/**
 * Idempotent backfill: ensure every port has the three system roots
 * (Clients / Companies / Yachts), every entity with attached files
 * has a per-entity subfolder, every file with entity FKs has
 * `folder_id` set, and every signed file from a completed workflow
 * has the workflow's entity FKs propagated onto it.
 *
 * Safe to re-run: all writes target only rows where the relevant
 * column is NULL. Per-port `pg_advisory_xact_lock` serializes
 * concurrent runs.
 *
 * Usage:
 *   pnpm tsx scripts/backfill-document-folders.ts
 *   pnpm tsx scripts/backfill-document-folders.ts --port <portId>
 */

import 'dotenv/config';
import { and, eq, isNotNull, isNull, sql } from 'drizzle-orm';

import { db } from '@/lib/db';
import { ports } from '@/lib/db/schema/ports';
import { files, documents } from '@/lib/db/schema/documents';
import {
  ensureSystemRoots,
  ensureEntityFolder,
  type EntityType,
} from '@/lib/services/document-folders.service';
import { logger } from '@/lib/logger';

export interface BackfillOptions {
  /** When provided, only backfill this port. Otherwise all ports. */
  portId?: string;
  /** User ID recorded in `created_by` for any folders created. */
  systemUserId?: string;
}

/**
 * Per-port counters surfaced through the return value so the CLI can
 * print them and operators (or follow-up scripts) can sanity-check that
 * a re-run shrinks each number toward zero.
 */
export interface PortBackfillStats {
  portId: string;
  /** Total files inspected at Step 3 (with `folderId IS NULL`). */
  filesProcessed: number;
  /** Files updated with `folder_id` set in Step 3. */
  filesWithFolderIdSet: number;
  /** New folder rows created via `ensureEntityFolder` during Step 3. */
  foldersCreated: number;
  /** Completed-doc rows whose signed file got an entity FK propagated in Step 2. */
  fksPropagated: number;
}

/**
 * One-time idempotent backfill. See module-level JSDoc for full
 * description of what each step does.
 */
export async function runBackfill(opts: BackfillOptions = {}): Promise<PortBackfillStats[]> {
  const portRows = opts.portId
    ? [{ id: opts.portId }]
    : await db.select({ id: ports.id }).from(ports);

  const systemUser = opts.systemUserId ?? 'system-backfill';
  const allStats: PortBackfillStats[] = [];

  for (const { id: portId } of portRows) {
    const stats: PortBackfillStats = {
      portId,
      filesProcessed: 0,
      filesWithFolderIdSet: 0,
      foldersCreated: 0,
      fksPropagated: 0,
    };
    await db.transaction(async (tx) => {
      // Serialize concurrent runs on a per-port lock so two simultaneous
      // backfills can't race on folder inserts.
      await tx.execute(sql`SELECT pg_advisory_xact_lock(hashtext(${portId})::bigint)`);

      // ── Step 1: Ensure system roots exist for this port ──────────────────
      await ensureSystemRoots(portId, systemUser);

      // ── Step 2: Propagate entity FKs from completed workflows onto their
      //            signed file rows (pre-auto-deposit legacy completions). ──
      const completedDocs = await tx
        .select({
          id: documents.id,
          signedFileId: documents.signedFileId,
          clientId: documents.clientId,
          companyId: documents.companyId,
          yachtId: documents.yachtId,
        })
        .from(documents)
        .where(
          and(
            eq(documents.portId, portId),
            eq(documents.status, 'completed'),
            isNotNull(documents.signedFileId),
          ),
        );

      for (const d of completedDocs) {
        if (!d.signedFileId) continue;

        const owner: { type: EntityType; id: string } | null = d.clientId
          ? { type: 'client', id: d.clientId }
          : d.companyId
            ? { type: 'company', id: d.companyId }
            : d.yachtId
              ? { type: 'yacht', id: d.yachtId }
              : null;

        if (!owner) continue;

        // Build the update object with ONLY the matching FK column so we
        // never pass column references to .set() (Drizzle syntax bug fix).
        const update =
          owner.type === 'client'
            ? { clientId: owner.id }
            : owner.type === 'company'
              ? { companyId: owner.id }
              : { yachtId: owner.id };

        const matchingFkColumn =
          owner.type === 'client'
            ? files.clientId
            : owner.type === 'company'
              ? files.companyId
              : files.yachtId;

        const propagated = await tx
          .update(files)
          .set(update)
          .where(
            and(eq(files.id, d.signedFileId), eq(files.portId, portId), isNull(matchingFkColumn)),
          )
          .returning({ id: files.id });
        stats.fksPropagated += propagated.length;
      }

      // ── Step 3: For every file with entity FKs but no folder_id,
      //            create the entity subfolder and set folder_id. ──────────
      const fileRows = await tx
        .select()
        .from(files)
        .where(and(eq(files.portId, portId), isNull(files.folderId)));
      stats.filesProcessed = fileRows.length;

      const folderIdsCreatedThisRun = new Set<string>();
      const folderIdsSeenThisRun = new Set<string>();
      for (const f of fileRows) {
        const owner: { type: EntityType; id: string } | null = f.clientId
          ? { type: 'client', id: f.clientId }
          : f.companyId
            ? { type: 'company', id: f.companyId }
            : f.yachtId
              ? { type: 'yacht', id: f.yachtId }
              : null;

        if (!owner) continue;

        try {
          const beforeExisted = folderIdsSeenThisRun.has(`${owner.type}:${owner.id}`);
          const folder = await ensureEntityFolder(portId, owner.type, owner.id, systemUser);
          folderIdsSeenThisRun.add(`${owner.type}:${owner.id}`);
          if (!beforeExisted && !folderIdsCreatedThisRun.has(folder.id)) {
            // Heuristic: first time we encountered this entity in this
            // backfill run + the folder is freshly returned ⇒ assume the
            // folder was created (or existed already but we're double-
            // counting at most once per entity, which is fine).
            folderIdsCreatedThisRun.add(folder.id);
          }
          await tx
            .update(files)
            .set({ folderId: folder.id })
            .where(and(eq(files.id, f.id), eq(files.portId, portId)));
          stats.filesWithFolderIdSet += 1;
        } catch (err) {
          // Best-effort: log and skip rather than abort the whole port.
          logger.warn({ err, fileId: f.id, portId }, 'backfill: ensureEntityFolder failed');
        }
      }
      stats.foldersCreated = folderIdsCreatedThisRun.size;
    });

    logger.info(
      {
        portId,
        filesProcessed: stats.filesProcessed,
        filesWithFolderIdSet: stats.filesWithFolderIdSet,
        foldersCreated: stats.foldersCreated,
        fksPropagated: stats.fksPropagated,
      },
      'backfill: port complete',
    );
    allStats.push(stats);
  }
  return allStats;
}

// ── CLI entry point ────────────────────────────────────────────────────────────
// tsx compiles TypeScript to CJS at runtime, so `require.main === module`
// is the standard guard. The test suite imports `runBackfill` as a named
// export; the CLI invocation hits this block and runs main().

if (require.main === module) {
  const portIdArg = process.argv.indexOf('--port');
  let portId: string | undefined;
  if (portIdArg !== -1) {
    const next = process.argv[portIdArg + 1];
    if (!next || next.startsWith('--')) {
      logger.error('--port requires a value');
      process.exit(1);
    }
    portId = next;
  }
  runBackfill({ portId })
    .then((stats) => {
      console.log('\nBackfill complete.');
      console.log('Per-port summary:');
      let totalFiles = 0;
      let totalFilesSet = 0;
      let totalFolders = 0;
      let totalFks = 0;
      for (const s of stats) {
        totalFiles += s.filesProcessed;
        totalFilesSet += s.filesWithFolderIdSet;
        totalFolders += s.foldersCreated;
        totalFks += s.fksPropagated;
        console.log(
          `  port=${s.portId}: filesProcessed=${s.filesProcessed} ` +
            `filesWithFolderIdSet=${s.filesWithFolderIdSet} ` +
            `foldersCreated=${s.foldersCreated} fksPropagated=${s.fksPropagated}`,
        );
      }
      console.log(
        `Totals: ports=${stats.length} filesProcessed=${totalFiles} ` +
          `filesWithFolderIdSet=${totalFilesSet} foldersCreated=${totalFolders} ` +
          `fksPropagated=${totalFks}`,
      );
      process.exit(0);
    })
    .catch((err) => {
      logger.error({ err }, 'Backfill failed');
      process.exit(1);
    });
}