using System;
using System.Collections.Generic;
using System.Text.RegularExpressions;
using UnityEngine;
using UnityEngine.UI;

// Usage: icon name in text is replaced by image
public class TextPic : Text
{
    [System.Serializable]
    public struct IconName
    {
        public string name;
        public Sprite sprite;
    }

    /// <summary>
    /// Regular expression to replace
    /// </summary>
    static readonly Regex s_Regex =
        new Regex(@"<quad name=(.+?) size=(\d*\.?\d+%?) width=(\d*\.?\d+%?) />", RegexOptions.Singleline);

    public IconName[] inspectorIconList;

    // Scale image by x, y
    [SerializeField]
    public Vector2 imageScalingFactor = Vector2.one;

    // Offset image by x, y
    [SerializeField]
    public Vector2 imageOffset = Vector2.zero;

    // Pad image by x
    public float imagePad;

    /// <summary>
    /// Image Pool
    /// </summary>
    readonly List<Image> m_ImagesPool = new List<Image>();

    /// <summary>
    /// Vertex Index
    /// </summary>
    readonly List<int> m_ImagesVertexIndex = new List<int>();

    /// <summary>
    /// After parsing the final text
    /// </summary>
    string m_OutputText;

    Dictionary<string, Sprite> iconList = new Dictionary<string, Sprite>();
    List<Vector2> positions = new List<Vector2>();

    public override void SetVerticesDirty()
    {
        base.SetVerticesDirty();
        UpdateQuadImage();
    }

    protected override void OnPopulateMesh(VertexHelper toFill)
    {
        var orignText = m_Text;
        m_Text = m_OutputText;
        base.OnPopulateMesh(toFill);
        m_Text = orignText;
        positions.Clear();

        var vert = new UIVertex();
        for (var i = 0; i < m_ImagesVertexIndex.Count; i++)
        {
            var endIndex = m_ImagesVertexIndex[i];
            var rt = m_ImagesPool[i].rectTransform;
            var size = rt.sizeDelta;
            if (endIndex < toFill.currentVertCount)
            {
                toFill.PopulateUIVertex(ref vert, endIndex);
                var position = new Vector2((vert.position.x + size.x / 2), (vert.position.y + size.y / 2));
                position += imageOffset;
                if (i > 0)
                {
                    var padVector = new Vector2(imagePad * i, 0);
                    position += padVector;
                }
                positions.Add(position);

                // Erase the lower left corner of the black specks
                var end = endIndex - 3;
                toFill.PopulateUIVertex(ref vert, end);
                var pos = vert.position;
                for (int j = endIndex; j > end; j--)
                {
                    toFill.PopulateUIVertex(ref vert, endIndex);
                    vert.position = pos;
                    toFill.SetUIVertex(vert, j);
                }
            }
        }

        if (m_ImagesVertexIndex.Count != 0)
        {
            m_ImagesVertexIndex.Clear();
        }
    }

    /**
	* Unity Inspector cant display Dictionary vars,
	* so we use this little hack to setup the iconList
	*/
    new void Start()
    {
        if (inspectorIconList != null)
        {
            foreach (IconName icon in inspectorIconList)
            {
                iconList.Add(icon.name, icon.sprite);
            }
        }
    }

    void UpdateQuadImage()
    {
#if UNITY_EDITOR
        if (UnityEditor.PrefabUtility.GetPrefabType(this) == UnityEditor.PrefabType.Prefab)
        {
            return;
        }
#endif

        m_OutputText = GetOutputText();
        m_ImagesVertexIndex.Clear();
        foreach (Match match in s_Regex.Matches(m_OutputText))
        {
            var picIndex = match.Index;
            var endIndex = picIndex * 4 + 3;
            m_ImagesVertexIndex.Add(endIndex);

            m_ImagesPool.RemoveAll(image => image == null);
            if (m_ImagesPool.Count == 0)
            {
                GetComponentsInChildren<Image>(m_ImagesPool);
            }
            if (m_ImagesVertexIndex.Count > m_ImagesPool.Count)
            {
                var resources = new DefaultControls.Resources();
                var go = DefaultControls.CreateImage(resources);
                go.layer = gameObject.layer;
                var rt = go.transform as RectTransform;
                if (rt)
                {
                    rt.SetParent(rectTransform);
                    rt.localPosition = Vector3.zero;
                    rt.localRotation = Quaternion.identity;
                    rt.localScale = Vector3.one;
                }
                m_ImagesPool.Add(go.GetComponent<Image>());
            }

            var spriteName = match.Groups[1].Value;
            var img = m_ImagesPool[m_ImagesVertexIndex.Count - 1];
            if (img.sprite == null || img.sprite.name != spriteName)
            {
                if (inspectorIconList != null && inspectorIconList.Length > 0)
                {
                    foreach (IconName icon in inspectorIconList)
                    {
                        if (icon.name == spriteName)
                        {
                            img.sprite = icon.sprite;
                            break;
                        }
                    }
                }
            }
            img.rectTransform.sizeDelta = new Vector2(fontSize * imageScalingFactor.x, fontSize * imageScalingFactor.y);
            img.enabled = true;
            if (positions.Count == m_ImagesPool.Count)
            {
                img.rectTransform.anchoredPosition = positions[m_ImagesVertexIndex.Count - 1];
            }
        }

        for (var i = m_ImagesVertexIndex.Count; i < m_ImagesPool.Count; i++)
        {
            if (m_ImagesPool[i])
            {
                m_ImagesPool[i].enabled = false;
            }
        }
    }

    string GetOutputText()
    {
        var fixedString = this.text;
        if (inspectorIconList != null && inspectorIconList.Length > 0)
        {
            foreach (IconName icon in inspectorIconList)
            {
                if (!string.IsNullOrEmpty(icon.name))
                {
                    fixedString = fixedString.Replace(icon.name, "<quad name=" + icon.name + " size=" + fontSize + " width=1 />");
                }
            }
        }
        return fixedString;
    }
}