118 lines
3.3 KiB
TypeScript
118 lines
3.3 KiB
TypeScript
import { FreshContext, Handlers } from "$fresh/server.ts";
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import { getImageContent } from "@lib/image.ts";
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import { SILVERBULLET_SERVER } from "@lib/env.ts";
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import { createLogger } from "@lib/log/index.ts";
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import { isLocalImage } from "@lib/string.ts";
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const log = createLogger("api/image");
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// Constants for image processing
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const CONFIG = {
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maxDimension: 2048,
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minDimension: 1,
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acceptedMimeTypes: new Set([
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"image/jpeg",
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"image/png",
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"image/webp",
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"image/gif",
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]),
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};
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interface ImageParams {
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image: string;
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height: number;
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width: number;
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}
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/**
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* Validates and parses URL parameters for image processing
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*/
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function parseParams(reqUrl: URL): ImageParams | string {
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try {
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const image = reqUrl.searchParams.get("image")?.replace(/^\//, "");
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if (!image) {
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return "Missing 'image' query parameter.";
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}
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// Parse dimensions with defaults
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const height = Math.floor(Number(reqUrl.searchParams.get("height")) || 0);
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const width = Math.floor(Number(reqUrl.searchParams.get("width")) || 0);
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// Validate dimensions
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if (height < 0 || width < 0) {
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return "Negative height or width is not supported.";
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}
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if (height > CONFIG.maxDimension || width > CONFIG.maxDimension) {
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return `Width and height cannot exceed ${CONFIG.maxDimension}.`;
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}
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// If dimensions are provided, ensure they're not too small
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if (
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(height > 0 && height < CONFIG.minDimension) ||
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(width > 0 && width < CONFIG.minDimension)
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) {
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return `Dimensions must be at least ${CONFIG.minDimension} pixel.`;
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}
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return { image, height, width };
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} catch (error) {
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log.error("Error parsing parameters:", error);
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return "Invalid parameters provided.";
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}
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}
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// Helper function to generate ETag
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async function generateETag(content: ArrayBuffer): Promise<string> {
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const hashBuffer = await crypto.subtle.digest("SHA-256", content);
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return `"${
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Array.from(new Uint8Array(hashBuffer))
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.map((b) => b.toString(16).padStart(2, "0"))
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.join("")
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}"`;
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}
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async function GET(req: Request, _ctx: FreshContext): Promise<Response> {
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try {
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const url = new URL(req.url);
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const params = parseParams(url);
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if (typeof params === "string") {
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return new Response(params, {
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status: 400,
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headers: { "Content-Type": "text/plain" },
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});
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}
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const imageUrl = isLocalImage(params.image)
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? `${SILVERBULLET_SERVER}/${params.image.replace(/^\//, "")}`
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: params.image;
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log.debug("Processing image request:", { imageUrl, params });
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const image = await getImageContent(imageUrl, params);
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// Generate ETag based on image content
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const eTag = await generateETag(image.content);
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// Set caching headers
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return new Response(image.content, {
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headers: {
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"Content-Type": image.mimeType,
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"Cache-Control": "public, max-age=31536000, immutable", // Cache for 1 year
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"ETag": eTag,
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"Last-Modified": new Date().toUTCString(), // Replace with image's actual modified date if available
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},
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});
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} catch (error) {
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log.error("Error processing image:", error);
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return new Response("Internal server error", {
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status: 500,
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headers: { "Content-Type": "text/plain" },
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});
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}
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}
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export const handler: Handlers = {
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GET,
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};
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