import { NextResponse } from "next/server"
import { readFile } from "node:fs/promises"
import { existsSync } from "node:fs"
import { join } from "node:path"
import { getManualsThumbnailsRoot } from "@/lib/manuals-paths"
import { getManualAssetFromStorage } from "@/lib/manuals-object-storage"

export const dynamic = "force-dynamic"

function buildPlaceholderSvg(label: string) {
  const safeLabel = label
    .replace(/&/g, "&")
    .replace(/</g, "&lt;")
    .replace(/>/g, "&gt;")
    .replace(/"/g, "&quot;")
    .replace(/'/g, "&#39;")

  return `
    <svg xmlns="http://www.w3.org/2000/svg" width="800" height="480" viewBox="0 0 800 480" fill="none">
      <rect width="800" height="480" rx="36" fill="#F5F1E6"/>
      <rect x="28" y="28" width="744" height="424" rx="28" fill="#FCFBF7" stroke="#DCC9A3" stroke-width="2"/>
      <circle cx="126" cy="124" r="54" fill="#E5D5B3"/>
      <path d="M102 124h48M126 100v48" stroke="#8A6730" stroke-width="10" stroke-linecap="round"/>
      <text x="400" y="184" text-anchor="middle" fill="#5C4320" font-size="40" font-family="Arial, sans-serif" font-weight="700">
        Manual Preview
      </text>
      <text x="400" y="236" text-anchor="middle" fill="#8A6730" font-size="24" font-family="Arial, sans-serif">
        Thumbnail unavailable
      </text>
      <text x="400" y="298" text-anchor="middle" fill="#7A6A4A" font-size="22" font-family="Arial, sans-serif">
        ${safeLabel}
      </text>
    </svg>
  `.trim()
}

function decodeSegments(pathArray: string[]) {
  return pathArray.map((segment) => {
    try {
      let decoded = segment
      while (decoded !== decodeURIComponent(decoded)) {
        decoded = decodeURIComponent(decoded)
      }
      return decoded
    } catch {
      return segment
    }
  })
}

function invalidPath(pathValue: string) {
  return pathValue.includes("..") || pathValue.startsWith("/")
}

function getContentType(pathValue: string) {
  if (pathValue.toLowerCase().endsWith(".png")) {
    return "image/png"
  }

  if (pathValue.toLowerCase().endsWith(".webp")) {
    return "image/webp"
  }

  return "image/jpeg"
}

export async function GET(
  _request: Request,
  { params }: { params: Promise<{ path: string[] }> },
) {
  try {
    const { path: pathArray } = await params
    const decodedPath = decodeSegments(pathArray)
    const filePath = decodedPath.join("/")
    const lowerPath = filePath.toLowerCase()

    if (
      invalidPath(filePath) ||
      (!lowerPath.endsWith(".jpg") && !lowerPath.endsWith(".jpeg") && !lowerPath.endsWith(".png") && !lowerPath.endsWith(".webp"))
    ) {
      return new NextResponse("Invalid path", { status: 400 })
    }

    const storageObject = await getManualAssetFromStorage("thumbnails", filePath)
    if (storageObject) {
      return new NextResponse(Buffer.from(storageObject.body), {
        headers: {
          "Content-Type": storageObject.contentType || getContentType(filePath),
          "Content-Disposition": `inline; filename="${encodeURIComponent(decodedPath.at(-1) || "thumbnail.jpg")}"`,
          "Cache-Control": "public, max-age=31536000, immutable",
          "X-Content-Type-Options": "nosniff",
        },
      })
    }

    const thumbnailsDir = getManualsThumbnailsRoot()
    const fullPath = join(thumbnailsDir, filePath)
    const normalizedFullPath = fullPath.replace(/\\/g, "/")
    const normalizedThumbnailsDir = thumbnailsDir.replace(/\\/g, "/")

    if (!existsSync(normalizedFullPath) && !existsSync(fullPath)) {
      const label = decodedPath.at(-1)?.replace(/\.(jpg|jpeg|png|webp)$/i, "") || "Rocky Mountain Vending"
      return new NextResponse(buildPlaceholderSvg(label), {
        headers: {
          "Content-Type": "image/svg+xml; charset=utf-8",
          "Cache-Control": "public, max-age=3600, stale-while-revalidate=86400",
          "X-Content-Type-Options": "nosniff",
        },
      })
    }

    const fileToRead = existsSync(normalizedFullPath) ? normalizedFullPath : fullPath
    const resolvedPath = fileToRead.replace(/\\/g, "/")
    if (!resolvedPath.startsWith(normalizedThumbnailsDir)) {
      return new NextResponse("Invalid path", { status: 400 })
    }

    const fileBuffer = await readFile(fileToRead)
    return new NextResponse(fileBuffer, {
      headers: {
        "Content-Type": getContentType(filePath),
        "Content-Disposition": `inline; filename="${encodeURIComponent(decodedPath.at(-1) || "thumbnail.jpg")}"`,
        "Cache-Control": "public, max-age=31536000, immutable",
        "X-Content-Type-Options": "nosniff",
      },
    })
  } catch (error) {
    console.error("[manuals-api] failed to serve thumbnail", error)
    return new NextResponse("Internal server error", { status: 500 })
  }
}