import type { Asset } from "@core/asset";
import type { ImageDocument } from "@core/document";
import type { Rect } from "@core/geometry";
import type { Layer } from "@core/layer";
import { getLayerMask } from "@core/layer-mask-utils";
import type { SelectionState } from "@editor/state";
import type { GenerateSettings } from "@editor/tools";
import { createDocumentReadIndex, resolveIndexedLayerBounds } from "@editor/document-indexes";
import { createNormalizedMaskSource, cropCanvas, cropMaskValuesToDataUrl, expandRectWithinBounds, loadImageCanvas } from "@platform/browser/maskRaster";

export type InpaintBundle = {
  inputImage: string;
  maskImage: string;
  width: number;
  height: number;
  targetLayerId: string;
  maskLayerId: string;
  sourceAssetId: string;
  maskAssetId: string;
  crop: {
    assetBounds: Rect;
    documentBounds: Rect;
    padding: number;
    maskedAreaOnly: boolean;
  };
  mask: {
    polarity: GenerateSettings["inpaint"]["maskPolarity"];
    activeBounds: Rect;
  };
  placement: {
    artboardId: string;
    layerName: string;
    transform: Extract<Layer, { type: "image" | "raster" }>["transform"];
  };
  backend: {
    growMaskBy: number;
    maskedContent: GenerateSettings["inpaint"]["maskedContent"];
    maskBlur: number;
    maskFeather: number;
    maskExpand: number;
    cropPadding: number;
  };
};

type InpaintTarget = {
  artboardId: string;
  layer: Extract<Layer, { type: "image" | "raster" }>;
  asset: Asset;
  bounds: Rect;
  maskLayer: Extract<Layer, { type: "image" | "raster" }>;
  maskAsset: Asset;
  maskBounds: Rect;
};

const modelMultiple = 8;
const minModelSize = 64;
const maxModelSize = 4096;

export async function buildInpaintBundle(document: ImageDocument, selection: SelectionState, settings: GenerateSettings): Promise<InpaintBundle> {
  const target = resolveInpaintTarget(document, selection);
  validateInpaintTarget(target);

  const width = Math.max(1, Math.round(target.asset.intrinsicSize.w));
  const height = Math.max(1, Math.round(target.asset.intrinsicSize.h));
  const normalizedMask = await createNormalizedMaskSource(target.maskAsset.source, width, height, {
    polarity: settings.inpaint.maskPolarity,
    expand: settings.inpaint.maskExpand,
    feather: settings.inpaint.maskFeather,
    blur: settings.inpaint.maskBlur,
    despeckle: settings.inpaint.maskDespeckle,
  });

  if (!normalizedMask.bounds) throw new Error("The selected layer mask has no inpaint pixels.");

  const crop = settings.inpaint.maskedAreaOnly
    ? expandRectWithinBounds(normalizedMask.bounds, settings.inpaint.cropPadding, { w: width, h: height }, modelMultiple, minModelSize)
    : { x: 0, y: 0, w: width, h: height };
  const outputWidth = toModelSize(crop.w, "width");
  const outputHeight = toModelSize(crop.h, "height");

  const inputCanvas = prepareMaskedContentInputCanvas(await loadImageCanvas(target.asset.source, width, height), normalizedMask.values, settings.inpaint.maskedContent);
  const inputImage = cropCanvas(inputCanvas, crop, outputWidth, outputHeight);
  const maskImage = cropMaskValuesToDataUrl(normalizedMask.values, width, height, crop, outputWidth, outputHeight);
  const scaleX = target.bounds.w / width;
  const scaleY = target.bounds.h / height;
  const documentBounds = {
    x: target.bounds.x + crop.x * scaleX,
    y: target.bounds.y + crop.y * scaleY,
    w: outputWidth * scaleX,
    h: outputHeight * scaleY,
  };

  return {
    inputImage,
    maskImage,
    width: outputWidth,
    height: outputHeight,
    targetLayerId: target.layer.id,
    maskLayerId: target.maskLayer.id,
    sourceAssetId: target.asset.id,
    maskAssetId: target.maskAsset.id,
    crop: {
      assetBounds: crop,
      documentBounds,
      padding: settings.inpaint.cropPadding,
      maskedAreaOnly: settings.inpaint.maskedAreaOnly,
    },
    mask: {
      polarity: settings.inpaint.maskPolarity,
      activeBounds: normalizedMask.bounds,
    },
    placement: {
      artboardId: target.artboardId,
      layerName: `${target.layer.name} inpaint`,
      transform: {
        position: { x: documentBounds.x, y: documentBounds.y },
        scale: { x: documentBounds.w / outputWidth, y: documentBounds.h / outputHeight },
        rotation: target.layer.transform.rotation,
      },
    },
    backend: {
      growMaskBy: settings.inpaint.growMaskBy,
      maskedContent: settings.inpaint.maskedContent,
      maskBlur: settings.inpaint.maskBlur,
      maskFeather: settings.inpaint.maskFeather,
      maskExpand: settings.inpaint.maskExpand,
      cropPadding: settings.inpaint.cropPadding,
    },
  };
}

function resolveInpaintTarget(document: ImageDocument, selection: SelectionState): InpaintTarget {
  if (selection.layerIds.length !== 1 || !selection.layerIds[0]) throw new Error("Select one image or raster layer to inpaint.");

  const documentIndex = createDocumentReadIndex(document);
  const layerInfo = documentIndex.layerInfoById.get(selection.layerIds[0]);
  if (!layerInfo || layerInfo.layer.type === "group") throw new Error("Select one image or raster layer to inpaint.");

  const asset = documentIndex.assetById.get(layerInfo.layer.assetId);
  if (!asset) throw new Error("The selected layer is missing its source image.");
  const layerMask = getLayerMask(layerInfo.layer);
  if (!layerMask?.enabled) throw new Error("Add a layer mask before running inpaint.");

  const maskLayer = documentIndex.layerById.get(layerMask.maskLayerId);
  if (!maskLayer || maskLayer.type === "group") throw new Error("The selected layer mask is missing.");

  const maskAsset = documentIndex.assetById.get(maskLayer.assetId);
  if (!maskAsset) throw new Error("The selected layer mask is missing its image data.");

  const bounds = resolveIndexedLayerBounds(documentIndex, layerInfo.layer);
  const maskBounds = resolveIndexedLayerBounds(documentIndex, maskLayer);
  if (!bounds || !maskBounds) throw new Error("Unable to resolve the selected layer and mask bounds.");

  return { artboardId: layerInfo.artboardId, layer: layerInfo.layer, asset, bounds, maskLayer, maskAsset, maskBounds };
}

function validateInpaintTarget(target: InpaintTarget) {
  if (target.asset.intrinsicSize.w <= 0 || target.asset.intrinsicSize.h <= 0) throw new Error("The selected image has an invalid size.");
  if (target.maskAsset.intrinsicSize.w <= 0 || target.maskAsset.intrinsicSize.h <= 0) throw new Error("The selected mask has an invalid size.");
  if (Math.round(target.asset.intrinsicSize.w) !== Math.round(target.maskAsset.intrinsicSize.w) || Math.round(target.asset.intrinsicSize.h) !== Math.round(target.maskAsset.intrinsicSize.h)) {
    throw new Error("The selected layer and mask image sizes do not match.");
  }
  if (!rectsAligned(target.bounds, target.maskBounds) || Math.abs(target.layer.transform.rotation - target.maskLayer.transform.rotation) > 0.001) {
    throw new Error("The selected layer and mask are not aligned.");
  }
}

function rectsAligned(a: Rect, b: Rect): boolean {
  return Math.abs(a.x - b.x) <= 0.5 && Math.abs(a.y - b.y) <= 0.5 && Math.abs(a.w - b.w) <= 0.5 && Math.abs(a.h - b.h) <= 0.5;
}

function toModelSize(value: number, axis: "width" | "height"): number {
  const rounded = Math.max(minModelSize, Math.ceil(value / modelMultiple) * modelMultiple);
  if (rounded > maxModelSize) throw new Error(`The inpaint ${axis} is too large for the model. Use masked-area inpaint or a smaller source.`);
  return rounded;
}

function prepareMaskedContentInputCanvas(sourceCanvas: HTMLCanvasElement, maskValues: Uint8ClampedArray, mode: GenerateSettings["inpaint"]["maskedContent"]): HTMLCanvasElement {
  if (mode === "neutral" || mode === "originalColor") return sourceCanvas;
  const context = sourceCanvas.getContext("2d");
  if (!context) return sourceCanvas;
  const imageData = context.getImageData(0, 0, sourceCanvas.width, sourceCanvas.height);
  imageData.data.set(applyMaskedContentModeToRgba(imageData.data, sourceCanvas.width, sourceCanvas.height, maskValues, mode));
  context.putImageData(imageData, 0, 0);
  return sourceCanvas;
}

export function applyMaskedContentModeToRgba(data: Uint8ClampedArray, width: number, height: number, maskValues: Uint8ClampedArray, mode: GenerateSettings["inpaint"]["maskedContent"]): Uint8ClampedArray {
  const next = new Uint8ClampedArray(data);
  if (mode === "neutral" || mode === "originalColor") return next;

  const edgeValues = mode === "edges" ? createEdgeMapValues(data, width, height) : undefined;

  for (let pixel = 0; pixel < width * height; pixel += 1) {
    const amount = (maskValues[pixel] ?? 0) / 255;
    if (amount <= 0) continue;

    const index = pixel * 4;
    const red = data[index] ?? 0;
    const green = data[index + 1] ?? 0;
    const blue = data[index + 2] ?? 0;
    const target = edgeValues ? edgeValues[pixel] ?? 128 : luminance(red, green, blue);
    next[index] = blendChannel(red, target, amount);
    next[index + 1] = blendChannel(green, target, amount);
    next[index + 2] = blendChannel(blue, target, amount);
  }

  return next;
}

function createEdgeMapValues(data: Uint8ClampedArray, width: number, height: number): Uint8ClampedArray {
  const gray = new Float32Array(width * height);
  const edges = new Uint8ClampedArray(width * height);

  for (let pixel = 0; pixel < width * height; pixel += 1) {
    const index = pixel * 4;
    gray[pixel] = luminance(data[index] ?? 0, data[index + 1] ?? 0, data[index + 2] ?? 0);
  }

  for (let y = 0; y < height; y += 1) {
    for (let x = 0; x < width; x += 1) {
      const gx =
        -sampleGray(gray, width, height, x - 1, y - 1) +
        sampleGray(gray, width, height, x + 1, y - 1) -
        2 * sampleGray(gray, width, height, x - 1, y) +
        2 * sampleGray(gray, width, height, x + 1, y) -
        sampleGray(gray, width, height, x - 1, y + 1) +
        sampleGray(gray, width, height, x + 1, y + 1);
      const gy =
        -sampleGray(gray, width, height, x - 1, y - 1) -
        2 * sampleGray(gray, width, height, x, y - 1) -
        sampleGray(gray, width, height, x + 1, y - 1) +
        sampleGray(gray, width, height, x - 1, y + 1) +
        2 * sampleGray(gray, width, height, x, y + 1) +
        sampleGray(gray, width, height, x + 1, y + 1);
      const magnitude = Math.hypot(gx, gy);
      edges[y * width + x] = Math.round(clampNumber(128 + Math.max(0, magnitude - 24) * 0.75, 128, 255));
    }
  }

  return edges;
}

function sampleGray(values: Float32Array, width: number, height: number, x: number, y: number): number {
  const clampedX = Math.max(0, Math.min(width - 1, x));
  const clampedY = Math.max(0, Math.min(height - 1, y));
  return values[clampedY * width + clampedX] ?? 0;
}

function luminance(red: number, green: number, blue: number): number {
  return Math.round(0.2126 * red + 0.7152 * green + 0.0722 * blue);
}

function blendChannel(previous: number, next: number, amount: number): number {
  return Math.round(previous * (1 - amount) + next * amount);
}

function clampNumber(value: number, min: number, max: number): number {
  return Math.max(min, Math.min(max, value));
}