import type { AgentPsdTemplateReplaceMode } from "@/lib/agents/psd-template-config";

export interface AgentPsdImagePlacement {
  scale: number;
  offsetX: number;
  offsetY: number;
}

export interface AgentPsdImageSize {
  width: number;
  height: number;
}

export function getDefaultAgentPsdImagePlacement(): AgentPsdImagePlacement {
  return {
    scale: 1,
    offsetX: 0,
    offsetY: 0,
  };
}

export function normalizeAgentPsdImagePlacement(
  value: Partial<AgentPsdImagePlacement> | null | undefined
): AgentPsdImagePlacement {
  const scale = Number(value?.scale);
  const offsetX = Number(value?.offsetX);
  const offsetY = Number(value?.offsetY);

  return {
    scale: Number.isFinite(scale) && scale > 0 ? Math.max(0.1, Math.min(8, scale)) : 1,
    offsetX: Number.isFinite(offsetX) ? offsetX : 0,
    offsetY: Number.isFinite(offsetY) ? offsetY : 0,
  };
}

function resolveBaseFittedSize(params: {
  containerWidth: number;
  containerHeight: number;
  imageWidth: number;
  imageHeight: number;
  replaceMode: AgentPsdTemplateReplaceMode;
}) {
  const { containerWidth, containerHeight, imageWidth, imageHeight, replaceMode } = params;
  const safeImageWidth = Math.max(1, imageWidth);
  const safeImageHeight = Math.max(1, imageHeight);

  if (replaceMode === "stretch") {
    return {
      width: containerWidth,
      height: containerHeight,
      left: 0,
      top: 0,
    };
  }

  const fitRatio =
    replaceMode === "contain"
      ? Math.min(containerWidth / safeImageWidth, containerHeight / safeImageHeight)
      : Math.max(containerWidth / safeImageWidth, containerHeight / safeImageHeight);

  const width = safeImageWidth * fitRatio;
  const height = safeImageHeight * fitRatio;

  return {
    width,
    height,
    left: (containerWidth - width) / 2,
    top: (containerHeight - height) / 2,
  };
}

export function resolveAgentPsdImagePlacementFrame(params: {
  containerWidth: number;
  containerHeight: number;
  imageWidth: number;
  imageHeight: number;
  replaceMode: AgentPsdTemplateReplaceMode;
  placement?: Partial<AgentPsdImagePlacement> | null;
}) {
  const { containerWidth, containerHeight, imageWidth, imageHeight, replaceMode } = params;
  const placement = normalizeAgentPsdImagePlacement(params.placement);
  const baseFrame = resolveBaseFittedSize({
    containerWidth,
    containerHeight,
    imageWidth,
    imageHeight,
    replaceMode,
  });

  const width = baseFrame.width * placement.scale;
  const height = baseFrame.height * placement.scale;
  const left = baseFrame.left - (width - baseFrame.width) / 2 + placement.offsetX;
  const top = baseFrame.top - (height - baseFrame.height) / 2 + placement.offsetY;

  return {
    width,
    height,
    left,
    top,
  };
}