import { and, eq, inArray, isNull } from "drizzle-orm";
import type { CircuitDeviceRowSnapshot } from "../../domain/models/circuit-device-row-structure-project-command.model.js";
import type { ExternalModelObjectSnapshot } from "../../external-model/domain/external-model-contracts.js";
import type { CircuitGroupCategory } from "../../shared/constants/circuit-group.js";
import type { AppDatabase } from "../database-context.js";
import { externalModelObjects } from "../schema/external-model-objects.js";
import { externalRoomMappings } from "../schema/external-room-mappings.js";

export interface ExternalObjectLinkTransition {
  expected: ExternalModelObjectSnapshot;
  target: ExternalModelObjectSnapshot;
}

export function loadExpectedExternalObjectTransitions(
  database: AppDatabase,
  projectId: string,
  transitions: ExternalObjectLinkTransition[],
  changedMessage: string
) {
  const byId = new Map(
    transitions.map((transition) => [transition.expected.id, transition])
  );
  const current = database.select().from(externalModelObjects)
    .where(inArray(externalModelObjects.id, [...byId.keys()])).all();
  if (current.length !== byId.size) {
    throw new Error("One or more external objects no longer exist.");
  }
  for (const object of current) {
    if (
      object.projectId !== projectId ||
      !snapshotsEqual(toExternalObjectSnapshot(object), byId.get(object.id)!.expected)
    ) {
      throw new Error(changedMessage);
    }
  }
  return transitions;
}

export function assertExternalObjectsCompatibleWithRow(input: {
  database: AppDatabase;
  projectId: string;
  row: CircuitDeviceRowSnapshot;
  distributionBoardId: string;
  category: CircuitGroupCategory;
  assignedObjects: ExternalModelObjectSnapshot[];
  allLinkedObjects: ExternalModelObjectSnapshot[];
  confirmedConflictObjectIds: ReadonlySet<string>;
}) {
  const mappings = input.database.select().from(externalRoomMappings)
    .where(eq(externalRoomMappings.projectId, input.projectId)).all();
  const roomIdByMappingId = new Map(mappings.map((mapping) => [mapping.id, mapping.roomId]));
  const markers = new Set(
    input.allLinkedObjects.map((object) =>
      object.acceptedSourceValues.selectionMarker.trim()
    )
  );
  if (markers.size > 1) {
    throw new Error("External objects with different selection markers require separate rows.");
  }
  for (const object of input.assignedObjects) {
    if (object.distributionBoardId !== input.distributionBoardId) {
      throw new Error("External object distribution does not match target circuit.");
    }
    if (object.planningValues.category !== input.category) {
      throw new Error("External object category does not match target circuit group.");
    }
    const roomId = object.externalRoomMappingId === null
      ? null
      : roomIdByMappingId.get(object.externalRoomMappingId) ?? null;
    if (roomId !== input.row.roomId) {
      throw new Error("External object room does not match target device row.");
    }
    if (
      !matchesRowPlanningValues(input.row, object) &&
      !input.confirmedConflictObjectIds.has(object.id)
    ) {
      throw new Error("External object planning values require explicit conflict confirmation.");
    }
  }
}

export function applyExternalObjectLinks(
  database: AppDatabase,
  transitions: ExternalObjectLinkTransition[],
  changedMessage: string
) {
  for (const { expected, target } of transitions) {
    const updated = database.update(externalModelObjects)
      .set({ circuitDeviceRowId: target.circuitDeviceRowId })
      .where(and(
        eq(externalModelObjects.id, expected.id),
        expected.circuitDeviceRowId === null
          ? isNull(externalModelObjects.circuitDeviceRowId)
          : eq(externalModelObjects.circuitDeviceRowId, expected.circuitDeviceRowId)
      )).run();
    if (updated.changes !== 1) throw new Error(changedMessage);
  }
}

export function toExternalObjectSnapshot(
  object: typeof externalModelObjects.$inferSelect
): ExternalModelObjectSnapshot {
  return { ...object };
}

export function snapshotsEqual(left: unknown, right: unknown) {
  return canonicalJson(left) === canonicalJson(right);
}

function matchesRowPlanningValues(
  row: CircuitDeviceRowSnapshot,
  object: ExternalModelObjectSnapshot
) {
  const planning = object.planningValues;
  return (
    row.displayName === (planning.displayName ?? row.displayName) &&
    row.linkedProjectDeviceId === object.linkedProjectDeviceId &&
    row.category === planning.category &&
    row.connectionKind === planning.connectionKind &&
    (planning.powerPerUnitW === null || row.powerPerUnit === planning.powerPerUnitW / 1000) &&
    row.simultaneityFactor === planning.simultaneityFactor &&
    row.cosPhi === planning.cosPhi &&
    row.costGroup === planning.costGroup &&
    row.remark === planning.remark
  );
}

function canonicalJson(value: unknown): string {
  if (Array.isArray(value)) return `[${value.map(canonicalJson).join(",")}]`;
  if (value !== null && typeof value === "object") {
    const record = value as Record<string, unknown>;
    return `{${Object.keys(record).sort().map((key) =>
      `${JSON.stringify(key)}:${canonicalJson(record[key])}`
    ).join(",")}}`;
  }
  return JSON.stringify(value);
}