (object o, ButtonPressEventArgs args)
        {
            if (args.Event.Button == 3) {
                var path = GetPathAtPos ((int)args.Event.X, (int)args.Event.Y);
                if (path != null) {
                    if (!PathIsSelected (path)) {
                        bool ctrl = (args.Event.State & Gdk.ModifierType.ControlMask) != 0;
                        bool shift = (args.Event.State & Gdk.ModifierType.ShiftMask) != 0;
                        if (ctrl) {
                            SelectPath (path);
                        } else if (shift) {
                            TreePath cursor;
                            CellRenderer cell;
                            if (GetCursor (out cursor, out cell)) {
                                TreePath first = cursor.Compare (path) < 0 ? cursor : path;
                                do {
                                    SelectPath (first);
                                    first.Next ();
                                } while (first != path && first != cursor && first != null);
                            } else {
                                SelectPath (path);
                            }
                        } else {
                            UnselectAll ();
                            SelectPath (path);
                        }
                    }
                    HandlePopupMenu (null, null);
                    args.RetVal = true;
                }
            }
        }

        void HandlePopupMenu (object o, PopupMenuArgs args)
        {
            app.Actions["PageContextMenu"].Activate ();
        }

        #endregion

        #region Drag and Drop event handling

        void HandleDragBegin (object o, DragBeginArgs args)
        {
            // Set the drag icon, otherwise it will be a whole page cell rendering,
            // which can be quite large and obscure the drop points
            bool single = SelectedItems.Length == 1;
            Gtk.Drag.SetIconStock (args.Context, single ? Stock.Dnd : Stock.DndMultiple, 0, 0);
        }

        void HandleDragLeave (object o, DragLeaveArgs args)
        {
            if (highlighted) {
                Gtk.Drag.Unhighlight (this);
                highlighted = false;
            }
            args.RetVal = true;
        }

        protected override bool OnDragMotion (Gdk.DragContext context, int x, int y, uint time_)
        {
            // Scroll if within 20 pixels of the top or bottom
            var parent = Parent.Parent as Gtk.ScrolledWindow;
            double rel_y = y - parent.Vadjustment.Value;
            if (rel_y < 20) {
                parent.Vadjustment.Value -= 30;
            } else if ((parent.Allocation.Height - rel_y) < 20) {
                parent.Vadjustment.Value = Math.Min (parent.Vadjustment.Upper - parent.Allocation.Height, parent.Vadjustment.Value + 30);
            }

            var targets = context.Targets.Select (t => (string)t);

            if (targets.Contains (move_internal_target.Target) || targets.Contains (move_external_target.Target)) {
                bool ret = base.OnDragMotion (context, x, y, time_);
                SetDestInfo (x, y);
                return ret;
            } else if (targets.Contains (uri_dest_target.Target)) {
                // TODO could do this (from Gtk+ docs) to make sure the uris are all .pdfs (or mime-sniffed as pdfs):
                /* If the decision whether the drop will be accepted or rejected can't be made based solely on the
                   cursor position and the type of the data, the handler may inspect the dragged data by calling gtk_drag_get_data() and
                   defer the gdk_drag_status() call to the "drag-data-received" handler. Note that you cannot not pass GTK_DEST_DEFAULT_DROP,
                   GTK_DEST_DEFAULT_MOTION or GTK_DEST_DEFAULT_ALL to gtk_drag_dest_set() when using the drag-motion signal that way. */
                Gdk.Drag.Status (context, DragAction.Copy, time_);
                if (!highlighted) {
                    Gtk.Drag.Highlight (this);
                    highlighted = true;
                }

                SetDestInfo (x, y);

                return true;
            }

            Gdk.Drag.Abort (context, time_);
            return false;
        }

        void SetDestInfo (int x, int y)
        {
            TreePath path;
            IconViewDropPosition pos;
            GetCorrectedPathAndPosition (x, y, out path, out pos);
            SetDragDestItem (path, pos);
        }

        void HandleDragDataGet(object o, DragDataGetArgs args)
        {
            if (args.Info == move_internal_target.Info) {
                var pages = new Hyena.Gui.DragDropList<Page> ();
                pages.AddRange (SelectedPages);
                pages.AssignToSelection (args.SelectionData, Gdk.Atom.Intern (move_internal_target.Target, false));
                args.RetVal = true;
            } else if (args.Info == move_external_target.Info) {
                string doc_and_pages = String.Format ("{0}{1}{2}", document.CurrentStateUri, newline[0], String.Join (",", SelectedPages.Select (p => p.Index.ToString ()).ToArray ()));
                byte [] data = System.Text.Encoding.UTF8.GetBytes (doc_and_pages);
                args.SelectionData.Set (Gdk.Atom.Intern (move_external_target.Target, false), 8, data);
                args.RetVal = true;
            } else if (args.Info == uri_src_target.Info) {
                // TODO implement page extraction via DnD?
                Console.WriteLine ("HandleDragDataGet, wants a uri list...");
            }
        }

        void GetCorrectedPathAndPosition (int x, int y, out TreePath path, out IconViewDropPosition pos)
        {
            GetDestItemAtPos (x, y, out path, out pos);

            // Convert drop above/below/into into DropLeft or DropRight based on the x coordinate
            if (path != null && (pos == IconViewDropPosition.DropAbove || pos == IconViewDropPosition.DropBelow || pos == IconViewDropPosition.DropInto)) {
                if (!path.Equals (GetPathAtPos (x + ItemSize/2, y))) {
                    pos = IconViewDropPosition.DropRight;
                } else {
                    pos = IconViewDropPosition.DropLeft;
                }
            }
        }

        int GetDropIndex (int x, int y)
        {
            TreePath path;
            TreeIter iter;
            IconViewDropPosition pos;
            GetCorrectedPathAndPosition (x, y, out path, out pos);
            if (path == null) {
                return -1;
            }

            store.GetIter (out iter, path);
            if (TreeIter.Zero.Equals (iter))
                return -1;

            var to_index = (store.GetValue (iter, PageListStore.PageColumn) as Page).Index;
            if (pos == IconViewDropPosition.DropRight) {
                to_index++;
            }

            return to_index;
        }

        static string [] newline = new string [] { "\r\n" };
        void HandleDragDataReceived (object o, DragDataReceivedArgs args)
        {
            args.RetVal = false;
            string target = (string)args.SelectionData.Target;
            if (target == move_internal_target.Target) {
                // Move pages within the document
                int to_index = GetDropIndex (args.X, args.Y);
                if (to_index < 0)
                    return;

                Hyena.Gui.DragDropList<Page> pages = args.SelectionData;
                to_index -= pages.Count (p => p.Index < to_index);
                var action = new MoveAction (document, pages, to_index);
                action.Do ();
                app.Actions.UndoManager.AddUndoAction (action);
                args.RetVal = true;
            } else if (target == move_external_target.Target) {
                int to_index = GetDropIndex (args.X, args.Y);
                if (to_index < 0)
                    return;

                string doc_and_pages = System.Text.Encoding.UTF8.GetString (args.SelectionData.Data);
                var pieces = doc_and_pages.Split (newline, StringSplitOptions.RemoveEmptyEntries);
                string uri = pieces[0];
                int [] pages = pieces[1].Split (',').Select (p => Int32.Parse (p)).ToArray ();

                document.AddFromUri (new Uri (uri), to_index, pages);
                args.RetVal = true;
            } else if (target == uri_src_target.Target) {
                var uris = System.Text.Encoding.UTF8.GetString (args.SelectionData.Data).Split (newline, StringSplitOptions.RemoveEmptyEntries);
                if (uris.Length == 1 && app.Document == null) {
                    app.LoadPath (uris[0]);
                    args.RetVal = true;
                } else {
                    int to_index = GetDropIndex (args.X, args.Y);
                    int uri_i = 0;

                    var add_pages = new System.Action (delegate {
                        // TODO somehow ask user for which pages of the docs to insert?
                        // TODO pwd handling - keyring#?
                        // TODO make action/undoable
                        for (; uri_i < uris.Length; uri_i++) {
                            var before_count = document.Count;
                            document.AddFromUri (new Uri (uris[uri_i]), to_index);
                            to_index += document.Count - before_count;
                        }
                    });

                    if (document == null || to_index < 0) {
                        // Load the first page, then add the other pages to it
                        app.LoadPath (uris[uri_i++], null, delegate {
                            if (document != null) {
                                to_index = document.Count;
                                add_pages ();
                            }
                        });
                    } else {
                        add_pages ();
                    }

                    args.RetVal = true;
                }
            }

            Gtk.Drag.Finish (args.Context, (bool)args.RetVal, false, args.Time);
        }

        #endregion

        #region Document event handling

        public void SetDocument (Document new_doc)
        {
            if (document != null) {
                document.PagesAdded   -= OnPagesAdded;
                document.PagesChanged -= OnPagesChanged;
                document.PagesRemoved -= OnPagesRemoved;
                document.PagesMoved   -= OnPagesMoved;
            }

            document = new_doc;
            document.PagesAdded   += OnPagesAdded;
            document.PagesChanged += OnPagesChanged;
            document.PagesRemoved += OnPagesRemoved;
            document.PagesMoved   += OnPagesMoved;

            store.SetDocument (document);
            page_selection_mode = PageSelectionMode.None;
            Refresh ();
            GrabFocus ();
        }

        void OnPagesAdded (int index, Page [] pages)
        {
            foreach (var page in pages) {
                store.InsertWithValues (index, store.GetValuesForPage (page));
            }

            UpdateAllPages ();
            Refresh ();
        }

        void OnPagesChanged (Page [] pages)
        {
            Refresh ();
        }

        void OnPagesRemoved (Page [] pages)
        {
            foreach (var page in pages) {
                var iter = store.GetIterForPage (page);
                if (!TreeIter.Zero.Equals (iter)) {
                    store.Remove (ref iter);
                }
            }

            UpdateAllPages ();
            Refresh ();
        }

        void OnPagesMoved ()
        {
            UpdateAllPages ();
            Refresh ();
        }

        void Refresh ()
        {
            if (!zoom_manually_set) {
                ZoomFit ();
            }

            RefreshSelection ();
        }

        void UpdateAllPages ()
        {
            foreach (var page in document.Pages) {
                var iter = store.GetIterForPage (page);
                if (!TreeIter.Zero.Equals (iter)) {
                    store.UpdateForPage (iter, page);
                    store.EmitRowChanged (store.GetPath (iter), iter);
                }
            }
        }

        #endregion

        bool zoom_manually_set;
        public void Zoom (int pixels)
        {
            Zoom (pixels, false);
        }

        public void Zoom (int pixels, bool absolute)
        {
            CanZoomIn = CanZoomOut = true;

            if (!zoom_manually_set) {
                zoom_manually_set = true;
                (app.Actions["ZoomFit"] as ToggleAction).Active = false;
            }

            int new_width = absolute ? pixels : ItemSize + pixels;
            if (new_width <= MIN_WIDTH) {
                CanZoomOut = false;
                new_width = MIN_WIDTH;
            } else if (new_width >= MAX_WIDTH) {
                CanZoomIn = false;
                new_width = MAX_WIDTH;
            }

            if (ItemSize == new_width) {
                return;
            }

            SetItemSize (new_width);

            var handler = ZoomChanged;
            if (handler != null) {
                handler ();
            }
        }

        int last_zoom, before_last_zoom;
        public void ZoomFit ()
        {
            if (document == null)
                return;

            if ((app.Actions["ZoomFit"] as ToggleAction).Active == false)
                return;

            zoom_manually_set = false;
            // Try to fit all pages into the view, with a minimum size
            var n = (double)document.Count;
            var width = (double)(Parent.Allocation.Width - 2 * (Margin + BorderWidth + 8)); // HACK this + 8 is total hack
            var height = (double)(Parent.Allocation.Height - 2 * (Margin + BorderWidth + 8)); // same

            var n_across = (int)Math.Ceiling (Math.Sqrt (width * n / height));
            var best_width = (int)Math.Floor ((width - (n_across + 1)*ColumnSpacing - n_across*2*FocusLineWidth) / n_across);

            // restrict to min/max
            best_width = Math.Min (MAX_WIDTH, Math.Max (MIN_WIDTH, best_width));

            if (best_width == ItemSize) {
                return;
            }

            // Total hack to avoid infinite SizeAllocate/ZoomFit loop
            if (best_width == before_last_zoom || best_width == last_zoom) {
                return;
            }

            before_last_zoom = last_zoom;
            last_zoom = ItemSize;

            SetItemSize (best_width);
            CanZoomOut = ItemSize > MIN_WIDTH;
            CanZoomIn  = ItemSize < MAX_WIDTH;

            var handler = ZoomChanged;
            if (handler != null) {
                handler ();
            }
        }

        public int ItemSize {
            get { return page_renderer.ItemSize; }
            set { page_renderer.ItemSize = value; }
        }

        private void SetItemSize (int w)
        {
            ItemSize = w;

            // HACK trigger gtk_icon_view_invalidate_sizes and queue_layout
            Orientation = Orientation.Horizontal;
            Orientation = Orientation.Vertical;
        }

        #region Selection

        string selection_match_query;
        public void SetSelectionMatchQuery (string query)
        {
            selection_match_query = query;
            SetPageSelectionMode (PageSelectionMode.Matching);
        }

        public void SetPageSelectionMode (PageSelectionMode mode)
        {
            page_selection_mode = mode;
            RefreshSelection ();
        }

        bool refreshing_selection;
        void RefreshSelection ()
        {
            refreshing_selection = true;

            if (page_selection_mode == PageSelectionMode.All) {
                SelectAll ();
            } else if (page_selection_mode != PageSelectionMode.None) {
                List<Page> matches = null;
                if (page_selection_mode == PageSelectionMode.Matching) {
                    matches = new List<Page> (app.Document.FindPagesMatching (selection_match_query));
                }

                int i = 1;
                foreach (var iter in store.TreeIters) {
                    var path = store.GetPath (iter);
                    bool select = false;

                    switch (page_selection_mode) {
                        case PageSelectionMode.Evens:
                            select = (i % 2) == 0;
                            break;
                        case PageSelectionMode.Odds:
                            select = (i % 2) == 1;
                            break;
                        case PageSelectionMode.Matching:
                            select = matches.Contains (store.GetValue (iter, PageListStore.PageColumn) as Page);
                            break;
                        case PageSelectionMode.Inverse:
                            select = !PathIsSelected (path);
                            break;
                    }

                    if (select) {
                        SelectPath (path);
                    } else {
                        UnselectPath (path);
                    }
                    i++;
                }
            }

            refreshing_selection = false;
            QueueDraw ();
        }

        #endregion
    }
}