/**
 * Campaign Grouping Service
 *
 * Shared grouping core called by all 3 trigger sites: the webhook path
 * (`webhook-service.ts`'s `triggerPhishingDetection()`), the cron sweep
 * (`phishing-sweep-service.ts`), and the on-demand
 * `POST /api/phishing/tickets/{id}/analyze` route. One deterministic,
 * testable function computes a tiered campaign key (CAMP-01) and
 * finds-or-creates a `campaigns` row (CAMP-02) — no duplicated matching
 * logic between callers, mirroring `phishing-detector.ts`'s shared-core
 * architecture.
 *
 * D-07 limitation (load-bearing, stated explicitly): `groupReportIntoCampaign`
 * always runs BEFORE `parseAndStoreMessage` on the automatic webhook path
 * (see `webhook-service.ts`'s `triggerPhishingDetection()` — grouping happens
 * first, parsing happens afterward inside `runGatedPhishingStages()`). That
 * means at grouping time the CURRENT report never has its own `messages`/
 * `indicators` row yet, so Tier 1 (Message-ID) and Tier 2 (attachment-hash/
 * URL-domain) — both of which require the report's OWN signal to search
 * for candidates — can never match on the automatic path's one-and-only
 * grouping call (subsequent webhook events short-circuit via
 * `skipIfAlreadyGrouped`). Automatic grouping therefore always resolves via
 * Tier 3 (normalized subject + company + 24h window).
 *
 * Bug fix (debug session phishing-recipient-seubert): Tier 3 previously
 * scoped its match to `reports.requester_contact_id` — i.e. it only ever
 * merged reports filed by the SAME reporting employee. Since Tier 3 is the
 * only tier automatic grouping can ever reach (see D-07 above), that meant
 * the same phishing campaign sent to and reported by MULTIPLE different
 * employees at the same company could never be consolidated into one
 * campaign — each recipient's report silently became its own single-report
 * campaign, so any single ticket's evidence/blast-radius view under-reported
 * the campaign's true recipient list. Tier 3 now scopes to company + subject
 * only (no contact/requester restriction), matching its `sender_subject_
 * client` name's original intent of grouping the same external campaign
 * across a company, independent of who reported it. (`sender` isn't
 * literally available yet at this point — see D-07 — so "client" scoping is
 * company-wide, deliberately wider than a single reporter.)
 */

import type { PoolClient } from 'pg';
import { postgresClient } from './postgres-client';

// =============================================================================
// Pure logic — tier-key helpers (mirrors matchesPhishingPatterns / computePhishingContentHash)
// =============================================================================

/**
 * D-03: strip leading Re:/Fwd:/Fw: (repeated, case-insensitive), lowercase, trim.
 */
export function normalizeSubject(subject: string | null): string {
  let s = (subject ?? '').trim();
  const prefixRe = /^(re|fwd|fw):\s*/i;
  while (prefixRe.test(s)) {
    s = s.replace(prefixRe, '').trim();
  }
  return s.toLowerCase();
}

/**
 * Pitfall 4: indicators.value for indicator_type='url' is a bare URL string,
 * not a domain — extract at read time, guarded (malformed/relative URLs are
 * possible in real-world phishing emails).
 */
export function extractUrlDomain(url: string): string | null {
  try {
    return new URL(url).hostname || null;
  } catch {
    return null;
  }
}

// =============================================================================
// Orchestration — groupReportIntoCampaign (mirrors detectPhishingTicket)
// =============================================================================

export interface GroupReportResult {
  campaignId: string;
  groupMethod: 'message_id' | 'attachment_or_url' | 'sender_subject_client';
  created: boolean;
}

interface OwnReportRow {
  title: string | null;
  company_id: number | null;
  created_at: string;
  campaign_id: string | null;
}

interface OwnMessageRow {
  id: string;
  message_id: string | null;
}

interface IndicatorRow {
  indicator_type: string;
  value: string;
}

interface CandidateIndicatorRow extends IndicatorRow {
  message_id: string;
}

interface Tier2CandidateRow {
  report_id: string;
  campaign_id: string;
  title: string | null;
  message_id: string;
}

/** Builds a `message_id:...` key — the strongest available signal (Tier 1). */
function computeTier1Key(messageId: string | null): string | null {
  return messageId ? `message_id:${messageId}` : null;
}

/** Builds an `attachment_or_url:...` key from own indicators + subject + sender (Tier 2). */
function computeTier2Key(
  attachmentHashes: string[],
  urlDomains: string[],
  normalizedSubject: string,
  senderValue: string | null
): string | null {
  if (!senderValue || !normalizedSubject) return null;
  if (attachmentHashes.length === 0 && urlDomains.length === 0) return null;
  const keyParts = [...attachmentHashes, ...urlDomains].sort();
  return `attachment_or_url:${keyParts.join(',')}:${normalizedSubject}:${senderValue}`;
}

/**
 * Builds a `sender_subject_client:...` key from normalized subject + company
 * (Tier 3) — deliberately company-wide, NOT scoped to a single reporting
 * contact, so the same campaign reported by different employees at the same
 * company still consolidates into one campaign (see file-level bug-fix note).
 */
function computeTier3Key(normalizedSubject: string, companyId: number | null): string | null {
  if (!normalizedSubject || !companyId) return null;
  return `sender_subject_client:${normalizedSubject}:${companyId}`;
}

/**
 * CR-02: decrements a now-abandoned origin campaign's report_count. Shared
 * by both places a report can be abandoned from its origin campaign — the
 * sibling-migration branch (moving to a DIFFERENT existing campaign) and the
 * signal-diverged create-new fall-through (moving to a brand-new campaign) —
 * so neither is left with a stale, inflated count. Decrement only; never
 * deletes the origin row even if its count reaches 0 (out of scope — see
 * CR-02 scope note at the call sites).
 */
async function decrementOriginCampaign(client: PoolClient, originCampaignId: string): Promise<void> {
  await client.query(
    `UPDATE campaigns
        SET report_count = report_count - 1, updated_at = NOW()
      WHERE id = $1`,
    [originCampaignId]
  );
}

/**
 * Shared entry point called by the webhook path, the cron sweep, and the
 * on-demand `/analyze` route. Looks up the report's own signal (message,
 * indicators, requester/company), tries Tier 1 -> Tier 2 -> Tier 3 matching
 * queries in order inside a single transaction (Pitfall 2 — `campaigns.
 * campaign_key` has no UNIQUE constraint), and either links the report to an
 * existing campaign (bumping report_count/last_seen_at, CAMP-02) or inserts a
 * new campaigns row.
 *
 * D-08: `opts.skipIfAlreadyGrouped` short-circuits (returns null) when the
 * report is already linked — used by the automatic webhook/cron path to
 * avoid redundant work on every re-fire/sweep pass. The `/analyze` route
 * omits this option so it always re-runs full tiered matching (it may
 * upgrade a Tier-3-only report to Tier 1 after `parseAndStoreMessage` has
 * just populated `messages`/`indicators` for the first time).
 *
 * D-04: never merges campaigns — attaches to the first/best tiered match
 * found, or creates a new campaign. Multi-campaign-merge logic is explicitly
 * out of scope this phase.
 */
export async function groupReportIntoCampaign(
  reportId: string,
  opts?: { skipIfAlreadyGrouped?: boolean }
): Promise<GroupReportResult | null> {
  try {
    if (opts?.skipIfAlreadyGrouped) {
      const existing = await postgresClient.query<{ campaign_id: string | null }>(
        `SELECT campaign_id::text AS campaign_id FROM reports WHERE id = $1`,
        [reportId]
      );
      if (existing.rows[0]?.campaign_id) {
        return null; // already grouped, short-circuit (D-08)
      }
    }

    return await postgresClient.transaction(async (client) => {
      const ownReportRes = await client.query<OwnReportRow>(
        `SELECT title, company_id, created_at, campaign_id::text AS campaign_id
           FROM reports
          WHERE id = $1`,
        [reportId]
      );
      const ownReport = ownReportRes.rows[0];
      if (!ownReport) {
        throw new Error(`groupReportIntoCampaign: report ${reportId} not found`);
      }

      const normalizedSubject = normalizeSubject(ownReport.title);

      // Own messages row, if `parseAndStoreMessage` has already run for this
      // report (D-07 — not the case for the automatic webhook/cron path
      // until an explicit /analyze call has happened at least once).
      const ownMessageRes = await client.query<OwnMessageRow>(
        `SELECT id::text AS id, message_id
           FROM messages
          WHERE report_id = $1
          LIMIT 1`,
        [reportId]
      );
      const ownMessage = ownMessageRes.rows[0] ?? null;

      let matchCampaignId: string | null = null;
      let matchGroupMethod: GroupReportResult['groupMethod'] | null = null;

      // ---------------------------------------------------------------------
      // Tier 1: Message-ID. Self-exclusion (`r.id != $2`) is REQUIRED — without
      // it this query would trivially match the report's own messages row
      // against itself, double-incrementing its own already-linked campaign
      // on every re-run (plan-checker finding).
      // ---------------------------------------------------------------------
      if (ownMessage?.message_id) {
        const tier1 = await client.query<{ campaign_id: string }>(
          `SELECT r.campaign_id::text AS campaign_id
             FROM messages m
             JOIN reports r ON r.id = m.report_id
            WHERE m.message_id = $1
              AND r.campaign_id IS NOT NULL
              AND r.id != $2
            ORDER BY r.created_at ASC
            LIMIT 1`,
          [ownMessage.message_id, reportId]
        );
        if (tier1.rows[0]?.campaign_id) {
          matchCampaignId = tier1.rows[0].campaign_id;
          matchGroupMethod = 'message_id';
        }
      }

      // ---------------------------------------------------------------------
      // Tier 2: attachment-hash / URL-domain + normalized subject + sender,
      // within a 24h window (D-02). Only reachable if the own report has its
      // own indicators (i.e. parseAndStoreMessage already ran for it).
      // Self-exclusion (`r.id != $1`) required for the same reason as Tier 1.
      // ---------------------------------------------------------------------
      let ownAttachmentHashes: string[] = [];
      let ownUrlDomains: string[] = [];
      let ownSenderValue: string | null = null;

      if (!matchCampaignId && ownMessage) {
        const ownIndicatorsRes = await client.query<IndicatorRow>(
          `SELECT indicator_type, value
             FROM indicators
            WHERE message_id = $1`,
          [ownMessage.id]
        );
        ownAttachmentHashes = ownIndicatorsRes.rows
          .filter((i) => i.indicator_type === 'attachment_hash')
          .map((i) => i.value);
        ownUrlDomains = ownIndicatorsRes.rows
          .filter((i) => i.indicator_type === 'url')
          .map((i) => extractUrlDomain(i.value))
          .filter((d): d is string => d !== null);
        ownSenderValue =
          ownIndicatorsRes.rows.find((i) => i.indicator_type === 'sender')?.value ?? null;

        if (
          (ownAttachmentHashes.length > 0 || ownUrlDomains.length > 0) &&
          ownSenderValue &&
          normalizedSubject
        ) {
          const tier2Candidates = await client.query<Tier2CandidateRow>(
            `SELECT r.id::text AS report_id, r.campaign_id::text AS campaign_id, r.title,
                    m.id::text AS message_id
               FROM messages m
               JOIN reports r ON r.id = m.report_id
              WHERE r.campaign_id IS NOT NULL
                AND r.id != $1
                AND r.created_at BETWEEN $2::timestamptz - INTERVAL '24 hours'
                                     AND $2::timestamptz + INTERVAL '24 hours'`,
            [reportId, ownReport.created_at]
          );

          if (tier2Candidates.rows.length > 0) {
            const candidateMessageIds = tier2Candidates.rows.map((c) => c.message_id);
            const candidateIndicatorsRes = await client.query<CandidateIndicatorRow>(
              `SELECT message_id::text AS message_id, indicator_type, value
                 FROM indicators
                WHERE message_id = ANY($1::uuid[])`,
              [candidateMessageIds]
            );
            const indicatorsByMessage = new Map<string, CandidateIndicatorRow[]>();
            for (const ind of candidateIndicatorsRes.rows) {
              const arr = indicatorsByMessage.get(ind.message_id) ?? [];
              arr.push(ind);
              indicatorsByMessage.set(ind.message_id, arr);
            }

            for (const candidate of tier2Candidates.rows) {
              if (normalizeSubject(candidate.title) !== normalizedSubject) continue;
              const candidateIndicators = indicatorsByMessage.get(candidate.message_id) ?? [];
              const candidateSender = candidateIndicators.find(
                (i) => i.indicator_type === 'sender'
              )?.value;
              if (candidateSender !== ownSenderValue) continue;
              const candidateHashes = candidateIndicators
                .filter((i) => i.indicator_type === 'attachment_hash')
                .map((i) => i.value);
              const candidateDomains = candidateIndicators
                .filter((i) => i.indicator_type === 'url')
                .map((i) => extractUrlDomain(i.value))
                .filter((d): d is string => d !== null);
              const hashMatch = ownAttachmentHashes.some((h) => candidateHashes.includes(h));
              const domainMatch = ownUrlDomains.some((d) => candidateDomains.includes(d));
              if (hashMatch || domainMatch) {
                matchCampaignId = candidate.campaign_id;
                matchGroupMethod = 'attachment_or_url';
                break;
              }
            }
          }
        }
      }

      // ---------------------------------------------------------------------
      // Tier 3: normalizeSubject(title) + company + 24h window (D-02, fixed
      // per file-level bug-fix note). Company-wide — deliberately NOT scoped
      // to `reports.requester_contact_id` — so the same campaign reported by
      // different employees at the same company still consolidates into one
      // campaign. Self-exclusion (`r.id != $2`) required for the same reason
      // as Tiers 1-2.
      // ---------------------------------------------------------------------
      if (!matchCampaignId && ownReport.company_id && normalizedSubject) {
        const tier3 = await client.query<{ campaign_id: string; title: string | null }>(
          `SELECT r.campaign_id::text AS campaign_id, r.title
             FROM reports r
            WHERE r.company_id = $1
              AND r.campaign_id IS NOT NULL
              AND r.id != $2
              AND r.created_at BETWEEN $3::timestamptz - INTERVAL '24 hours'
                                   AND $3::timestamptz + INTERVAL '24 hours'
            ORDER BY r.created_at ASC`,
          [ownReport.company_id, reportId, ownReport.created_at]
        );
        const match = tier3.rows.find((r) => normalizeSubject(r.title) === normalizedSubject);
        if (match) {
          matchCampaignId = match.campaign_id;
          matchGroupMethod = 'sender_subject_client';
        }
      }

      // ---------------------------------------------------------------------
      // Own-signal tier keys, computed once here and reused by both the
      // own-campaign revalidation guard (CR-03, below) and the create-new
      // fall-through further down — avoids computing them twice.
      // ---------------------------------------------------------------------
      const tier1Key = computeTier1Key(ownMessage?.message_id ?? null);
      const tier2Key = computeTier2Key(
        ownAttachmentHashes,
        ownUrlDomains,
        normalizedSubject,
        ownSenderValue
      );
      const tier3Key = computeTier3Key(normalizedSubject, ownReport.company_id);
      const currentKeys = [tier1Key, tier2Key, tier3Key, `report:${reportId}`].filter(
        (k): k is string => k !== null
      );

      // ---------------------------------------------------------------------
      // Find-or-create against `campaigns` (CAMP-02).
      // ---------------------------------------------------------------------
      if (matchCampaignId && matchGroupMethod) {
        // CR-01/CAMP-02 no-op guard: tier queries only exclude the report's
        // OWN row (`r.id != $x`), not its siblings already in the same
        // campaign. Since `/analyze` re-runs grouping unconditionally
        // (D-08), a report already linked to campaign X can re-match X via
        // a sibling row on every repeat call, inflating `report_count`
        // without bound. If the match resolves to the report's own current
        // campaign, it's already correctly linked — skip both UPDATEs.
        if (matchCampaignId === ownReport.campaign_id) {
          return { campaignId: matchCampaignId, groupMethod: matchGroupMethod, created: false };
        }
        await client.query(
          `UPDATE campaigns
              SET report_count = report_count + 1, last_seen_at = NOW(), updated_at = NOW()
            WHERE id = $1`,
          [matchCampaignId]
        );
        await client.query(
          `UPDATE reports SET campaign_id = $1, updated_at = NOW() WHERE id = $2`,
          [matchCampaignId, reportId]
        );
        // CR-02: if the report had a DIFFERENT prior campaign (the
        // same-campaign case returned above; a never-grouped report has no
        // origin — D-08), decrement it so it doesn't keep a permanently
        // stale report_count for a report it no longer holds. Scope:
        // decrement only, never delete the origin row even if its count
        // reaches 0 (deleting introduces FK-cascade/detail-route risk out of
        // scope for this gap fix; an empty campaign is a strictly lesser
        // problem than a stale count).
        if (ownReport.campaign_id) {
          await decrementOriginCampaign(client, ownReport.campaign_id);
        }
        return { campaignId: matchCampaignId, groupMethod: matchGroupMethod, created: false };
      }

      // ---------------------------------------------------------------------
      // CR-03: no sibling matched on any tier (matchCampaignId is null).
      // Every tier query above self-excludes the report's own row
      // (`r.id != $x`), so a single-report campaign (no sibling report
      // exists yet — the common case for any brand-new phishing lure before
      // a second person reports it) always reaches here with matchCampaignId
      // still null. Pre-fix, control fell straight into "create new
      // campaign" below, abandoning the report's still-valid campaign and
      // producing a SECOND campaigns row with the identical campaign_key on
      // every repeat /analyze call. This guard sits OUTSIDE the sibling-
      // match branch above precisely because it must only run when NO
      // sibling matched — it never suppresses a legitimate D-08 sibling
      // upgrade, which returns from the branch above instead.
      // ---------------------------------------------------------------------
      if (!matchCampaignId && ownReport.campaign_id) {
        const ownCampaignRes = await client.query<{ campaign_key: string; group_method: string }>(
          `SELECT campaign_key, group_method
             FROM campaigns
            WHERE id = $1`,
          [ownReport.campaign_id]
        );
        const ownCampaign = ownCampaignRes.rows[0];
        if (ownCampaign && currentKeys.includes(ownCampaign.campaign_key)) {
          // The report's own campaign still satisfies its freshly-recomputed
          // current tier key — it's still validly linked, reuse it as-is.
          return {
            campaignId: ownReport.campaign_id,
            groupMethod: ownCampaign.group_method as GroupReportResult['groupMethod'],
            created: false,
          };
        }
        // CR-02: own campaign row is gone, or the report's signal has
        // genuinely diverged from its stored key — this report is about to
        // be abandoned from its origin campaign in favor of a brand-new one
        // below (the same class of abandonment as the sibling-migration
        // branch above, just landing on a new row instead of an existing
        // sibling's). Decrement now so the origin doesn't show a stale
        // count. Falls through to create-new unchanged.
        await decrementOriginCampaign(client, ownReport.campaign_id);
      }

      // No match on any tier — create a new campaign. Prefer the strongest
      // available key (Tier 1 > Tier 2 > Tier 3) so future duplicates of THIS
      // report can match it; do NOT set/transition campaigns.status (leave
      // migration default 'open' — Phase 19/20's concern).
      let newCampaignKey: string;
      let newGroupMethod: GroupReportResult['groupMethod'];
      if (tier1Key) {
        newCampaignKey = tier1Key;
        newGroupMethod = 'message_id';
      } else if (tier2Key) {
        newCampaignKey = tier2Key;
        newGroupMethod = 'attachment_or_url';
      } else if (tier3Key) {
        newCampaignKey = tier3Key;
        newGroupMethod = 'sender_subject_client';
      } else {
        newCampaignKey = `report:${reportId}`;
        newGroupMethod = 'sender_subject_client';
      }

      const newCampaign = await client.query<{ id: string }>(
        `INSERT INTO campaigns (campaign_key, group_method, first_seen_at, last_seen_at, report_count)
         VALUES ($1, $2, NOW(), NOW(), 1)
         RETURNING id::text AS id`,
        [newCampaignKey, newGroupMethod]
      );
      const newCampaignId = newCampaign.rows[0].id;

      await client.query(
        `UPDATE reports SET campaign_id = $1, updated_at = NOW() WHERE id = $2`,
        [newCampaignId, reportId]
      );

      return { campaignId: newCampaignId, groupMethod: newGroupMethod, created: true };
    });
  } catch (error) {
    console.error('[CAMPAIGN-GROUPING] Failed to group report into campaign', reportId, error);
    throw error;
  }
}