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

public class AliasModel
{
    public static readonly Regex AnimationRegex = new Regex(@"^[a-zA-Z]+");
    
    private readonly List<(int, Mesh)> animationMeshes = new List<(int, Mesh)>();   // TODO: make this a fixed array after initialization

    public void AddAnimation(int startFrame, Mesh mesh)
    {
        animationMeshes.Add((startFrame, mesh));
    }

    public int GetAnimationFrameCount(float frameNum)
    {
        if (!FindAnimation((int)frameNum, out Mesh mesh, out int startFrame))
            return 0;

        return mesh.GetBlendShapeFrameCount(0);
    }

    public void Animate(float frameNum, out Mesh mesh, out float blendWeight)
    {
        blendWeight = 0;
        
        int frameIndex = (int)frameNum;
        if (!FindAnimation(frameIndex, out mesh, out int startFrame))
            return;

        int numFrames = mesh.GetBlendShapeFrameCount(0);
        blendWeight = ((frameNum - startFrame) / numFrames) % 1;
    }

    private bool FindAnimation(int frameIndex, out Mesh mesh, out int startFrame)
    {
        mesh = null;
        startFrame = 0;
        
        for (int i = 0; i < animationMeshes.Count; ++i)
        {
            startFrame = animationMeshes[i].Item1;
            if (frameIndex >= startFrame)
            {
                mesh = animationMeshes[i].Item2;
                return true;
            }
        }

        return false;   // Shouldn't happen
    }
}