import { mkdtempSync, writeFileSync, readFileSync, rmSync } from 'node:fs'
import { join } from 'node:path'
import { tmpdir } from 'node:os'
import { runFfmpeg } from '../ffmpeg'
import { imageDimensions } from '../resolution'
export async function fitStill(data: Buffer, width: number, height: number) {
  const dir=mkdtempSync(join(tmpdir(),'studio2-fit-'))
  try {
    const input=join(dir,'source'),output=join(dir,'fitted.png')
    writeFileSync(input,data)
    await runFfmpeg(['-y','-i',input,'-vf',`scale=${width}:${height}:force_original_aspect_ratio=decrease,pad=${width}:${height}:(ow-iw)/2:(oh-ih)/2:color=black,setsar=1`,'-frames:v','1',output])
    return readFileSync(output)
  } finally { rmSync(dir,{recursive:true,force:true}) }
}
/** Only scale/pad when the still's aspect truly differs from the job canvas.
 * A matching frame (typical extend handoff) must reach Comfy byte-identical. */
export function needsFit(data: Buffer, width: number, height: number) {
  const size = imageDimensions(data)
  if (!size?.width || !size?.height) return true
  if (size.width === width && size.height === height) return false
  const target = width / height, actual = size.width / size.height
  return Math.abs(target - actual) > 0.01
}