/**
 * 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, between, eq, 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 { PIPELINE_STAGES } from '@/lib/constants';
import {
  ALL_RANGES,
  isCustomRange,
  rangeToBounds,
  type CustomDateRange,
  type DateRange,
  type PresetDateRange,
} from '@/lib/analytics/range';

// Re-export the shared types for callers that already import from this
// module - keeps the existing public API intact.
export { ALL_RANGES, isCustomRange, rangeToBounds };
export type { DateRange, PresetDateRange, CustomDateRange };

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

/**
 * Snapshot key. Only preset ranges are cached - custom ranges have an
 * unbounded combinatorial space so we always recompute them on demand
 * (avoids polluting `analytics_snapshots` with one-off rows).
 */
export type MetricId = `${MetricBase}.${PresetDateRange}`;
export const ALL_METRICS: readonly MetricBase[] = [
  'pipeline_funnel',
  'occupancy_timeline',
  '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 LeadSourceAttributionData {
  slices: Array<{ source: string; count: number }>;
}

export type SnapshotData = PipelineFunnelData | OccupancyTimelineData | 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 (rangeToBounds, rangeToDays, rangeSpanDays) moved to
// @/lib/analytics/range - that file is client-safe (no DB imports) so it
// can be used from React components AND this server module.

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

export async function computePipelineFunnel(
  portId: string,
  range: DateRange,
): Promise<PipelineFunnelData> {
  const { from, to } = rangeToBounds(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),
        between(interests.createdAt, from, to),
        sql`(${interests.outcome} IS NULL OR ${interests.outcome} = 'won')`,
      ),
    )
    .groupBy(interests.pipelineStage);

  const counts = new Map(stageRows.map((r) => [r.stage, r.count]));
  // First stage in the canonical order anchors the conversion percentage.
  const top = counts.get(PIPELINE_STAGES[0]) ?? 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),
        between(interests.createdAt, from, to),
        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 { from, to } = rangeToBounds(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;

  // Occupancy = cumulative count of berths sold (i.e. won deals) on or
  // before each day. Per 2026-05-14 decision, the canonical occupancy
  // signal is "the deal closed and money changed hands" - reservations
  // are merely holds and don't count as occupied. Sources from
  // `interests.outcome='won'` + `outcome_at::date`; primary-berth link
  // via `interest_berths` so multi-berth deals contribute every linked
  // berth once. Single round-trip via generate_series cross-join with a
  // sold_berths CTE.
  const fromStr = from.toISOString().slice(0, 10);
  const toStr = new Date(to.getTime() - 86_400_000).toISOString().slice(0, 10);
  const rows = await db.execute<{ day: string; occupied: number }>(
    sql`
      WITH days AS (
        SELECT generate_series(${fromStr}::date, ${toStr}::date, '1 day'::interval)::date AS day
      ),
      sold_berths AS (
        SELECT DISTINCT ib.berth_id, (i.outcome_at AT TIME ZONE 'UTC')::date AS sold_on
        FROM interests i
        INNER JOIN interest_berths ib ON ib.interest_id = i.id
        WHERE i.port_id = ${portId}
          AND i.outcome = 'won'
          AND i.outcome_at IS NOT NULL
          AND i.archived_at IS NULL
      )
      SELECT
        to_char(days.day, 'YYYY-MM-DD') AS day,
        COUNT(DISTINCT sb.berth_id)::int AS occupied
      FROM days
      LEFT JOIN sold_berths sb ON sb.sold_on <= days.day
      GROUP BY days.day
      ORDER BY days.day
    `,
  );
  const points: OccupancyTimelineData['points'] = rows.map((r) => {
    const occupied = Number(r.occupied) || 0;
    const occupancyPct = total === 0 ? 0 : Math.round((occupied / total) * 1000) / 10;
    return { date: r.day, occupied, total, occupancyPct };
  });
  return { points };
}

export async function computeLeadSourceAttribution(
  portId: string,
  range: DateRange,
): Promise<LeadSourceAttributionData> {
  const { from, to } = rangeToBounds(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),
        between(interests.createdAt, from, to),
      ),
    )
    .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) ──────────────────────────
//
// Custom ranges always recompute (cache key would be unbounded). Preset
// ranges go cache → compute → write-back as before.

export async function getPipelineFunnel(
  portId: string,
  range: DateRange,
): Promise<PipelineFunnelData> {
  if (isCustomRange(range)) return computePipelineFunnel(portId, range);
  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> {
  if (isCustomRange(range)) return computeOccupancyTimeline(portId, range);
  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 getLeadSourceAttribution(
  portId: string,
  range: DateRange,
): Promise<LeadSourceAttributionData> {
  if (isCustomRange(range)) return computeLeadSourceAttribution(portId, range);
  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, leadSource] = await Promise.all([
      computePipelineFunnel(portId, range),
      computeOccupancyTimeline(portId, range),
      computeLeadSourceAttribution(portId, range),
    ]);
    await Promise.all([
      writeSnapshot(portId, `pipeline_funnel.${range}`, funnel),
      writeSnapshot(portId, `occupancy_timeline.${range}`, occupancy),
      writeSnapshot(portId, `lead_source_attribution.${range}`, leadSource),
    ]);
  }
}