from __future__ import annotations

from collections import defaultdict
from collections.abc import Mapping, Sequence
from urllib.parse import quote

from sqlalchemy import func
from sqlalchemy.orm import Session

from govoplan_core.core.modules import ModuleContext
from govoplan_core.core.search import (
    SearchAuthorizationRequest,
    SearchBackfillPage,
    SearchBackfillRequest,
    SearchDocument,
    SearchResourceType,
)
from govoplan_reporting.backend.db.models import (
    ReportingDefinitionGrant,
    ReportingDefinitionIdentity,
    ReportingDefinitionRevision,
)
from govoplan_reporting.backend.definitions import can_read_definition


PROVIDER_ID = "reporting.reports"
RESOURCE_TYPE = "report"


class ReportingSearchSource:
    def resource_types(self) -> Sequence[SearchResourceType]:
        return (
            SearchResourceType(
                provider_id=PROVIDER_ID,
                module_id="reporting",
                resource_type=RESOURCE_TYPE,
                label="Reports",
                requires_authorization_recheck=True,
            ),
        )

    def backfill(
        self,
        session: object,
        *,
        request: SearchBackfillRequest,
    ) -> SearchBackfillPage:
        if request.provider_id != PROVIDER_ID or request.resource_type != RESOURCE_TYPE:
            raise ValueError("Unsupported Reporting search source.")
        db = _session(session)
        query = db.query(ReportingDefinitionRevision).filter(
            ReportingDefinitionRevision.tenant_id == request.tenant_id,
            ReportingDefinitionRevision.definition_kind == "report",
            ReportingDefinitionRevision.status != "retired",
            ReportingDefinitionRevision.superseded_at.is_(None),
        )
        if request.cursor:
            query = query.filter(ReportingDefinitionRevision.id > request.cursor)
        rows = (
            query.order_by(ReportingDefinitionRevision.id.asc())
            .limit(request.limit + 1)
            .all()
        )
        has_more = len(rows) > request.limit
        selected = rows[: request.limit]
        tokens = _acl_tokens(db, selected)
        high_watermark = (
            db.query(func.max(ReportingDefinitionRevision.updated_at))
            .filter(
                ReportingDefinitionRevision.tenant_id == request.tenant_id,
                ReportingDefinitionRevision.definition_kind == "report",
                ReportingDefinitionRevision.superseded_at.is_(None),
            )
            .scalar()
        )
        return SearchBackfillPage(
            documents=tuple(
                _document(row, tokens[row.definition_id]) for row in selected
            ),
            next_cursor=selected[-1].id if has_more and selected else None,
            complete=not has_more,
            high_watermark=(
                high_watermark.isoformat() if high_watermark is not None else None
            ),
        )

    def authorize(
        self,
        session: object,
        principal: object,
        *,
        requests: Sequence[SearchAuthorizationRequest],
    ) -> Mapping[str, bool]:
        db = _session(session)
        tenant_id = str(getattr(principal, "tenant_id", "") or "")
        decisions = {request.reference.key: False for request in requests}
        for request in requests:
            reference = request.reference
            if (
                reference.tenant_id != tenant_id
                or reference.module_id != "reporting"
                or reference.resource_type != RESOURCE_TYPE
            ):
                continue
            decisions[reference.key] = can_read_definition(
                db,
                principal,
                definition_kind="report",
                definition_id=reference.resource_id,
            )
        return decisions


def create_reporting_search_source(
    context: ModuleContext,
) -> ReportingSearchSource:
    del context
    return ReportingSearchSource()


def _document(
    row: ReportingDefinitionRevision,
    tokens: tuple[str, ...],
) -> SearchDocument:
    restricted_tokens = tuple(
        dict.fromkeys((*tokens, "scope:reporting:definition:admin"))
    )
    return SearchDocument(
        tenant_id=row.tenant_id,
        module_id="reporting",
        provider_id=PROVIDER_ID,
        resource_type=RESOURCE_TYPE,
        resource_id=row.definition_id,
        title=row.name,
        url=f"/reporting?reportId={quote(row.definition_id, safe='')}",
        summary=row.description,
        body=row.description,
        keywords=(row.definition_key, row.status),
        visibility=row.visibility,
        acl_tokens=restricted_tokens if row.visibility == "restricted" else (),
        source_revision=str(row.revision),
        source_updated_at=row.updated_at or row.recorded_at,
        metadata={
            "definition_key": row.definition_key,
            "status": row.status,
            "content_hash": row.content_hash,
        },
        requires_authorization_recheck=True,
    )


def _acl_tokens(
    session: Session,
    rows: Sequence[ReportingDefinitionRevision],
) -> Mapping[str, tuple[str, ...]]:
    result: dict[str, list[str]] = defaultdict(list)
    if not rows:
        return result
    identity_ids = {row.identity_id for row in rows}
    for identity in (
        session.query(ReportingDefinitionIdentity)
        .filter(ReportingDefinitionIdentity.id.in_(identity_ids))
        .all()
    ):
        if identity.created_by:
            result[identity.definition_id].append(f"account:{identity.created_by}")
    definition_ids = {row.definition_id for row in rows}
    grants = (
        session.query(ReportingDefinitionGrant)
        .filter(
            ReportingDefinitionGrant.tenant_id == rows[0].tenant_id,
            ReportingDefinitionGrant.definition_kind == "report",
            ReportingDefinitionGrant.definition_id.in_(definition_ids),
            ReportingDefinitionGrant.active.is_(True),
        )
        .all()
    )
    for grant in grants:
        prefix = (
            "function"
            if grant.subject_kind == "function_assignment"
            else grant.subject_kind
        )
        result[grant.definition_id].append(f"{prefix}:{grant.subject_id}")
    return {
        definition_id: tuple(dict.fromkeys(values))
        for definition_id, values in result.items()
    }


def _session(value: object) -> Session:
    if not isinstance(value, Session):
        raise TypeError("Reporting search requires a SQLAlchemy session.")
    return value


__all__ = [
    "PROVIDER_ID",
    "RESOURCE_TYPE",
    "ReportingSearchSource",
    "create_reporting_search_source",
]