using System;
using System.Diagnostics;
using System.Numerics;
using Dalamud.Interface;
using Dalamud.Interface.GameFonts;
using ImGuiNET;
using OtterGui;
using OtterGui.Raii;
using Penumbra.UI.Classes;

namespace Penumbra.UI;

public partial class ConfigWindow
{
    private partial class ModPanel
    {
        // We use a big, nice game font for the title.
        private readonly GameFontHandle _nameFont =
            Dalamud.PluginInterface.UiBuilder.GetGameFontHandle( new GameFontStyle( GameFontFamilyAndSize.Jupiter23 ) );

        // Header data.
        private string _modName          = string.Empty;
        private string _modAuthor        = string.Empty;
        private string _modVersion       = string.Empty;
        private string _modWebsite       = string.Empty;
        private string _modWebsiteButton = string.Empty;
        private bool   _websiteValid;

        private float _modNameWidth;
        private float _modAuthorWidth;
        private float _modVersionWidth;
        private float _modWebsiteButtonWidth;
        private float _secondRowWidth;

        // Draw the header for the current mod,
        // consisting of its name, version, author and website, if they exist.
        private void DrawModHeader()
        {
            var offset = DrawModName();
            DrawVersion( offset );
            DrawSecondRow( offset );
        }

        // Draw the mod name in the game font with a 2px border, centered,
        // with at least the width of the version space to each side.
        private float DrawModName()
        {
            var decidingWidth = Math.Max( _secondRowWidth, ImGui.GetWindowWidth() );
            var offsetWidth   = ( decidingWidth - _modNameWidth ) / 2;
            var offsetVersion = _modVersion.Length > 0
                ? _modVersionWidth + ImGui.GetStyle().ItemSpacing.X + ImGui.GetStyle().WindowPadding.X
                : 0;
            var offset = Math.Max( offsetWidth, offsetVersion );
            if( offset > 0 )
            {
                ImGui.SetCursorPosX( offset );
            }

            using var color = ImRaii.PushColor( ImGuiCol.Border, Colors.MetaInfoText );
            using var style = ImRaii.PushStyle( ImGuiStyleVar.FrameBorderSize, 2 * ImGuiHelpers.GlobalScale );
            using var font  = ImRaii.PushFont( _nameFont.ImFont, _nameFont.Available );
            ImGuiUtil.DrawTextButton( _modName, Vector2.Zero, 0 );
            return offset;
        }

        // Draw the version in the top-right corner.
        private void DrawVersion( float offset )
        {
            var oldPos = ImGui.GetCursorPos();
            ImGui.SetCursorPos( new Vector2( 2 * offset + _modNameWidth - _modVersionWidth - ImGui.GetStyle().WindowPadding.X,
                ImGui.GetStyle().FramePadding.Y ) );
            ImGuiUtil.TextColored( Colors.MetaInfoText, _modVersion );
            ImGui.SetCursorPos( oldPos );
        }

        // Draw author and website if they exist. The website is a button if it is valid.
        // Usually, author begins at the left boundary of the name,
        // and website ends at the right boundary of the name.
        // If their combined width is larger than the name, they are combined-centered.
        private void DrawSecondRow( float offset )
        {
            if( _modAuthor.Length == 0 )
            {
                if( _modWebsiteButton.Length == 0 )
                {
                    ImGui.NewLine();
                    return;
                }

                offset += ( _modNameWidth - _modWebsiteButtonWidth ) / 2;
                ImGui.SetCursorPosX( offset );
                DrawWebsite();
            }
            else if( _modWebsiteButton.Length == 0 )
            {
                offset += ( _modNameWidth - _modAuthorWidth ) / 2;
                ImGui.SetCursorPosX( offset );
                DrawAuthor();
            }
            else if( _secondRowWidth < _modNameWidth )
            {
                ImGui.SetCursorPosX( offset );
                DrawAuthor();
                ImGui.SameLine( offset + _modNameWidth - _modWebsiteButtonWidth );
                DrawWebsite();
            }
            else
            {
                offset -= ( _secondRowWidth - _modNameWidth ) / 2;
                if( offset > 0 )
                {
                    ImGui.SetCursorPosX( offset );
                }

                DrawAuthor();
                ImGui.SameLine();
                DrawWebsite();
            }
        }

        // Draw the author text.
        private void DrawAuthor()
        {
            using var style = ImRaii.PushStyle( ImGuiStyleVar.ItemSpacing, Vector2.Zero );
            ImGuiUtil.TextColored( Colors.MetaInfoText, "by " );
            ImGui.SameLine();
            style.Pop();
            ImGui.TextUnformatted( _mod.Author );
        }

        // Draw either a website button if the source is a valid website address,
        // or a source text if it is not.
        private void DrawWebsite()
        {
            if( _websiteValid )
            {
                if( ImGui.SmallButton( _modWebsiteButton ) )
                {
                    try
                    {
                        var process = new ProcessStartInfo( _modWebsite )
                        {
                            UseShellExecute = true,
                        };
                        Process.Start( process );
                    }
                    catch
                    {
                        // ignored
                    }
                }

                ImGuiUtil.HoverTooltip( _modWebsite );
            }
            else
            {
                using var style = ImRaii.PushStyle( ImGuiStyleVar.ItemSpacing, Vector2.Zero );
                ImGuiUtil.TextColored( Colors.MetaInfoText, "from " );
                ImGui.SameLine();
                style.Pop();
                ImGui.TextUnformatted( _mod.Website );
            }
        }

        // Update all mod header data. Should someone change frame padding or item spacing,
        // or his default font, this will break, but he will just have to select a different mod to restore.
        private void UpdateModData()
        {
            // Name
            var name = $" {_mod.Name} ";
            if( name != _modName )
            {
                using var font = ImRaii.PushFont( _nameFont.ImFont, _nameFont.Available );
                _modName      = name;
                _modNameWidth = ImGui.CalcTextSize( name ).X + 2 * ( ImGui.GetStyle().FramePadding.X + 2 * ImGuiHelpers.GlobalScale );
            }

            // Author
            var author = _mod.Author.IsEmpty ? string.Empty : $"by  {_mod.Author}";
            if( author != _modAuthor )
            {
                _modAuthor      = author;
                _modAuthorWidth = ImGui.CalcTextSize( author ).X;
                _secondRowWidth = _modAuthorWidth + _modWebsiteButtonWidth + ImGui.GetStyle().ItemSpacing.X;
            }

            // Version
            var version = _mod.Version.Length > 0 ? $"({_mod.Version})" : string.Empty;
            if( version != _modVersion )
            {
                _modVersion      = version;
                _modVersionWidth = ImGui.CalcTextSize( version ).X;
            }

            // Website
            if( _modWebsite != _mod.Website )
            {
                _modWebsite = _mod.Website;
                _websiteValid = Uri.TryCreate( _modWebsite, UriKind.Absolute, out var uriResult )
                 && ( uriResult.Scheme == Uri.UriSchemeHttps || uriResult.Scheme == Uri.UriSchemeHttp );
                _modWebsiteButton = _websiteValid ? "Open Website" : _modWebsite.Length == 0 ? string.Empty : $"from  {_modWebsite}";
                _modWebsiteButtonWidth = _websiteValid
                    ? ImGui.CalcTextSize( _modWebsiteButton ).X + 2 * ImGui.GetStyle().FramePadding.X
                    : ImGui.CalcTextSize( _modWebsiteButton ).X;
                _secondRowWidth = _modAuthorWidth + _modWebsiteButtonWidth + ImGui.GetStyle().ItemSpacing.X;
            }
        }
    }
}