/**
 * Checks the rows `settings-service.ts` reads from `user_settings`, and turns
 * them into the {@link UserSettings} the settings endpoints answer.
 *
 * @module
 */

import type { SQLOutputValue } from "node:sqlite";
import type { UserSettings } from "../../shared/settings.ts";
import { isColorScheme, isStyleName } from "../../shared/theme.ts";

/**
 * Stored by `updateSettings` and read back by `getSettings`. A user without a
 * row has the defaults.
 */
export interface UserSettingsRow {
  user_id: string;
  /** A style name, or null for the instance's. */
  style: string | null;
  color_scheme: string | null;
  /** 0 or 1. */
  digest_weekly: number;
  /** 0 or 1. */
  digest_monthly: number;
  updated_at: string;
  [key: string]: SQLOutputValue;
}

/**
 * Names the column of each setting, for the queries that pick users by one,
 * as `digest-service.ts` does by its digest's switch.
 */
export const SETTINGS_COLUMNS: Record<keyof UserSettings, string> = {
  style: "style",
  colorScheme: "color_scheme",
  digestWeekly: "digest_weekly",
  digestMonthly: "digest_monthly",
};

/**
 * Checks whether `obj`, a row `getSettings` selected, is a
 * {@link UserSettingsRow}.
 */
export function isUserSettingsRow(obj: unknown): obj is UserSettingsRow {
  return !!obj && typeof obj === "object" &&
    "user_id" in obj && typeof obj.user_id === "string" &&
    "style" in obj && (obj.style === null || typeof obj.style === "string") &&
    "color_scheme" in obj &&
    (obj.color_scheme === null || typeof obj.color_scheme === "string") &&
    "digest_weekly" in obj && typeof obj.digest_weekly === "number" &&
    "digest_monthly" in obj && typeof obj.digest_monthly === "number" &&
    "updated_at" in obj && typeof obj.updated_at === "string";
}

/**
 * Converts a row to the {@link UserSettings} the client gets. A style or
 * scheme the code no longer knows, as after one is removed, reads as unset.
 */
export function settingsRowToApi(row: UserSettingsRow): UserSettings {
  return {
    style: isStyleName(row.style) ? row.style : null,
    colorScheme: isColorScheme(row.color_scheme) ? row.color_scheme : null,
    digestWeekly: row.digest_weekly === 1,
    digestMonthly: row.digest_monthly === 1,
  };
}