// ---------------------------------------------------------------------------
// File diff classification — compares local files against a remote file map
// ---------------------------------------------------------------------------

import { MODEL_EXTENSIONS } from './constants'
import type { FileChange, PushFile } from './types'

export interface DiffResult {
  /** Map of lowercase filename → change status (for commit message) */
  fileChanges: Map<string, FileChange>
  /** Files that actually need to be pushed (new or changed) */
  changedFilesToPush: PushFile[]
  /** Filenames that were on remote but not in the new upload */
  deletedFileNames: string[]
  /** Full paths for deletion on remote */
  deletePaths: string[]
}

/**
 * Classify each file as new, changed, or unchanged by comparing against
 * the remote file map.
 *
 * Rules:
 * - Models: always re-pushed,
 *   but marked as 'unchanged' in the commit message when the folder already
 *   exists (we keep the current behavior of always delivering the model file).
 * - Textures: compared by size (not compressed, reliable).
 * - Orphan remote files: classified as deletions.
 */
export function classifyFileChanges(
  filesToPush: PushFile[],
  remoteFileMap: Map<string, number>,
  folderPath: string,
): DiffResult {
  const fileChanges = new Map<string, FileChange>()
  const changedFilesToPush: PushFile[] = []

  for (const f of filesToPush) {
    const filename = f.path.split('/').pop() ?? ''
    const ext = filename.slice(filename.lastIndexOf('.')).toLowerCase()
    const isModel = MODEL_EXTENSIONS.has(ext)

    if (isModel) {
      // Model: always re-push since compression makes size comparison unreliable.
      // Mark as 'unchanged' for the commit message when the folder already exists.
      const remoteSize = remoteFileMap.get(filename.toLowerCase())
      fileChanges.set(filename.toLowerCase(), remoteSize === undefined ? 'new' : 'unchanged')
      changedFilesToPush.push(f)
    } else {
      // Texture: compare by size
      const localSize = Buffer.from(f.contentBase64, 'base64').length
      const remoteSize = remoteFileMap.get(filename.toLowerCase())

      if (remoteSize === undefined) {
        fileChanges.set(filename.toLowerCase(), 'new')
        changedFilesToPush.push(f)
      } else if (remoteSize !== localSize) {
        fileChanges.set(filename.toLowerCase(), 'changed')
        changedFilesToPush.push(f)
      } else {
        fileChanges.set(filename.toLowerCase(), 'unchanged')
      }
    }
  }

  // Files on remote not in the new upload → deleted (orphans)
  const newFileNames = new Set(filesToPush.map((f) => (f.path.split('/').pop() ?? '').toLowerCase()))
  const deletedFileNames: string[] = []
  const deletePaths: string[] = []
  for (const [name] of remoteFileMap) {
    if (!newFileNames.has(name)) {
      deletedFileNames.push(name)
      deletePaths.push(`${folderPath}/${name}`)
    }
  }

  return { fileChanges, changedFilesToPush, deletedFileNames, deletePaths }
}