1 files changed, 103 insertions, 0 deletions
diff --git a/deno/mail-relay/config.ts b/deno/mail-relay/config.ts
new file mode 100644
index 0000000..d58b163
--- /dev/null
+++ b/deno/mail-relay/config.ts
@@ -0,0 +1,103 @@
+export const APP_PREFIX = "crupest";
+export const APP_NAME = "mail-server";
+
+export interface ConfigItemDefinition {
+  description: string;
+  default?: string;
+  secret?: boolean;
+}
+
+export const CONFIG_DEFINITIONS = {
+  mailDomain: {
+    description: "the part after `@` of an address",
+  },
+  dataPath: {
+    description: "path to save app persistent data",
+  },
+  ldaPath: {
+    description: "full path of lda executable",
+    "default": "/dovecot/libexec/dovecot/dovecot-lda",
+  },
+  inboundFallback: {
+    description: "comma separated addresses used as fallback recipients",
+    "default": "",
+  },
+  awsInboundPath: {
+    description: "(random set) path for aws sns",
+  },
+  awsInboundKey: {
+    description: "(random set) http header Authorization for aws sns",
+  },
+  awsRegion: {
+    description: "aws region",
+  },
+  awsUser: {
+    description: "aws access key id",
+  },
+  awsPassword: {
+    description: "aws secret access key",
+    secret: true,
+  },
+  awsMailBucket: {
+    description: "aws s3 bucket saving raw mails",
+    secret: true,
+  },
+} as const satisfies Record<string, ConfigItemDefinition>;
+
+type ConfigDefinitions = typeof CONFIG_DEFINITIONS;
+type ConfigNames = keyof ConfigDefinitions;
+type ConfigMap = {
+  [K in ConfigNames]: ConfigDefinitions[K] & {
+    readonly env: string;
+    readonly value: string;
+  };
+};
+
+function resolveConfig(): ConfigMap {
+  const result: Record<string, ConfigMap[ConfigNames]> = {};
+  for (const [name, def] of Object.entries(CONFIG_DEFINITIONS)) {
+    const env = `${APP_PREFIX}-${APP_NAME}-${
+      name.replace(/[A-Z]/g, (m) => "-" + m.toLowerCase())
+    }`.replaceAll("-", "_").toUpperCase();
+    const value = Deno.env.get(env) ?? (def as ConfigItemDefinition).default;
+    if (value == null) {
+      throw new Error(`Required env ${env} (${def.description}) is not set.`);
+    }
+    result[name] = { ...def, env, value };
+  }
+  return result as ConfigMap;
+}
+
+export class Config {
+  #config = resolveConfig();
+
+  readonly HTTP_HOST = "0.0.0.0";
+  readonly HTTP_PORT = 2345;
+  readonly SMTP_HOST = "127.0.0.1";
+  readonly SMTP_PORT = 2346;
+
+  getAllConfig<K extends ConfigNames>(key: K): ConfigMap[K] {
+    return this.#config[key];
+  }
+
+  get(key: ConfigNames): string {
+    return this.getAllConfig(key).value;
+  }
+
+  getList(key: ConfigNames, separator: string = ","): string[] {
+    const value = this.get(key);
+    if (value.length === 0) return [];
+    return value.split(separator);
+  }
+
+  [Symbol.for("Deno.customInspect")]() {
+    return Object.entries(this.#config).map(([key, item]) =>
+      `${key} [env: ${item.env}]: ${
+        (item as ConfigItemDefinition).secret === true ? "***" : item.value
+      }`
+    ).join("\n");
+  }
+}
+
+const config = new Config();
+export default config;