1 files changed, 99 insertions, 0 deletions
diff --git a/src/config.ts b/src/config.ts
new file mode 100644
index 0000000..14dbd4f
--- /dev/null
+++ b/src/config.ts
@@ -0,0 +1,99 @@
+import { readFileSync } from "node:fs";
+import { isLogLevel, type LogLevel } from "./logging.js";
+import { isValidTimeZone } from "./timezone.js";
+
+export const DEFAULT_CONFIG_PATH = "/etc/mattertimesync/config.json";
+
+export interface Config {
+  /** Directory holding persistent Matter fabric state and service state. Contains secrets. */
+  storagePath: string;
+  /** IANA time-zone name, e.g. "America/Chicago". Never a fixed UTC offset. */
+  timezone: string;
+  logLevel: LogLevel;
+}
+
+export class ConfigError extends Error {}
+
+const DEFAULTS = {
+  timezone: "America/Chicago",
+  logLevel: "info" as LogLevel,
+};
+
+export function loadConfig(path: string): Config {
+  let raw: string;
+  try {
+    raw = readFileSync(path, "utf8");
+  } catch (cause) {
+    throw new ConfigError(
+      `Cannot read configuration file ${path}: ${cause instanceof Error ? cause.message : String(cause)}`,
+    );
+  }
+
+  let parsed: unknown;
+  try {
+    parsed = JSON.parse(raw);
+  } catch (cause) {
+    throw new ConfigError(
+      `Configuration file ${path} is not valid JSON: ${cause instanceof Error ? cause.message : String(cause)}`,
+    );
+  }
+
+  return validateConfig(parsed, path);
+}
+
+export function validateConfig(parsed: unknown, source = "configuration"): Config {
+  if (typeof parsed !== "object" || parsed === null || Array.isArray(parsed)) {
+    throw new ConfigError(`${source}: top-level value must be a JSON object`);
+  }
+  const record = parsed as Record<string, unknown>;
+
+  // Device membership lives in controller storage, not the configuration, so
+  // there is deliberately no nodeId field; commands take --node instead.
+  const known = new Set(["storagePath", "timezone", "logLevel"]);
+  for (const key of Object.keys(record)) {
+    if (!known.has(key)) {
+      throw new ConfigError(`${source}: unknown field "${key}"`);
+    }
+  }
+
+  const storagePath = record["storagePath"];
+  if (typeof storagePath !== "string" || storagePath.length === 0) {
+    throw new ConfigError(`${source}: "storagePath" is required and must be a non-empty string`);
+  }
+
+  const timezone = record["timezone"] === undefined ? DEFAULTS.timezone : record["timezone"];
+  if (typeof timezone !== "string" || !isValidTimeZone(timezone)) {
+    throw new ConfigError(
+      `${source}: "timezone" must be a valid IANA time-zone name (got ${JSON.stringify(timezone)})`,
+    );
+  }
+
+  const logLevel = record["logLevel"] === undefined ? DEFAULTS.logLevel : record["logLevel"];
+  if (!isLogLevel(logLevel)) {
+    throw new ConfigError(`${source}: "logLevel" must be one of debug, info, warn, error`);
+  }
+
+  return { storagePath, timezone, logLevel };
+}
+
+/**
+ * Parses a node ID given on the command line (--node). Node IDs are 64-bit
+ * values; they are carried as decimal strings so they never pass through a
+ * lossy JavaScript number.
+ */
+export function parseNodeId(value: unknown, source = "--node"): bigint {
+  if (typeof value === "string" && /^\d+$/.test(value)) {
+    return toNodeId(BigInt(value), source);
+  }
+  if (typeof value === "number" && Number.isSafeInteger(value) && value >= 0) {
+    return toNodeId(BigInt(value), source);
+  }
+  throw new ConfigError(`${source}: node ID must be a decimal string; got ${JSON.stringify(value)}`);
+}
+
+function toNodeId(value: bigint, source: string): bigint {
+  if (value < 0n || value >= 1n << 64n) {
+    throw new ConfigError(`${source}: node ID must fit in an unsigned 64-bit integer`);
+  }
+  return value;
+}