import { db as defaultDb } from '$lib/server/db';
import { dashboardSettings } from '$lib/server/db/schema';
import {
	SETTINGS_DEFAULTS,
	type SettingsKey,
	type StatsSettings
} from '$lib/types/stats';
import type { StatsDb } from './db';

const SETTINGS_KEYS = Object.keys(SETTINGS_DEFAULTS) as SettingsKey[];

/** `core_plays_per_week` → `STATS_CORE_PLAYS_PER_WEEK` */
export function settingsEnvVar(key: SettingsKey): string {
	return `STATS_${key.toUpperCase()}`;
}

/** Defaults from `SETTINGS_DEFAULTS`, overridden by `STATS_*` env vars. */
export function envSettings(): StatsSettings {
	const out = { ...SETTINGS_DEFAULTS } as StatsSettings;
	for (const key of SETTINGS_KEYS) {
		const raw = Bun.env[settingsEnvVar(key)];
		if (raw === undefined || raw === '') continue;
		const value = Number(raw);
		if (Number.isFinite(value)) out[key] = value;
	}
	return out;
}

function coerce(key: SettingsKey, raw: string): number {
	const value = Number(raw);
	return Number.isFinite(value) ? value : SETTINGS_DEFAULTS[key];
}

/**
 * Reads persisted overrides from `dashboard_settings` and overlays them on the
 * env/default baseline. Safe to call when the table does not yet exist.
 */
export async function getSettings(database: StatsDb = defaultDb): Promise<StatsSettings> {
	const settings = envSettings();
	try {
		const rows = await database.select().from(dashboardSettings);
		for (const row of rows) {
			if ((SETTINGS_KEYS as string[]).includes(row.key)) {
				settings[row.key as SettingsKey] = coerce(row.key as SettingsKey, row.value);
			}
		}
	} catch {
		// Table missing / DB unavailable — fall back to defaults.
	}
	return settings;
}

/** Upserts a partial set of setting overrides. */
export async function updateSettings(
	partial: Partial<StatsSettings>,
	database: StatsDb = defaultDb
): Promise<StatsSettings> {
	const now = new Date();
	for (const [key, value] of Object.entries(partial)) {
		if (!(SETTINGS_KEYS as string[]).includes(key)) continue;
		if (value === undefined || value === null || !Number.isFinite(value)) continue;
		await database
			.insert(dashboardSettings)
			.values({ key, value: String(value), updatedAt: now })
			.onConflictDoUpdate({
				target: dashboardSettings.key,
				set: { value: String(value), updatedAt: now }
			});
	}
	return getSettings(database);
}

/** Stable short hash of the resolved settings — used to detect stale snapshots. */
export function hashSettings(settings: StatsSettings): string {
	const canonical = SETTINGS_KEYS.map((k) => `${k}=${settings[k]}`).join(';');
	const digest = new Bun.CryptoHasher('sha256').update(canonical).digest('hex');
	return digest.slice(0, 12);
}

export async function configVersion(database: StatsDb = defaultDb): Promise<string> {
	return hashSettings(await getSettings(database));
}