import { CircuitDeviceRowRepository } from "../../db/repositories/circuit-device-row.repository.js";
import { CircuitListRepository } from "../../db/repositories/circuit-list.repository.js";
import { CircuitRepository } from "../../db/repositories/circuit.repository.js";
import { CircuitSectionRepository } from "../../db/repositories/circuit-section.repository.js";
import { ProjectDeviceRepository } from "../../db/repositories/project-device.repository.js";
import type {
  CreateCircuitDeviceRowInput,
  CreateCircuitInput,
  CreateCircuitWithDeviceRowsInput,
  MoveCircuitDeviceRowInput,
  MoveCircuitDeviceRowsBulkInput,
  ReorderSectionCircuitsInput,
  UpdateSectionEquipmentIdentifiersInput,
  UpdateCircuitDeviceRowInput,
  UpdateCircuitInput,
} from "../../shared/validation/circuit.schemas.js";
import { CircuitNumberingService } from "./circuit-numbering.service.js";
import { projectDeviceSyncFields } from "../../shared/constants/project-device-sync-fields.js";
import {
  parseOverriddenFields,
  serializeOverriddenFields,
} from "./project-device-sync.service.js";

export class CircuitWriteService {
  private readonly circuitRepository: CircuitRepository;
  private readonly circuitSectionRepository: CircuitSectionRepository;
  private readonly circuitListRepository: CircuitListRepository;
  private readonly deviceRowRepository: CircuitDeviceRowRepository;
  private readonly projectDeviceRepository: ProjectDeviceRepository;
  private readonly numberingService: CircuitNumberingService;

  constructor(deps?: {
    circuitRepository?: CircuitRepository;
    circuitSectionRepository?: CircuitSectionRepository;
    circuitListRepository?: CircuitListRepository;
    deviceRowRepository?: CircuitDeviceRowRepository;
    projectDeviceRepository?: ProjectDeviceRepository;
    numberingService?: CircuitNumberingService;
  }) {
    this.circuitRepository = deps?.circuitRepository ?? new CircuitRepository();
    this.circuitSectionRepository = deps?.circuitSectionRepository ?? new CircuitSectionRepository();
    this.circuitListRepository = deps?.circuitListRepository ?? new CircuitListRepository();
    this.deviceRowRepository = deps?.deviceRowRepository ?? new CircuitDeviceRowRepository();
    this.projectDeviceRepository = deps?.projectDeviceRepository ?? new ProjectDeviceRepository();
    this.numberingService = deps?.numberingService ?? new CircuitNumberingService();
  }

  // Ensures writes never connect a section to the wrong circuit list.
  private async assertSectionInList(sectionId: string, circuitListId: string) {
    const section = await this.circuitSectionRepository.findById(sectionId);
    if (!section) {
      throw new Error("Invalid section id.");
    }
    if (section.circuitListId !== circuitListId) {
      throw new Error("Section does not belong to circuit list.");
    }
    return section;
  }

  // Enforces BMK uniqueness inside one circuit list.
  private async assertUniqueEquipmentIdentifier(
    circuitListId: string,
    equipmentIdentifier: string,
    excludeCircuitId?: string
  ) {
    const exists = await this.circuitRepository.existsByEquipmentIdentifier(
      circuitListId,
      equipmentIdentifier,
      excludeCircuitId
    );
    if (exists) {
      throw new Error("Duplicate equipmentIdentifier in circuit list.");
    }
  }

  // Validates linked project-device id against owning project of the circuit list.
  private async assertValidLinkedProjectDeviceForProject(
    projectId: string,
    linkedProjectDeviceId?: string
  ) {
    if (!linkedProjectDeviceId) {
      return;
    }
    const device = await this.projectDeviceRepository.findById(projectId, linkedProjectDeviceId);
    if (!device) {
      throw new Error("Invalid linked project device id.");
    }
  }

  private async assertValidLinkedProjectDevice(circuitId: string, linkedProjectDeviceId?: string) {
    if (!linkedProjectDeviceId) {
      return;
    }
    const circuit = await this.circuitRepository.findById(circuitId);
    if (!circuit) {
      throw new Error("Invalid circuit id.");
    }
    const list = await this.circuitListRepository.findByIdByListIdOnly(circuit.circuitListId);
    if (!list) {
      throw new Error("Circuit list not found.");
    }
    await this.assertValidLinkedProjectDeviceForProject(list.projectId, linkedProjectDeviceId);
  }

  async createCircuit(projectId: string, circuitListId: string, input: CreateCircuitInput) {
    const list = await this.circuitListRepository.findById(projectId, circuitListId);
    if (!list) {
      throw new Error("Circuit list not found in project.");
    }
    await this.assertSectionInList(input.sectionId, circuitListId);
    await this.assertUniqueEquipmentIdentifier(circuitListId, input.equipmentIdentifier);
    const id = await this.circuitRepository.create({
      circuitListId,
      sectionId: input.sectionId,
      equipmentIdentifier: input.equipmentIdentifier,
      displayName: input.displayName,
      sortOrder: input.sortOrder,
      protectionType: input.protectionType,
      protectionRatedCurrent: input.protectionRatedCurrent,
      protectionCharacteristic: input.protectionCharacteristic,
      cableType: input.cableType,
      cableCrossSection: input.cableCrossSection,
      cableLength: input.cableLength,
      rcdAssignment: input.rcdAssignment,
      terminalDesignation: input.terminalDesignation,
      voltage: input.voltage,
      controlRequirement: input.controlRequirement,
      status: input.status,
      isReserve: input.isReserve ?? true,
      remark: input.remark,
    });
    return this.circuitRepository.findById(id);
  }

  async createCircuitWithDeviceRows(
    projectId: string,
    circuitListId: string,
    input: CreateCircuitWithDeviceRowsInput
  ) {
    const list = await this.circuitListRepository.findById(projectId, circuitListId);
    if (!list) {
      throw new Error("Circuit list not found in project.");
    }
    await this.assertSectionInList(input.circuit.sectionId, circuitListId);
    await this.assertUniqueEquipmentIdentifier(
      circuitListId,
      input.circuit.equipmentIdentifier
    );
    for (const row of input.deviceRows) {
      await this.assertValidLinkedProjectDeviceForProject(
        list.projectId,
        row.linkedProjectDeviceId
      );
    }

    const created = this.deviceRowRepository.createCircuitWithDeviceRowsTransactional({
      circuit: {
        circuitListId,
        ...input.circuit,
        isReserve: false,
      },
      deviceRows: input.deviceRows,
    });
    const circuit = await this.circuitRepository.findById(created.circuitId);
    const deviceRows = await Promise.all(
      created.rowIds.map((rowId) => this.deviceRowRepository.findById(rowId))
    );
    if (!circuit || deviceRows.some((row) => !row)) {
      throw new Error("Der angelegte Stromkreis konnte nicht geladen werden.");
    }
    return {
      circuit,
      deviceRows,
    };
  }

  async updateCircuit(circuitId: string, input: UpdateCircuitInput) {
    const current = await this.circuitRepository.findById(circuitId);
    if (!current) {
      throw new Error("Invalid circuit id.");
    }

    const sectionId = input.sectionId ?? current.sectionId;
    const equipmentIdentifier = input.equipmentIdentifier ?? current.equipmentIdentifier;
    const sortOrder = input.sortOrder ?? current.sortOrder;
    await this.assertSectionInList(sectionId, current.circuitListId);
    await this.assertUniqueEquipmentIdentifier(current.circuitListId, equipmentIdentifier, circuitId);

    await this.circuitRepository.update(circuitId, {
      sectionId,
      equipmentIdentifier,
      displayName: input.displayName ?? current.displayName ?? undefined,
      sortOrder,
      protectionType: input.protectionType ?? current.protectionType ?? undefined,
      protectionRatedCurrent: input.protectionRatedCurrent ?? current.protectionRatedCurrent ?? undefined,
      protectionCharacteristic:
        input.protectionCharacteristic ?? current.protectionCharacteristic ?? undefined,
      cableType: input.cableType ?? current.cableType ?? undefined,
      cableCrossSection: input.cableCrossSection ?? current.cableCrossSection ?? undefined,
      cableLength: input.cableLength ?? current.cableLength ?? undefined,
      rcdAssignment: input.rcdAssignment ?? current.rcdAssignment ?? undefined,
      terminalDesignation: input.terminalDesignation ?? current.terminalDesignation ?? undefined,
      voltage: input.voltage ?? current.voltage ?? undefined,
      controlRequirement: input.controlRequirement ?? current.controlRequirement ?? undefined,
      status: input.status ?? current.status ?? undefined,
      isReserve: input.isReserve ?? Boolean(current.isReserve),
      remark: input.remark ?? current.remark ?? undefined,
    });
    return this.circuitRepository.findById(circuitId);
  }

  async deleteCircuit(circuitId: string) {
    const current = await this.circuitRepository.findById(circuitId);
    if (!current) {
      throw new Error("Invalid circuit id.");
    }
    await this.circuitRepository.delete(circuitId);
  }

  async createDeviceRow(circuitId: string, input: CreateCircuitDeviceRowInput) {
    const circuit = await this.circuitRepository.findById(circuitId);
    if (!circuit) {
      throw new Error("Invalid circuit id.");
    }
    await this.assertValidLinkedProjectDevice(circuitId, input.linkedProjectDeviceId);

    const rowId = this.deviceRowRepository.createInCircuitTransactional({
      circuitId,
      linkedProjectDeviceId: input.linkedProjectDeviceId,
      sortOrder: input.sortOrder,
      name: input.name,
      displayName: input.displayName,
      phaseType: input.phaseType,
      connectionKind: input.connectionKind,
      costGroup: input.costGroup,
      category: input.category,
      level: input.level,
      roomId: input.roomId,
      roomNumberSnapshot: input.roomNumberSnapshot,
      roomNameSnapshot: input.roomNameSnapshot,
      quantity: input.quantity,
      powerPerUnit: input.powerPerUnit,
      simultaneityFactor: input.simultaneityFactor,
      cosPhi: input.cosPhi,
      remark: input.remark,
      overriddenFields: input.overriddenFields,
    });

    return this.deviceRowRepository.findById(rowId);
  }

  async updateDeviceRow(rowId: string, input: UpdateCircuitDeviceRowInput) {
    const current = await this.deviceRowRepository.findById(rowId);
    if (!current) {
      throw new Error("Invalid device row id.");
    }
    await this.assertValidLinkedProjectDevice(current.circuitId, input.linkedProjectDeviceId);
    let overriddenFields = input.overriddenFields ?? current.overriddenFields ?? undefined;
    if (current.linkedProjectDeviceId && input.overriddenFields === undefined) {
      const overrides = new Set(parseOverriddenFields(current.overriddenFields));
      const inputValues = input as Record<string, unknown>;
      const currentValues = current as unknown as Record<string, unknown>;
      for (const field of projectDeviceSyncFields) {
        if (
          Object.prototype.hasOwnProperty.call(input, field) &&
          (inputValues[field] ?? null) !== (currentValues[field] ?? null)
        ) {
          overrides.add(field);
        }
      }
      overriddenFields = serializeOverriddenFields(overrides);
    }
    await this.deviceRowRepository.update(rowId, {
      linkedProjectDeviceId: input.linkedProjectDeviceId ?? current.linkedProjectDeviceId ?? undefined,
      name: input.name ?? current.name,
      displayName: input.displayName ?? current.displayName,
      phaseType: input.phaseType ?? current.phaseType ?? undefined,
      connectionKind: input.connectionKind ?? current.connectionKind ?? undefined,
      costGroup: input.costGroup ?? current.costGroup ?? undefined,
      category: input.category ?? current.category ?? undefined,
      level: input.level ?? current.level ?? undefined,
      roomId: input.roomId ?? current.roomId ?? undefined,
      roomNumberSnapshot: input.roomNumberSnapshot ?? current.roomNumberSnapshot ?? undefined,
      roomNameSnapshot: input.roomNameSnapshot ?? current.roomNameSnapshot ?? undefined,
      quantity: input.quantity ?? current.quantity,
      powerPerUnit: input.powerPerUnit ?? current.powerPerUnit,
      simultaneityFactor: input.simultaneityFactor ?? current.simultaneityFactor,
      cosPhi: input.cosPhi ?? current.cosPhi ?? undefined,
      remark: input.remark ?? current.remark ?? undefined,
      overriddenFields,
    });
    return this.deviceRowRepository.findById(rowId);
  }

  async deleteDeviceRow(rowId: string) {
    const current = await this.deviceRowRepository.findById(rowId);
    if (!current) {
      throw new Error("Invalid device row id.");
    }
    const circuit = await this.circuitRepository.findById(current.circuitId);
    if (!circuit) {
      throw new Error("Invalid circuit id.");
    }
    this.deviceRowRepository.deleteFromCircuitTransactional(rowId, circuit.id);
  }

  async moveDeviceRow(rowId: string, input: MoveCircuitDeviceRowInput) {
    const row = await this.deviceRowRepository.findById(rowId);
    if (!row) {
      throw new Error("Invalid device row id.");
    }

    const sourceCircuit = await this.circuitRepository.findById(row.circuitId);
    if (!sourceCircuit) {
      throw new Error("Invalid circuit id.");
    }

    let targetCircuit = input.targetCircuitId
      ? await this.circuitRepository.findById(input.targetCircuitId)
      : null;
    if (input.targetCircuitId && !targetCircuit) {
      throw new Error("Invalid target circuit id.");
    }

    let createTargetCircuit:
      | {
          circuitListId: string;
          sectionId: string;
          equipmentIdentifier: string;
          displayName: string;
          sortOrder: number;
        }
      | undefined;

    // Placeholder-target move prepares a new circuit explicitly. Its creation and
    // the row assignment are committed together without renumbering other circuits.
    if (!targetCircuit) {
      if (!input.targetSectionId || !input.createNewCircuit) {
        throw new Error("Invalid move target.");
      }
      const section = await this.assertSectionInList(input.targetSectionId, sourceCircuit.circuitListId);
      const nextIdentifier = await this.numberingService.getNextIdentifier(section.id);
      const sectionCircuits = await this.circuitRepository.listBySection(section.id);
      const nextSortOrder =
        sectionCircuits.length > 0 ? Math.max(...sectionCircuits.map((circuit) => circuit.sortOrder)) + 10 : 10;
      createTargetCircuit = {
        circuitListId: sourceCircuit.circuitListId,
        sectionId: section.id,
        equipmentIdentifier: nextIdentifier,
        displayName: "Neuer Stromkreis",
        sortOrder: nextSortOrder,
      };
    }

    if (targetCircuit && targetCircuit.circuitListId !== sourceCircuit.circuitListId) {
      throw new Error("Target circuit does not belong to same circuit list.");
    }
    if (targetCircuit?.id === sourceCircuit.id) {
      return this.deviceRowRepository.findById(rowId);
    }

    this.deviceRowRepository.moveRowsTransactional({
      rows: [{ id: row.id, expectedCircuitId: row.circuitId }],
      targetCircuitId: targetCircuit?.id,
      createTargetCircuit,
    });

    return this.deviceRowRepository.findById(rowId);
  }

  async moveDeviceRowsBulk(input: MoveCircuitDeviceRowsBulkInput) {
    // Bulk move keeps input order and resolves all source circuits first so undo can
    // restore per-source assignment deterministically.
    const uniqueRowIds = [...new Set(input.rowIds)];
    if (uniqueRowIds.length === 0) {
      throw new Error("No device rows provided.");
    }

    const rows = [];
    for (const rowId of uniqueRowIds) {
      const row = await this.deviceRowRepository.findById(rowId);
      if (!row) {
        throw new Error("Invalid device row id.");
      }
      rows.push(row);
    }

    const sourceCircuits = new Map<string, Awaited<ReturnType<CircuitRepository["findById"]>>>();
    for (const row of rows) {
      if (!sourceCircuits.has(row.circuitId)) {
        const circuit = await this.circuitRepository.findById(row.circuitId);
        if (!circuit) {
          throw new Error("Invalid circuit id.");
        }
        sourceCircuits.set(row.circuitId, circuit);
      }
    }

    const referenceSourceCircuit = sourceCircuits.get(rows[0].circuitId)!;
    let targetCircuit = input.targetCircuitId
      ? await this.circuitRepository.findById(input.targetCircuitId)
      : null;
    if (input.targetCircuitId && !targetCircuit) {
      throw new Error("Invalid target circuit id.");
    }

    // Bulk placeholder move prepares exactly one new circuit as common target.
    // Its actual creation happens together with the row moves in one transaction.
    let createTargetCircuit:
      | {
          circuitListId: string;
          sectionId: string;
          equipmentIdentifier: string;
          displayName: string;
          sortOrder: number;
        }
      | undefined;
    if (!targetCircuit) {
      if (!input.targetSectionId || !input.createNewCircuit) {
        throw new Error("Invalid move target.");
      }
      const section = await this.assertSectionInList(input.targetSectionId, referenceSourceCircuit.circuitListId);
      const nextIdentifier = await this.numberingService.getNextIdentifier(section.id);
      const sectionCircuits = await this.circuitRepository.listBySection(section.id);
      const nextSortOrder =
        sectionCircuits.length > 0 ? Math.max(...sectionCircuits.map((circuit) => circuit.sortOrder)) + 10 : 10;
      createTargetCircuit = {
        circuitListId: referenceSourceCircuit.circuitListId,
        sectionId: section.id,
        equipmentIdentifier: nextIdentifier,
        displayName: "Neuer Stromkreis",
        sortOrder: nextSortOrder,
      };
    }

    const targetCircuitListId = targetCircuit?.circuitListId ?? createTargetCircuit!.circuitListId;
    for (const sourceCircuit of sourceCircuits.values()) {
      if (sourceCircuit.circuitListId !== targetCircuitListId) {
        throw new Error("All moved rows must belong to same circuit list as target.");
      }
    }

    return this.deviceRowRepository.moveRowsTransactional({
      rows: rows.map((row) => ({ id: row.id, expectedCircuitId: row.circuitId })),
      targetCircuitId: targetCircuit?.id,
      createTargetCircuit,
    });
  }

  async getNextIdentifier(sectionId: string) {
    return this.numberingService.getNextIdentifier(sectionId);
  }

  async renumberSection(sectionId: string) {
    // Explicit renumber operation for one section only.
    // Never renumbers other sections and never runs implicitly during move/sort operations.
    const section = await this.circuitSectionRepository.findById(sectionId);
    if (!section) {
      throw new Error("Invalid section id.");
    }
    const sectionCircuits = await this.circuitRepository.listBySection(sectionId);
    const otherCircuits = (await this.circuitRepository.listByCircuitList(section.circuitListId)).filter(
      (circuit) => circuit.sectionId !== sectionId
    );
    const otherIdentifiers = new Set(otherCircuits.map((circuit) => circuit.equipmentIdentifier));

    const finalAssignments: Array<{ id: string; equipmentIdentifier: string }> = [];
    let index = 1;
    for (const circuit of sectionCircuits) {
      let candidate = `${section.prefix}${index}`;
      while (otherIdentifiers.has(candidate)) {
        index += 1;
        candidate = `${section.prefix}${index}`;
      }
      finalAssignments.push({ id: circuit.id, equipmentIdentifier: candidate });
      index += 1;
    }
    // Uses safe two-phase identifier update to avoid UNIQUE collisions during swaps.
    await this.circuitRepository.updateEquipmentIdentifiersSafely(
      section.circuitListId,
      finalAssignments,
      sectionId
    );

    return this.circuitRepository.listBySection(sectionId);
  }

  async updateSectionEquipmentIdentifiers(
    sectionId: string,
    input: UpdateSectionEquipmentIdentifiersInput
  ) {
    const section = await this.circuitSectionRepository.findById(sectionId);
    if (!section) {
      throw new Error("Invalid section id.");
    }
    const sectionCircuits = await this.circuitRepository.listBySection(sectionId);
    const sectionIds = new Set(sectionCircuits.map((circuit) => circuit.id));
    if (input.identifiers.length !== sectionCircuits.length) {
      throw new Error("identifiers must include all circuits in the section.");
    }
    for (const entry of input.identifiers) {
      if (!sectionIds.has(entry.circuitId)) {
        throw new Error("Circuit id does not belong to section.");
      }
    }

    await this.circuitRepository.updateEquipmentIdentifiersSafely(
      section.circuitListId,
      input.identifiers.map((entry) => ({ id: entry.circuitId, equipmentIdentifier: entry.equipmentIdentifier })),
      sectionId
    );
    return this.circuitRepository.listBySection(sectionId);
  }

  async reorderCircuitsInSection(sectionId: string, input: ReorderSectionCircuitsInput) {
    // Reorder updates sortOrder only. BMKs remain unchanged; users may renumber explicitly later.
    const section = await this.circuitSectionRepository.findById(sectionId);
    if (!section) {
      throw new Error("Invalid section id.");
    }
    const sectionCircuits = await this.circuitRepository.listBySection(sectionId);
    const sectionIds = new Set(sectionCircuits.map((circuit) => circuit.id));
    if (sectionCircuits.length !== input.orderedCircuitIds.length) {
      throw new Error("orderedCircuitIds must include all circuits of the section.");
    }
    for (const circuitId of input.orderedCircuitIds) {
      if (!sectionIds.has(circuitId)) {
        throw new Error("Circuit id does not belong to section.");
      }
    }

    this.circuitRepository.updateSortOrdersSafely(sectionId, input.orderedCircuitIds);
    return this.circuitRepository.listBySection(sectionId);
  }
}