"""Backend-specific ref type mapping for Memory Gateway v2."""
from __future__ import annotations

from .schemas_v2 import BackendType, MemoryRefType


OPENVIKING_REF_TYPE_MAP = {
    "session_archive": MemoryRefType.SESSION_ARCHIVE,
    "context_resource": MemoryRefType.CONTEXT_RESOURCE,
    "resource": MemoryRefType.CONTEXT_RESOURCE,
    "session_summary": MemoryRefType.SESSION_ARCHIVE,
}

EVERMEMOS_REF_TYPE_MAP = {
    "message_memory": MemoryRefType.MESSAGE_MEMORY,
    "episodic_memory": MemoryRefType.EPISODIC_MEMORY,
    "episode": MemoryRefType.EPISODIC_MEMORY,
    "profile": MemoryRefType.PROFILE,
    "long_term_memory": MemoryRefType.LONG_TERM_MEMORY,
    "memory": MemoryRefType.LONG_TERM_MEMORY,
    "preference": MemoryRefType.PROFILE,
}

OBSIDIAN_REF_TYPE_MAP = {
    "review_draft": MemoryRefType.DRAFT_REVIEW,
    "draft_review": MemoryRefType.DRAFT_REVIEW,
}


def map_backend_ref_type(
    backend_type: BackendType,
    backend_ref_type: str | None,
) -> tuple[MemoryRefType, dict[str, str]]:
    """Map backend-native ref type to a Gateway MemoryRefType.

    Unknown values fall back to a backend-appropriate default and preserve the
    original value in returned metadata for later inspection.
    """
    raw_type = (backend_ref_type or "").strip()
    normalized = raw_type.lower()

    if backend_type == BackendType.OPENVIKING:
        mapped = OPENVIKING_REF_TYPE_MAP.get(normalized, MemoryRefType.SESSION_ARCHIVE)
    elif backend_type == BackendType.EVERMEMOS:
        mapped = EVERMEMOS_REF_TYPE_MAP.get(normalized, MemoryRefType.LONG_TERM_MEMORY)
    elif backend_type == BackendType.OBSIDIAN:
        mapped = OBSIDIAN_REF_TYPE_MAP.get(normalized, MemoryRefType.DRAFT_REVIEW)
    else:
        mapped = MemoryRefType.LONG_TERM_MEMORY

    metadata: dict[str, str] = {}
    if raw_type and raw_type not in {mapped.value, normalized}:
        metadata["original_ref_type"] = raw_type
    elif raw_type and normalized not in _known_backend_ref_types(backend_type):
        metadata["original_ref_type"] = raw_type
    return mapped, metadata


def _known_backend_ref_types(backend_type: BackendType) -> set[str]:
    if backend_type == BackendType.OPENVIKING:
        return set(OPENVIKING_REF_TYPE_MAP)
    if backend_type == BackendType.EVERMEMOS:
        return set(EVERMEMOS_REF_TYPE_MAP)
    if backend_type == BackendType.OBSIDIAN:
        return set(OBSIDIAN_REF_TYPE_MAP)
    return set()