using System;
using UnityEngine;
using UnityEngine.UI;

namespace LeTai.TrueShadow
{
class ShadowSettingSnapshot
{
    public readonly TrueShadow    shadow;
    public readonly Canvas        canvas;
    public readonly RectTransform canvasRt;
    public readonly bool          shouldAntialiasImprint;
    public readonly float         canvasScale;
    public readonly float         size;
    public readonly Vector2       canvasRelativeOffset;
    public readonly Vector2       dimensions;

    internal ShadowSettingSnapshot(TrueShadow shadow)
    {
        this.shadow = shadow;
        canvas      = shadow.Graphic.canvas;
        canvasRt    = (RectTransform) canvas.transform;

        var meshBound = shadow.SpriteMesh.bounds;

        shouldAntialiasImprint = canvas.renderMode != RenderMode.ScreenSpaceOverlay;

        canvasScale = canvas.scaleFactor;

        var canvasRelativeRotation = Quaternion.Inverse(canvasRt.rotation) * shadow.RectTransform.rotation;
        canvasRelativeOffset = shadow.Offset.Rotate(-canvasRelativeRotation.eulerAngles.z) * canvasScale;

        dimensions = (Vector2) meshBound.size * canvasScale;
        size       = shadow.Size * canvasScale;

        CalcHash();
    }

    const int DIMENSIONS_HASH_STEP = 1;

    void CalcHash()
    {
        var graphic = shadow.Graphic;

        int canvasScaleHash = (int) (canvasScale * 1e4);
        int insetHash       = shadow.Inset ? 1 : 0;

        var clearColor = shadow.ClearColor;
        var imageColor = graphic.color;
        int colorHash = HashUtils.CombineHashCodes(
            shadow.IgnoreCasterColor ? 1 : 0,
            (int) shadow.ColorBleedMode,
            (int) (imageColor.r * 255),
            (int) (imageColor.g * 255),
            (int) (imageColor.b * 255),
            (int) (imageColor.a * 255),
            (int) (clearColor.r * 255),
            (int) (clearColor.g * 255),
            (int) (clearColor.b * 255),
            (int) (clearColor.a * 255)
        );

        // Hack until we have separated cutout cache, or proper sibling mode
        int offsetHash = HashUtils.CombineHashCodes(
            shadow.Cutout ? 1 : 0,
            (int) (canvasRelativeOffset.x * 100),
            (int) (canvasRelativeOffset.y * 100)
        );

        // Tiled type cannot be batched by similar size
        int dimensionHash = graphic is Image im && im.type == Image.Type.Tiled
                                ? dimensions.GetHashCode()
                                : HashUtils.CombineHashCodes(
                                    Mathf.CeilToInt(dimensions.x / DIMENSIONS_HASH_STEP) * DIMENSIONS_HASH_STEP,
                                    Mathf.CeilToInt(dimensions.y / DIMENSIONS_HASH_STEP) * DIMENSIONS_HASH_STEP
                                );

        var sizeHash = Mathf.CeilToInt(size * 100);

        var commonHash = HashUtils.CombineHashCodes(
            shadow.TextureRevision,
            canvasScaleHash,
            insetHash,
            colorHash,
            offsetHash,
            dimensionHash,
            sizeHash
        );

        switch (graphic)
        {
        case Image image:
            int spriteHash = 0;
            if (image.sprite)
                spriteHash = image.sprite.GetHashCode();

            int imageHash = HashUtils.CombineHashCodes(
                (int) image.type,
                (int) (image.fillAmount * 360 * 20),
                (int) image.fillMethod,
                image.fillOrigin,
                image.fillClockwise ? 1 : 0
            );

            hash = HashUtils.CombineHashCodes(
                commonHash,
                spriteHash,
                imageHash
            );
            break;
        case RawImage rawImage:
            var textureHash = 0;
            if (rawImage.texture)
                textureHash = rawImage.texture.GetInstanceID();

            hash = HashUtils.CombineHashCodes(
                commonHash,
                textureHash
            );
            break;
        case Text text:
            var textHash = HashUtils.CombineHashCodes(
                text.text.GetHashCode(),
                text.font.GetHashCode(),
                text.fontSize,
                (int) text.lineSpacing * 100,
                (int) text.alignment
            );
            hash = HashUtils.CombineHashCodes(
                commonHash,
                textHash
            );
            break;
        default:
            hash = commonHash;
            break;
        }
    }

    int hash;

    // ReSharper disable once NonReadonlyMemberInGetHashCode
    public override int GetHashCode() => hash;

    public override bool Equals(object obj)
    {
        if (obj == null) return false;

        return GetHashCode() == obj.GetHashCode();
    }
}
}