import type { TileAnalysisResult } from '@/types/tileTypes'

const PIXEL_SAMPLE_RATE = 4

self.onmessage = async (e: MessageEvent) => {
  const { imageData, tileId, tileName } = e.data
  const result = analyzeTile(imageData, tileId, tileName)
  self.postMessage(result)
}

function analyzeTile(imageData: ImageData, tileId: string, tileName: string): TileAnalysisResult {
  const { r, g, b } = getDominantColorFast(imageData)
  const edge = getEdgeComplexityFast(imageData)
  const namePrefix = tileName.split('_')[0]
  return {
    tileId,
    color: { r, g, b },
    edge,
    namePrefix
  }
}

function getDominantColorFast(imageData: ImageData) {
  const data = new Uint8ClampedArray(imageData.data.buffer)
  let r = 0,
    g = 0,
    b = 0,
    total = 0
  const length = data.length

  for (let i = 0; i < length; i += 4 * PIXEL_SAMPLE_RATE) {
    if (data[i + 3] > 0) {
      r += data[i]
      g += data[i + 1]
      b += data[i + 2]
      total++
    }
  }

  return total > 0
    ? {
        r: Math.round(r / total),
        g: Math.round(g / total),
        b: Math.round(b / total)
      }
    : { r: 0, g: 0, b: 0 }
}

function getEdgeComplexityFast(imageData: ImageData) {
  const data = new Uint8ClampedArray(imageData.data.buffer)
  const width = imageData.width
  const height = imageData.height
  let edgePixels = 0

  // Only check every other row/column
  for (let y = 0; y < height; y += PIXEL_SAMPLE_RATE * 2) {
    for (let x = 0; x < width; x += PIXEL_SAMPLE_RATE * 2) {
      const i = (y * width + x) * 4
      if (data[i + 3] > 0 && (x === 0 || y === 0 || x >= width - PIXEL_SAMPLE_RATE || y >= height - PIXEL_SAMPLE_RATE || data[i - 4 * PIXEL_SAMPLE_RATE + 3] === 0)) {
        edgePixels++
      }
    }
  }
  return edgePixels * PIXEL_SAMPLE_RATE * 2
}