/**
 * Phase B analytics service. Reads pre-computed snapshots from
 * `analytics_snapshots`; recomputes on demand if older than `SNAPSHOT_TTL_MS`.
 * The recurring `analytics-refresh` BullMQ job (PR3) warms the table
 * every 15 minutes per port × per metric.
 */

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

import { db } from '@/lib/db';
import { analyticsSnapshots } from '@/lib/db/schema/insights';
import { interests } from '@/lib/db/schema/interests';
import { invoices } from '@/lib/db/schema/financial';
import { berthReservations } from '@/lib/db/schema/reservations';
import { PIPELINE_STAGES } from '@/lib/constants';

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

export type MetricBase =
  | 'pipeline_funnel'
  | 'occupancy_timeline'
  | 'revenue_breakdown'
  | 'lead_source_attribution';

export type MetricId = `${MetricBase}.${DateRange}`;

export const ALL_RANGES: readonly DateRange[] = ['today', '7d', '30d', '90d'] as const;
export const ALL_METRICS: readonly MetricBase[] = [
  'pipeline_funnel',
  'occupancy_timeline',
  'revenue_breakdown',
  'lead_source_attribution',
] as const;

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

// ─── Output shapes ────────────────────────────────────────────────────────────

export interface PipelineFunnelData {
  stages: Array<{ stage: string; count: number; conversionPct: number }>;
  /** Counts of terminal lost/cancelled outcomes in the range. Surfaces below
   *  the funnel so users can see leakage without it polluting the conversion
   *  math. Total = sum of these counts. */
  lost: { count: number; byOutcome: Record<string, number> };
}

export interface OccupancyTimelineData {
  points: Array<{ date: string; occupied: number; total: number; occupancyPct: number }>;
}

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

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

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

// ─── Cache layer ──────────────────────────────────────────────────────────────

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() },
    });
}

// ─── Range helpers ────────────────────────────────────────────────────────────

function rangeToCutoff(range: DateRange): Date {
  const now = Date.now();
  switch (range) {
    case 'today':
      return new Date(now - 1 * 86_400_000);
    case '7d':
      return new Date(now - 7 * 86_400_000);
    case '30d':
      return new Date(now - 30 * 86_400_000);
    case '90d':
      return new Date(now - 90 * 86_400_000);
  }
}

function rangeToDays(range: DateRange): number {
  switch (range) {
    case 'today':
      return 1;
    case '7d':
      return 7;
    case '30d':
      return 30;
    case '90d':
      return 90;
  }
}

// ─── Computations ─────────────────────────────────────────────────────────────

export async function computePipelineFunnel(
  portId: string,
  range: DateRange,
): Promise<PipelineFunnelData> {
  const cutoff = rangeToCutoff(range);

  // Stage counts EXCLUDE lost/cancelled outcomes — those never become
  // conversions, so polluting the funnel with them gives meaningless math.
  // Lost is reported separately in the `lost` block.
  const stageRows = await db
    .select({ stage: interests.pipelineStage, count: sql<number>`count(*)::int` })
    .from(interests)
    .where(
      and(
        eq(interests.portId, portId),
        isNull(interests.archivedAt),
        gte(interests.createdAt, cutoff),
        sql`(${interests.outcome} IS NULL OR ${interests.outcome} = 'won')`,
      ),
    )
    .groupBy(interests.pipelineStage);

  const counts = new Map(stageRows.map((r) => [r.stage, r.count]));
  const top = counts.get('open') ?? 0;

  const stages = PIPELINE_STAGES.map((stage) => {
    const count = counts.get(stage) ?? 0;
    const conversionPct = top === 0 ? 0 : Math.round((count / top) * 1000) / 10;
    return { stage, count, conversionPct };
  });

  // Lost / cancelled summary. Same date-range filter as the funnel.
  const lostRows = await db
    .select({ outcome: interests.outcome, count: sql<number>`count(*)::int` })
    .from(interests)
    .where(
      and(
        eq(interests.portId, portId),
        isNull(interests.archivedAt),
        gte(interests.createdAt, cutoff),
        sql`${interests.outcome} IS NOT NULL AND ${interests.outcome} != 'won'`,
      ),
    )
    .groupBy(interests.outcome);

  const byOutcome: Record<string, number> = {};
  let lostTotal = 0;
  for (const row of lostRows) {
    if (!row.outcome) continue;
    byOutcome[row.outcome] = row.count;
    lostTotal += row.count;
  }

  return { stages, lost: { count: lostTotal, byOutcome } };
}

export async function computeOccupancyTimeline(
  portId: string,
  range: DateRange,
): Promise<OccupancyTimelineData> {
  const days = rangeToDays(range);
  // Total berths per port (current count — assumes no churn).
  const totalRow = await db.execute<{ total: number }>(
    sql`SELECT count(*)::int AS total FROM berths WHERE port_id = ${portId}`,
  );
  const total = totalRow[0]?.total ?? 0;

  // For each day in range, count berths that have an active reservation
  // covering that day. A reservation is "covering" if start_date <= day
  // AND (end_date IS NULL OR end_date >= day).
  const points: OccupancyTimelineData['points'] = [];
  for (let i = days - 1; i >= 0; i--) {
    const day = new Date(Date.now() - i * 86_400_000);
    const dayStr = day.toISOString().slice(0, 10);
    const occRow = await db
      .select({ occupied: sql<number>`count(distinct ${berthReservations.berthId})::int` })
      .from(berthReservations)
      .where(
        and(
          eq(berthReservations.portId, portId),
          eq(berthReservations.status, 'active'),
          sql`${berthReservations.startDate} <= ${dayStr}::date`,
          sql`(${berthReservations.endDate} IS NULL OR ${berthReservations.endDate} >= ${dayStr}::date)`,
        ),
      );
    const occupied = occRow[0]?.occupied ?? 0;
    const occupancyPct = total === 0 ? 0 : Math.round((occupied / total) * 1000) / 10;
    points.push({ date: dayStr, occupied, total, occupancyPct });
  }
  return { points };
}

export async function computeRevenueBreakdown(
  portId: string,
  range: DateRange,
): Promise<RevenueBreakdownData> {
  const cutoff = rangeToCutoff(range);
  const rows = await db
    .select({
      status: invoices.status,
      currency: invoices.currency,
      amount: sql<string>`coalesce(sum(${invoices.total}), 0)::text`,
    })
    .from(invoices)
    .where(
      and(
        eq(invoices.portId, portId),
        isNull(invoices.archivedAt),
        gte(invoices.createdAt, cutoff),
      ),
    )
    .groupBy(invoices.status, invoices.currency);

  return {
    bars: rows.map((r) => ({
      status: r.status,
      currency: r.currency,
      amount: Number(r.amount),
    })),
  };
}

export async function computeLeadSourceAttribution(
  portId: string,
  range: DateRange,
): Promise<LeadSourceAttributionData> {
  const cutoff = rangeToCutoff(range);
  const rows = await db
    .select({ source: interests.source, count: sql<number>`count(*)::int` })
    .from(interests)
    .where(
      and(
        eq(interests.portId, portId),
        isNull(interests.archivedAt),
        gte(interests.createdAt, cutoff),
      ),
    )
    .groupBy(interests.source);

  return {
    slices: rows
      .map((r) => ({
        source: r.source ?? 'unspecified',
        count: r.count,
      }))
      .sort((a, b) => b.count - a.count),
  };
}

// ─── Public read API (cache → compute → write back) ──────────────────────────

export async function getPipelineFunnel(
  portId: string,
  range: DateRange,
): Promise<PipelineFunnelData> {
  const metricId = `pipeline_funnel.${range}` as const;
  const cached = await readSnapshot<PipelineFunnelData>(portId, metricId);
  if (cached) return cached;
  const fresh = await computePipelineFunnel(portId, range);
  await writeSnapshot(portId, metricId, fresh);
  return fresh;
}

export async function getOccupancyTimeline(
  portId: string,
  range: DateRange,
): Promise<OccupancyTimelineData> {
  const metricId = `occupancy_timeline.${range}` as const;
  const cached = await readSnapshot<OccupancyTimelineData>(portId, metricId);
  if (cached) return cached;
  const fresh = await computeOccupancyTimeline(portId, range);
  await writeSnapshot(portId, metricId, fresh);
  return fresh;
}

export async function getRevenueBreakdown(
  portId: string,
  range: DateRange,
): Promise<RevenueBreakdownData> {
  const metricId = `revenue_breakdown.${range}` as const;
  const cached = await readSnapshot<RevenueBreakdownData>(portId, metricId);
  if (cached) return cached;
  const fresh = await computeRevenueBreakdown(portId, range);
  await writeSnapshot(portId, metricId, fresh);
  return fresh;
}

export async function getLeadSourceAttribution(
  portId: string,
  range: DateRange,
): Promise<LeadSourceAttributionData> {
  const metricId = `lead_source_attribution.${range}` as const;
  const cached = await readSnapshot<LeadSourceAttributionData>(portId, metricId);
  if (cached) return cached;
  const fresh = await computeLeadSourceAttribution(portId, range);
  await writeSnapshot(portId, metricId, fresh);
  return fresh;
}

// ─── Cron entrypoint: warm every (port × metric × range) ────────────────────

export async function refreshSnapshotsForPort(portId: string): Promise<void> {
  for (const range of ALL_RANGES) {
    const [funnel, occupancy, revenue, leadSource] = await Promise.all([
      computePipelineFunnel(portId, range),
      computeOccupancyTimeline(portId, range),
      computeRevenueBreakdown(portId, range),
      computeLeadSourceAttribution(portId, range),
    ]);
    await Promise.all([
      writeSnapshot(portId, `pipeline_funnel.${range}`, funnel),
      writeSnapshot(portId, `occupancy_timeline.${range}`, occupancy),
      writeSnapshot(portId, `revenue_breakdown.${range}`, revenue),
      writeSnapshot(portId, `lead_source_attribution.${range}`, leadSource),
    ]);
  }
}