import type { Pool, PoolClient } from 'pg';
import type { AnalyticsEventInput } from '../../../shared/analytics/events.js';
import type { AnalyticsMetricBucket } from '../../../shared/types.js';

type DbClient = Pool | PoolClient;

type AnalyticsBucketRow = {
  key: string;
  count: string;
};

export async function insertAnalyticsEvent(db: DbClient, input: AnalyticsEventInput) {
  await db.query(
    `
      insert into public.analytics_events (
        event_name,
        event_source,
        user_id,
        workspace_id,
        plan_code,
        addon_code,
        resource,
        amount,
        currency,
        metadata_json,
        occurred_at
      )
      values ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10, coalesce($11::timestamptz, now()))
    `,
    [
      input.eventName,
      input.eventSource,
      input.userId ?? null,
      input.workspaceId ?? null,
      input.planCode ?? null,
      input.addonCode ?? null,
      input.resource ?? null,
      input.amount ?? null,
      input.currency ?? null,
      input.metadata ?? {},
      input.occurredAt ?? null,
    ],
  );
}

export function listAnalyticsCountsByEvent(db: DbClient, sinceIso: string): Promise<AnalyticsMetricBucket[]> {
  return listBuckets(db, sinceIso, 'event_name', `event_name`);
}

export function listPricingPlanSelectionCounts(db: DbClient, sinceIso: string): Promise<AnalyticsMetricBucket[]> {
  return listBuckets(db, sinceIso, `coalesce(plan_code, metadata_json->>'planCode', 'unknown')`, `event_name = 'pricing_plan_selected'`);
}

export function listQuotaExhaustionCounts(db: DbClient, sinceIso: string): Promise<AnalyticsMetricBucket[]> {
  return listBuckets(db, sinceIso, `coalesce(resource, metadata_json->>'resource', 'unknown')`, `event_name = 'quota_exhausted_blocked'`);
}

export function listUpgradeTriggerCounts(db: DbClient, sinceIso: string): Promise<AnalyticsMetricBucket[]> {
  return listBuckets(
    db,
    sinceIso,
    `coalesce(metadata_json->>'denialReason', event_name)`,
    `event_name in ('quota_exhausted_blocked', 'feature_gate_encountered')`,
  );
}

export function listAddonAttachCounts(db: DbClient, sinceIso: string): Promise<AnalyticsMetricBucket[]> {
  return listBuckets(db, sinceIso, `coalesce(addon_code, metadata_json->>'addonCode', 'unknown')`, `event_name = 'addon_purchase_completed'`);
}

export function listPlanMixCounts(db: DbClient, sinceIso: string): Promise<AnalyticsMetricBucket[]> {
  return listBuckets(db, sinceIso, `coalesce(plan_code, metadata_json->>'planCode', 'unknown')`, `event_name in ('checkout_completed', 'plan_changed')`);
}

export function listChurnSignalCounts(db: DbClient, sinceIso: string): Promise<AnalyticsMetricBucket[]> {
  return listBuckets(db, sinceIso, `event_name`, `event_name in ('subscription_canceled', 'payment_failed')`);
}

export function listExpansionSignalCounts(db: DbClient, sinceIso: string): Promise<AnalyticsMetricBucket[]> {
  return listBuckets(db, sinceIso, `event_name`, `event_name in ('checkout_completed', 'addon_purchase_completed', 'plan_changed')`);
}

async function listBuckets(
  db: DbClient,
  sinceIso: string,
  keyExpression: string,
  filterSql: string,
): Promise<AnalyticsMetricBucket[]> {
  const result = await db.query<AnalyticsBucketRow>(
    `
      select ${keyExpression} as key, count(*)::text as count
      from public.analytics_events
      where occurred_at >= $1
        and ${filterSql}
      group by 1
      order by count(*) desc, 1 asc
    `,
    [sinceIso],
  );

  return result.rows.map((row) => ({
    key: row.key,
    count: Number(row.count),
  }));
}