using OpenTK;
using RecrownedAthenaeum.Graphics.Render;
using System;
using System.Text;

namespace RecrownedAthenaeum.Graphics.UI.Modular.Modules
{
    /// <summary>
    /// Represents text for the UI.
    /// </summary>
    public class Text : UIModule
    {
        private SpriteFont font;
        private float scale = 1f;
        private Vector2 position;
        private string originalText;
        private string displayedText;
        private Vector2 modifiedTextSize;

        /// <summary>
        /// Centers the text int bounds.
        /// </summary>
        public bool centered;

        /// <summary>
        /// Whether or not to try and wrap text automatically. Meaning will check and attempt to wrap every update.
        /// </summary>
        public bool autoWrap;

        /// <summary>
        /// Whether or not to automatically scale the text every update. Happens after auto wrap if enabled.
        /// </summary>
        public bool autoScale;

        /// <summary>
        /// Should this use ellipses? Will perform this operation before auto wrapping or auto scalling.
        /// </summary>
        public bool useEllipses;

        /// <summary>
        /// The text to use for the ellipsis.
        /// </summary>
        public string ellipsis = "...";
        private string ModifiedText { get { return displayedText; } set { displayedText = value; modifiedTextSize = font.MeasureString(value); } }

        /// <summary>
        /// The string to be displayed.
        /// </summary>
        public string Content { get { return originalText; } set { originalText = value; if (value == null) value = ellipsis; modifiedTextSize = font.MeasureString(value); displayedText = value; } }

        /// <summary>
        /// Creates a UI text object.
        /// </summary>
        /// <param name="font">The font to use.</param>
        /// <param name="content">The string for the text.</param>
        public Text(SpriteFont font, string content = null)
        {
            this.font = font ?? throw new ArgumentNullException("Font cannot be null.");
            Content = content;
        }

        /// <summary>
        /// Updates the positioning and attempts to perform any operations that were marked automatic.
        /// </summary>
        /// <param name="gameTime">The game time.</param>
        public override void Update(GameTime gameTime)
        {
            position.X = X;
            position.Y = Y;

            if (useEllipses) AttemptToApplyEllipsis();
            if (autoWrap) AttemptToWrapText();
            if (autoScale) AttemptToScaleFont();
            if (centered) Center();

            base.Update(gameTime);
        }

        /// <summary>
        /// Draws the text.
        /// </summary>
        /// <param name="batch">Batch to use.</param>
        public override void Draw(ConsistentSpriteBatch batch)
        {
            batch.DrawString(font, Content, position, color, 0f, default(Vector2), scale, SpriteEffects.None, 0f);
            base.Draw(batch);
        }

        /// <summary>
        /// Attempts to apply ellipsis. Checks of nessecary.
        /// </summary>
        public void AttemptToApplyEllipsis()
        {
            if (modifiedTextSize.X * scale > Width && ModifiedText.Length > ellipsis.Length + 1)
            {
                RemoveLineBreaks();
                StringBuilder stringBuilder = new StringBuilder(ModifiedText);
                do
                {
                    stringBuilder.Remove(stringBuilder.Length, ellipsis.Length - 1);
                    stringBuilder.Insert(stringBuilder.Length, ellipsis);
                }
                while (font.MeasureString(stringBuilder).X * scale > Width);

                ModifiedText = stringBuilder.ToString();
            }
        }

        /// <summary>
        /// Attempts to scale the font. Checks if nessecary.
        /// </summary>
        public void AttemptToScaleFont()
        {

            if (Width < Height)
            {
                if (Math.Round(modifiedTextSize.X * scale ) != Width)
                {
                    scale = Width / modifiedTextSize.X;
                }
            }
            else
            {
                if (Math.Round(modifiedTextSize.Y * scale ) != Height)
                {
                    scale = Height / (modifiedTextSize.Y);
                }
            }
        }

        /// <summary>
        /// Removes line breaks.
        /// </summary>
        public void RemoveLineBreaks()
        {
            ModifiedText = ModifiedText.Replace("\n", " ");
        }

        /// <summary>
        /// Resets to original text.
        /// </summary>
        public void ResetToOriginalText()
        {
            Content = originalText;
        }

        /// <summary>
        /// Attempts to wrap text. Checks if nessecary.
        /// </summary>
        /// <param name="unwrap">If true, will first unwrap text, and the wrap again. This occurs before nessecity check.</param>
        public void AttemptToWrapText(bool unwrap = false)
        {
            if (unwrap) RemoveLineBreaks();
            if (modifiedTextSize.X * scale > Width)
            {
                ModifiedText = ModifiedText.Replace("\n", " ");
                string[] words = ModifiedText.Split(' ');
                StringBuilder stringBuilder = new StringBuilder();
                float currentScaledLineWidth = 0f;

                for (int w = 0; w < words.Length; w++)
                {
                    string word = words[w];
                    float scaledWidth = font.MeasureString(word).X * scale;

                    if (currentScaledLineWidth + scaledWidth <= Width)
                    {
                        stringBuilder.Append(word);
                        currentScaledLineWidth += scaledWidth;
                    }
                    else
                    {
                        stringBuilder.AppendLine();
                        currentScaledLineWidth = 0;
                    }
                }
                ModifiedText = stringBuilder.ToString();
            }
        }

        private bool Center()
        {
            Vector2 textSize = new Vector2(modifiedTextSize.X * scale, modifiedTextSize.Y * scale);

            if (textSize.X <= Width)
            {
                position.X = X + (Width - textSize.X) / 2f;
            }
            else
            {
                return false;
            }

            if (textSize.Y <= Height)
            {
                position.Y = Y + (Height - textSize.Y) / 2f;
            }
            else
            {
                return false;
            }

            return true;
        }
    }
}