work on UI components

This commit introduces some HTML and javascript (and tests for it) to use in constructing the new UI. This is partial work that is not yet finished.

9 files changed, 766 insertions, 67 deletions

diff --git a/html/DOM_helpers.js b/html/DOM_helpers.js
index 55320cb..88092e5 100644
--- a/html/DOM_helpers.js
+++ b/html/DOM_helpers.js
@@ -70,7 +70,7 @@ function clone_template(template_id)
 
     while (to_process.length > 0) {
 	const element = to_process.pop();
-	const template_key = element.getAttribute("data-template");
+	let template_key = element.getAttribute("data-template") || element.id;
 
 	if (template_key)
 	    result_object[template_key] = element;
diff --git a/html/base.css b/html/base.css
index dde50e7..6085f5f 100644
--- a/html/base.css
+++ b/html/base.css
@@ -34,101 +34,51 @@ body {
     overflow: auto;
 }
 
-.bold, h2 {
+.bold, h1, h2, h3 {
     font-weight: bold;
 }
 
+h1, h2, h3 {
+    margin: 0.3em;
+    text-shadow: 0 0 0 #454;
+}
+
 h2 {
-    margin: 8px;
     font-size: 120%;
 }
 
 h3 {
-    padding: 5px;
     font-size: 108%;
-    text-shadow: 0 0 0 #454;
 }
 
-textarea {
-    font-family: monospace;
+li {
+    margin-top: 0.25em;
+    margin-bottom: 0.25em;
 }
 
-input[type="checkbox"], input[type="radio"], .hide {
-    display: none;
-}
-
-.camouflage {
-    visibility: hidden;
+li:first-child {
+    margin-top: 0;
 }
 
-.show_next:not(:checked)+* {
+.hide {
     display: none;
 }
 
-.show_hide_next2:not(:checked)+* {
-    display: none;
-}
-
-.show_hide_next2:checked+*+* {
-    display: none;
-}
-
-button, .button {
+button {
     background-color: #4CAF50;
     border: none;
-    border-radius: 8px;
+    border-radius: 0.4em;
     color: white;
     text-align: center;
     text-decoration: none;
     display: inline-block;
-    padding: 6px 12px;
-    margin: 2px 0px;
+    padding: 0.4em 0.8em;
     -moz-user-select: none;
     user-select: none;
     cursor: pointer;
-    font: 400 15px sans-serif;
-}
-
-button.slimbutton, .button.slimbutton {
-    padding: 2px 4px;
-    margin: 0;
+    font: 400 0.9em sans-serif;
 }
 
 button:hover, .button:hover {
     box-shadow: 0 6px 8px 0 rgba(0,0,0,0.24), 0 17px 50px 0 rgba(0,0,0,0.19);
 }
-
-aside {
-    background: #3f8dc6;
-    margin: 5px 0;
-    padding: 0.3em 1em;
-    border-radius: 3px;
-    color: #fff;
-}
-
-textarea: {
-    resize: none;
-}
-
-.has_bottom_line::after, .has_upper_line::before {
-    content: "";
-    display: block;
-    height: 8px;
-    background: linear-gradient(transparent, #555);
-}
-
-.has_bottom_line::after {
-    background: linear-gradient(#555, transparent);
-}
-
-.has_bottom_thin_line {
-    border-bottom: dashed #4CAF50 1px;
-}
-
-.has_upper_thin_line {
-    border-top: dashed #4CAF50 1px;
-}
-
-.nowrap {
-    white-space: nowrap;
-}
diff --git a/html/dialog.html b/html/dialog.html
new file mode 100644
index 0000000..d4e69b9
--- /dev/null
+++ b/html/dialog.html
@@ -0,0 +1,72 @@
+#IF !DIALOG_LOADED
+#DEFINE DIALOG_LOADED
+<!--
+    SPDX-License-Identifier: GPL-3.0-or-later OR CC-BY-SA-4.0
+
+    Show an error/info/question dalog.
+
+    This file is part of Haketilo.
+
+    Copyright (C) 2022 Wojtek Kosior <koszko@koszko.org>
+
+    File is dual-licensed. You can choose either GPLv3+, CC BY-SA or both.
+
+    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 3 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, see <https://www.gnu.org/licenses/>.
+
+    I, Wojtek Kosior, thereby promise not to sue for violation of this file's
+    licenses. Although I request that you do not make use of this code in a
+    proprietary program, I am not going to enforce this in court.
+  -->
+
+<!--
+    This is not a standalone page. This file is meant to be imported into other
+    HTML code.
+  -->
+
+#LOADCSS html/reset.css
+#LOADCSS html/base.css
+<style>
+  .left_space {
+      margin-left: 3em;
+  }
+  .right_space {
+      margin-right: 3em;
+  }
+  .dialog_buts {
+      margin-right: auto;
+      margin-left: auto;
+      max-width: -moz-fit-content;
+      max-width: fit-content;
+  }
+  .dialog_msg {
+      margin-bottom: 2em;
+      text-align: center;
+  }
+  .dialog_main_div {
+      margin: 1.4em;
+  }
+</style>
+<template>
+  <div id="dialog" data-template="main_div" class="dialog_main_div">
+    <div data-template="msg" class="dialog_msg"></div>
+    <div data-template="ask_buts" class="dialog_buts">
+      <button data-template="yes_but" class="right_space">Yes</button>
+      <button data-template="no_but" class="left_space">No</button>
+    </div>
+    <div data-template="conf_buts" class="dialog_buts">
+      <button data-template="ok_but">Ok</button>
+    </div>
+  </div>
+</template>
+#ENDIF
diff --git a/html/dialog.js b/html/dialog.js
new file mode 100644
index 0000000..6345b2d
--- /dev/null
+++ b/html/dialog.js
@@ -0,0 +1,112 @@
+/**
+ * This file is part of Haketilo.
+ *
+ * Function: Showing and error/info/confirmation dialog.
+ *
+ * Copyright (C) 2022 Wojtek Kosior
+ *
+ * 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 3 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.
+ *
+ * As additional permission under GNU GPL version 3 section 7, you
+ * may distribute forms of that code without the copy of the GNU
+ * GPL normally required by section 4, provided you include this
+ * license notice and, in case of non-source distribution, a URL
+ * through which recipients can access the Corresponding Source.
+ * If you modify file(s) with this exception, you may extend this
+ * exception to your version of the file(s), but you are not
+ * obligated to do so. If you do not wish to do so, delete this
+ * exception statement from your version.
+ *
+ * As a special exception to the GPL, any HTML file which merely
+ * makes function calls to this code, and for that purpose
+ * includes it by reference shall be deemed a separate work for
+ * copyright law purposes. If you modify this code, you may extend
+ * this exception to your version of the code, but you are not
+ * obligated to do so. If you do not wish to do so, delete this
+ * exception statement from your version.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ *
+ * I, Wojtek Kosior, thereby promise not to sue for violation of this file's
+ * license. Although I request that you do not make use of this code in a
+ * proprietary program, I am not going to enforce this in court.
+ */
+
+#FROM html/DOM_helpers.js IMPORT clone_template
+#FROM common/lock.js IMPORT make_lock, lock, unlock
+
+function make(on_dialog_show, on_dialog_hide)
+{
+    const dialog_context = clone_template("dialog");
+    Object.assign(dialog_context, {
+	on_dialog_show,
+	on_dialog_hide,
+	shown: false,
+	queue: 0,
+	lock: make_lock(),
+	callback: null
+    });
+
+    for (const [id, val] of [["yes", true], ["no", false], ["ok", undefined]]) {
+	const but = dialog_context[`${id}_but`];
+	but.haketilo_dialog_result = val;
+	but.addEventListener("click", e => close_dialog(dialog_context, e));
+    }
+
+    return dialog_context;
+}
+#EXPORT make
+
+function close_dialog(dialog_context, event)
+{
+    if (dialog_context.queue > 0)
+	dialog_context.callback(event.target.haketilo_dialog_result);
+}
+
+async function show_dialog(dialog_context, shown_buts_id, msg)
+{
+    dialog_context.queue++;
+
+    if (!dialog_context.shown) {
+	dialog_context.shown = true;
+	dialog_context.on_dialog_show();
+    }
+
+    await lock(dialog_context.lock);
+
+    dialog_context.msg.innerText = msg;
+    for (const buts_id of ["ask_buts", "conf_buts"]) {
+	const action = buts_id == shown_buts_id ? "remove" : "add";
+	dialog_context[buts_id].classList[action]("hide");
+    }
+
+    const result = await new Promise(cb => dialog_context.callback = cb);
+
+    if (--dialog_context.queue == 0) {
+	dialog_context.shown = false;
+	dialog_context.on_dialog_hide();
+    }
+
+    unlock(dialog_context.lock);
+
+    return result;
+}
+
+const error = (ctx, msg) => show_dialog(ctx, "conf_buts", msg);
+#EXPORT error
+
+/* info() and error() are the same for now, we might later change that. */
+const info = error;
+#EXPORT info
+
+const ask = (ctx, msg) => show_dialog(ctx, "ask_buts", msg);
+#EXPORT ask
diff --git a/html/grid.css b/html/grid.css
new file mode 100644
index 0000000..59b5bb7
--- /dev/null
+++ b/html/grid.css
@@ -0,0 +1,75 @@
+/*
+ * SPDX-License-Identifier: GPL-3.0-or-later OR CC-BY-SA-4.0
+ *
+ * Styling for use with `display: grid`.
+ *
+ * This file is part of Haketilo.
+ *
+ * Copyright (C) 2022 Wojtek Kosior <koszko@koszko.org>
+ *
+ * File is dual-licensed. You can choose either GPLv3+, CC BY-SA or both.
+ *
+ * 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 3 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, see <https://www.gnu.org/licenses/>.
+ *
+ * I, Wojtek Kosior, thereby promise not to sue for violation of this file's
+ * licenses. Although I request that you do not make use of this code in a
+ * proprietary program, I am not going to enforce this in court.
+ */
+
+.grid_2 {
+    display: grid;
+    grid-template-columns: 1fr 1fr;
+}
+
+.grid_col_1 {
+    grid-column: 1 / span 1;
+}
+
+.grid_col_2 {
+    grid-column: 2 / span 1;
+}
+
+.grid_col_both {
+    grid-column: 1 / span 2;
+}
+
+span.grid_col_1 {
+    text-align: right;
+}
+
+.grid_col_both {
+    text-align: center;
+}
+
+div.grid_col_both {
+    text-align: initial;
+}
+
+.grid_2>span {
+    margin-top: 0.75em;
+}
+
+.grid_form>span {
+    margin-top: 1.5em;
+    margin-left: 1em;
+    margin-right: 1em;
+}
+
+.grid_form>span {
+    font-weight: bold;
+}
+
+span.grid_col_2 {
+    font-weight: initial;
+}
diff --git a/html/item_list.html b/html/item_list.html
new file mode 100644
index 0000000..41c7734
--- /dev/null
+++ b/html/item_list.html
@@ -0,0 +1,61 @@
+#IF !ITEM_LIST_LOADED
+#DEFINE ITEM_LIST_LOADED
+<!--
+    SPDX-License-Identifier: GPL-3.0-or-later OR CC-BY-SA-4.0
+
+    Show a list of resources/mappings.
+
+    This file is part of Haketilo.
+
+    Copyright (C) 2022 Wojtek Kosior <koszko@koszko.org>
+
+    File is dual-licensed. You can choose either GPLv3+, CC BY-SA or both.
+
+    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 3 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, see <https://www.gnu.org/licenses/>.
+
+    I, Wojtek Kosior, thereby promise not to sue for violation of this file's
+    licenses. Although I request that you do not make use of this code in a
+    proprietary program, I am not going to enforce this in court.
+  -->
+
+<!--
+    This is not a standalone page. This file is meant to be imported into other
+    HTML code.
+  -->
+
+#INCLUDE html/item_preview.html
+#INCLUDE html/dialog.html
+
+#LOADCSS html/reset.css
+#LOADCSS html/base.css
+#LOADCSS html/grid.css
+<style>
+  .item_li_highlight {
+      background-color: #c0c0c0;
+  }
+</style>
+<template>
+  <div id="item_list" data-template="main_div" class="grid_2">
+    <ul data-template="ul"></ul>
+    <div data-template="preview_container">
+      <!-- preview div will be dynamically inserted here -->
+
+      <button data-template="remove_but">Remove</button>
+      <!--<button data-template="export_but">Export</button>-->
+    </div>
+    <div data-template="dialog_container" class="hide">
+    </div>
+  </div>
+</template>
+#ENDIF
diff --git a/html/item_list.js b/html/item_list.js
new file mode 100644
index 0000000..f6b9bd3
--- /dev/null
+++ b/html/item_list.js
@@ -0,0 +1,189 @@
+/**
+ * This file is part of Haketilo.
+ *
+ * Function: Showing a list of resources/mappings in a browser.
+ *
+ * Copyright (C) 2022 Wojtek Kosior
+ *
+ * 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 3 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.
+ *
+ * As additional permission under GNU GPL version 3 section 7, you
+ * may distribute forms of that code without the copy of the GNU
+ * GPL normally required by section 4, provided you include this
+ * license notice and, in case of non-source distribution, a URL
+ * through which recipients can access the Corresponding Source.
+ * If you modify file(s) with this exception, you may extend this
+ * exception to your version of the file(s), but you are not
+ * obligated to do so. If you do not wish to do so, delete this
+ * exception statement from your version.
+ *
+ * As a special exception to the GPL, any HTML file which merely
+ * makes function calls to this code, and for that purpose
+ * includes it by reference shall be deemed a separate work for
+ * copyright law purposes. If you modify this code, you may extend
+ * this exception to your version of the code, but you are not
+ * obligated to do so. If you do not wish to do so, delete this
+ * exception statement from your version.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ *
+ * I, Wojtek Kosior, thereby promise not to sue for violation of this file's
+ * license. Although I request that you do not make use of this code in a
+ * proprietary program, I am not going to enforce this in court.
+ */
+
+#IMPORT common/indexeddb.js AS haketilodb
+#IMPORT html/dialog.js
+
+#FROM html/item_preview.js IMPORT resource_preview, mapping_preview
+#FROM html/DOM_helpers.js IMPORT clone_template
+
+function preview_item(list_ctx, item, ignore_dialog=false)
+{
+    if (list_ctx.dialog_ctx.shown && !ignore_dialog)
+	return;
+
+    list_ctx.preview_ctx =
+	list_ctx.preview_cb(item.definition, list_ctx.preview_ctx);
+    list_ctx.preview_container
+	.prepend(list_ctx.preview_ctx.main_div);
+
+    if (list_ctx.previewed_item !== null)
+	list_ctx.previewed_item.li.classList.remove("item_li_highlight");
+
+    list_ctx.previewed_item = item;
+    item.li.classList.add("item_li_highlight");
+
+    list_ctx.preview_container.classList.remove("hide");
+}
+
+function insert_item(list_ctx, definition, idx)
+{
+    const li = document.createElement("li");
+    li.innerText = definition.long_name;
+    if (idx)
+	list_ctx.items[idx - 1].li.after(li);
+    else
+	list_ctx.ul.prepend(li);
+
+    const item = {definition, li};
+    list_ctx.items.splice(idx, 0, item);
+    list_ctx.by_identifier.set(definition.identifier, item);
+
+    li.addEventListener("click", () => preview_item(list_ctx, item));
+
+    return item;
+}
+
+const coll = new Intl.Collator();
+
+function item_cmp(def1, def2)
+{
+    return coll.compare(def1.long_name, def2.long_name) ||
+	coll.compare(def1.identifier, def2.identifier);
+}
+
+function find_item_idx(definition)
+{
+    /* Perform a binary search of item's (new or not) index in sorted array. */
+    let left = 0, right = list_ctx.items.length;
+
+    while (left < right) {
+	const mid = (left + right) >> 1;
+	if (item_cmp(definition, list_ctx.items[mid].definition) > 0)
+	    left = mid + 1;
+	else /* <= 0 */
+	    right = mid;
+    }
+
+    return left;
+}
+
+function item_changed(list_ctx, change)
+{
+
+    /* Remove item. */
+    const old_item = list_ctx.by_identifier.get(change.key);
+    if (old_item !== undefined) {
+	list_ctx.items.splice(find_item_idx(old_item.definition), 1);
+	list_ctx.by_identifier.delete(change.key);
+	old_item.li.remove();
+
+	if (list_ctx.previewed_item === old_item) {
+	    list_ctx.preview_container.classList.add("hide");
+	    list_ctx.previewed_item = null;
+	}
+    }
+
+    if (change.new_val === undefined)
+	return;
+
+    const new_item = insert_item(list_ctx, change.new_val,
+				 find_item_idx(change.new_val));
+    if (list_ctx.previewed_item === old_item)
+	preview_item(list_ctx, new_item, true);
+}
+
+async function item_list(preview_cb, track_cb)
+{
+    const list_ctx = clone_template("item_list");
+
+    const [tracking, definitions] =
+	  await track_cb(ch => item_changed(list_ctx, ch));
+
+    definitions.sort(item_cmp);
+
+    Object.assign(list_ctx, {
+	items: [],
+	by_identifier: new Map(),
+	tracking,
+	previewed_item: null,
+	preview_cb,
+	dialog_ctx: dialog.make(() => on_dialog_show(list_ctx),
+				() => on_dialog_hide(list_ctx))
+    });
+    list_ctx.dialog_container.append(list_ctx.dialog_ctx.main_div);
+
+    for (const def of definitions)
+	insert_item(list_ctx, def, list_ctx.items.length);
+
+    return list_ctx;
+}
+
+function on_dialog_show(list_ctx)
+{
+    list_ctx.ul;
+    list_ctx.preview_container.classList.add("hide");
+    list_ctx.dialog_container.classList.remove("hide");
+}
+
+function on_dialog_hide(list_ctx)
+{
+    list_ctx.ul;
+    list_ctx.preview_container.classList.remove("hide");
+    list_ctx.dialog_container.classList.add("hide");
+}
+
+const resource_list =
+      () => item_list(resource_preview, haketilodb.track.resources);
+#EXPORT resource_list
+
+const mapping_list =
+      () => item_list(mapping_preview, haketilodb.track.mappings);
+#EXPORT mapping_list
+
+function destroy_list(list_ctx)
+{
+    haketilodb.untrack(list_ctx.tracking);
+    list_ctx.main_div.remove();
+}
+#EXPORT destroy_list
diff --git a/html/item_preview.html b/html/item_preview.html
new file mode 100644
index 0000000..76c6da6
--- /dev/null
+++ b/html/item_preview.html
@@ -0,0 +1,89 @@
+#IF !ITEM_PREVIEW_LOADED
+#DEFINE ITEM_PREVIEW_LOADED
+<!--
+    SPDX-License-Identifier: GPL-3.0-or-later OR CC-BY-SA-4.0
+
+    Show preview of a resource/mapping.
+
+    This file is part of Haketilo.
+
+    Copyright (C) 2022 Wojtek Kosior <koszko@koszko.org>
+
+    File is dual-licensed. You can choose either GPLv3+, CC BY-SA or both.
+
+    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 3 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, see <https://www.gnu.org/licenses/>.
+
+    I, Wojtek Kosior, thereby promise not to sue for violation of this file's
+    licenses. Although I request that you do not make use of this code in a
+    proprietary program, I am not going to enforce this in court.
+  -->
+
+<!--
+    This is not a standalone page. This file is meant to be imported into other
+    HTML code.
+  -->
+
+#LOADCSS html/reset.css
+#LOADCSS html/base.css
+#LOADCSS html/grid.css
+<style>
+  .dialog_main_div {
+      margin: 1.4em;
+  }
+</style>
+<template>
+  <div id="resource_preview_div" data-template="main_div"
+       class="grid_2 grid_form preview_main_div">
+    <h3 class="grid_col_both">resource preview</h3>
+    <span class="grid_col_1">identifier:</span>
+    <span data-template="identifier" class="grid_col_2">...</span>
+    <span class="grid_col_1">long name:</span>
+    <span data-template="long_name" class="grid_col_2">...</span>
+    <span class="grid_col_1">UUID:</span>
+    <span data-template="uuid" class="grid_col_2">...</span>
+    <span class="grid_col_1">version:</span>
+    <span data-template="version" class="grid_col_2">...</span>
+    <span class="grid_col_1">description:</span>
+    <span data-template="description" class="grid_col_2">...</span>
+    <span class="grid_col_1">dependencies:</span>
+    <span class="grid_col_2"><ul data-template="dependencies"></ul></span>
+    <span class="grid_col_1">scripts:</span>
+    <span class="grid_col_2"><ul data-template="scripts"></ul></span>
+    <span class="grid_col_1">source name:</span>
+    <span data-template="source_name" class="grid_col_2">...</span>
+    <span class="grid_col_1">copyright:</span>
+    <span class="grid_col_2"><ul data-template="copyright"></ul></span>
+  </div>
+  <div id="mapping_preview_div" data-template="main_div"
+       class="grid_2 grid_form">
+    <h3 class="grid_col_both">mapping preview</h3>
+    <span class="grid_col_1">identifier:</span>
+    <span data-template="identifier" class="grid_col_2">...</span>
+    <span class="grid_col_1">long name:</span>
+    <span data-template="long_name" class="grid_col_2">...</span>
+    <span class="grid_col_1">UUID:</span>
+    <span data-template="uuid" class="grid_col_2">...</span>
+    <span class="grid_col_1">version:</span>
+    <span data-template="version" class="grid_col_2">...</span>
+    <span class="grid_col_1">description:</span>
+    <span data-template="description" class="grid_col_2">...</span>
+    <span class="grid_col_both">payloads:</span>
+    <div data-template="payloads" class="grid_col_both grid_2"></div>
+    <span class="grid_col_1">source name:</span>
+    <span data-template="source_name" class="grid_col_2">...</span>
+    <span class="grid_col_1">copyright:</span>
+    <span class="grid_col_2"><ul data-template="copyright"></ul></span>
+  </div>
+</template>
+#ENDIF
diff --git a/html/item_preview.js b/html/item_preview.js
new file mode 100644
index 0000000..f59e30e
--- /dev/null
+++ b/html/item_preview.js
@@ -0,0 +1,151 @@
+/**
+ * This file is part of Haketilo.
+ *
+ * Function: Showing resource/mapping details in a browser.
+ *
+ * Copyright (C) 2022 Wojtek Kosior
+ *
+ * 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 3 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.
+ *
+ * As additional permission under GNU GPL version 3 section 7, you
+ * may distribute forms of that code without the copy of the GNU
+ * GPL normally required by section 4, provided you include this
+ * license notice and, in case of non-source distribution, a URL
+ * through which recipients can access the Corresponding Source.
+ * If you modify file(s) with this exception, you may extend this
+ * exception to your version of the file(s), but you are not
+ * obligated to do so. If you do not wish to do so, delete this
+ * exception statement from your version.
+ *
+ * As a special exception to the GPL, any HTML file which merely
+ * makes function calls to this code, and for that purpose
+ * includes it by reference shall be deemed a separate work for
+ * copyright law purposes. If you modify this code, you may extend
+ * this exception to your version of the code, but you are not
+ * obligated to do so. If you do not wish to do so, delete this
+ * exception statement from your version.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ *
+ * I, Wojtek Kosior, thereby promise not to sue for violation of this file's
+ * license. Although I request that you do not make use of this code in a
+ * proprietary program, I am not going to enforce this in court.
+ */
+
+#IMPORT common/indexeddb.js AS haketilodb
+#IMPORT html/dialog.js
+
+#FROM html/DOM_helpers.js IMPORT clone_template
+
+function populate_list(ul, items)
+{
+    for (const item of items) {
+	const li = document.createElement("li");
+	li.append(item);
+	ul.append(li);
+    }
+}
+
+async function file_link_clicked(preview_object, file_ref, event)
+{
+    event.preventDefault();
+
+    const db = await haketilodb.get();
+    const file = await haketilodb.idb_get(db.transaction("files"),
+					  "files", file_ref.hash_key);
+    if (file === undefined) {
+	dialog.error(preview_object.dialog_context,
+		     "File missing from Haketilo's inernal database :(");
+    } else {
+	const encoded_file = encodeURIComponent(file.contents);
+	open(`data:text/plain;charset=utf8,${encoded_file}`, '_blank');
+    }
+}
+
+function make_file_link(preview_object, file_ref)
+{
+    const a = document.createElement("a");
+    a.href = "javascript:void(0)";
+    a.innerText = file_ref.file;
+    a.addEventListener("click",
+		       e => file_link_clicked(preview_object, file_ref, e));
+
+    return a;
+}
+
+function resource_preview(resource, preview_object, dialog_context)
+{
+    if (preview_object === undefined)
+	preview_object = clone_template("resource_preview_div");
+
+    preview_object.identifier.innerText  = resource.identifier;
+    preview_object.long_name.innerText   = resource.long_name;
+    preview_object.uuid.innerText        = resource.uuid;
+    preview_object.version.innerText     =
+	`${resource.version.join(".")}-${resource.revision}`;
+    preview_object.description.innerText = resource.description;
+    preview_object.source_name.innerText = resource.source_name;
+
+    [...preview_object.dependencies.childNodes].forEach(n => n.remove());
+    populate_list(preview_object.dependencies, resource.dependencies);
+
+    const link_maker = file_ref => make_file_link(preview_object, file_ref);
+
+    [...preview_object.scripts.childNodes].forEach(n => n.remove());
+    populate_list(preview_object.scripts, resource.scripts.map(link_maker));
+
+    [...preview_object.copyright.childNodes].forEach(n => n.remove());
+    populate_list(preview_object.copyright,
+		  resource.source_copyright.map(link_maker));
+
+    preview_object.dialog_context = dialog_context;
+
+    return preview_object;
+}
+#EXPORT resource_preview
+
+function mapping_preview(mapping, preview_object, dialog_context)
+{
+    if (preview_object === undefined)
+	preview_object = clone_template("mapping_preview_div");
+
+    preview_object.identifier.innerText  = mapping.identifier;
+    preview_object.long_name.innerText   = mapping.long_name;
+    preview_object.uuid.innerText        = mapping.uuid;
+    preview_object.version.innerText     = mapping.version.join(".");
+    preview_object.description.innerText = mapping.description;
+    preview_object.source_name.innerText = mapping.source_name;
+
+    [...preview_object.payloads.childNodes].forEach(n => n.remove());
+    for (const [pattern, payload] of Object.entries(mapping.payloads).sort()) {
+	/* We use a non-breaking space because normal space would be ignored. */
+	const [nbsp, rarrow] = [160, 0x2192].map(n => String.fromCodePoint(n));
+	const texts = [`${pattern}${nbsp}`, `${rarrow}  ${payload.identifier}`];
+	for (let i = 0; i < texts.length; i++) {
+	    const span = document.createElement("span");
+	    span.innerText = texts[i];
+	    span.classList.add(`grid_col_${i + 1}`);
+	    preview_object.payloads.append(span);
+	}
+    }
+
+    const link_maker = file_ref => make_file_link(preview_object, file_ref);
+
+    [...preview_object.copyright.childNodes].forEach(n => n.remove());
+    populate_list(preview_object.copyright,
+		  mapping.source_copyright.map(link_maker));
+
+    preview_object.dialog_context = dialog_context;
+
+    return preview_object;
+}
+#EXPORT mapping_preview