// P4 Files (AK-P4a) §3/§7 — domain service for the Files module.
//
// Pure-ish server logic: builds/queries File rows (always tenant-scoped),
// orchestrates chunked upload + assembly, enforces visibility (404, not 403),
// and fans out to the scan/preview queues. NO React/UI imports. Routes call
// these functions from their loaders/actions and build the View-Model from the
// returned rows.
//
// Tenant isolation is enforced THREEFOLD: every query carries `where: { tenantId }`
// (app-level scoping), the storage keys carry the `tenants/{tenantId}/` prefix
// (assertFileKeyBelongsToTenant), and every DB access runs inside withTenantRLS()
// (R-P2b) so `app.tenant_id` is set for the policies shipped in
// local/AK-P4a-merge-migration.sql. Until that RLS block is activated (P5 cutover)
// the wrapper is a harmless no-op (a transaction that sets a GUC no policy reads);
// it makes Files RLS-ready without changing runtime behaviour.
//
// Wrapping rules (so activation is safe): slow I/O (S3, queue) stays OUTSIDE the
// transaction, and functions never nest withTenantRLS() — internal composition
// goes through *WithTx(tx, ...) helpers that take the active transaction client.

import { CatalogError, foundationErrors } from "@toolctrl/foundation";
import { buildFileStorageKeys, buildUploadChunkKey, uploadChunkPrefix } from "@toolctrl/storage";
import {
  FILE_UPLOAD_CHUNK_SIZE_BYTES,
  FILE_UPLOAD_MAX_FILE_SIZE_BYTES,
} from "@toolctrl/view-models";
import { withTenantRLS, type TenantRlsClient } from "~/utils/db/.server/tenantRls.server";
import { assembleChunkedUpload, deleteFile, putBufferAsFile, resolveStorageBucket } from "./storageService";
import { enqueueFileScan } from "./fileScanQueue.server";
import { enqueueFilePreview } from "./filePreviewQueue.server";

/**
 * Domain error carrying an i18n message key (M002 Klartext). Routes map
 * `messageKey` to a catalog error / VM error branch — never a bare HTTP code.
 */
export class FileServiceError extends Error {
  readonly messageKey: string;
  constructor(messageKey: string) {
    super(messageKey);
    this.name = "FileServiceError";
    this.messageKey = messageKey;
  }
}

export type FileEntityType =
  | "contact"
  | "company"
  | "lead"
  | "deal"
  | "project"
  | "user"
  | "form_submission"
  | "order"
  | "task"
  | "appointment";

export type FileSource = "manual_upload" | "customer_portal" | "form_submission" | "email_attachment" | "automation" | "api";

/**
 * Curated upload allow-list for the Files module. Deliberately broader than the
 * shared scan `DEFAULT_ALLOW_LIST` (which is per-context and lacks HEIC) — Files
 * is a general document store and HEIC is mandatory (iPhone photos, AK-P4a).
 * The shared allow-list stays untouched (mergeable boilerplate). Layer-2 ClamAV
 * still scans the stored bytes regardless of declared MIME.
 */
export const FILES_ALLOWED_MIME_TYPES: ReadonlySet<string> = new Set([
  "image/png",
  "image/jpeg",
  "image/webp",
  "image/gif",
  "image/heic",
  "image/heif",
  "application/pdf",
  "text/plain",
  "text/markdown",
  "text/csv",
  "application/vnd.openxmlformats-officedocument.wordprocessingml.document",
  "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet",
  "application/vnd.openxmlformats-officedocument.presentationml.presentation",
]);

export type FileVisibilityContext = {
  userId: string;
  /** The user's permission names for this tenant (from getPermissionsByUser). */
  permissions: readonly string[];
};

function hasPermission(ctx: FileVisibilityContext, permission: string): boolean {
  return ctx.permissions.includes(permission);
}

// --- Upload session -------------------------------------------------------

export type CreateUploadSessionInput = {
  tenantId: string;
  userId: string;
  originalFilename: string;
  mimeType: string;
  totalSizeBytes: number;
};

export type CreateUploadSessionResult = {
  uploadId: string;
  chunkSize: number;
  totalChunks: number;
};

export async function createUploadSession(input: CreateUploadSessionInput): Promise<CreateUploadSessionResult> {
  if (input.totalSizeBytes <= 0) {
    throw new FileServiceError("files.error.emptyFile");
  }
  if (input.totalSizeBytes > FILE_UPLOAD_MAX_FILE_SIZE_BYTES) {
    throw new FileServiceError("files.error.tooLarge");
  }
  if (!FILES_ALLOWED_MIME_TYPES.has(input.mimeType)) {
    throw new FileServiceError("files.error.mimeBlocked");
  }
  const totalChunks = Math.max(1, Math.ceil(input.totalSizeBytes / FILE_UPLOAD_CHUNK_SIZE_BYTES));
  const expiresAt = new Date(Date.now() + 24 * 60 * 60 * 1000);
  const upload = await withTenantRLS(input.tenantId, (tx) =>
    tx.fileUpload.create({
      data: {
        tenantId: input.tenantId,
        createdByUserId: input.userId,
        originalFilename: input.originalFilename,
        totalSizeBytes: input.totalSizeBytes,
        mimeType: input.mimeType,
        totalChunks,
        status: "in_progress",
        expiresAt,
      },
      select: { id: true },
    }),
  );
  return { uploadId: upload.id, chunkSize: FILE_UPLOAD_CHUNK_SIZE_BYTES, totalChunks };
}

export type StoreUploadChunkInput = {
  tenantId: string;
  userId: string;
  uploadId: string;
  chunkIndex: number;
  bytes: Uint8Array;
};

export async function storeUploadChunk(input: StoreUploadChunkInput): Promise<{ receivedChunks: number; totalChunks: number }> {
  const upload = await withTenantRLS(input.tenantId, (tx) =>
    tx.fileUpload.findFirst({
      where: { id: input.uploadId, tenantId: input.tenantId, createdByUserId: input.userId },
      select: { id: true, status: true, totalChunks: true, expiresAt: true },
    }),
  );
  if (!upload) {
    throw new CatalogError(foundationErrors.notFound, { uploadId: input.uploadId });
  }
  if (upload.status !== "in_progress") {
    throw new FileServiceError("files.error.uploadNotActive");
  }
  if (upload.expiresAt.getTime() < Date.now()) {
    throw new FileServiceError("files.error.uploadExpired");
  }
  if (input.chunkIndex < 0 || input.chunkIndex >= upload.totalChunks) {
    throw new FileServiceError("files.error.chunkIndexOutOfRange");
  }

  const bucket = resolveStorageBucket();
  const chunkKey = buildUploadChunkKey(input.tenantId, input.uploadId, input.chunkIndex);
  // S3 PUT stays OUTSIDE the RLS transaction (no slow I/O inside a tx).
  await putBufferAsFile({ bucket, key: chunkKey, body: input.bytes, contentType: "application/octet-stream" });

  // Persist the chunk + recount in one tenant-scoped transaction.
  const received = await withTenantRLS(input.tenantId, async (tx) => {
    // Upsert so a retried chunk does not double-count receivedChunks.
    const existing = await tx.fileUploadChunk.findUnique({
      where: { uploadId_chunkIndex: { uploadId: input.uploadId, chunkIndex: input.chunkIndex } },
      select: { id: true },
    });
    if (existing) {
      await tx.fileUploadChunk.update({
        where: { uploadId_chunkIndex: { uploadId: input.uploadId, chunkIndex: input.chunkIndex } },
        data: { storageKey: chunkKey, sizeBytes: input.bytes.byteLength },
      });
    } else {
      await tx.fileUploadChunk.create({
        data: {
          tenantId: input.tenantId,
          uploadId: input.uploadId,
          chunkIndex: input.chunkIndex,
          storageKey: chunkKey,
          sizeBytes: input.bytes.byteLength,
        },
      });
    }

    const count = await tx.fileUploadChunk.count({ where: { uploadId: input.uploadId, tenantId: input.tenantId } });
    await tx.fileUpload.update({ where: { id: input.uploadId }, data: { receivedChunks: count } });
    return count;
  });
  return { receivedChunks: received, totalChunks: upload.totalChunks };
}

export type CompleteUploadInput = {
  tenantId: string;
  userId: string;
  uploadId: string;
  displayName?: string;
  source?: FileSource;
  createdByPortalUserId?: string | null;
  isDemoData?: boolean;
};

export type CompletedFile = {
  id: string;
  displayName: string;
  mimeType: string;
  sizeBytes: number;
  storageKey: string;
};

export async function completeUpload(input: CompleteUploadInput): Promise<CompletedFile> {
  // Segment 1 (DB): validate the session, read the chunk manifest and create the
  // pending File row. The File id is needed for the storage key, so the row is
  // created here (before S3 assembly). All contiguous DB work, no slow I/O.
  const { upload, chunks, file } = await withTenantRLS(input.tenantId, async (tx) => {
    const session = await tx.fileUpload.findFirst({
      where: { id: input.uploadId, tenantId: input.tenantId, createdByUserId: input.userId },
      select: { id: true, status: true, totalChunks: true, originalFilename: true, mimeType: true, totalSizeBytes: true },
    });
    if (!session) {
      throw new CatalogError(foundationErrors.notFound, { uploadId: input.uploadId });
    }
    if (session.status !== "in_progress") {
      throw new FileServiceError("files.error.uploadNotActive");
    }

    const manifest = await tx.fileUploadChunk.findMany({
      where: { uploadId: input.uploadId, tenantId: input.tenantId },
      orderBy: { chunkIndex: "asc" },
      select: { chunkIndex: true, storageKey: true },
    });
    if (manifest.length !== session.totalChunks) {
      throw new FileServiceError("files.error.uploadIncomplete");
    }
    // Verify contiguous 0..totalChunks-1 ordering.
    for (let index = 0; index < manifest.length; index += 1) {
      if (manifest[index].chunkIndex !== index) {
        throw new FileServiceError("files.error.uploadIncomplete");
      }
    }

    const created = await tx.file.create({
      data: {
        tenantId: input.tenantId,
        createdByUserId: input.userId,
        displayName: (input.displayName ?? session.originalFilename).slice(0, 255),
        mimeType: session.mimeType,
        sizeBytes: session.totalSizeBytes,
        storageKey: "", // set after assembly below
        source: input.source ?? "manual_upload",
        createdByPortalUserId: input.createdByPortalUserId ?? null,
        isDemoData: input.isDemoData ?? false,
        previewStatus: "pending",
        scanStatus: "pending",
      },
      select: { id: true, displayName: true, mimeType: true, sizeBytes: true },
    });
    return { upload: session, chunks: manifest, file: created };
  });

  const bucket = resolveStorageBucket();
  const { original } = buildFileStorageKeys(input.tenantId, file.id);
  try {
    // S3 assembly stays OUTSIDE the RLS transaction.
    await assembleChunkedUpload({
      bucket,
      targetKey: original,
      chunkSourceKeys: chunks.map((chunk) => chunk.storageKey),
      contentType: upload.mimeType,
    });
  } catch (error) {
    // Roll the half-created File back so a failed assembly leaves no orphan row.
    await withTenantRLS(input.tenantId, async (tx) => {
      await tx.file.delete({ where: { id: file.id } }).catch(() => {});
      await tx.fileUpload.update({ where: { id: input.uploadId }, data: { status: "failed", failureReason: "assembly-failed" } }).catch(() => {});
    }).catch(() => {});
    throw error instanceof FileServiceError ? error : new FileServiceError("files.error.assemblyFailed");
  }

  await withTenantRLS(input.tenantId, (tx) => tx.file.update({ where: { id: file.id }, data: { storageKey: original } }));

  // Clean up temp chunk objects (best-effort, S3 outside the tx) + mark the
  // session done in one tenant-scoped transaction.
  await Promise.all(chunks.map((chunk) => deleteFile({ bucket, key: chunk.storageKey }).catch(() => {})));
  await withTenantRLS(input.tenantId, async (tx) => {
    await tx.fileUploadChunk.deleteMany({ where: { uploadId: input.uploadId, tenantId: input.tenantId } }).catch(() => {});
    await tx.fileUpload.update({ where: { id: input.uploadId }, data: { status: "completed", targetFileId: file.id } });
  });

  // Fan out async scan (ClamAV, layer 2) + preview generation. When scanning is
  // disabled (dev / SCAN_QUEUE_ENABLED!=true) the enqueue is a no-op; in that
  // case mark the file scanStatus=skipped so the fail-closed media proxy (§6)
  // still serves it. In prod the file stays scanStatus=pending until the worker
  // writes a clean/infected verdict.
  const scanResult = await enqueueFileScan({ bucket, key: original, tenantId: input.tenantId, contentType: upload.mimeType, fileId: file.id }).catch(
    () => ({ enqueued: false, reason: "queue-unavailable" }) as const,
  );
  if (!scanResult.enqueued && scanResult.reason === "scan-disabled") {
    await withTenantRLS(input.tenantId, (tx) => tx.file.update({ where: { id: file.id }, data: { scanStatus: "skipped" } })).catch(() => {});
  }
  await enqueueFilePreview({ fileId: file.id, tenantId: input.tenantId, bucket, storageKey: original, mimeType: upload.mimeType }).catch(() => {});

  return { id: file.id, displayName: file.displayName, mimeType: file.mimeType, sizeBytes: file.sizeBytes, storageKey: original };
}

// --- Visibility / read ----------------------------------------------------

export type FileRow = {
  id: string;
  tenantId: string;
  createdByUserId: string;
  assignedToUserId: string | null;
  displayName: string;
  mimeType: string;
  sizeBytes: number;
  storageKey: string;
  previewStorageKey: string | null;
  thumbnailStorageKey: string | null;
  previewStatus: string;
  scanStatus: string;
  tags: string[];
  notes: string | null;
  source: string;
  createdAt: Date;
  archivedAt: Date | null;
};

/**
 * Owner/link visibility for files.read_own (§7). Visible when the user owns or
 * is assigned the file, OR holds files.read_all, OR a readable FileEntityLink
 * exists. v1 link-readability is minimal (the link's mere existence in-tenant);
 * full transitive entity-permission checks are v2.
 */
// Internal: visibility check on an already-loaded file, using the active RLS
// transaction client (no own transaction → safe to call inside withTenantRLS).
async function isFileVisibleWithTx(
  tx: TenantRlsClient,
  file: Pick<FileRow, "id" | "tenantId" | "createdByUserId" | "assignedToUserId">,
  ctx: FileVisibilityContext,
): Promise<boolean> {
  if (hasPermission(ctx, "files.read_all")) {
    return true;
  }
  if (file.createdByUserId === ctx.userId || file.assignedToUserId === ctx.userId) {
    return true;
  }
  const link = await tx.fileEntityLink.findFirst({
    where: { fileId: file.id, tenantId: file.tenantId },
    select: { id: true },
  });
  return Boolean(link);
}

export async function isFileVisible(file: Pick<FileRow, "id" | "tenantId" | "createdByUserId" | "assignedToUserId">, ctx: FileVisibilityContext): Promise<boolean> {
  // Fast paths need no DB; only the link lookup opens a tenant-scoped transaction.
  if (hasPermission(ctx, "files.read_all") || file.createdByUserId === ctx.userId || file.assignedToUserId === ctx.userId) {
    return true;
  }
  return withTenantRLS(file.tenantId, (tx) => isFileVisibleWithTx(tx, file, ctx));
}

// Internal: load + visibility on the active transaction client (no own tx).
async function getVisibleFileOrThrowWithTx(tx: TenantRlsClient, tenantId: string, fileId: string, ctx: FileVisibilityContext): Promise<FileRow> {
  const file = await tx.file.findFirst({ where: { id: fileId, tenantId } });
  if (!file) {
    throw new CatalogError(foundationErrors.notFound, { fileId });
  }
  if (!(await isFileVisibleWithTx(tx, file as FileRow, ctx))) {
    throw new CatalogError(foundationErrors.notFound, { fileId });
  }
  return file as FileRow;
}

/** Load a single file (tenant-scoped) and enforce visibility, else 404. */
export async function getVisibleFileOrThrow(tenantId: string, fileId: string, ctx: FileVisibilityContext): Promise<FileRow> {
  return withTenantRLS(tenantId, (tx) => getVisibleFileOrThrowWithTx(tx, tenantId, fileId, ctx));
}

export type FileLink = { entityType: string; entityId: string; linkRole: string | null };

/** Load a file with its entity links (tenant-scoped + visibility), else 404. */
export async function getVisibleFileWithLinks(
  tenantId: string,
  fileId: string,
  ctx: FileVisibilityContext,
): Promise<{ file: FileRow; links: FileLink[] }> {
  return withTenantRLS(tenantId, async (tx) => {
    const file = await getVisibleFileOrThrowWithTx(tx, tenantId, fileId, ctx);
    const links = await tx.fileEntityLink.findMany({
      where: { fileId, tenantId },
      select: { entityType: true, entityId: true, linkRole: true },
      orderBy: { createdAt: "asc" },
    });
    return { file, links: links as FileLink[] };
  });
}

export type ListFilesFilter = {
  mimeGroup?: string | null;
  tags?: readonly string[];
  assignedToUserId?: string | null;
  includeArchived?: boolean;
};

const MIME_GROUP_PREFIX: Record<string, string> = { image: "image/", pdf: "application/pdf", text: "text/" };

/**
 * List files for the browser (tenant-scoped + read_own visibility), newest
 * first, cursor-paginated. Visibility for non-read_all users: owner/assignee or
 * any linked file (v1 minimal, §7).
 */
export async function listFilesForBrowser(input: {
  tenantId: string;
  ctx: FileVisibilityContext;
  filter?: ListFilesFilter;
  cursor?: string | null;
  limit?: number;
}): Promise<{ rows: FileRow[]; nextCursor: string | null }> {
  const limit = Math.min(Math.max(input.limit ?? 50, 1), 100);
  const filter = input.filter ?? {};
  const visibility = hasPermission(input.ctx, "files.read_all")
    ? {}
    : {
        OR: [
          { createdByUserId: input.ctx.userId },
          { assignedToUserId: input.ctx.userId },
          { links: { some: { tenantId: input.tenantId } } },
        ],
      };
  const mimePrefix = filter.mimeGroup ? MIME_GROUP_PREFIX[filter.mimeGroup] : undefined;
  const where = {
    tenantId: input.tenantId,
    ...(filter.includeArchived ? {} : { archivedAt: null }),
    ...(filter.assignedToUserId ? { assignedToUserId: filter.assignedToUserId } : {}),
    ...(filter.tags && filter.tags.length > 0 ? { tags: { hasEvery: [...filter.tags] } } : {}),
    ...(mimePrefix ? { mimeType: { startsWith: mimePrefix } } : {}),
    ...visibility,
  };
  const rows = await withTenantRLS(input.tenantId, (tx) =>
    tx.file.findMany({
      where,
      orderBy: { createdAt: "desc" },
      take: limit + 1,
      ...(input.cursor ? { cursor: { id: input.cursor }, skip: 1 } : {}),
    }),
  );
  const nextCursor = rows.length > limit ? rows[limit - 1].id : null;
  return { rows: rows.slice(0, limit) as FileRow[], nextCursor };
}

// --- Mutations ------------------------------------------------------------

export async function linkFile(input: {
  tenantId: string;
  userId: string;
  fileId: string;
  entityType: FileEntityType;
  entityId: string;
  linkRole?: string | null;
}): Promise<void> {
  await withTenantRLS(input.tenantId, async (tx) => {
    // Ensure the file belongs to the tenant before linking.
    const file = await tx.file.findFirst({ where: { id: input.fileId, tenantId: input.tenantId }, select: { id: true } });
    if (!file) {
      throw new CatalogError(foundationErrors.notFound, { fileId: input.fileId });
    }
    await tx.fileEntityLink.upsert({
      where: { fileId_entityType_entityId: { fileId: input.fileId, entityType: input.entityType, entityId: input.entityId } },
      update: { linkRole: input.linkRole ?? null },
      create: {
        tenantId: input.tenantId,
        createdByUserId: input.userId,
        fileId: input.fileId,
        entityType: input.entityType,
        entityId: input.entityId,
        linkRole: input.linkRole ?? null,
      },
    });
  });
}

export async function unlinkFile(input: { tenantId: string; fileId: string; entityType: FileEntityType; entityId: string }): Promise<void> {
  await withTenantRLS(input.tenantId, (tx) =>
    tx.fileEntityLink.deleteMany({
      where: { tenantId: input.tenantId, fileId: input.fileId, entityType: input.entityType, entityId: input.entityId },
    }),
  );
}

export async function archiveFile(input: { tenantId: string; fileId: string }): Promise<void> {
  await withTenantRLS(input.tenantId, (tx) =>
    tx.file.updateMany({ where: { id: input.fileId, tenantId: input.tenantId }, data: { archivedAt: new Date() } }),
  );
}

export async function reactivateFile(input: { tenantId: string; fileId: string }): Promise<void> {
  await withTenantRLS(input.tenantId, (tx) =>
    tx.file.updateMany({ where: { id: input.fileId, tenantId: input.tenantId }, data: { archivedAt: null } }),
  );
}

export async function updateFileMeta(input: {
  tenantId: string;
  fileId: string;
  tags?: string[];
  notes?: string | null;
  assignedToUserId?: string | null;
  displayName?: string;
}): Promise<void> {
  await withTenantRLS(input.tenantId, (tx) =>
    tx.file.updateMany({
      where: { id: input.fileId, tenantId: input.tenantId },
      data: {
        ...(input.tags !== undefined ? { tags: input.tags } : {}),
        ...(input.notes !== undefined ? { notes: input.notes } : {}),
        ...(input.assignedToUserId !== undefined ? { assignedToUserId: input.assignedToUserId } : {}),
        ...(input.displayName !== undefined ? { displayName: input.displayName.slice(0, 255) } : {}),
      },
    }),
  );
}

export async function regenerateFilePreview(input: { tenantId: string; fileId: string }): Promise<void> {
  const file = await withTenantRLS(input.tenantId, async (tx) => {
    const row = await tx.file.findFirst({
      where: { id: input.fileId, tenantId: input.tenantId },
      select: { id: true, storageKey: true, mimeType: true, previewStatus: true },
    });
    if (!row) {
      throw new CatalogError(foundationErrors.notFound, { fileId: input.fileId });
    }
    if (row.previewStatus !== "failed") {
      throw new FileServiceError("files.error.previewNotRegenerable");
    }
    await tx.file.update({ where: { id: row.id }, data: { previewStatus: "pending" } });
    return row;
  });
  const bucket = resolveStorageBucket();
  // Enqueue stays OUTSIDE the RLS transaction.
  await enqueueFilePreview({ fileId: file.id, tenantId: input.tenantId, bucket, storageKey: file.storageKey, mimeType: file.mimeType }).catch(() => {});
}

export async function hardDeleteFile(input: { tenantId: string; fileId: string }): Promise<void> {
  const file = await withTenantRLS(input.tenantId, (tx) =>
    tx.file.findFirst({
      where: { id: input.fileId, tenantId: input.tenantId },
      select: { id: true, storageKey: true, previewStorageKey: true, thumbnailStorageKey: true },
    }),
  );
  if (!file) {
    throw new CatalogError(foundationErrors.notFound, { fileId: input.fileId });
  }
  const bucket = resolveStorageBucket();
  // S3 deletes stay OUTSIDE the RLS transaction.
  for (const key of [file.storageKey, file.previewStorageKey, file.thumbnailStorageKey]) {
    if (key) {
      await deleteFile({ bucket, key }).catch(() => {});
    }
  }
  // FileEntityLink rows cascade on File delete (schema onDelete: Cascade).
  await withTenantRLS(input.tenantId, (tx) => tx.file.delete({ where: { id: file.id } }));
}

/** Best-effort cleanup of all temp chunk objects of an upload session. */
export async function purgeUploadChunks(tenantId: string, uploadId: string, chunkKeys: readonly string[]): Promise<void> {
  const bucket = resolveStorageBucket();
  await Promise.all(chunkKeys.map((key) => deleteFile({ bucket, key }).catch(() => {})));
  void uploadChunkPrefix(tenantId, uploadId);
}