/** Types and helpers for PostgreSQL monitoring API. */

export const POSTGRES_POLL_MS = 20_000;
export const POSTGRES_SLOW_POLL_MS = 60_000;

export type PostgresOverview = {
	collected_at: string;
	connections: {
		active: number;
		idle: number;
		total: number;
		max_connections: number;
	};
	database: {
		backends: number;
		xact_commit: number;
		xact_rollback: number;
		deadlocks: number;
		blks_hit: number;
		blks_read: number;
		cache_hit_pct: number;
	};
	database_size_bytes: number;
	memory_settings: {
		shared_buffers: string;
		work_mem: string;
		effective_cache_size: string;
	};
	replication: Array<{
		client_addr?: string;
		state: string;
		sync_state?: string;
		lag_ms?: number;
	}>;
	pg_stat_statements_enabled: boolean;
};

export type PostgresQueryRow = {
	queryid?: number;
	query: string;
	calls: number;
	total_exec_ms: number;
	mean_exec_ms: number;
	rows: number;
};

export type PostgresQueriesResponse = {
	collected_at: string;
	source: string;
	items: PostgresQueryRow[];
	statements_available?: boolean;
	statements_hint?: string;
};

export type PostgresLockRow = {
	locktype: string;
	mode: string;
	granted: boolean;
	pid: number;
	usename?: string;
	state?: string;
	query?: string;
	blocked: boolean;
};

export type PostgresTableRow = {
	relname: string;
	total_bytes: number;
	idx_scan: number;
	seq_scan: number;
	n_dead_tup: number;
	bloat_ratio?: number;
	last_autovacuum?: string;
};

export type PostgresRecommendation = {
	severity: string;
	code: string;
	title: string;
	detail: string;
	refs?: string[];
};

export type PostgresRecommendationsResponse = {
	collected_at: string;
	items: PostgresRecommendation[];
};

export type PostgresMaintLog = {
	id: string;
	kind: string;
	target_table?: string;
	dry_run: boolean;
	status: string;
	error?: string;
	created_at: string;
};

export type CorrelationResponse = {
	window_minutes: number;
	points: Array<{
		timestamp: string;
		pipeline_refresh_p99_ms?: number;
		cache_hit_pct?: number;
	}>;
};

export function formatBytes(n: number): string {
	if (n >= 1 << 30) return `${(n / (1 << 30)).toFixed(1)} GiB`;
	if (n >= 1 << 20) return `${(n / (1 << 20)).toFixed(1)} MiB`;
	if (n >= 1 << 10) return `${(n / (1 << 10)).toFixed(1)} KiB`;
	return `${n} B`;
}

export function connUsagePct(ov: PostgresOverview | null): number {
	if (!ov?.connections.max_connections) return 0;
	return Math.min(100, (ov.connections.total / ov.connections.max_connections) * 100);
}