6 files changed, 319 insertions, 0 deletions
diff --git a/deno/base/config.ts b/deno/base/config.ts
new file mode 100644
index 0000000..8fce1d8
--- /dev/null
+++ b/deno/base/config.ts
@@ -0,0 +1,93 @@
+import { camelCaseToKebabCase } from "./text.ts";
+
+export interface ConfigDefinitionItem {
+  readonly description: string;
+  readonly default?: string;
+  readonly secret?: boolean;
+}
+
+interface ConfigMapItem extends ConfigDefinitionItem {
+  readonly env: string;
+  value?: string;
+}
+
+export type ConfigDefinition<K extends string = string> = Record<
+  K,
+  ConfigDefinitionItem
+>;
+type ConfigMap<K extends string = string> = Record<K, ConfigMapItem>;
+
+export class ConfigProvider<K extends string> {
+  readonly #prefix: string;
+  readonly #map: ConfigMap<K>;
+
+  constructor(prefix: string, ...definitions: Partial<ConfigDefinition<K>>[]) {
+    this.#prefix = prefix;
+
+    const map: ConfigMap = {};
+    for (const definition of definitions) {
+      for (const [key, def] of Object.entries(definition as ConfigDefinition)) {
+        map[key] = {
+          ...def,
+          env: `${this.#prefix}-${camelCaseToKebabCase(key as string)}`
+            .replaceAll("-", "_")
+            .toUpperCase(),
+        };
+      }
+    }
+    this.#map = map as ConfigMap<K>;
+  }
+
+  resolveFromEnv(options?: { keys?: K[] }) {
+    const keys = options?.keys ?? Object.keys(this.#map);
+    for (const key of keys) {
+      const { env, description, default: _default } = this.#map[key as K];
+      const value = Deno.env.get(env) ?? _default;
+      if (value == null) {
+        throw new Error(`Required env ${env} (${description}) is not set.`);
+      }
+      this.#map[key as K].value = value;
+    }
+  }
+
+  get(key: K): string {
+    if (!(key in this.#map)) {
+      throw new Error(`Unknown config key ${key as string}.`);
+    }
+    if (this.#map[key].value == null) {
+      this.resolveFromEnv({ keys: [key] });
+    }
+    return this.#map[key].value!;
+  }
+
+  set(key: K, value: string) {
+    if (!(key in this.#map)) {
+      throw new Error(`Unknown config key ${key as string}.`);
+    }
+    this.#map[key].value = value;
+  }
+
+  getInt(key: K): number {
+    return Number(this.get(key));
+  }
+
+  getList(key: K, separator: string = ","): string[] {
+    const value = this.get(key);
+    if (value.length === 0) return [];
+    return value.split(separator);
+  }
+
+  [Symbol.for("Deno.customInspect")]() {
+    const getValueString = (item: ConfigMapItem): string => {
+      if (item.value == null) return "(unresolved)";
+      if (item.secret === true) return "***";
+      return item.value;
+    };
+
+    return Object.entries(this.#map as ConfigMap)
+      .map(
+        ([key, item]) => `${key} [env: ${item.env}]: ${getValueString(item)}`,
+      )
+      .join("\n");
+  }
+}
diff --git a/deno/base/cron.ts b/deno/base/cron.ts
new file mode 100644
index 0000000..bf0a0be
--- /dev/null
+++ b/deno/base/cron.ts
@@ -0,0 +1,43 @@
+export type CronCallback = (task: CronTask) => Promise<void>;
+
+export interface CronTaskConfig {
+  readonly name: string;
+  readonly interval: number;
+  readonly callback: CronCallback;
+  readonly startNow?: boolean;
+}
+
+export class CronTask {
+  #timerTag: number | null = null;
+
+  constructor(public readonly config: CronTaskConfig) {
+    if (config.interval <= 0) {
+      throw new Error("Cron task interval must be positive.");
+    }
+
+    if (config.startNow === true) {
+      this.start();
+    }
+  }
+
+  get running(): boolean {
+    return this.#timerTag != null;
+  }
+
+  start() {
+    if (this.#timerTag == null) {
+      this.#timerTag = setInterval(
+        this.config.callback,
+        this.config.interval,
+        this,
+      );
+    }
+  }
+
+  stop() {
+    if (this.#timerTag != null) {
+      clearInterval(this.#timerTag);
+      this.#timerTag = null;
+    }
+  }
+}
diff --git a/deno/base/date.ts b/deno/base/date.ts
new file mode 100644
index 0000000..e65691e
--- /dev/null
+++ b/deno/base/date.ts
@@ -0,0 +1,6 @@
+export function toFileNameString(date: Date, dateOnly?: boolean): string {
+  const str = date.toISOString();
+  return dateOnly === true
+    ? str.slice(0, str.indexOf("T"))
+    : str.replaceAll(/:|\./g, "-");
+}
diff --git a/deno/base/deno.json b/deno/base/deno.json
new file mode 100644
index 0000000..2c2d550
--- /dev/null
+++ b/deno/base/deno.json
@@ -0,0 +1,11 @@
+{
+  "name": "@crupest/base",
+  "version": "0.1.0",
+  "exports": {
+    "./config": "./config.ts",
+    "./cron": "./cron.ts",
+    "./date": "./date.ts",
+    "./text": "./text.ts",
+    "./log": "./log.ts"
+  }
+}
diff --git a/deno/base/log.ts b/deno/base/log.ts
new file mode 100644
index 0000000..d0a5b80
--- /dev/null
+++ b/deno/base/log.ts
@@ -0,0 +1,163 @@
+import { join } from "@std/path";
+
+import { toFileNameString } from "./date.ts";
+
+export type LogLevel = "error" | "warn" | "info";
+
+export interface LogEntry {
+  content: [unknown, ...unknown[]];
+  level?: LogLevel;
+  cause?: unknown;
+}
+
+export interface LogEntryBuilder {
+  withLevel(level: LogLevel): LogEntryBuilder;
+  withCause(cause: unknown): LogEntryBuilder;
+  setError(error: boolean): LogEntryBuilder;
+  write(): void;
+}
+
+export interface ExternalLogStream extends Disposable {
+  stream: WritableStream;
+}
+
+export class Logger {
+  #indentSize = 2;
+  #externalLogDir?: string;
+
+  #contextStack: { depth: number; level: LogLevel }[] = [
+    { depth: 0, level: "info" },
+  ];
+
+  get #context() {
+    return this.#contextStack.at(-1)!;
+  }
+
+  get indentSize() {
+    return this.#indentSize;
+  }
+
+  set indentSize(value: number) {
+    this.#indentSize = value;
+  }
+
+  get externalLogDir() {
+    return this.#externalLogDir;
+  }
+
+  set externalLogDir(value: string | undefined) {
+    this.#externalLogDir = value;
+    if (value != null) {
+      Deno.mkdirSync(value, {
+        recursive: true,
+      });
+    }
+  }
+
+  write(entry: LogEntry): void {
+    const { content, level, cause } = entry;
+    const [message, ...rest] = content;
+    console[level ?? this.#context.level](
+      " ".repeat(this.#indentSize * this.#context.depth) + String(message),
+      ...(cause != null ? [cause, ...rest] : rest),
+    );
+  }
+
+  push(entry: LogEntry): Disposable {
+    this.write(entry);
+    this.#contextStack.push({
+      depth: this.#context.depth + 1,
+      level: entry.level ?? this.#context.level,
+    });
+    return {
+      [Symbol.dispose]: () => {
+        this.#contextStack.pop();
+      },
+    };
+  }
+
+  info(message: unknown, ...args: unknown[]) {
+    this.write({ level: "info", content: [message, ...args] });
+  }
+
+  warn(message: unknown, ...args: unknown[]) {
+    this.write({ level: "warn", content: [message, ...args] });
+  }
+
+  error(message: unknown, ...args: unknown[]) {
+    this.write({ level: "error", content: [message, ...args] });
+  }
+
+  builder(message: unknown, ...args: unknown[]): LogEntryBuilder {
+    const entry: LogEntry = {
+      content: [message, ...args],
+      level: "info",
+      cause: undefined,
+    };
+    const builder: LogEntryBuilder = {
+      withCause: (cause) => {
+        entry.cause = cause;
+        return builder;
+      },
+      withLevel: (level) => {
+        entry.level = level;
+        return builder;
+      },
+      setError: (error) => {
+        if (error) entry.level = "error";
+        return builder;
+      },
+      write: () => {
+        this.write(entry);
+      },
+    };
+    return builder;
+  }
+
+  async createExternalLogStream(
+    name: string,
+    options?: {
+      noTime?: boolean;
+    },
+  ): Promise<ExternalLogStream> {
+    if (name.includes("/")) {
+      throw new Error(`External log stream's name (${name}) contains '/'.`);
+    }
+    if (this.#externalLogDir == null) {
+      throw new Error("External log directory is not set.");
+    }
+
+    const logPath = join(
+      this.#externalLogDir,
+      options?.noTime === true
+        ? name
+        : `${name}-${toFileNameString(new Date())}`,
+    );
+
+    const file = await Deno.open(logPath, {
+      read: false,
+      write: true,
+      append: true,
+      create: true,
+    });
+    return {
+      stream: file.writable,
+      [Symbol.dispose]: file[Symbol.dispose].bind(file),
+    };
+  }
+
+  async createExternalLogStreamsForProgram(
+    program: string,
+  ): Promise<{ stdout: WritableStream; stderr: WritableStream } & Disposable> {
+    const stdout = await this.createExternalLogStream(`${program}-stdout`);
+    const stderr = await this.createExternalLogStream(`${program}-stderr`);
+    return {
+      stdout: stdout.stream,
+      stderr: stderr.stream,
+      [Symbol.dispose]: () => {
+        stdout[Symbol.dispose]();
+        stderr[Symbol.dispose]();
+      },
+    };
+  }
+}
diff --git a/deno/base/text.ts b/deno/base/text.ts
new file mode 100644
index 0000000..f3e4020
--- /dev/null
+++ b/deno/base/text.ts
@@ -0,0 +1,3 @@
+export function camelCaseToKebabCase(str: string): string {
+  return str.replace(/[A-Z]/g, (m) => "-" + m.toLowerCase());
+}