using System;
using System.Collections.Generic;
using System.Threading;
using System.Threading.Tasks;
using Transpose.Core;
using Tesserae;
using static Transpose.Core.dom;
using static Tesserae.UI;

namespace Tesserae.Tests
{
    internal static class App
    {
        private static readonly List<MarkedMatch> Matches = new List<MarkedMatch>();

        private static HTMLElement             _root;
        private static TextBlock               _summary;
        private static int                     _current;
        private static CancellationTokenSource _cts;

        private static void Main()
        {
            var prose = VStack().WS().Children(
                TextBlock("The Tesserae toolkit").MediumPlus().SemiBold(),
                TextBlock("Tesserae is a UI toolkit for building web applications in C#. A Tesserae application composes components, and each component renders plain DOM elements.").PT(8),
                TextBlock("Highlighting folds diacritics, so searching for 'cafe' also finds the cafe down the street spelled 'café'.").PT(8),
                TextBlock("Repeated words are all found: toolkit, toolkit, toolkit.").PT(8));

            _root    = prose.Render();
            _summary = TextBlock("no matches").NoWrap().W(80).TextCenter();

            var searchBox = SearchBox("Find in document...")
               .SearchAsYouType()
               .OnSearch((s, term) => SearchAsync(term).FireAndForget());

            var component = VStack().WS().Children(
                HStack().AlignItemsCenter().Children(
                    searchBox.W(240),
                    Button().SetIcon(UIcons.AngleLeft).NoBorder().NoBackground().OnClick(() => Focus(_current - 1)).PL(8),
                    _summary,
                    Button().SetIcon(UIcons.AngleRight).NoBorder().NoBackground().OnClick(() => Focus(_current + 1))),
                Raw(_root).PT(16));

            document.body.style.overflow = "hidden";
            MountCenteredToBody(component.Width(520.px()).Padding(16.px()));
        }

        private static async Task SearchAsync(string term)
        {
            _cts?.Cancel();
            _cts = new CancellationTokenSource();

            Matches.Clear();
            _current = 0;
            await MarkHighlighter.UnmarkAsync(_root, cancellationToken: _cts.Token);

            if (!string.IsNullOrWhiteSpace(term))
            {
                await MarkHighlighter.MarkAsync(_root, term, new MarkOptions(), m => Matches.Add(m), _cts.Token);
            }

            if (Matches.Count > 0)
            {
                MarkHighlighter.FocusResult(_root, Matches[0], scrollIntoViewIfNeeded: false);
            }

            Summarize();
        }

        private static void Focus(int index)
        {
            if (Matches.Count == 0) return;

            _current = Math.Max(0, Math.Min(index, Matches.Count - 1));
            MarkHighlighter.FocusResult(_root, Matches[_current], scrollIntoViewIfNeeded: true);
            Summarize();
        }

        private static void Summarize()
        {
            if (Matches.Count == 0) _summary.Text = "no matches";
            else if (Matches.Count == 1) _summary.Text = "1 match";
            else _summary.Text = (_current + 1) + " / " + Matches.Count;
        }
    }
}