/*
 Utility functions to store and load coordinates to and from module memory
 Coordinates are assumed to be an array of coordinate pairs ([[x1,y1], [x2,y2], [x3,y3]])
*/

/**
 * Allocate memory for coordinates and stores them in a flat representation.
 * Returns a pointer to the buffer. The length of the buffer is coords.length * 2
 * @param {*} module 
 * @param {Array} coords - An array of coordinate pairs
 */
export function storeCoords(module, coords) {
  const buffer = module._malloc(coords.length * 2 * 8)
  const heap = new Float64Array(module.HEAPF64.buffer, buffer, coords.length * 2)
  for (let i = 0; i < coords.length; i++) {
      heap[2*i] = coords[i][0]
      heap[2*i + 1] = coords[i][1]
  }
  return buffer
}

/**
 * Loads coordinates from the memory by the result pointer.
 * Frees the resultpointer and the result before returning
 * @param {*} module 
 * @param {*} result - pointer to Uint32 array of length 2. Stores the resultPointer and resultLength
 */
export function loadResultAndFreeMemory(module, result) {
  const [resultPointer, resultLength] = new Uint32Array(module.HEAPU32.buffer, result, 2)
  const simplified = new Float64Array(module.HEAPF64.buffer, resultPointer, resultLength)
  const coords = unflattenCoords(simplified)
  module._free(result)
  module._free(resultPointer)
  return coords
}

/**
 * Loads coordinates from the memory by the result pointer without freeing memory.
 * For benchmarking purposes
 * @param {*} module 
 * @param {*} result - pointer to Uint32 array of length 2. Stores the resultPointer and resultLength
 */
export function loadResult(module, result) {
  const [resultPointer, resultLength] = new Uint32Array(module.HEAPU32.buffer, result, 2)
  const simplified = new Float64Array(module.HEAPF64.buffer, resultPointer, resultLength)
  return unflattenCoords(simplified)
}

/**
 * Transforms a flat array to an array coordinate pairs
 * @param {Array} flattened - length must be even
 */
export function unflattenCoords (flattened) {
  const coords = []
  let x, y
  for (let i = 0; i < flattened.length; i += 2) {
      x = flattened[i]
      y = flattened[i + 1]
      coords.push([x, y])
  }
  return coords
}