import { randomUUID } from 'crypto'
import { dirname, join } from 'path'
import { mkdir, readdir, readFile, rm, writeFile } from 'fs/promises'
import { existsSync } from 'fs'
import { TMP_DIR } from '@/lib/constants'
import { getModelAssetPath } from '@/lib/model-paths'
import { prepareGitAssets } from '@/lib/prepare-git-assets'
import type { ParsedFile, PreparedAssetSummary, PushFile } from '@/lib/types'

const STAGING_ROOT = join(TMP_DIR, 'staging')
const STAGING_TTL_MS = 60 * 60 * 1000

interface StagedOriginalFile {
  filename: string
  size: number
  isModel: boolean
}

interface StagedPreparedData {
  modelFilename: string
  compressed: boolean
  compressionError?: string
  assetSummaries: PreparedAssetSummary[]
}

interface StagingManifest {
  stagingId: string
  folderName: string
  createdAt: number
  originals: StagedOriginalFile[]
  prepared?: StagedPreparedData
}

interface PreparedStageAssetsResult {
  folderName: string
  filesToPush: PushFile[]
  modelFilename: string
  assetSummaries: PreparedAssetSummary[]
  compressed: boolean
  compressionError?: string
}

function getStageDir(stagingId: string) {
  return join(STAGING_ROOT, stagingId)
}

function getOriginalDir(stagingId: string) {
  return join(getStageDir(stagingId), 'original')
}

function getPreparedDir(stagingId: string) {
  return join(getStageDir(stagingId), 'prepared')
}

function getManifestPath(stagingId: string) {
  return join(getStageDir(stagingId), 'manifest.json')
}

async function ensureParentDir(filePath: string) {
  await mkdir(dirname(filePath), { recursive: true })
}

async function writeManifest(manifest: StagingManifest) {
  await ensureParentDir(getManifestPath(manifest.stagingId))
  await writeFile(getManifestPath(manifest.stagingId), JSON.stringify(manifest, null, 2), 'utf-8')
}

async function cleanupExpiredStagingUploads() {
  if (!existsSync(STAGING_ROOT)) return

  const entries = await readdir(STAGING_ROOT, { withFileTypes: true })
  const now = Date.now()

  for (const entry of entries) {
    if (!entry.isDirectory()) continue

    const stagingId = entry.name

    try {
      const manifest = await readStagedManifest(stagingId)
      if (now - manifest.createdAt > STAGING_TTL_MS) {
        await cleanupStagingUpload(stagingId)
      }
    } catch {
      await cleanupStagingUpload(stagingId).catch(() => {})
    }
  }
}

export async function createStagingUpload(folderName: string, parsedFiles: ParsedFile[]) {
  await cleanupExpiredStagingUploads()

  const stagingId = randomUUID()
  const originalDir = getOriginalDir(stagingId)
  await mkdir(originalDir, { recursive: true })

  const originals: StagedOriginalFile[] = []

  for (const file of parsedFiles) {
    const filePath = join(originalDir, file.filename)
    await ensureParentDir(filePath)
    await writeFile(filePath, file.buffer)
    originals.push({ filename: file.filename, size: file.buffer.length, isModel: file.isModel })
  }

  const manifest: StagingManifest = {
    stagingId,
    folderName,
    createdAt: Date.now(),
    originals,
  }

  await writeManifest(manifest)

  return {
    stagingId,
    folderName,
    filesCount: originals.length,
  }
}

export async function readStagedManifest(stagingId: string): Promise<StagingManifest> {
  const manifestPath = getManifestPath(stagingId)
  const content = await readFile(manifestPath, 'utf-8')
  return JSON.parse(content) as StagingManifest
}

async function readOriginalParsedFiles(stagingId: string, manifest: StagingManifest): Promise<ParsedFile[]> {
  const originalDir = getOriginalDir(stagingId)

  return Promise.all(
    manifest.originals.map(async (file) => ({
      filename: file.filename,
      buffer: await readFile(join(originalDir, file.filename)),
      isModel: file.isModel,
    })),
  )
}

async function buildPreparedPushFiles(stagingId: string, manifest: StagingManifest): Promise<PushFile[]> {
  const preparedDir = getPreparedDir(stagingId)

  return Promise.all(
    manifest.originals.map(async (file) => {
      const buffer = await readFile(join(preparedDir, file.filename))
      return {
        path: getModelAssetPath(manifest.folderName, file.filename),
        contentBase64: buffer.toString('base64'),
      }
    }),
  )
}

export async function ensurePreparedStagingAssets(stagingId: string): Promise<PreparedStageAssetsResult> {
  const manifest = await readStagedManifest(stagingId)

  if (!manifest.prepared) {
    const parsedFiles = await readOriginalParsedFiles(stagingId, manifest)
    const prepared = await prepareGitAssets({ folderName: manifest.folderName, parsedFiles })
    const preparedDir = getPreparedDir(stagingId)
    await mkdir(preparedDir, { recursive: true })

    for (const file of prepared.filesToPush) {
      const filename = file.path.split('/').pop()
      if (!filename) continue
      const outputPath = join(preparedDir, filename)
      await ensureParentDir(outputPath)
      await writeFile(outputPath, Buffer.from(file.contentBase64, 'base64'))
    }

    manifest.prepared = {
      modelFilename: prepared.modelFilename,
      compressed: prepared.compressed,
      compressionError: prepared.compressionError,
      assetSummaries: prepared.assetSummaries,
    }

    await writeManifest(manifest)
  }

  return {
    folderName: manifest.folderName,
    filesToPush: await buildPreparedPushFiles(stagingId, manifest),
    modelFilename: manifest.prepared.modelFilename,
    assetSummaries: manifest.prepared.assetSummaries,
    compressed: manifest.prepared.compressed,
    compressionError: manifest.prepared.compressionError,
  }
}

export async function readStagedOriginalFiles(stagingId: string): Promise<{ folderName: string; files: ParsedFile[] }> {
  const manifest = await readStagedManifest(stagingId)
  return {
    folderName: manifest.folderName,
    files: await readOriginalParsedFiles(stagingId, manifest),
  }
}

export async function cleanupStagingUpload(stagingId: string) {
  await rm(getStageDir(stagingId), { recursive: true, force: true })
}