Publicate/src/Editors/MarkdownEditor.vala

using Gtk;
using Adw;
using GtkCommonMark;

namespace Publicate.Editors {

    public class MarkdownEditor : Box, EditorWidget, Savable {

        private Paned paned_view;

        private Box toolbar;
        private GtkCommonMark.MarkdownView? markdown_view = null;
        private GtkSource.View text_view;
        private GtkSource.Buffer source_buffer;
        private GtkSource.LanguageManager language_manager;
        private GtkSource.StyleSchemeManager style_manager;
        
        private ScrolledWindow source_scroller;
        private ScrolledWindow? markdown_scroller = null;

        private ViewerWindow window;
        private TabPage page;

        private DropDown style_selector;
        private ToggleButton bold_button;
        private ToggleButton italic_button;
        private Button insert_link;
        private Button insert_image;
        private ToggleButton preview_button;

        private const string STYLE_HEADING_1 = "Heading 1";
        private const string STYLE_HEADING_2 = "Heading 2";
        private const string STYLE_HEADING_3 = "Heading 3";
        private const string STYLE_HEADING_4 = "Heading 4";
        private const string STYLE_HEADING_5 = "Heading 5";
        private const string STYLE_HEADING_6 = "Heading 6";
        private const string STYLE_QUOTATION = "Quotation";
        private const string STYLE_PREFORMATTED = "Preformatted";
        private const string STYLE_PARAGRAPH = "Paragraph";

        private Spelling.Checker spell_checker;
        private Spelling.TextBufferAdapter spell_adapter;
        private bool inhibit_toolbar_updates = false;

        private Gee.HashMap<string, Gdk.Pixbuf> pixbuf_cache = new Gee.HashMap<string, Gdk.Pixbuf>();

        public Adw.TabPage tab_page { get {
            return page;
        } }

        public string asset_name { get{
            return asset.name;
        } }


        private bool unsaved = false;
        public bool has_unsaved_changes { get{
            return unsaved;
        } }


        private Ppub.Asset asset;

        public MarkdownEditor(ViewerWindow win, TabView tab_view) {
            window = win;
            orientation = Orientation.VERTICAL;

            source_scroller = new ScrolledWindow ();
            paned_view = new Paned(Orientation.HORIZONTAL);

            text_view = new GtkSource.View ();
            language_manager = new GtkSource.LanguageManager ();
            style_manager = new GtkSource.StyleSchemeManager();
            text_view.monospace = true;
            text_view.show_line_numbers = true;
            text_view.auto_indent = true;
            source_buffer = (GtkSource.Buffer) text_view.buffer;
            language_manager.append_search_path("/usr/share/publicate/gtk-source-view");
            source_buffer.language = language_manager.get_language("ppub-markdown");
            text_view.hexpand = true;
            text_view.set_wrap_mode (WrapMode.WORD_CHAR);
            text_view.top_margin = 18;
            text_view.bottom_margin = 18;
            text_view.left_margin = 18;
            text_view.right_margin = 18;
            text_view.buffer.changed.connect (() => update_preview());

            spell_checker = Spelling.Checker.get_default();
            spell_adapter = new Spelling.TextBufferAdapter(source_buffer, spell_checker);
            text_view.set_extra_menu(spell_adapter.get_menu_model());
            text_view.insert_action_group("spelling", spell_adapter);

            spell_adapter.set_enabled(true);

            source_scroller.set_policy (PolicyType.NEVER, PolicyType.AUTOMATIC);
            source_scroller.vexpand = true;
            source_scroller.vadjustment.value_changed.connect(sync_scroll);
            source_scroller.child = text_view;
            

            var source_box = new Box(Orientation.VERTICAL, 0);
            source_box.append(source_scroller);
            paned_view.start_child = source_box;

            Gtk.Settings.get_default().notify["gtk-application-prefer-dark-theme"].connect(() => configure_tags());
            configure_tags();

            toolbar = new Box(Orientation.HORIZONTAL, 8);
            toolbar.margin_start = 8;
            toolbar.margin_end = 8;
            toolbar.margin_top = 8;
            toolbar.margin_bottom = 8;
            style_selector = new DropDown.from_strings(new string[] {STYLE_HEADING_1, STYLE_HEADING_2, STYLE_HEADING_3, STYLE_HEADING_4, STYLE_HEADING_5, STYLE_HEADING_6, STYLE_QUOTATION, STYLE_PREFORMATTED, STYLE_PARAGRAPH});
            toolbar.append(style_selector);
            bold_button = new ToggleButton();
            bold_button.child = new Image.from_icon_name("format-text-bold-symbolic");
            bold_button.tooltip_text = "Bold";
            bold_button.clicked.connect(() => toggle_bold());
            toolbar.append(bold_button);
            italic_button = new ToggleButton();
            italic_button.child = new Image.from_icon_name("format-text-italic-symbolic");
            italic_button.tooltip_text = "Italic";
            italic_button.clicked.connect(() => toggle_italic());
            toolbar.append(italic_button);
            insert_link = new Button.from_icon_name("insert-link-symbolic");
            insert_link.tooltip_text = "Insert link";
            insert_link.hexpand = true;
            insert_link.halign = Align.END;
            insert_link.clicked.connect(() => insert_link_clicked());
            toolbar.append(insert_link);
            insert_image = new Button.from_icon_name("insert-image-symbolic");
            insert_image.tooltip_text = "Insert image";
            insert_image.clicked.connect(() => insert_image_clicked());
            toolbar.append(insert_image);
            preview_button = new ToggleButton();
            preview_button.child = new Image.from_icon_name("view-dual-symbolic");
            preview_button.tooltip_text = "Markdown Preview";
            preview_button.active = true;
            preview_button.clicked.connect(() => toggle_preview());
            toolbar.append(preview_button);
            source_box.append(toolbar);

            source_buffer.cursor_moved.connect(() => update_toolbar());
            source_buffer.highlight_updated.connect(() => update_toolbar());
            append(paned_view);
            initialise_preview();

            page = tab_view.add_page (this, null);
        }

        private void initialise_preview() {
            markdown_scroller = new ScrolledWindow ();
            markdown_scroller.set_policy (PolicyType.NEVER, PolicyType.AUTOMATIC);
            markdown_scroller.vexpand = true;

            markdown_view = new GtkCommonMark.MarkdownView ();
            markdown_view.hexpand = true;
            markdown_view.set_wrap_mode (WrapMode.WORD_CHAR);
            markdown_view.widget_embedded.connect(widget_embedded);
            
            markdown_scroller.child = markdown_view;
            //  markdown_scroller.hadjustment.changed.connect(() => sync_scroll());
            paned_view.end_child = markdown_scroller;
            set_leaflet_size();
            configure_tags();
        }

        private void destruct_preview() {
            paned_view.end_child = null;
            markdown_scroller = null;
            markdown_view = null;
        }

        public void set_zoom_percentage (int percent) {
            if(markdown_view != null) {
                var scale = (float)percent / 100f;
                markdown_view.tag_manager.font_scale = scale;
            }
        }
        
        public async void load_asset (Ppub.Publication publication, Ppub.Asset asset) {
            if(markdown_view != null) {
                markdown_view.buffer.set_text("", 0);
            }
            page.title = asset.name;
            this.asset = asset;

            text_view.buffer.set_text("", 0);
            MemoryOutputStream os = new MemoryOutputStream (null, GLib.realloc, GLib.free);
            yield os.splice_async (publication.read_asset (asset.name), OutputStreamSpliceFlags.CLOSE_SOURCE | OutputStreamSpliceFlags.CLOSE_TARGET);
            var text = os.steal_data ();
            text.length = (int) os.get_data_size ();

            text_view.buffer.set_text ((string)text, text.length);
            set_tab_name(false);

            Timeout.add_once(100, () => set_leaflet_size());
        }

        private void set_leaflet_size() {
            paned_view.position = int.max(300, paned_view.get_width() / 2);
        }

        public void save_asset(Ppub.Builder builder) {
            var article_data = get_text().to_utf8();
            var article_stream = new MemoryInputStream.from_data((uint8[])article_data);
            var compression_info = new Ppub.CompressionInfo(article_stream);
            article_stream.seek(0, SeekType.SET);

            builder.add_asset(asset.name, asset.mimetype, article_stream, Invercargill.Iterate.nothing<string>(), compression_info);
            set_tab_name(false);
        }

        protected async void widget_embedded(GtkCommonMark.MarkdownViewEmbeddedWidgetHost widget, string file, string title) {
            var image = new Gtk.Picture();
            image.content_fit = Gtk.ContentFit.FILL;
            widget.append (image);

            Gdk.Pixbuf pixbuf;
            if(pixbuf_cache.has_key(file)) {
                pixbuf = pixbuf_cache[file];
            }
            else {
                pixbuf = yield new Gdk.Pixbuf.from_stream_async (window.publication.read_asset (file), null);
                pixbuf_cache.set(file, pixbuf);
            }

            image.set_pixbuf (pixbuf);

            widget.available_width_changed.connect(wid => {
                image.width_request = wid;
                var ratio = image.get_paintable().get_intrinsic_aspect_ratio ();
                image.height_request = (int)(wid / ratio);
            });

            image.destroy.connect(() => print("IT gone\n"));
        }


        private void configure_tags() {
            var link = new LinkButton("");
            if(markdown_view != null) {
                markdown_view.tag_manager.update_link_colour(link.get_color());
            }

            if(Gtk.Settings.get_default().gtk_application_prefer_dark_theme) {
                source_buffer.style_scheme = style_manager.get_scheme("Adwaita-dark");
            }
            else {
                source_buffer.style_scheme = style_manager.get_scheme("Adwaita");
            }
        }

        private void update_preview(bool changes = true) {
            if(changes) {
                set_tab_name(true);
            }
            if(markdown_view == null) {
                return;
            }
            var text = get_text();
            markdown_view.buffer.set_text("", 0);
            markdown_view.load_from_string((string)text);
        }

        public string get_text() {
            TextIter start_iter;
            TextIter end_iter;
            text_view.buffer.get_start_iter (out start_iter);
            text_view.buffer.get_end_iter (out end_iter);

            var text = text_view.buffer.get_text (start_iter, end_iter, true);
            return text;
        }

        private void sync_scroll() {
            if(markdown_scroller != null) {
                set_scroll_from_frac(markdown_scroller, get_scroll_frac(source_scroller));
            }
        }

        private static double get_scroll_frac(ScrolledWindow scroller) {
            return (scroller.vadjustment.value/(scroller.vadjustment.upper - scroller.vadjustment.page_size));
        }

        private void set_scroll_from_frac(ScrolledWindow scroller, double frac) {
            scroller.vadjustment.value = (scroller.vadjustment.upper - scroller.vadjustment.page_size)*frac;
        }

        private void set_tab_name(bool unsaved) {
            this.unsaved = unsaved;
            if(unsaved) {
                tab_page.title = @"⏺  $(asset.name)";
            }
            else {
                tab_page.title = asset.name;
            }
        }

        private void update_toolbar() {
            if(inhibit_toolbar_updates) {
                print("Toolbar update inhibited\n");
                return;
            }
            TextIter iter_start;
            TextIter iter_end;
            source_buffer.get_iter_at_offset(out iter_start, source_buffer.cursor_position);

            var multi_line = false;
            if(source_buffer.has_selection) {
                source_buffer.get_selection_bounds(out iter_start, out iter_end);
                multi_line = (iter_start.get_line() != iter_end.get_line());
            }

            var classes = Invercargill.Wrap.array<string>(source_buffer.get_context_classes_at_iter(iter_start));

            // Disable formatting changes if the selection is over many lines or the "no-format" class is applied
            toolbar.sensitive = !multi_line && !classes.any(c => c == "no-format");

            print(@"$(classes.to_string(s => s, " "))\n");
            
            set_line_style_type_in_dropdown(get_line_style_from_buffer());

            bold_button.active = classes.any(c => c == "b");
            italic_button.active = classes.any(c => c == "i");
        }

        private int get_line_style_from_buffer() {
            TextIter iter;
            source_buffer.get_iter_at_offset(out iter, source_buffer.cursor_position);
            if(iter.ends_line()) {
                iter.backward_char();
            }
            var classes = Invercargill.Wrap.array<string>(source_buffer.get_context_classes_at_iter(iter));
            var heading = classes.first_or_default(c => c.has_prefix("h") && c.length == 2);
            if(heading != null) {
                var level = int.parse(heading[1:2]);
                return level - 1;
            }
            else if(classes.any(c => c == "quot")) {
                return 6;
            }
            else if(classes.any(c => c == "pre")) {
                return 7;
            }
            return 8;
        }

        private void remove_line_style() {
            TextIter iter;
            source_buffer.get_iter_at_offset(out iter, source_buffer.cursor_position);
            if(iter.ends_line()) {
                iter.backward_char();
            }
            var classes = Invercargill.Wrap.array<string>(source_buffer.get_context_classes_at_iter(iter));
            var line_no = iter.get_line();

            var heading = classes.first_or_default(c => c.has_prefix("h") && c.length == 2);
            if(heading != null) {
                var level = int.parse(heading[1:2]);
                source_buffer.get_iter_at_line(out iter, line_no);
                iter.forward_chars(level+1);
                for(int i = 0; i <= level; i++) {
                    source_buffer.backspace(ref iter, false, true);
                }
            }
            else if(classes.any(c => c == "quot")) {
                source_buffer.get_iter_at_line(out iter, line_no);
                iter.forward_chars(2);
                source_buffer.backspace(ref iter, false, true);
                source_buffer.backspace(ref iter, false, true);
            }
        }

        private void set_line_style_type_in_dropdown(uint type) {
            style_selector.notify["selected"].disconnect(set_line_style);
            style_selector.selected = type;
            style_selector.notify["selected"].connect(set_line_style);
        }

        private void set_line_style() {
            var style = style_selector.selected;
            inhibit_toolbar_updates = true;
            source_buffer.begin_user_action();
            remove_line_style();

            print(@"Set style $style\n");
            if(style < 6) {
                // Headings
                format_line_heading(style + 1);
            }
            else if(style == 6) {
                format_line_quote();
            }
            else if(style == 7) {
                format_line_preformatted();
            }

            set_line_style_type_in_dropdown(style);
            inhibit_toolbar_updates = false;
            source_buffer.end_user_action();
        }

        private void format_line_heading(uint level) {
            TextIter iter;
            source_buffer.get_iter_at_offset(out iter, source_buffer.cursor_position);
            var line_no = iter.get_line();
            source_buffer.get_iter_at_line(out iter, line_no);
            for(var i = 0; i < level; i++) {
                source_buffer.insert(ref iter, "#", 1);
            }
            source_buffer.insert(ref iter, " ", 1);
            iter.forward_line();
            iter.backward_char();
            source_buffer.place_cursor(iter);
        }

        private void format_line_quote() {
            TextIter iter;
            source_buffer.get_iter_at_offset(out iter, source_buffer.cursor_position);
            var line_no = iter.get_line();
            source_buffer.get_iter_at_line(out iter, line_no);
            source_buffer.insert(ref iter, "> ", 2);
            iter.forward_line();
            iter.backward_char();
            source_buffer.place_cursor(iter);
        }

        private void format_line_preformatted() {
            TextIter iter;
            source_buffer.get_iter_at_offset(out iter, source_buffer.cursor_position);
            var line_no = iter.get_line();
            source_buffer.get_iter_at_line(out iter, line_no);
            source_buffer.insert(ref iter, "```\n", 4);
            iter.forward_line();
            iter.backward_char();
            source_buffer.insert(ref iter, "\n```", 4);
            iter.forward_line();
            iter.backward_chars(5);
            source_buffer.place_cursor(iter);
        }

        private void format_text_bold() {
            TextIter iter_start;
            TextIter iter_end;
            if(source_buffer.has_selection) {
                source_buffer.get_selection_bounds(out iter_start, out iter_end);
            }
            else {
                source_buffer.get_iter_at_offset(out iter_start, source_buffer.cursor_position);
                source_buffer.get_iter_at_offset(out iter_end, source_buffer.cursor_position);
                if(!iter_start.starts_word()) {
                    iter_start.backward_word_start();
                }
                if(!iter_end.ends_word()) {
                    iter_end.forward_word_end();
                }
            }

            var difference = iter_end.get_offset() - iter_start.get_offset();
            source_buffer.insert(ref iter_start, "**", 2);
            iter_start.forward_chars(difference);
            source_buffer.insert(ref iter_start, "**", 2);
        }

        private void format_text_unbold() {
            TextIter iter;
            source_buffer.get_iter_at_offset(out iter, source_buffer.cursor_position);
            source_buffer.iter_forward_to_context_class_toggle(ref iter, "b");
            var end_pos = iter.get_offset();
            source_buffer.iter_backward_to_context_class_toggle(ref iter, "b");
            iter.forward_chars(2);
            source_buffer.backspace(ref iter, false, true);
            source_buffer.backspace(ref iter, false, true);
            iter.set_offset(end_pos-2);
            source_buffer.backspace(ref iter, false, true);
            source_buffer.backspace(ref iter, false, true);
        }

        private void toggle_bold() {
            source_buffer.begin_user_action();
            if(!bold_button.active) {
                format_text_unbold();
            }
            else {
                format_text_bold();
            }
            source_buffer.end_user_action();
        }

        private void format_text_italic() {
            TextIter iter_start;
            TextIter iter_end;
            if(source_buffer.has_selection) {
                source_buffer.get_selection_bounds(out iter_start, out iter_end);
            }
            else {
                source_buffer.get_iter_at_offset(out iter_start, source_buffer.cursor_position);
                source_buffer.get_iter_at_offset(out iter_end, source_buffer.cursor_position);
                if(!iter_start.starts_word()) {
                    iter_start.backward_word_start();
                }
                if(!iter_end.ends_word()) {
                    iter_end.forward_word_end();
                }
            }

            var difference = iter_end.get_offset() - iter_start.get_offset();
            source_buffer.insert(ref iter_start, "*", 1);
            iter_start.forward_chars(difference);
            source_buffer.insert(ref iter_start, "*", 1);
        }

        private void format_text_unitalic() {
            TextIter iter;
            source_buffer.get_iter_at_offset(out iter, source_buffer.cursor_position);
            source_buffer.iter_forward_to_context_class_toggle(ref iter, "i");
            var end_pos = iter.get_offset();
            source_buffer.iter_backward_to_context_class_toggle(ref iter, "i");
            iter.forward_chars(1);
            source_buffer.backspace(ref iter, false, true);
            iter.set_offset(end_pos-1);
            source_buffer.backspace(ref iter, false, true);
        }

        private void toggle_italic() {
            source_buffer.begin_user_action();
            if(!italic_button.active) {
                format_text_unitalic();
            }
            else {
                format_text_italic();
            }
            source_buffer.end_user_action();
        }

        private void insert_link_clicked() {
            string selected = null;
            if(source_buffer.has_selection) {
                TextIter iter_start;
                TextIter iter_end;
                source_buffer.get_selection_bounds(out iter_start, out iter_end);
                selected = iter_start.get_text(iter_end);
            }

            var win = new AddLinkWindow(selected);
            win.insert_link.connect(link_insert);
            win.set_transient_for(window);
            win.modal = true;
            win.present();
        }

        private void link_insert(string url, string? label) {
            TextIter iter;
            source_buffer.begin_user_action();
            if(source_buffer.has_selection) {
                TextIter iter_end;
                source_buffer.get_selection_bounds(out iter, out iter_end);
                source_buffer.delete(ref iter, ref iter_end);
            }
            else {
                source_buffer.get_iter_at_offset(out iter, source_buffer.cursor_position);
            }
            var link = "";
            if(label != null) {
                link = @"[$label]($url)";
            }
            else {
                link = @"<$url>";
            }
            source_buffer.insert(ref iter, link, link.length);
            source_buffer.end_user_action();
        }

        private void insert_image_clicked() {
            string selected = null;
            if(source_buffer.has_selection) {
                TextIter iter_start;
                TextIter iter_end;
                source_buffer.get_selection_bounds(out iter_start, out iter_end);
                selected = iter_start.get_text(iter_end);
            }

            var win = new AddImageWindow(selected, window);
            win.insert_image.connect(image_insert);
            win.set_transient_for(window);
            win.modal = true;
            win.present();
        }

        private void image_insert(string url, string label) {
            TextIter iter;
            source_buffer.begin_user_action();
            if(source_buffer.has_selection) {
                TextIter iter_end;
                source_buffer.get_selection_bounds(out iter, out iter_end);
                source_buffer.delete(ref iter, ref iter_end);
            }
            else {
                source_buffer.get_iter_at_offset(out iter, source_buffer.cursor_position);
            }
            var link = @"![$label]($url)";
            source_buffer.insert(ref iter, link, link.length);
            source_buffer.end_user_action();
        }

        private void toggle_preview() {
            if(preview_button.active) {
                initialise_preview();
                update_preview(false);
            }
            else {
                destruct_preview();
            }
        }
        
    }

    public class AddLinkWindow : Adw.Window {

        public signal void insert_link(string url, string? text);
        private EntryRow url_entry;
        private EntryRow text_entry;

        public AddLinkWindow(string? text) {

            title = "Insert link";
            var box = new Box(Orientation.VERTICAL, 18);
            var header = new Adw.HeaderBar();
            header.show_end_title_buttons = false;
            box.append(header);

            var insert_button = new Button.with_label("Insert");
            var cancel_button = new Button.with_label("Cancel");
            insert_button.add_css_class("suggested-action");
            insert_button.clicked.connect(() => insert());
            cancel_button.clicked.connect(() => close());
            header.pack_start(cancel_button);
            header.pack_end(insert_button);

            var group = new PreferencesGroup();
            group.width_request = 400;
            group.title = "Link properties";
            group.margin_bottom = 18;
            group.margin_end = 18;
            group.margin_start = 18;

            url_entry = new EntryRow ();
            url_entry.title = "URI";
            group.add(url_entry);

            text_entry = new EntryRow ();
            text_entry.title = "Label (optional)";
            group.add(text_entry);

            if(text != null) {
                try {
                    Uri.is_valid(text, UriFlags.NONE);
                    url_entry.text = text;
                }
                catch (Error e) {
                    text_entry.text = text;
                }
            }

            box.append(group);
            content = box;
        }

        private void insert() {
            string text = null;
            if(text_entry.text.chomp().chug() != "" || text_entry.text == url_entry.text) {
                text = text_entry.text;
            }
            insert_link(url_entry.text, text);
            close();
        }

    }

    public class AddImageWindow : Adw.Window {

        public signal void insert_image(string url, string text);
        private FileChooserRow file_entry;
        private EntryRow text_entry;

        public AddImageWindow(string? text, ViewerWindow win) {

            title = "Insert link";
            var box = new Box(Orientation.VERTICAL, 18);
            var header = new Adw.HeaderBar();
            header.show_end_title_buttons = false;
            box.append(header);

            var insert_button = new Button.with_label("Insert");
            var cancel_button = new Button.with_label("Cancel");
            insert_button.add_css_class("suggested-action");
            insert_button.clicked.connect(() => insert());
            cancel_button.clicked.connect(() => close());
            header.pack_start(cancel_button);
            header.pack_end(insert_button);

            var group = new PreferencesGroup();
            group.width_request = 400;
            group.title = "Link properties";
            group.margin_bottom = 18;
            group.margin_end = 18;
            group.margin_start = 18;

            file_entry = new FileChooserRow(win);
            file_entry.title = "Image file";
            file_entry.set_assets(win.publication.assets.where(a => a.mimetype.has_prefix ("image/")));
            group.add(file_entry);

            text_entry = new EntryRow ();
            text_entry.title = "Image description";
            group.add(text_entry);

            if(text != null) {
                text_entry.text = text;
            }

            box.append(group);
            content = box;
        }

        private void insert() {
            insert_image(file_entry.selected_asset, text_entry.text);
            close();
        }

    }
}