/**
 * Phase B analytics service. Reads pre-computed snapshots from
 * `analytics_snapshots` keyed by `metric_id` and recomputes on demand if
 * the cached row is older than `SNAPSHOT_TTL_MS`. The recomputation jobs
 * land in `analytics-snapshot-job.ts` (PR3).
 */

import { and, eq } from 'drizzle-orm';

import { db } from '@/lib/db';
import { analyticsSnapshots } from '@/lib/db/schema/insights';

export type DateRange = '7d' | '30d' | '90d' | 'today';

export type MetricId =
  | `pipeline_funnel.${DateRange}`
  | `occupancy_timeline.${DateRange}`
  | `revenue_breakdown.${DateRange}`
  | `lead_source_attribution.${DateRange}`;

export const SNAPSHOT_TTL_MS = 15 * 60 * 1000; // 15 minutes

export interface PipelineFunnelData {
  stages: Array<{ stage: string; count: number; conversionPct: number }>;
}

export interface OccupancyTimelineData {
  points: Array<{ date: string; available: number; underOffer: number; sold: number }>;
}

export interface RevenueBreakdownData {
  bars: Array<{ category: string; amount: number; currency: string }>;
}

export interface LeadSourceAttributionData {
  slices: Array<{ source: string; count: number }>;
}

export type SnapshotData =
  | PipelineFunnelData
  | OccupancyTimelineData
  | RevenueBreakdownData
  | LeadSourceAttributionData;

/**
 * Read a snapshot by `(portId, metricId)`. Returns null when missing or
 * stale; the caller should request a recompute (or the recurring job
 * eventually fills it).
 */
export async function readSnapshot<T extends SnapshotData>(
  portId: string,
  metricId: MetricId,
): Promise<T | null> {
  const row = await db.query.analyticsSnapshots.findFirst({
    where: and(eq(analyticsSnapshots.portId, portId), eq(analyticsSnapshots.metricId, metricId)),
  });
  if (!row) return null;
  const age = Date.now() - row.computedAt.getTime();
  if (age > SNAPSHOT_TTL_MS) return null;
  return row.data as T;
}

export async function writeSnapshot(
  portId: string,
  metricId: MetricId,
  data: SnapshotData,
): Promise<void> {
  await db
    .insert(analyticsSnapshots)
    .values({ portId, metricId, data })
    .onConflictDoUpdate({
      target: [analyticsSnapshots.portId, analyticsSnapshots.metricId],
      set: { data, computedAt: new Date() },
    });
}

// Computation entrypoints — bodies land in PR3 along with the recurring
// snapshot job. Exported as no-op stubs so PR1's tsc/lint stay green.

export async function computePipelineFunnel(
  _portId: string,
  _range: DateRange,
): Promise<PipelineFunnelData> {
  return { stages: [] };
}

export async function computeOccupancyTimeline(
  _portId: string,
  _range: DateRange,
): Promise<OccupancyTimelineData> {
  return { points: [] };
}

export async function computeRevenueBreakdown(
  _portId: string,
  _range: DateRange,
): Promise<RevenueBreakdownData> {
  return { bars: [] };
}

export async function computeLeadSourceAttribution(
  _portId: string,
  _range: DateRange,
): Promise<LeadSourceAttributionData> {
  return { slices: [] };
}