import type { ImageDimensions, ResizeResult } from "./types" import { extractBase64Data } from "../../tools/look-at/mime-type-inference" import { log } from "../../shared" import { resizeImageFallback } from "./png-fallback-resizer" const ANTHROPIC_MAX_LONG_EDGE = 1568 const ANTHROPIC_MAX_FILE_SIZE = 5 * 1024 * 1024 type SharpFormat = "jpeg" | "png" | "gif" | "webp" interface SharpMetadata { width?: number height?: number } interface SharpInstance { resize(width: number, height: number, options: { fit: "inside" }): SharpInstance toFormat(format: SharpFormat, options?: { quality?: number }): SharpInstance toBuffer(): Promise metadata(): Promise } type SharpFactory = (input: Buffer) => SharpInstance function resolveSharpFactory(sharpModule: unknown): SharpFactory | null { if (typeof sharpModule === "function") { return sharpModule as SharpFactory } if (!sharpModule || typeof sharpModule !== "object") { return null } const defaultExport = Reflect.get(sharpModule, "default") return typeof defaultExport === "function" ? (defaultExport as SharpFactory) : null } function resolveSharpFormat(mimeType: string): SharpFormat { const normalizedMime = mimeType.toLowerCase() if (normalizedMime === "image/png") { return "png" } if (normalizedMime === "image/gif") { return "gif" } if (normalizedMime === "image/webp") { return "webp" } return "jpeg" } function canAdjustQuality(format: SharpFormat): boolean { return format === "jpeg" || format === "webp" } function toDimensions(metadata: SharpMetadata): ImageDimensions | null { const { width, height } = metadata if (!width || !height) { return null } return { width, height } } async function renderResizedBuffer(args: { sharpFactory: SharpFactory inputBuffer: Buffer target: ImageDimensions format: SharpFormat quality?: number }): Promise { const { sharpFactory, inputBuffer, target, format, quality } = args return sharpFactory(inputBuffer) .resize(target.width, target.height, { fit: "inside" }) .toFormat(format, quality ? { quality } : undefined) .toBuffer() } function getErrorMessage(error: unknown): string { return error instanceof Error ? error.message : String(error) } function loadSharpModule(): Promise { return Function('return import("sharp").catch(() => null)')() as Promise } export function calculateTargetDimensions( width: number, height: number, maxLongEdge = ANTHROPIC_MAX_LONG_EDGE, ): ImageDimensions | null { if (width <= 0 || height <= 0 || maxLongEdge <= 0) { return null } const longEdge = Math.max(width, height) if (longEdge <= maxLongEdge) { return null } if (width >= height) { return { width: maxLongEdge, height: Math.max(1, Math.floor((height * maxLongEdge) / width)), } } return { width: Math.max(1, Math.floor((width * maxLongEdge) / height)), height: maxLongEdge, } } export async function resizeImage( base64DataUrl: string, mimeType: string, target: ImageDimensions, deps: { loadSharpModule?: () => Promise } = {}, ): Promise { try { const sharpModule = await (deps.loadSharpModule?.() ?? loadSharpModule()) if (!sharpModule) { log("[read-image-resizer] sharp unavailable, attempting pure-JS fallback") return resizeImageFallback(base64DataUrl, mimeType, target) } const sharpFactory = resolveSharpFactory(sharpModule) if (!sharpFactory) { log("[read-image-resizer] sharp import has unexpected shape, attempting pure-JS fallback") return resizeImageFallback(base64DataUrl, mimeType, target) } const rawBase64 = extractBase64Data(base64DataUrl) if (!rawBase64) { return null } const inputBuffer = Buffer.from(rawBase64, "base64") if (inputBuffer.length === 0) { return null } const original = toDimensions(await sharpFactory(inputBuffer).metadata()) if (!original) { return null } const format = resolveSharpFormat(mimeType) let resizedBuffer = await renderResizedBuffer({ sharpFactory, inputBuffer, target, format, }) if (resizedBuffer.length > ANTHROPIC_MAX_FILE_SIZE && canAdjustQuality(format)) { for (const quality of [80, 60, 40]) { resizedBuffer = await renderResizedBuffer({ sharpFactory, inputBuffer, target, format, quality, }) if (resizedBuffer.length <= ANTHROPIC_MAX_FILE_SIZE) { break } } } const resized = toDimensions(await sharpFactory(resizedBuffer).metadata()) if (!resized) { return null } return { resizedDataUrl: `data:${mimeType};base64,${resizedBuffer.toString("base64")}`, original, resized, } } catch (error) { log("[read-image-resizer] resize failed", { error: getErrorMessage(error), mimeType, target, }) return null } }