// server/src/routes/uploads-resized.js
import fs from 'node:fs'
import path from 'node:path'
import { findOriginalFile, getOrCreateResized, SUPPORTED_FORMATS, VALID_WIDTHS } from '../lib/image-resize.js'

const CACHE_CONTROL_IMMUTABLE = 'public, max-age=31536000, immutable'
const CACHE_CONTROL_SHORT = 'public, max-age=86400'

/**
 * Register GET /uploads-resized/* route for on-demand image resizing.
 * Must be registered BEFORE fastify-static for /uploads/.
 */
export function registerUploadsResized(fastify) {
  fastify.get('/uploads-resized/*', async (request, reply) => {
    const rawPath = request.params['*']
    const url = new URL(request.url, 'http://localhost')
    const widthParam = url.searchParams.get('w')

    // Parse: [subdir/]filename.format
    const parts = rawPath.split('/')
    let filename, subdir = ''

    if (parts.length > 1) {
      subdir = parts.slice(0, -1).join('/') + '/'
      filename = parts[parts.length - 1]
    } else {
      filename = parts[0]
    }

    const dotIdx = filename.lastIndexOf('.')
    if (dotIdx === -1) {
      return reply.code(400).send({ error: 'Invalid request: no format specified' })
    }

    const uuid = filename.slice(0, dotIdx)
    const format = filename.slice(dotIdx + 1).toLowerCase()

    if (!SUPPORTED_FORMATS.has(format)) {
      return reply.code(400).send({ error: `Unsupported format: ${format}. Use avif or webp.` })
    }

    // Validate width
    let width = null
    if (widthParam) {
      const w = parseInt(widthParam, 10)
      if (!VALID_WIDTHS.includes(w)) {
        return reply.code(400).send({ error: `Invalid width: ${widthParam}. Use: ${VALID_WIDTHS.join(', ')}` })
      }
      width = w
    }

    // If no width requested, serve original with short cache
    if (!width) {
      const originalPath = await findOriginalFile(uuid, subdir || undefined)
      if (!originalPath) {
        return reply.code(404).send({ error: 'Image not found' })
      }
      reply.header('Cache-Control', CACHE_CONTROL_SHORT)
      reply.header('Content-Type', format === 'avif' ? 'image/avif' : 'image/webp')
      return reply.send(fs.createReadStream(originalPath))
    }

    const result = await getOrCreateResized(uuid, width, format, subdir || undefined)
    if (!result) {
      return reply.code(404).send({ error: 'Image not found' })
    }

    reply.header('Cache-Control', CACHE_CONTROL_IMMUTABLE)
    reply.header('Content-Type', format === 'avif' ? 'image/avif' : 'image/webp')
    return reply.send(fs.createReadStream(result.path))
  })
}