feat: build out discord support agent (#4)

### Explanation

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### Issue

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### Attestations

- [x] I have read and agree to the [Code of Conduct](https://docs.nhcarrigan.com/community/coc/)
- [x] I have read and agree to the [Community Guidelines](https://docs.nhcarrigan.com/community/guide/).
- [x] My contribution complies with the [Contributor Covenant](https://docs.nhcarrigan.com/dev/covenant/).

### Dependencies

- [x] I have pinned the dependencies to a specific patch version.

### Style

- [x] I have run the linter and resolved any errors.
- [x] My pull request uses an appropriate title, matching the conventional commit standards.
- [x] My scope of feat/fix/chore/etc. correctly matches the nature of changes in my pull request.

### Tests

- [ ] My contribution adds new code, and I have added tests to cover it.
- [ ] My contribution modifies existing code, and I have updated the tests to reflect these changes.
- [ ] All new and existing tests pass locally with my changes.
- [ ] Code coverage remains at or above the configured threshold.

### Documentation

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Reviewed-on: #4
Co-authored-by: Naomi Carrigan <commits@nhcarrigan.com>
Co-committed-by: Naomi Carrigan <commits@nhcarrigan.com>

bot/prod/utils/calculateCost.js

@@ -0,0 +1,23 @@
+/**
+ * @copyright nhcarrigan
+ * @license Naomi's Public License
+ * @author Naomi Carrigan
+ */
+import { logger } from "./logger.js";
+/**
+ * Calculates the cost of a command run by a user, and sends to
+ * our logging service.
+ * @param usage -- The usage payload from Anthropic.
+ * @param uuid -- The Discord ID of the user who ran the command.
+ */
+export const calculateCost = async (usage, uuid) => {
+    const inputCost = usage.input_tokens * (3 / 1_000_000);
+    const outputCost = usage.output_tokens * (15 / 1_000_000);
+    const totalCost = inputCost + outputCost;
+    await logger.log("info", `User ${uuid} used the bot, which accepted ${usage.input_tokens.toString()} tokens and generated ${usage.output_tokens.toString()} tokens.
+
+    Total cost: ${totalCost.toLocaleString("en-GB", {
+        currency: "USD",
+        style: "currency",
+    })}`);
+};

bot/prod/utils/checkEntitlement.js

@@ -0,0 +1,41 @@
+/**
+ * @copyright nhcarrigan
+ * @license Naomi's Public License
+ * @author Naomi Carrigan
+ */
+import { entitledGuilds, entitledUsers } from "../config/entitlements.js";
+/**
+ * Checks if a user has subscribed.
+ * @param hikari - Hikari's Discord instance.
+ * @param user - The user to check.
+ * @returns A boolean indicating whether the user has an active subscription.
+ */
+const checkUserEntitlement = async (hikari, user) => {
+    if (entitledUsers.includes(user.id)) {
+        return true;
+    }
+    const entitlements = await hikari.application?.entitlements.fetch({
+        excludeDeleted: true,
+        excludeEnded: true,
+        user: user,
+    });
+    return Boolean(entitlements && entitlements.size > 0);
+};
+/**
+ * Checks if a guild has subscribed.
+ * @param hikari - Hikari's Discord instance.
+ * @param guild - The guild to check.
+ * @returns A boolean indicating whether the guild has an active subscription.
+ */
+const checkGuildEntitlement = async (hikari, guild) => {
+    if (entitledGuilds.includes(guild.id)) {
+        return true;
+    }
+    const entitlements = await hikari.application?.entitlements.fetch({
+        excludeDeleted: true,
+        excludeEnded: true,
+        guild: guild,
+    });
+    return Boolean(entitlements && entitlements.size > 0);
+};
+export { checkUserEntitlement, checkGuildEntitlement };

bot/prod/utils/errorHandler.js

@@ -0,0 +1,20 @@
+/**
+ * @copyright nhcarrigan
+ * @license Naomi's Public License
+ * @author Naomi Carrigan
+ */
+import { logger } from "./logger.js";
+/**
+ * Generates a UUID for an error, sends the error to the logger,
+ * and returns the UUID to be shared with the user.
+ * @param error - The error to log.
+ * @param context - The context in which the error occurred.
+ * @returns A UUID string assigned to the error.
+ */
+export const errorHandler = async (error, context) => {
+    const id = crypto.randomUUID();
+    await logger.error(`${context} - Error ID: ${id}`, error instanceof Error
+        ? error
+        : new Error(String(error)));
+    return id;
+};

bot/prod/utils/logger.js

@@ -0,0 +1,7 @@
+/**
+ * @copyright nhcarrigan
+ * @license Naomi's Public License
+ * @author Naomi Carrigan
+ */
+import { Logger } from "@nhcarrigan/logger";
+export const logger = new Logger("Hikari Bot", process.env.LOG_TOKEN ?? "");