"""Verified post-blind expert comparison with no model or mutation capability."""

from __future__ import annotations

import hashlib
import json
import logging
from collections import Counter, defaultdict
from typing import Protocol

from gcmd_classifier.datasets.comparison_models import (
    ComparisonCategoryCounts,
    ComparisonComponentHashes,
    ComparisonRelationship,
    ComparisonRunStatus,
    DatasetComparisonItem,
    DatasetComparisonResult,
    ExpertOnlyAssignment,
    HierarchyRelationshipKind,
    HumanReviewRecord,
    PersistedComparisonOutcome,
    ProposalType,
)
from gcmd_classifier.datasets.errors import DatasetComparisonError
from gcmd_classifier.datasets.expert_resolution import resolve_expert_assignments
from gcmd_classifier.datasets.models import (
    ComparisonCategory,
    DatasetClassificationOutcome,
    DatasetClassificationResult,
    DatasetReviewStatus,
)
from gcmd_classifier.datasets.runtime_models import (
    ArtifactType,
    ExpertSourceBinding,
    SealedExpertArtifactEnvelope,
    VerifiedPersistedBlindResultReference,
)
from gcmd_classifier.datasets.runtime_persistence import DatasetArtifactStore
from gcmd_classifier.logging_config import get_logger, log_event
from gcmd_classifier.vocabulary.index import VocabularyIndex

COMPARISON_POLICY = "dataset-comparison-policy-v1"
RESOLUTION_POLICY = "expert-resolution-policy-v1"
NORMALIZATION_POLICY = "case-whitespace-normalization-v1"
REVIEW_POLICY = "dataset-initial-review-v1"


class ExpertUnsealer(Protocol):
    def unseal(self, persisted_bytes: bytes) -> SealedExpertArtifactEnvelope:
        """Open typed expert bytes only after prerequisite verification."""


class TypedExpertUnsealer:
    def unseal(self, persisted_bytes: bytes) -> SealedExpertArtifactEnvelope:
        return SealedExpertArtifactEnvelope.model_validate_json(persisted_bytes)


def _json_default(value: object) -> object:
    if hasattr(value, "model_dump"):
        return value.model_dump(mode="json")
    if hasattr(value, "value"):
        return value.value
    raise TypeError(f"Unsupported canonical comparison value: {type(value).__name__}")


def _canonical(value: object) -> bytes:
    return json.dumps(
        value,
        sort_keys=True,
        separators=(",", ":"),
        ensure_ascii=False,
        default=_json_default,
    ).encode()


def _hash(value: object) -> str:
    return hashlib.sha256(_canonical(value)).hexdigest()


def _distance(vocabulary: VocabularyIndex, ancestor: str, descendant: str) -> int:
    ancestors = vocabulary.ancestors_of(descendant)
    return ancestors.index(ancestor) + 1


def _verified_inputs(
    *,
    store: DatasetArtifactStore,
    session_id: str,
    verified: VerifiedPersistedBlindResultReference,
    vocabulary: VocabularyIndex,
    unsealer: ExpertUnsealer,
) -> tuple[DatasetClassificationResult, SealedExpertArtifactEnvelope]:
    if not isinstance(verified, VerifiedPersistedBlindResultReference):
        raise DatasetComparisonError(
            "COMPARISON_PREREQUISITE_INVALID", "A verified blind reference is required."
        )
    run = verified.run
    blind_bytes = store.load_verified(run, session_id, verified.artifact)
    cmr_bytes = store.load_verified(run, session_id, verified.cmr_source_artifact)
    sealed_bytes = store.load_verified(run, session_id, verified.sealed_expert_artifact)
    binding_bytes = store.load_verified(run, session_id, verified.expert_source_binding_artifact)
    try:
        blind = DatasetClassificationResult.model_validate_json(blind_bytes)
        binding = ExpertSourceBinding.model_validate_json(binding_bytes)
    except Exception as exc:
        raise DatasetComparisonError(
            "COMPARISON_PREREQUISITE_INVALID", "Persisted blind or binding schema is invalid."
        ) from exc
    if (
        verified.blind_result_sha256 != verified.artifact.sha256
        or verified.cmr_source_sha256 != verified.cmr_source_artifact.sha256
        or verified.sealed_expert_artifact_sha256 != verified.sealed_expert_artifact.sha256
        or verified.expert_source_binding_sha256 != verified.expert_source_binding_artifact.sha256
        or blind.identity != verified.identity
        or blind.dataset_key != verified.identity.concept_id
        or blind.evidence_packet_sha256 != verified.evidence_packet_sha256
        or blind.processing_status.value != "completed"
        or blind.classification_outcome is None
        or blind.classification_outcome.value != verified.completed_blind_status
        or binding.identity != verified.identity
        or binding.run != verified.run
        or binding.cmr_source_sha256 != verified.cmr_source_sha256
        or binding.sealed_expert_artifact_sha256 != verified.sealed_expert_artifact_sha256
        or binding.sealed_payload_sha256 != verified.sealed_payload_sha256
        or vocabulary.vocabulary_version != verified.vocabulary_hash
    ):
        raise DatasetComparisonError(
            "COMPARISON_PROVENANCE_INVALID",
            "Blind, expert, or hierarchy provenance does not agree.",
        )
    try:
        source = json.loads(cmr_bytes)
        item = source["items"][0]
        exact = (
            item["meta"]["concept-id"],
            item["meta"]["native-id"],
            item["umm"]["ShortName"],
            item["umm"]["Version"],
            item["meta"]["revision-id"],
        )
    except (ValueError, KeyError, IndexError, TypeError) as exc:
        raise DatasetComparisonError(
            "EXPERT_SOURCE_INVALID", "Persisted CMR source is invalid."
        ) from exc
    identity = verified.identity
    if exact != (
        identity.concept_id,
        identity.native_id,
        identity.short_name,
        identity.version,
        identity.cmr_revision_id,
    ):
        raise DatasetComparisonError("EXPERT_SOURCE_IDENTITY_MISMATCH", "CMR identity differs.")
    # Authorization occurs only after every non-expert prerequisite above succeeds.
    try:
        envelope = unsealer.unseal(sealed_bytes)
    except Exception as exc:
        raise DatasetComparisonError(
            "EXPERT_UNSEAL_FAILED", "Sealed expert artifact is invalid."
        ) from exc
    if (
        envelope.identity != identity
        or envelope.cmr_source_sha256 != verified.cmr_source_sha256
        or envelope.sealed_payload_sha256 != verified.sealed_payload_sha256
        or tuple(item["umm"].get("ScienceKeywords", ())) != envelope.sealed_payload.science_keywords
    ):
        raise DatasetComparisonError(
            "EXPERT_SOURCE_BINDING_INVALID", "Unsealed expert source differs."
        )
    return blind, envelope


def _relationships(blind_uuid, experts, vocabulary):
    by_uuid: dict[str, list[int]] = defaultdict(list)
    for item in experts:
        by_uuid[item.UUID].append(item.source_position)
    relationships = []
    for expert_uuid in sorted(by_uuid):
        positions = tuple(by_uuid[expert_uuid])
        if blind_uuid == expert_uuid:
            kind = HierarchyRelationshipKind.EXACT
            distance = 0
            path = vocabulary.get(blind_uuid).path_components
        elif vocabulary.is_descendant(blind_uuid, expert_uuid):
            kind = HierarchyRelationshipKind.BLIND_DESCENDANT
            distance = _distance(vocabulary, expert_uuid, blind_uuid)
            path = vocabulary.get(blind_uuid).path_components
        elif vocabulary.is_descendant(expert_uuid, blind_uuid):
            kind = HierarchyRelationshipKind.EXPERT_DESCENDANT
            distance = _distance(vocabulary, blind_uuid, expert_uuid)
            path = vocabulary.get(expert_uuid).path_components
        else:
            kind = HierarchyRelationshipKind.INDEPENDENT
            distance = None
            path = ()
        relationships.append(
            ComparisonRelationship(
                relationship=kind,
                expert_UUID=expert_uuid,
                expert_source_positions=positions,
                distance=distance,
                authoritative_path=path,
            )
        )
    return tuple(relationships)


def _item(index, blind, experts, unresolved, vocabulary):
    relationships = list(_relationships(blind.UUID, experts, vocabulary))
    if unresolved:
        relationships.extend(
            ComparisonRelationship(
                relationship=HierarchyRelationshipKind.UNRESOLVED,
                expert_source_positions=(item.source_position,),
            )
            for item in unresolved
        )
        category = ComparisonCategory.REVIEW_REQUIRED
        primary = HierarchyRelationshipKind.UNRESOLVED
        proposal = ProposalType.NONE
        review = True
        reasons = tuple(sorted({item.resolution_status.value for item in unresolved}))
        rationale = "Unresolved expert assignments prevent safe deterministic categorization."
    else:
        kinds = {item.relationship for item in relationships}
        if HierarchyRelationshipKind.EXACT in kinds:
            category = ComparisonCategory.ALREADY_ASSIGNED
            primary = HierarchyRelationshipKind.EXACT
            rationale = "Blind terminal UUID exactly matches an existing expert assignment."
        elif HierarchyRelationshipKind.EXPERT_DESCENDANT in kinds:
            category = ComparisonCategory.REDUNDANT_RESULT
            primary = HierarchyRelationshipKind.EXPERT_DESCENDANT
            rationale = "A more specific expert descendant already exists; no change is proposed."
        elif HierarchyRelationshipKind.BLIND_DESCENDANT in kinds:
            category = ComparisonCategory.PROPOSED_REFINEMENT
            primary = HierarchyRelationshipKind.BLIND_DESCENDANT
            rationale = (
                "Blind assignment is a strict descendant of an existing broader expert assignment."
            )
        else:
            category = ComparisonCategory.PROPOSED_ADDITION
            primary = HierarchyRelationshipKind.INDEPENDENT
            rationale = "Blind assignment is independent of every resolved expert assignment."
        proposal = {
            ComparisonCategory.PROPOSED_ADDITION: ProposalType.ADDITION,
            ComparisonCategory.PROPOSED_REFINEMENT: ProposalType.REFINEMENT,
        }.get(category, ProposalType.NONE)
        review = category in {
            ComparisonCategory.PROPOSED_ADDITION,
            ComparisonCategory.PROPOSED_REFINEMENT,
        }
        reasons = (category.value,) if review else ()
    related = tuple(
        sorted({position for item in relationships for position in item.expert_source_positions})
    )
    material = {
        "blind_index": index,
        "blind_uuid": blind.UUID,
        "category": category.value,
        "relationships": [item.model_dump(mode="json") for item in relationships],
    }
    return DatasetComparisonItem(
        comparison_item_id=_hash(material),
        blind_index=index,
        blind_classification=blind,
        category=category.value,
        primary_relationship=primary,
        relationships=tuple(relationships),
        related_expert_source_positions=related,
        proposal_type=proposal,
        rationale=rationale,
        review_required=review,
        review_reason_codes=reasons,
    )


def _comparison_hash_material(result: DatasetComparisonResult) -> dict:
    return result.model_dump(mode="json", exclude={"comparison_sha256", "comparison_artifact"})


def compare_verified_dataset(
    *,
    store: DatasetArtifactStore,
    session_id: str,
    verified: VerifiedPersistedBlindResultReference,
    vocabulary: VocabularyIndex,
    unsealer: ExpertUnsealer | None = None,
    logger: logging.Logger | None = None,
) -> PersistedComparisonOutcome:
    """Resolve, compare, persist, and verify advisory records with zero model calls."""
    blind, envelope = _verified_inputs(
        store=store,
        session_id=session_id,
        verified=verified,
        vocabulary=vocabulary,
        unsealer=unsealer or TypedExpertUnsealer(),
    )
    resolved, unresolved, duplicates = resolve_expert_assignments(
        envelope.sealed_payload.science_keywords, vocabulary
    )
    items = tuple(
        _item(index, item, resolved, unresolved, vocabulary)
        for index, item in enumerate(blind.classifications)
    )
    counts = Counter(item.category for item in items)
    category_counts = ComparisonCategoryCounts(
        **{name: counts[name] for name in ComparisonCategoryCounts.model_fields}
    )
    related_uuids = {
        relationship.expert_UUID
        for item in items
        for relationship in item.relationships
        if relationship.expert_UUID
        and relationship.relationship is not HierarchyRelationshipKind.INDEPENDENT
    }
    positions: dict[str, list[int]] = defaultdict(list)
    paths = {}
    for item in resolved:
        positions[item.UUID].append(item.source_position)
        paths[item.UUID] = item.canonical_path
    expert_only = tuple(
        ExpertOnlyAssignment(
            UUID=uuid, source_positions=tuple(positions[uuid]), canonical_path=paths[uuid]
        )
        for uuid in sorted(positions)
        if uuid not in related_uuids
    )
    policy_identity = {
        "comparison": COMPARISON_POLICY,
        "resolution": RESOLUTION_POLICY,
        "normalization": NORMALIZATION_POLICY,
        "review": REVIEW_POLICY,
        "schema": "dataset-comparison-v2",
        "vocabulary": vocabulary.vocabulary_version,
    }
    component_hashes = ComparisonComponentHashes(
        blind_input_sha256=verified.blind_result_sha256,
        expert_input_sha256=verified.sealed_payload_sha256,
        resolved_experts_sha256=_hash(
            {"resolved": resolved, "unresolved": unresolved, "duplicates": duplicates}
        ),
        comparison_items_sha256=_hash(items),
        policy_identity_sha256=_hash(policy_identity),
    )
    comparison_id = _hash(
        {
            "blind": verified.blind_result_sha256,
            "expert": verified.sealed_payload_sha256,
            "vocabulary": vocabulary.vocabulary_version,
            **policy_identity,
        }
    )
    review_reasons = tuple(
        sorted(
            {reason for item in items for reason in item.review_reason_codes}
            | {item.resolution_status.value for item in unresolved}
        )
    )
    draft = DatasetComparisonResult(
        comparison_id=comparison_id,
        comparison_sha256="0" * 64,
        comparison_policy_version=COMPARISON_POLICY,
        expert_resolution_policy_version=RESOLUTION_POLICY,
        normalization_policy_version=NORMALIZATION_POLICY,
        review_policy_version=REVIEW_POLICY,
        run_id=verified.run.run_id,
        identity=verified.identity,
        verified_blind_result=verified,
        blind_result_sha256=verified.blind_result_sha256,
        evidence_packet_sha256=verified.evidence_packet_sha256,
        expert_source_artifact=verified.cmr_source_artifact,
        expert_source_sha256=verified.cmr_source_sha256,
        sealed_expert_artifact=verified.sealed_expert_artifact,
        sealed_payload_sha256=verified.sealed_payload_sha256,
        vocabulary_hash=vocabulary.vocabulary_version,
        comparison_status=(
            ComparisonRunStatus.BLIND_NOT_CLASSIFIED
            if blind.classification_outcome is DatasetClassificationOutcome.NOT_CLASSIFIED
            else ComparisonRunStatus.BLIND_CLASSIFIED
        ),
        resolved_expert_assignments=resolved,
        unresolved_expert_assignments=unresolved,
        expert_duplicate_groups=duplicates,
        comparison_items=items,
        expert_only_assignments=expert_only,
        category_counts=category_counts,
        review_status=(
            DatasetReviewStatus.PENDING if review_reasons else DatasetReviewStatus.NOT_REQUIRED
        ),
        review_required_reasons=review_reasons,
        component_hashes=component_hashes,
    )
    comparison = draft.model_copy(
        update={"comparison_sha256": _hash(_comparison_hash_material(draft))}
    )
    reference = store.persist_json(
        run=verified.run,
        session_id=session_id,
        relative_name="comparison.json",
        value=comparison,
        artifact_type=ArtifactType.COMPARISON,
        schema_name="dataset-comparison-v2",
        upstream_sha256=(verified.blind_result_sha256, verified.sealed_payload_sha256),
        validate=lambda data: DatasetComparisonResult.model_validate_json(data),
    )
    persisted = DatasetComparisonResult.model_validate_json(
        store.load_verified(verified.run, session_id, reference)
    )
    if persisted.comparison_sha256 != _hash(_comparison_hash_material(persisted)):
        raise DatasetComparisonError(
            "COMPARISON_HASH_INVALID", "Persisted comparison hash is invalid."
        )
    item_review_records = tuple(
        HumanReviewRecord(
            review_record_id=_hash(
                {"comparison": comparison.comparison_sha256, "item": item.comparison_item_id}
            ),
            comparison_sha256=comparison.comparison_sha256,
            comparison_item_id=item.comparison_item_id,
            identity=comparison.identity,
            blind_classification=item.blind_classification,
            related_expert_source_positions=item.related_expert_source_positions,
            comparison_category=item.category,
            proposal_type=item.proposal_type,
            relationships=item.relationships,
            review_reason_codes=item.review_reason_codes,
            comparison_policy_version=COMPARISON_POLICY,
            review_policy_version=REVIEW_POLICY,
            blind_result_sha256=verified.blind_result_sha256,
            sealed_payload_sha256=verified.sealed_payload_sha256,
        )
        for item in items
        if item.review_required
    )
    unresolved_review_records = tuple(
        HumanReviewRecord(
            review_record_id=_hash(
                {
                    "comparison": comparison.comparison_sha256,
                    "unresolved_source_position": item.source_position,
                }
            ),
            comparison_sha256=comparison.comparison_sha256,
            comparison_item_id=_hash({"unresolved_source_position": item.source_position}),
            identity=comparison.identity,
            related_expert_source_positions=(item.source_position,),
            comparison_category=ComparisonCategory.REVIEW_REQUIRED,
            proposal_type=ProposalType.NONE,
            relationships=(
                ComparisonRelationship(
                    relationship=HierarchyRelationshipKind.UNRESOLVED,
                    expert_source_positions=(item.source_position,),
                ),
            ),
            review_reason_codes=(item.resolution_status.value,),
            comparison_policy_version=COMPARISON_POLICY,
            review_policy_version=REVIEW_POLICY,
            blind_result_sha256=verified.blind_result_sha256,
            sealed_payload_sha256=verified.sealed_payload_sha256,
        )
        for item in unresolved
    )
    review_records = (*item_review_records, *unresolved_review_records)
    review_refs = tuple(
        store.persist_json(
            run=verified.run,
            session_id=session_id,
            relative_name=f"reviews/{record.review_record_id}.json",
            value=record,
            artifact_type=ArtifactType.HUMAN_REVIEW,
            schema_name="dataset-human-review-v1",
            upstream_sha256=(comparison.comparison_sha256,),
            validate=lambda data: HumanReviewRecord.model_validate_json(data),
        )
        for record in review_records
    )
    log_event(
        logger or get_logger("gcmd_classifier.datasets.comparison"),
        "dataset_comparison_completed",
        run_id=verified.run.run_id,
        concept_id=verified.identity.concept_id,
        blind_result_sha256=verified.blind_result_sha256,
        expert_source_sha256=verified.cmr_source_sha256,
        hierarchy_hash=vocabulary.vocabulary_version,
        comparison_sha256=comparison.comparison_sha256,
        resolved_count=len(resolved),
        unresolved_count=len(unresolved),
        duplicate_group_count=len(duplicates),
        category_counts=category_counts.model_dump(),
        review_record_count=len(review_records),
        comparison_reference=reference.relative_path,
    )
    return PersistedComparisonOutcome(
        comparison=comparison,
        comparison_artifact=reference,
        review_records=review_records,
        review_artifacts=review_refs,
    )