"""Validation and bounded loading for KnowledgeFS query-image UploadFile references."""

from __future__ import annotations

import base64
import hashlib
import hmac
import json
import time
from collections.abc import Mapping, Sequence
from dataclasses import dataclass, field
from typing import Literal, Protocol

from configs import dify_config
from core.app.file_access import DatabaseFileAccessController
from core.db.session_factory import session_factory
from core.workflow.file_reference import parse_file_reference
from extensions.ext_storage import storage
from graphon.file import File, FileTransferMethod, FileType
from graphon.file import helpers as file_helpers
from libs.datetime_utils import naive_utc_now
from models import ToolFile
from models.enums import CreatorUserRole
from models.model import UploadFile
from services.file_service import FileService

QUERY_IMAGE_MAX_COUNT = 4
QUERY_IMAGE_MAX_BYTES = 10 * 1024 * 1024
QUERY_IMAGE_MAX_TOTAL_BYTES = 32 * 1024 * 1024
QUERY_IMAGE_MIME_TYPES = frozenset({"image/gif", "image/jpeg", "image/png", "image/webp"})
WORKFLOW_QUERY_IMAGE_GRANT_TTL_SECONDS = 5 * 60
_WORKFLOW_QUERY_IMAGE_GRANT_DOMAIN = b"knowledge-fs-workflow-query-image-v1"
_WORKFLOW_QUERY_IMAGE_GRANT_VERSION = 1


class KnowledgeFSQueryImageError(ValueError):
    """A safe validation error raised before query model or retrieval work starts."""

    def __init__(self, code: str, message: str) -> None:
        super().__init__(message)
        self.code = code


@dataclass(frozen=True)
class KnowledgeFSQueryImageMetadata:
    upload_file_id: str
    byte_size: int
    mime_type: str


@dataclass(frozen=True)
class KnowledgeFSResolvedQueryImage(KnowledgeFSQueryImageMetadata):
    body: bytes
    sha256: str


@dataclass(frozen=True)
class KnowledgeFSQueryImagePreview:
    """Display metadata and a short-lived signed URL for one persisted query-image reference."""

    upload_file_id: str
    name: str
    mime_type: str | None
    byte_size: int
    preview_url: str


class KnowledgeFSQueryImagePreviewPort(Protocol):
    def __call__(
        self, *, tenant_id: str, account_id: str, upload_file_ids: Sequence[str]
    ) -> Mapping[str, KnowledgeFSQueryImagePreview]: ...


@dataclass(frozen=True)
class KnowledgeFSWorkflowQueryImageReference:
    """One workflow-authorized Dify file reference safe to forward through KnowledgeFS."""

    upload_file_id: str
    access_grant: str = field(repr=False)
    byte_size: int
    mime_type: str


@dataclass(frozen=True)
class _QueryImageStorageRecord:
    key: str
    mime_type: str
    size: int


@dataclass(frozen=True)
class _WorkflowQueryImageGrant:
    expires_at: int
    file_id: str
    file_kind: Literal["tool_file", "upload_file"]
    subject_id: str
    tenant_id: str


def validate_query_image_references(
    *,
    tenant_id: str,
    account_id: str,
    upload_file_ids: Sequence[str],
    mark_used: bool,
) -> list[KnowledgeFSQueryImageMetadata]:
    """Validate tenant/actor ownership and static bounds in one database round trip."""

    normalized_ids = _validate_reference_ids(upload_file_ids)
    if not normalized_ids:
        return []

    with session_factory.create_session() as session:
        files_by_id = FileService.get_upload_files_by_ids(tenant_id, normalized_ids, session=session)
        result: list[KnowledgeFSQueryImageMetadata] = []
        total_bytes = 0
        for upload_file_id in normalized_ids:
            upload_file = files_by_id.get(upload_file_id)
            if upload_file is None:
                raise KnowledgeFSQueryImageError("QUERY_IMAGE_NOT_FOUND", "Query image was not found")
            _assert_actor_owned(upload_file, account_id=account_id)
            mime_type = _validate_metadata(upload_file)
            total_bytes += upload_file.size
            result.append(
                KnowledgeFSQueryImageMetadata(
                    upload_file_id=upload_file_id,
                    byte_size=upload_file.size,
                    mime_type=mime_type,
                )
            )
            if mark_used:
                upload_file.used = True
                upload_file.used_by = account_id
                upload_file.used_at = naive_utc_now()

        if total_bytes > QUERY_IMAGE_MAX_TOTAL_BYTES:
            raise KnowledgeFSQueryImageError(
                "QUERY_IMAGE_TOTAL_TOO_LARGE",
                f"Query images exceed aggregate max bytes {QUERY_IMAGE_MAX_TOTAL_BYTES}",
            )
        if mark_used:
            session.commit()
        return result


def load_query_image_previews(
    *,
    tenant_id: str,
    account_id: str,
    upload_file_ids: Sequence[str],
) -> dict[str, KnowledgeFSQueryImagePreview]:
    """Resolve preview URLs for the query images a persisted run was asked with.

    Only files the acting account still owns are returned, mirroring the write-side ownership
    rule; a reference whose file was deleted since is simply absent so history can render a
    placeholder instead of failing.
    """

    unique_ids = list(dict.fromkeys(str(value).strip() for value in upload_file_ids if str(value).strip()))
    if not unique_ids:
        return {}

    with session_factory.create_session() as session:
        files_by_id = FileService.get_upload_files_by_ids(tenant_id, unique_ids, session=session)
        previews: dict[str, KnowledgeFSQueryImagePreview] = {}
        for upload_file_id in unique_ids:
            upload_file = files_by_id.get(upload_file_id)
            if (
                upload_file is None
                or upload_file.created_by_role != CreatorUserRole.ACCOUNT
                or upload_file.created_by != account_id
            ):
                continue
            previews[upload_file_id] = KnowledgeFSQueryImagePreview(
                upload_file_id=upload_file_id,
                name=upload_file.name,
                mime_type=upload_file.mime_type,
                byte_size=upload_file.size,
                preview_url=file_helpers.get_signed_file_url(upload_file_id=upload_file_id),
            )
        return previews


def issue_workflow_query_image_reference(
    *,
    app_id: str,
    file: File,
    tenant_id: str,
    now: int | None = None,
) -> KnowledgeFSWorkflowQueryImageReference:
    """Authorize one graph file before an app-scoped KnowledgeFS request.

    The current workflow file-access scope remains authoritative.  The short-lived grant lets the
    inner storage endpoint prove that this exact file was selected by an authorized workflow run;
    KnowledgeFS never receives Dify storage keys or a tenant-wide file capability.
    """

    normalized_app_id = app_id.strip()
    normalized_tenant_id = tenant_id.strip()
    if not normalized_app_id or not normalized_tenant_id:
        raise KnowledgeFSQueryImageError("QUERY_IMAGE_CONTEXT_INVALID", "Workflow query image context is invalid")
    if file.type is not FileType.IMAGE:
        raise KnowledgeFSQueryImageError("QUERY_IMAGE_MIME_UNSUPPORTED", "Workflow query file must be an image")
    reference = parse_file_reference(file.reference)
    if reference is None:
        raise KnowledgeFSQueryImageError(
            "QUERY_IMAGE_REFERENCE_UNSUPPORTED",
            "Workflow query image must be backed by Dify-managed storage",
        )

    controller = DatabaseFileAccessController()
    file_kind: Literal["tool_file", "upload_file"]
    with session_factory.create_session() as session:
        if file.transfer_method is FileTransferMethod.TOOL_FILE:
            tool_file = controller.get_tool_file(session=session, file_id=reference.record_id)
            file_kind = "tool_file"
            if tool_file is None or tool_file.tenant_id != normalized_tenant_id:
                raise KnowledgeFSQueryImageError("QUERY_IMAGE_NOT_FOUND", "Query image was not found")
            mime_type = _validate_image_metadata(mime_type=tool_file.mimetype, size=tool_file.size)
            byte_size = tool_file.size
        elif file.transfer_method in {
            FileTransferMethod.LOCAL_FILE,
            FileTransferMethod.DATASOURCE_FILE,
            FileTransferMethod.REMOTE_URL,
        }:
            upload_file = controller.get_upload_file(session=session, file_id=reference.record_id)
            file_kind = "upload_file"
            if upload_file is None or upload_file.tenant_id != normalized_tenant_id:
                raise KnowledgeFSQueryImageError("QUERY_IMAGE_NOT_FOUND", "Query image was not found")
            mime_type = _validate_image_metadata(mime_type=upload_file.mime_type, size=upload_file.size)
            byte_size = upload_file.size
        else:  # pragma: no cover - FileTransferMethod is exhaustive, retained for forward compatibility.
            raise KnowledgeFSQueryImageError(
                "QUERY_IMAGE_REFERENCE_UNSUPPORTED",
                "Workflow query image transfer method is not supported",
            )

    issued_at = int(time.time()) if now is None else now
    grant = _WorkflowQueryImageGrant(
        expires_at=issued_at + WORKFLOW_QUERY_IMAGE_GRANT_TTL_SECONDS,
        file_id=reference.record_id,
        file_kind=file_kind,
        subject_id=f"dify-app:{normalized_app_id}",
        tenant_id=normalized_tenant_id,
    )
    return KnowledgeFSWorkflowQueryImageReference(
        access_grant=_encode_workflow_query_image_grant(grant),
        # The existing wire name remains uploadFileId for compatibility.  The signed grant carries
        # the authoritative backing kind, so tool files cannot be confused with UploadFile rows.
        upload_file_id=reference.record_id,
        byte_size=byte_size,
        mime_type=mime_type,
    )


def load_query_image(
    *,
    tenant_id: str,
    upload_file_id: str,
    account_id: str | None = None,
    access_grant: str | None = None,
    subject_id: str | None = None,
) -> KnowledgeFSResolvedQueryImage:
    """Load and sniff one actor-owned or workflow-granted image from configured storage."""

    normalized_ids = _validate_reference_ids([upload_file_id])
    if access_grant:
        grant = _decode_workflow_query_image_grant(
            access_grant,
            expected_file_id=upload_file_id,
            expected_subject_id=subject_id,
            expected_tenant_id=tenant_id,
        )
        record = _load_granted_query_image_record(grant)
    else:
        if not account_id:
            raise KnowledgeFSQueryImageError("QUERY_IMAGE_SUBJECT_INVALID", "Query image subject is invalid")
        with session_factory.create_session() as session:
            upload_file = FileService.get_upload_files_by_ids(tenant_id, normalized_ids, session=session).get(
                upload_file_id
            )
            if upload_file is None:
                raise KnowledgeFSQueryImageError("QUERY_IMAGE_NOT_FOUND", "Query image was not found")
            _assert_actor_owned(upload_file, account_id=account_id)
            record = _QueryImageStorageRecord(
                key=upload_file.key,
                mime_type=_validate_metadata(upload_file),
                size=upload_file.size,
            )

    body = _load_bounded_body(object_key=record.key, expected_size=record.size)
    if not body:
        raise KnowledgeFSQueryImageError("QUERY_IMAGE_EMPTY", "Query image is empty")
    detected_mime_type = _detect_image_mime_type(body)
    if detected_mime_type != record.mime_type:
        raise KnowledgeFSQueryImageError(
            "QUERY_IMAGE_MIME_MISMATCH", "Query image content does not match its MIME type"
        )

    return KnowledgeFSResolvedQueryImage(
        upload_file_id=upload_file_id,
        byte_size=len(body),
        mime_type=detected_mime_type,
        body=body,
        sha256=hashlib.sha256(body).hexdigest(),
    )


def _load_bounded_body(*, object_key: str, expected_size: int) -> bytes:
    chunks: list[bytes] = []
    total_bytes = 0
    stream = storage.load(object_key, stream=True)
    try:
        for chunk in stream:
            if not isinstance(chunk, (bytes, bytearray, memoryview)):
                raise KnowledgeFSQueryImageError("QUERY_IMAGE_SIZE_INVALID", "Query image stream is invalid")
            body_chunk = bytes(chunk)
            total_bytes += len(body_chunk)
            if total_bytes > QUERY_IMAGE_MAX_BYTES or total_bytes > expected_size:
                raise KnowledgeFSQueryImageError(
                    "QUERY_IMAGE_SIZE_INVALID", "Query image size does not match its metadata"
                )
            chunks.append(body_chunk)
    finally:
        close = getattr(stream, "close", None)
        if callable(close):
            close()

    if total_bytes != expected_size:
        raise KnowledgeFSQueryImageError("QUERY_IMAGE_SIZE_INVALID", "Query image size does not match its metadata")
    return b"".join(chunks)


def _validate_reference_ids(upload_file_ids: Sequence[str]) -> list[str]:
    normalized = [str(value).strip() for value in upload_file_ids]
    if len(normalized) > QUERY_IMAGE_MAX_COUNT:
        raise KnowledgeFSQueryImageError(
            "QUERY_IMAGE_COUNT_EXCEEDED", f"queryImages exceeds max count {QUERY_IMAGE_MAX_COUNT}"
        )
    if any(not value for value in normalized):
        raise KnowledgeFSQueryImageError("QUERY_IMAGE_REFERENCE_INVALID", "Query image reference is invalid")
    if len(set(normalized)) != len(normalized):
        raise KnowledgeFSQueryImageError(
            "QUERY_IMAGE_REFERENCE_DUPLICATE", "queryImages must not contain duplicate uploadFileId values"
        )
    return normalized


def _assert_actor_owned(upload_file: UploadFile, *, account_id: str) -> None:
    if upload_file.created_by_role != CreatorUserRole.ACCOUNT or upload_file.created_by != account_id:
        # Deliberately use the same not-found result as an unknown id to avoid disclosing foreign files.
        raise KnowledgeFSQueryImageError("QUERY_IMAGE_NOT_FOUND", "Query image was not found")


def _validate_metadata(upload_file: UploadFile) -> str:
    return _validate_image_metadata(mime_type=upload_file.mime_type, size=upload_file.size)


def _validate_image_metadata(*, mime_type: str | None, size: int) -> str:
    mime_type = (mime_type or "").split(";", 1)[0].strip().lower()
    if mime_type not in QUERY_IMAGE_MIME_TYPES:
        raise KnowledgeFSQueryImageError("QUERY_IMAGE_MIME_UNSUPPORTED", "Query image MIME type is not supported")
    if size < 1:
        raise KnowledgeFSQueryImageError("QUERY_IMAGE_EMPTY", "Query image is empty")
    if size > QUERY_IMAGE_MAX_BYTES:
        raise KnowledgeFSQueryImageError(
            "QUERY_IMAGE_TOO_LARGE", f"Query image exceeds max bytes {QUERY_IMAGE_MAX_BYTES}"
        )
    return mime_type


def _load_granted_query_image_record(grant: _WorkflowQueryImageGrant) -> _QueryImageStorageRecord:
    with session_factory.create_session() as session:
        if grant.file_kind == "tool_file":
            tool_file = session.get(ToolFile, grant.file_id)
            if tool_file is None or tool_file.tenant_id != grant.tenant_id:
                raise KnowledgeFSQueryImageError("QUERY_IMAGE_NOT_FOUND", "Query image was not found")
            return _QueryImageStorageRecord(
                key=tool_file.file_key,
                mime_type=_validate_image_metadata(mime_type=tool_file.mimetype, size=tool_file.size),
                size=tool_file.size,
            )
        upload_file = FileService.get_upload_files_by_ids(
            grant.tenant_id,
            [grant.file_id],
            session=session,
        ).get(grant.file_id)
        if upload_file is None:
            raise KnowledgeFSQueryImageError("QUERY_IMAGE_NOT_FOUND", "Query image was not found")
        return _QueryImageStorageRecord(
            key=upload_file.key,
            mime_type=_validate_metadata(upload_file),
            size=upload_file.size,
        )


def _encode_workflow_query_image_grant(grant: _WorkflowQueryImageGrant) -> str:
    payload = json.dumps(
        {
            "exp": grant.expires_at,
            "fileId": grant.file_id,
            "fileKind": grant.file_kind,
            "subjectId": grant.subject_id,
            "tenantId": grant.tenant_id,
            "v": _WORKFLOW_QUERY_IMAGE_GRANT_VERSION,
        },
        separators=(",", ":"),
        sort_keys=True,
    ).encode()
    encoded_payload = _base64url_encode(payload)
    signature = hmac.new(
        dify_config.SECRET_KEY.encode(),
        _WORKFLOW_QUERY_IMAGE_GRANT_DOMAIN + b"." + encoded_payload.encode(),
        hashlib.sha256,
    ).digest()
    return f"{encoded_payload}.{_base64url_encode(signature)}"


def _decode_workflow_query_image_grant(
    value: str,
    *,
    expected_file_id: str,
    expected_subject_id: str | None,
    expected_tenant_id: str,
) -> _WorkflowQueryImageGrant:
    if not expected_subject_id or len(value) > 2_048:
        raise KnowledgeFSQueryImageError("QUERY_IMAGE_GRANT_INVALID", "Workflow query image grant is invalid")
    try:
        encoded_payload, encoded_signature = value.split(".", 1)
        payload = _base64url_decode(encoded_payload)
        signature = _base64url_decode(encoded_signature)
        expected_signature = hmac.new(
            dify_config.SECRET_KEY.encode(),
            _WORKFLOW_QUERY_IMAGE_GRANT_DOMAIN + b"." + encoded_payload.encode(),
            hashlib.sha256,
        ).digest()
        if not hmac.compare_digest(signature, expected_signature):
            raise ValueError("signature mismatch")
        raw = json.loads(payload)
        if not isinstance(raw, dict):
            raise ValueError("payload must be an object")
        grant = _WorkflowQueryImageGrant(
            expires_at=int(raw["exp"]),
            file_id=str(raw["fileId"]),
            file_kind=raw["fileKind"],
            subject_id=str(raw["subjectId"]),
            tenant_id=str(raw["tenantId"]),
        )
        if raw.get("v") != _WORKFLOW_QUERY_IMAGE_GRANT_VERSION or grant.file_kind not in {
            "tool_file",
            "upload_file",
        }:
            raise ValueError("unsupported grant")
    except (KeyError, TypeError, ValueError, json.JSONDecodeError) as exc:
        raise KnowledgeFSQueryImageError("QUERY_IMAGE_GRANT_INVALID", "Workflow query image grant is invalid") from exc
    if grant.expires_at <= int(time.time()):
        raise KnowledgeFSQueryImageError("QUERY_IMAGE_GRANT_EXPIRED", "Workflow query image grant has expired")
    if (
        grant.file_id != expected_file_id
        or grant.subject_id != expected_subject_id
        or grant.tenant_id != expected_tenant_id
    ):
        raise KnowledgeFSQueryImageError("QUERY_IMAGE_GRANT_INVALID", "Workflow query image grant is invalid")
    return grant


def _base64url_encode(value: bytes) -> str:
    return base64.urlsafe_b64encode(value).rstrip(b"=").decode()


def _base64url_decode(value: str) -> bytes:
    return base64.urlsafe_b64decode(value + "=" * (-len(value) % 4))


def _detect_image_mime_type(body: bytes) -> str:
    if body.startswith(b"\x89PNG\r\n\x1a\n"):
        return "image/png"
    if body.startswith(b"\xff\xd8\xff"):
        return "image/jpeg"
    if body.startswith((b"GIF87a", b"GIF89a")):
        return "image/gif"
    if len(body) >= 12 and body.startswith(b"RIFF") and body[8:12] == b"WEBP":
        return "image/webp"
    raise KnowledgeFSQueryImageError("QUERY_IMAGE_CONTENT_UNSUPPORTED", "Query image content is not supported")