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

import { db } from '@/lib/db';
import { redis } from '@/lib/redis';
import { interests, interestBerths, interestNotes } from '@/lib/db/schema/interests';
import { reminders } from '@/lib/db/schema/operations';
import { emailThreads } from '@/lib/db/schema/email';
import { logger } from '@/lib/logger';
import { PIPELINE_STAGES } from '@/lib/constants';
import { NotFoundError } from '@/lib/errors';

// ─── Types ────────────────────────────────────────────────────────────────────

export interface InterestScore {
  totalScore: number; // 0-100 (normalised)
  breakdown: {
    pipelineAge: number; // 0-100
    stageSpeed: number; // 0-100
    documentCompleteness: number; // 0-100
    engagement: number; // 0-100
    berthLinked: number; // 0 or 25
  };
  calculatedAt: Date;
}

// ─── Redis cache ──────────────────────────────────────────────────────────────

// Cache key includes portId so a foreign-port caller hitting the same
// interestId never sees a port-A cached value. (Even if interestId is
// already globally unique, baking portId into the key means a stale or
// hostile caller cannot reuse cached entries across tenants.)
const SCORE_KEY = (portId: string, interestId: string) => `interest-score:${portId}:${interestId}`;
const SCORE_TTL = 3600; // 1 hour

// ─── Scoring helpers ──────────────────────────────────────────────────────────

function scorePipelineAge(createdAt: Date): number {
  const days = Math.floor((Date.now() - createdAt.getTime()) / (1000 * 60 * 60 * 24));
  if (days <= 30) return 100;
  if (days <= 60) return 80;
  if (days <= 90) return 60;
  if (days <= 180) return 40;
  return 20;
}

function scoreStageSpeed(createdAt: Date, pipelineStage: string): number {
  const idx = PIPELINE_STAGES.indexOf(pipelineStage as (typeof PIPELINE_STAGES)[number]);
  const stageIndex = idx === -1 ? 0 : idx;
  if (stageIndex === 0) {
    // Still at open - no progression
    return 0;
  }

  const daysSinceCreation = Math.max(1, (Date.now() - createdAt.getTime()) / (1000 * 60 * 60 * 24));

  // Average days per stage transition
  const avgDaysPerStage = daysSinceCreation / stageIndex;

  // Thresholds: <7 days/stage = great, <14 = ok, <30 = slow, >=30 = cold
  if (avgDaysPerStage < 7) return 100;
  if (avgDaysPerStage < 14) return 75;
  if (avgDaysPerStage < 30) return 50;
  if (avgDaysPerStage < 60) return 25;
  return 10;
}

function scoreDocumentCompleteness(interest: {
  eoiStatus: string | null;
  contractStatus: string | null;
  depositStatus: string | null;
  dateEoiSigned: Date | null;
  dateContractSigned: Date | null;
  dateDepositReceived: Date | null;
}): number {
  let score = 0;

  // EOI signed
  if (interest.eoiStatus === 'signed' || interest.dateEoiSigned != null) {
    score += 30;
  }
  // Contract
  if (interest.contractStatus === 'signed' || interest.dateContractSigned != null) {
    score += 30;
  }
  // Deposit
  if (
    interest.depositStatus === 'received' ||
    interest.depositStatus === 'paid' ||
    interest.dateDepositReceived != null
  ) {
    score += 40;
  }

  return Math.min(score, 100);
}

// ─── Main scoring function ────────────────────────────────────────────────────

export async function calculateInterestScore(
  interestId: string,
  portId: string,
): Promise<InterestScore> {
  // Verify the interest belongs to the caller's port BEFORE returning a
  // cached value. The cache key now includes portId, but defense-in-depth:
  // a port-B caller passing a port-A interestId still gets NotFound
  // instead of a leaked score.
  const interest = await db.query.interests.findFirst({
    where: and(eq(interests.id, interestId), eq(interests.portId, portId)),
  });

  if (!interest) {
    throw new NotFoundError('interest');
  }

  // Try cache (port-scoped key)
  try {
    const cached = await redis.get(SCORE_KEY(portId, interestId));
    if (cached) {
      const parsed = JSON.parse(cached) as InterestScore & { calculatedAt: string };
      return { ...parsed, calculatedAt: new Date(parsed.calculatedAt) };
    }
  } catch (err) {
    logger.warn({ err, interestId }, 'Redis cache read failed for interest score');
  }

  // 1. Pipeline age
  const pipelineAge = scorePipelineAge(interest.createdAt);

  // 2. Stage speed
  const stageSpeed = scoreStageSpeed(interest.createdAt, interest.pipelineStage);

  // 3. Document completeness
  const documentCompleteness = scoreDocumentCompleteness(interest);

  // 4. Engagement - notes, emails, reminders in last 30 days
  const thirtyDaysAgo = new Date(Date.now() - 30 * 24 * 60 * 60 * 1000);

  const [notesResult, remindersResult, emailResult, berthLinkResult] = await Promise.all([
    db
      .select({ value: count() })
      .from(interestNotes)
      .where(
        and(eq(interestNotes.interestId, interestId), gte(interestNotes.createdAt, thirtyDaysAgo)),
      ),
    db
      .select({ value: count() })
      .from(reminders)
      .where(
        and(
          eq(reminders.interestId, interestId),
          eq(reminders.status, 'completed'),
          gte(reminders.completedAt, thirtyDaysAgo),
        ),
      ),
    db
      .select({ value: count() })
      .from(emailThreads)
      .where(
        and(
          eq(emailThreads.clientId, interest.clientId),
          eq(emailThreads.portId, portId),
          gte(emailThreads.lastMessageAt, thirtyDaysAgo),
        ),
      ),
    // Plan §3.4: any junction row counts as "berth linked", not just the
    // primary - the score awards engagement for an interest that has *any*
    // berth association at all.
    db
      .select({ value: count() })
      .from(interestBerths)
      .where(eq(interestBerths.interestId, interestId)),
  ]);

  const notesCount = notesResult[0]?.value ?? 0;
  const remindersCount = remindersResult[0]?.value ?? 0;
  const emailCount = emailResult[0]?.value ?? 0;

  const notesScore = Math.min(notesCount * 10, 50);
  const emailScore = Math.min(emailCount * 5, 30);
  const remindersScore = Math.min(remindersCount * 10, 20);
  const engagement = Math.min(notesScore + emailScore + remindersScore, 100);

  // 5. Berth linked - true when the interest has at least one junction row.
  const berthLinked = (berthLinkResult[0]?.value ?? 0) > 0 ? 25 : 0;

  // ── Normalise: max raw = 100+100+100+100+25 = 425 → /425 * 100 ──
  const RAW_MAX = 425;
  const rawTotal = pipelineAge + stageSpeed + documentCompleteness + engagement + berthLinked;
  const totalScore = Math.round((rawTotal / RAW_MAX) * 100);

  const result: InterestScore = {
    totalScore,
    breakdown: {
      pipelineAge,
      stageSpeed,
      documentCompleteness,
      engagement,
      berthLinked,
    },
    calculatedAt: new Date(),
  };

  // Write to cache (fire-and-forget)
  redis
    .setex(SCORE_KEY(portId, interestId), SCORE_TTL, JSON.stringify(result))
    .catch((err) =>
      logger.warn({ err, interestId }, 'Redis cache write failed for interest score'),
    );

  return result;
}

// ─── Bulk scoring ─────────────────────────────────────────────────────────────

/**
 * Score every active interest in a port. The previous implementation
 * fanned out one scoring call per interest, each issuing 1 redis read +
 * 1 interests.findFirst + 4 count queries → 6N round trips per
 * dashboard render (≈6000 for a 1k-interest port). Cold-cache flushes
 * pegged the API for a couple of seconds.
 *
 * The new path replaces those 4N count queries with 4 grouped queries
 * (one per dimension, filtered by inArray on the port's interest ids)
 * and merges in JS. The redis cache is still consulted, but only as a
 * map merged onto the freshly computed scores so cached values short-
 * circuit recomputation without re-issuing the per-row count fan-out.
 */
export async function calculateBulkScores(
  portId: string,
): Promise<Array<{ interestId: string; score: InterestScore }>> {
  const allInterests = await db
    .select({
      id: interests.id,
      clientId: interests.clientId,
      pipelineStage: interests.pipelineStage,
      createdAt: interests.createdAt,
      eoiStatus: interests.eoiStatus,
      contractStatus: interests.contractStatus,
      depositStatus: interests.depositStatus,
      dateEoiSigned: interests.dateEoiSigned,
      dateContractSigned: interests.dateContractSigned,
      dateDepositReceived: interests.dateDepositReceived,
    })
    .from(interests)
    .where(and(eq(interests.portId, portId), isNull(interests.archivedAt)));

  if (allInterests.length === 0) return [];

  const ids = allInterests.map((i) => i.id);
  const clientIds = Array.from(
    new Set(allInterests.map((i) => i.clientId).filter((v): v is string => Boolean(v))),
  );
  const thirtyDaysAgo = new Date(Date.now() - 30 * 24 * 60 * 60 * 1000);

  // Four grouped aggregates against the port's interest set. Each is a
  // single index-friendly scan on `interest_id` (or `client_id` for the
  // email-threads case) - no per-row round trips.
  const [notesGrouped, remindersGrouped, emailsGrouped, berthLinksGrouped] = await Promise.all([
    db
      .select({ interestId: interestNotes.interestId, value: count() })
      .from(interestNotes)
      .where(
        and(inArray(interestNotes.interestId, ids), gte(interestNotes.createdAt, thirtyDaysAgo)),
      )
      .groupBy(interestNotes.interestId),
    db
      .select({ interestId: reminders.interestId, value: count() })
      .from(reminders)
      .where(
        and(
          inArray(reminders.interestId, ids),
          eq(reminders.status, 'completed'),
          gte(reminders.completedAt, thirtyDaysAgo),
        ),
      )
      .groupBy(reminders.interestId),
    clientIds.length > 0
      ? db
          .select({ clientId: emailThreads.clientId, value: count() })
          .from(emailThreads)
          .where(
            and(
              inArray(emailThreads.clientId, clientIds),
              eq(emailThreads.portId, portId),
              gte(emailThreads.lastMessageAt, thirtyDaysAgo),
            ),
          )
          .groupBy(emailThreads.clientId)
      : Promise.resolve([] as Array<{ clientId: string | null; value: number }>),
    db
      .select({ interestId: interestBerths.interestId, value: count() })
      .from(interestBerths)
      .where(inArray(interestBerths.interestId, ids))
      .groupBy(interestBerths.interestId),
  ]);

  const notesByInterest = new Map(
    notesGrouped
      .filter((r): r is { interestId: string; value: number } => r.interestId !== null)
      .map((r) => [r.interestId, r.value]),
  );
  const remindersByInterest = new Map(
    remindersGrouped
      .filter((r): r is { interestId: string; value: number } => r.interestId !== null)
      .map((r) => [r.interestId, r.value]),
  );
  const emailsByClient = new Map(
    emailsGrouped
      .filter((r): r is { clientId: string; value: number } => r.clientId !== null)
      .map((r) => [r.clientId, r.value]),
  );
  const berthLinksByInterest = new Map(
    berthLinksGrouped
      .filter((r): r is { interestId: string; value: number } => r.interestId !== null)
      .map((r) => [r.interestId, r.value]),
  );

  const RAW_MAX = 425;
  const calculatedAt = new Date();
  const calculatedAtIso = calculatedAt.toISOString();

  const scored = allInterests.map((interest) => {
    const pipelineAge = scorePipelineAge(interest.createdAt);
    const stageSpeed = scoreStageSpeed(interest.createdAt, interest.pipelineStage);
    const documentCompleteness = scoreDocumentCompleteness({
      eoiStatus: interest.eoiStatus,
      contractStatus: interest.contractStatus,
      depositStatus: interest.depositStatus,
      dateEoiSigned: interest.dateEoiSigned,
      dateContractSigned: interest.dateContractSigned,
      dateDepositReceived: interest.dateDepositReceived,
    });

    const notesCount = notesByInterest.get(interest.id) ?? 0;
    const remindersCount = remindersByInterest.get(interest.id) ?? 0;
    const emailCount = interest.clientId ? (emailsByClient.get(interest.clientId) ?? 0) : 0;
    const notesScore = Math.min(notesCount * 10, 50);
    const emailScore = Math.min(emailCount * 5, 30);
    const remindersScore = Math.min(remindersCount * 10, 20);
    const engagement = Math.min(notesScore + emailScore + remindersScore, 100);

    const berthLinked = (berthLinksByInterest.get(interest.id) ?? 0) > 0 ? 25 : 0;

    const rawTotal = pipelineAge + stageSpeed + documentCompleteness + engagement + berthLinked;
    const totalScore = Math.round((rawTotal / RAW_MAX) * 100);

    const score: InterestScore = {
      totalScore,
      breakdown: { pipelineAge, stageSpeed, documentCompleteness, engagement, berthLinked },
      calculatedAt,
    };
    return { interestId: interest.id, score };
  });

  // Refresh the redis cache for each interest in a single pipeline so
  // single-interest reads downstream short-circuit the per-row queries.
  // Fire-and-forget - bulk scoring's correctness doesn't depend on the
  // cache write succeeding.
  redis
    .pipeline(
      scored.map(({ interestId, score }) => [
        'setex',
        SCORE_KEY(portId, interestId),
        SCORE_TTL,
        JSON.stringify({ ...score, calculatedAt: calculatedAtIso }),
      ]),
    )
    .exec()
    .catch((err) => logger.warn({ err, portId }, 'Redis bulk cache write failed'));

  return scored;
}