1 files changed, 145 insertions, 0 deletions
diff --git a/apps/web/src/services/storage/quota.ts b/apps/web/src/services/storage/quota.ts
new file mode 100644
index 00000000..1eb6028e
--- /dev/null
+++ b/apps/web/src/services/storage/quota.ts
@@ -0,0 +1,145 @@
+const BYTE_UNITS = ["B", "KB", "MB", "GB", "TB"] as const;
+
+export const STORAGE_HEADROOM_RESERVE_BYTES = 50 * 1024 * 1024;
+
+export interface StorageQuotaStatus {
+	quotaBytes: number | null;
+	usageBytes: number | null;
+	headroomBytes: number | null;
+	availableBytes: number | null;
+}
+
+export interface StorageCapacityCheckResult {
+	canStore: boolean;
+	reason: "enough-space" | "insufficient-space" | "estimate-unavailable";
+	availableBytes: number | null;
+}
+
+function normalizeByteValue({ value }: { value: unknown }): number | null {
+	if (typeof value !== "number" || !Number.isFinite(value) || value < 0) {
+		return null;
+	}
+
+	return value;
+}
+
+export function formatStorageBytes({ bytes }: { bytes: number }): string {
+	if (!Number.isFinite(bytes) || bytes <= 0) {
+		return "0 B";
+	}
+
+	let value = bytes;
+	let unitIndex = 0;
+
+	while (value >= 1024 && unitIndex < BYTE_UNITS.length - 1) {
+		value /= 1024;
+		unitIndex += 1;
+	}
+
+	const precision = value >= 10 || unitIndex === 0 ? 0 : 1;
+	return `${value.toFixed(precision)} ${BYTE_UNITS[unitIndex]}`;
+}
+
+export async function readStorageQuotaStatus(): Promise<StorageQuotaStatus> {
+	if (
+		typeof navigator === "undefined" ||
+		!navigator.storage ||
+		typeof navigator.storage.estimate !== "function"
+	) {
+		return {
+			quotaBytes: null,
+			usageBytes: null,
+			headroomBytes: null,
+			availableBytes: null,
+		};
+	}
+
+	const estimate = await navigator.storage.estimate();
+	const quotaBytes = normalizeByteValue({ value: estimate.quota });
+	const usageBytes = normalizeByteValue({ value: estimate.usage });
+
+	if (quotaBytes === null || usageBytes === null) {
+		return {
+			quotaBytes,
+			usageBytes,
+			headroomBytes: null,
+			availableBytes: null,
+		};
+	}
+
+	const headroomBytes = Math.max(quotaBytes - usageBytes, 0);
+	const availableBytes = Math.max(
+		headroomBytes - STORAGE_HEADROOM_RESERVE_BYTES,
+		0,
+	);
+
+	return {
+		quotaBytes,
+		usageBytes,
+		headroomBytes,
+		availableBytes,
+	};
+}
+
+export function evaluateStorageCapacity({
+	requiredBytes,
+	quotaStatus,
+}: {
+	requiredBytes: number;
+	quotaStatus: StorageQuotaStatus;
+}): StorageCapacityCheckResult {
+	if (quotaStatus.availableBytes === null) {
+		return {
+			canStore: true,
+			reason: "estimate-unavailable",
+			availableBytes: null,
+		};
+	}
+
+	if (requiredBytes > quotaStatus.availableBytes) {
+		return {
+			canStore: false,
+			reason: "insufficient-space",
+			availableBytes: quotaStatus.availableBytes,
+		};
+	}
+
+	return {
+		canStore: true,
+		reason: "enough-space",
+		availableBytes: quotaStatus.availableBytes,
+	};
+}
+
+export class StorageQuotaExceededError extends Error {
+	requiredBytes: number;
+
+	constructor({ requiredBytes }: { requiredBytes: number }) {
+		super(
+			`Not enough browser storage to save a ${formatStorageBytes({ bytes: requiredBytes })} file.`,
+		);
+
+		this.name = "StorageQuotaExceededError";
+		this.requiredBytes = requiredBytes;
+	}
+}
+
+export function isStorageQuotaExceededError({
+	error,
+}: {
+	error: unknown;
+}): boolean {
+	if (error instanceof StorageQuotaExceededError) {
+		return true;
+	}
+
+	if (!(error instanceof Error)) {
+		return false;
+	}
+
+	return (
+		error.name === "QuotaExceededError" ||
+		error.name === "NS_ERROR_DOM_QUOTA_REACHED" ||
+		error.message.toLowerCase().includes("quota")
+	);
+}