import {
  BadRequestException,
  ConflictException,
  Injectable,
  Logger,
} from '@nestjs/common';
import { Readable } from 'stream';
import type { TCurrentUser } from '@tria-plc/api-common/modules/auth/types/current-user.type';

import { ContractDocumentViewModelBuilder } from '../../contracts/contract-document-view-model.builder';
import { ContractRendererService } from '../../contracts/contract-renderer.service';
import { ContractPdfService } from '../../contracts/contract-pdf.service';
import { ContractViewModel } from '../../contracts/contract-view-model.builder';
import { MinioService } from '../minio/minio.service';
import { FileRecord } from '../files/entities/file.entity';
import { assertCanApproveBookingStep } from '../../common/freight-permission.util';
import { ApprovalRulesService } from '../rule-engine/services/approval-rules.service';
import { CargoTypesService } from '../rule-engine/services/cargo-types.service';
import { DropdownSettingsService } from '../dropdown-settings/dropdown-settings.service';
import { FilesService } from '../files/files.service';
import { SignaturesService } from '../signatures/signatures.service';
import { ContractPricingService } from './contract-pricing.service';
import { ClearanceMilestoneService } from './clearance-milestone.service';
import { ContractsRepository } from './contracts.repository';
import { ContractsService } from './contracts.service';
import { contractClearanceSettingCode } from './contract-clearance.util';
import { Contract } from './entities/contract.entity';
import { ContractSignerRole } from './entities/contract-signature.entity';
import { SignContractDto } from './dto/sign-contract.dto';

/**
 * Dropdown-settings code holding the admin-configured contract validity options
 * (each option's `value` is a day count). The staff accept dialog reads the same
 * code, so accept can only use a configured duration. See the seed migration
 * `SeedContractValidityPeriods`.
 */
const CONTRACT_VALIDITY_PERIODS_CODE = 'contract_validity_periods';

/** Status-machine guard mirroring booking-status.util. */
function assertContractStatus(contract: Contract, allowed: string[]): void {
  if (!allowed.includes(contract.status)) {
    throw new ConflictException(
      `Cannot perform this action on status "${contract.status}". Allowed: ${allowed.join(', ')}`,
    );
  }
}

@Injectable()
export class ContractTransitionService {
  private readonly logger = new Logger(ContractTransitionService.name);

  constructor(
    private readonly contractsRepository: ContractsRepository,
    private readonly contractsService: ContractsService,
    private readonly pricingService: ContractPricingService,
    private readonly approvalRulesService: ApprovalRulesService,
    private readonly cargoTypesService: CargoTypesService,
    private readonly dropdownSettingsService: DropdownSettingsService,
    private readonly filesService: FilesService,
    private readonly signaturesService: SignaturesService,
    private readonly milestoneService: ClearanceMilestoneService,
    private readonly documentViewModelBuilder: ContractDocumentViewModelBuilder,
    private readonly renderer: ContractRendererService,
    private readonly pdfService: ContractPdfService,
    private readonly minioService: MinioService,
  ) {}

  /** Customer submits the contract for approval → SUBMITTED; freeze unit rates. */
  async submit(contractId: string): Promise<Contract> {
    const contract = await this.contractsService.findById(contractId);
    assertContractStatus(contract, ['DRAFT', 'CHANGES_REQUESTED']);

    await this.pricingService.generatePrice(contractId);
    await this.pricingService.freezeRateSnapshots(contractId);

    await this.contractsRepository.update(contractId, {
      status: 'SUBMITTED',
    } as never);
    return this.contractsService.findById(contractId);
  }

  /** Confirm a price change before submit (mirrors booking confirm-submit). */
  async confirmSubmit(contractId: string): Promise<Contract> {
    const contract = await this.contractsService.findById(contractId);
    assertContractStatus(contract, ['PRICE_CHANGED_PENDING_CONFIRM']);

    await this.pricingService.generatePrice(contractId);
    await this.pricingService.freezeRateSnapshots(contractId);

    await this.contractsRepository.update(contractId, {
      status: 'SUBMITTED',
    } as never);
    return this.contractsService.findById(contractId);
  }

  /**
   * Line staff accepts intake: set the validity window from validityDays and
   * instantiate the approval steps from approval_rules → PENDING_APPROVAL.
   */
  async staffAccept(
    contractId: string,
    actorId: string,
    validityDays: number,
  ): Promise<Contract> {
    const contract = await this.contractsService.findById(contractId);
    assertContractStatus(contract, ['SUBMITTED']);

    if (!Number.isInteger(validityDays) || validityDays < 1) {
      throw new BadRequestException(
        'A contract validity (in days) is required to accept this contract.',
      );
    }

    await this.assertValidityDaysConfigured(validityDays);

    const validFrom = new Date();
    const validUntil = new Date(validFrom);
    validUntil.setDate(validUntil.getDate() + validityDays);

    await this.instantiateApprovalSteps(contract);

    await this.contractsRepository.update(contractId, {
      status: 'PENDING_APPROVAL',
      approvedByStaffId: actorId,
      approvedByStaffAt: validFrom,
      contractValidityDays: validityDays,
      contractValidFrom: validFrom,
      contractValidUntil: validUntil,
    } as never);
    return this.contractsService.findById(contractId);
  }

  /**
   * Ensure the chosen validity (days) is one of the admin-configured options in
   * the `contract_validity_periods` dropdown setting. If the setting is missing
   * or has no options yet, fall back to the DTO range check (already applied) so
   * acceptance is never hard-blocked before an admin configures the list.
   */
  private async assertValidityDaysConfigured(validityDays: number): Promise<void> {
    let setting;
    try {
      setting = await this.dropdownSettingsService.getByCode(
        CONTRACT_VALIDITY_PERIODS_CODE,
      );
    } catch {
      // Not configured yet — keep the flow working with the DTO range only.
      return;
    }

    const allowed = (setting.children ?? [])
      .map((o) => Number(o.value))
      .filter((n) => Number.isFinite(n));
    if (allowed.length === 0) return;

    if (!allowed.includes(validityDays)) {
      throw new BadRequestException(
        `Validity ${validityDays} days is not a configured option. Allowed: ${allowed
          .sort((a, b) => a - b)
          .join(', ')} days.`,
      );
    }
  }

  /**
   * Build contract approval steps from the system approval_rules chain (US-06:
   * container → line staff + director; bulk → directors + CEO). Mirrors the
   * booking transition's instantiateApprovalSteps but writes contract steps.
   */
  private async instantiateApprovalSteps(contract: Contract): Promise<void> {
    if ((contract.approvalSteps?.length ?? 0) > 0) return;

    const cargoTypeId =
      (contract.cargoScope ?? []).find((c) => c.cargoTypeId)?.cargoTypeId ?? null;

    // US-06 routing: bulk always needs director approval; container needs it only
    // when its cargo type flags it. Resolve the chain via the same approval_rules
    // source of truth the booking flow uses (no booking row is created here).
    let requiresDirectorApproval = contract.freightType === 'BULK';
    if (cargoTypeId) {
      const cargoType = await this.cargoTypesService.findById(cargoTypeId);
      if (cargoType?.requiresDirectorApproval) {
        requiresDirectorApproval = true;
      }
    }

    const chain = await this.approvalRulesService.findChain(requiresDirectorApproval);
    if (chain.length === 0) {
      throw new BadRequestException(
        `Approval chain could not be loaded for requiresDirectorApproval=${requiresDirectorApproval}.`,
      );
    }

    for (const rule of chain) {
      await this.contractsRepository.createApprovalStep({
        contractId: contract.id,
        stepOrder: rule.stepOrder,
        requiredRole: rule.requiredRole,
        blocksRole: rule.blocksRole ?? null,
        status: 'PENDING',
      });
    }
  }

  async requestChanges(
    contractId: string,
    note: string,
    actorId: string,
  ): Promise<Contract> {
    const contract = await this.contractsService.findById(contractId);
    assertContractStatus(contract, ['SUBMITTED']);

    await this.contractsRepository.createReviewNote(
      contractId,
      note,
      'CHANGES_REQUESTED',
      actorId,
      'STAFF',
    );
    await this.contractsRepository.update(contractId, {
      status: 'CHANGES_REQUESTED',
    } as never);
    return this.contractsService.findById(contractId);
  }

  async reject(contractId: string, reason: string, actorId: string): Promise<Contract> {
    const contract = await this.contractsService.findById(contractId);
    assertContractStatus(contract, ['SUBMITTED', 'PENDING_APPROVAL']);

    await this.contractsRepository.createReviewNote(
      contractId,
      reason,
      'REJECTION',
      actorId,
      'STAFF',
    );
    await this.contractsRepository.update(contractId, {
      status: 'REJECTED',
    } as never);
    return this.contractsService.findById(contractId);
  }

  /** Approve one approval step in sequence; → APPROVED when all complete. */
  async approveStep(
    contractId: string,
    stepId: string,
    actorId: string,
    requiredRole: string,
    authUser?: TCurrentUser,
  ): Promise<Contract> {
    if (authUser) {
      assertCanApproveBookingStep(authUser, requiredRole);
    }

    const contract = await this.contractsService.findById(contractId);
    assertContractStatus(contract, ['PENDING_APPROVAL', 'APPROVED_PENDING_SIGNATURE']);

    const step = await this.contractsRepository.findApprovalStepById(contractId, stepId);
    if (!step || step.status !== 'PENDING') {
      throw new BadRequestException('Approval step not found or already actioned');
    }

    const next = await this.contractsRepository.findNextPendingApprovalStep(contractId);
    if (!next || next.id !== step.id) {
      throw new BadRequestException('Approval steps must be completed in order');
    }
    if (step.requiredRole !== requiredRole) {
      throw new BadRequestException(
        `Step requires role ${step.requiredRole}, not ${requiredRole}`,
      );
    }
    if (step.blocksRole && step.blocksRole === requiredRole) {
      throw new BadRequestException(`Role ${requiredRole} is blocked for this step`);
    }

    await this.contractsRepository.completeApprovalStep(step.id, actorId, 'APPROVED');

    // Record who acted on this step, but DO NOT advance the contract status here —
    // approving one step (e.g. LINE_STAFF) must not finalize the chain while later
    // steps (e.g. DIRECTOR) are still pending. Status only moves to APPROVED once
    // every step in the chain is complete; until then the contract stays in
    // PENDING_APPROVAL so the next required role can act.
    const updates: Record<string, unknown> = {};
    const now = new Date();
    if (requiredRole === 'LINE_STAFF') {
      updates.approvedByStaffId = actorId;
      updates.approvedByStaffAt = now;
    } else if (requiredRole === 'DIRECTOR') {
      updates.signedByDirectorId = actorId;
      updates.signedByDirectorAt = now;
    } else if (requiredRole === 'CEO') {
      updates.signedByCeoId = actorId;
      updates.signedByCeoAt = now;
    }

    const allDone = await this.contractsRepository.allApprovalStepsComplete(contractId);
    updates.status = allDone ? 'APPROVED' : 'PENDING_APPROVAL';

    if (Object.keys(updates).length > 0) {
      await this.contractsRepository.update(contractId, updates as never);
    }
    return this.contractsService.findById(contractId);
  }

  /**
   * Render the contract PDF from the Contract aggregate, store it via FilesService,
   * stamp the template key, and move to CONTRACT_READY. PDF rendering (Puppeteer/
   * Chromium) is best-effort and must NOT block the contract from becoming ready —
   * the document is (re)rendered lazily on view/download once Chromium is available.
   */
  async generateContract(contractId: string): Promise<Contract> {
    const contract = await this.contractsService.findById(contractId);
    assertContractStatus(contract, ['APPROVED', 'APPROVED_PENDING_SIGNATURE']);

    const { view } = await this.documentViewModelBuilder.build(contractId);

    try {
      await this.upsertContractPdf(contractId, contract.reference, view);
    } catch (err) {
      this.logger.warn(
        `Contract PDF deferred for ${contract.reference}: ${err}. It will render on view/download once Chromium is available.`,
      );
    }

    await this.contractsRepository.update(contractId, {
      status: 'CONTRACT_READY',
      contractTemplateKey: view.templateKey,
      contractGeneratedAt: new Date(),
    } as never);
    return this.contractsService.findById(contractId);
  }

  /**
   * Build the contract PDF view-model and rendered HTML for portal/backoffice
   * signing. Sourced entirely from the Contract aggregate (unit-rate schedule, no
   * totals). Returns the view-model, the rendered HTML and the signature rows.
   */
  async getContractDocumentView(contractId: string): Promise<{
    view: ContractViewModel;
    html: string;
    signatures: ContractViewModel['signatures'];
  }> {
    const { view } = await this.documentViewModelBuilder.build(contractId);
    await this.inlineSignatureImages(view.signatures);
    const html = this.renderer.render(view);
    return { view, html, signatures: view.signatures };
  }

  /**
   * Rebuild the stored `contract` PDF from the current aggregate (now including
   * the latest signatures) so the downloaded/viewed file matches the live HTML
   * view. Best-effort — a Chromium hiccup must never fail the signing
   * transaction; the doc still re-renders live on /contract/view.
   */
  private async regenerateContractPdf(
    contractId: string,
    reference: string,
  ): Promise<void> {
    try {
      const { view } = await this.documentViewModelBuilder.build(contractId);
      await this.upsertContractPdf(contractId, reference, view);
    } catch (err) {
      this.logger.warn(
        `Signed contract PDF regen deferred for ${reference}: ${err}. It re-renders live on view.`,
      );
    }
  }

  /** Render the contract PDF and upsert it as the `contract` file on the contract. */
  private async upsertContractPdf(
    contractId: string,
    reference: string,
    view: ContractViewModel,
  ): Promise<FileRecord> {
    await this.inlineSignatureImages(view.signatures);
    const html = this.renderer.render(view);
    const pdfBuffer = await this.pdfService.htmlToPdfBuffer(html);
    const file: Express.Multer.File = {
      fieldname: 'contract',
      originalname: `contract-${reference}.pdf`,
      encoding: '7bit',
      mimetype: 'application/pdf',
      size: pdfBuffer.length,
      buffer: pdfBuffer,
      stream: Readable.from(pdfBuffer),
      destination: '',
      filename: '',
      path: '',
    };

    return this.filesService.upsertByCode({
      resourceId: contractId,
      resource: 'contracts',
      code: 'contract',
      file,
    });
  }

  /** Replace MinIO signature URLs with inline data URIs so they render in the PDF. */
  private async inlineSignatureImages(
    signatures: Array<{ signatureImageUrl?: string | null }>,
  ): Promise<void> {
    for (const sig of signatures) {
      if (!sig.signatureImageUrl) continue;
      try {
        if (sig.signatureImageUrl.startsWith('data:')) continue;
        const objectName = this.minioService.getObjectNameFromUrl(
          sig.signatureImageUrl,
        );
        const stream = await this.minioService.getFileStream(objectName);
        const buffer = await this.streamToBuffer(stream);
        sig.signatureImageUrl = `data:image/png;base64,${buffer.toString('base64')}`;
      } catch {
        /* keep original url */
      }
    }
  }

  private streamToBuffer(stream: Readable): Promise<Buffer> {
    return new Promise((resolve, reject) => {
      const chunks: Buffer[] = [];
      stream.on('data', (chunk: Buffer | string) => {
        chunks.push(Buffer.isBuffer(chunk) ? chunk : Buffer.from(chunk));
      });
      stream.on('error', reject);
      stream.on('end', () => resolve(Buffer.concat(chunks)));
    });
  }

  /** Apply a digital signature row (mirrors booking-contract.service). */
  private async applySignature(
    contract: Contract,
    dto: SignContractDto,
    options: { signerUserId?: string },
  ): Promise<void> {
    const role = dto.role as ContractSignerRole;

    // Resolve the signature image. The client may send a freshly-drawn image, or
    // omit it to reuse the signer's saved profile signature. Fall back to the
    // saved one whenever no image is supplied.
    let imageBase64 = dto.signatureImageBase64;
    let signerDisplayName = dto.signerDisplayName;
    if (!imageBase64 && options.signerUserId) {
      const saved = await this.signaturesService.getForUser(options.signerUserId);
      if (saved?.signatureImageUrl) {
        imageBase64 = saved.signatureImageUrl;
        signerDisplayName = signerDisplayName || saved.signerDisplayName;
      }
    }
    if (!imageBase64) {
      throw new BadRequestException(
        'No signature provided and no saved signature found on the profile.',
      );
    }

    const raw = imageBase64.includes(',')
      ? imageBase64.split(',')[1]!
      : imageBase64;
    const buffer = Buffer.from(raw, 'base64');
    const sigFile: Express.Multer.File = {
      fieldname: `signature_${role.toLowerCase()}`,
      originalname: `signature-${role.toLowerCase()}-${contract.reference}.png`,
      encoding: '7bit',
      mimetype: 'image/png',
      size: buffer.length,
      buffer,
      stream: Readable.from(buffer),
      destination: '',
      filename: '',
      path: '',
    };

    const fileRecord = await this.filesService.upsertByCode({
      resourceId: contract.id,
      resource: 'contracts',
      code: `signature_${role.toLowerCase()}`,
      file: sigFile,
    });

    await this.contractsRepository.saveSignature({
      contractId: contract.id,
      role,
      signerDisplayName,
      signedAt: new Date(),
      signatureFileId: fileRecord.id,
      consentText: dto.consentText ?? null,
    });

    // Only (re)save the reusable profile signature when the signer drew a NEW
    // image. Reusing the saved signature must not rewrite it with itself.
    if (options.signerUserId && dto.signatureImageBase64) {
      try {
        await this.signaturesService.upsertForUser({
          userId: options.signerUserId,
          signerDisplayName,
          signatureImageBase64: dto.signatureImageBase64,
        });
      } catch (err) {
        this.logger.warn(
          `Could not save reusable signature for user ${options.signerUserId}: ${err}`,
        );
      }
    }
  }

  /** Customer signs the ready contract → SIGNED_CUSTOMER. */
  async sign(
    contractId: string,
    dto: SignContractDto,
    options: { signerUserId?: string },
  ): Promise<Contract> {
    const contract = await this.contractsService.findById(contractId);

    if (dto.role === 'CUSTOMER') {
      assertContractStatus(contract, ['CONTRACT_READY']);
      const existing = await this.contractsRepository.findSignature(contractId, 'CUSTOMER');
      if (existing) {
        throw new BadRequestException('Customer has already signed this contract');
      }
      await this.applySignature(contract, dto, options);
      await this.contractsRepository.update(contractId, {
        status: 'SIGNED_CUSTOMER',
        customerSignedAt: new Date(),
      } as never);
      await this.regenerateContractPdf(contractId, contract.reference);
      return this.contractsService.findById(contractId);
    }

    return this.counterSign(contractId, dto, options);
  }

  /**
   * Staff/Director/CEO counter-sign → branch on the execution path. A customs
   * border (IMPORT/EXPORT) always requires a clearance gate before any shipment;
   * who reviews differs:
   *  - Path B (customs bundled): customer uploads GL-input docs, GL reviews, GL
   *    uploads output, then GL creates the booking.
   *  - Path A (no customs): the customer clears the cargo himself and uploads his
   *    own clearance proof; Operations reviews it; then the CUSTOMER books.
   * DOMESTIC/intercity has no border, so it goes straight to executed.
   */
  async counterSign(
    contractId: string,
    dto: SignContractDto,
    options: { signerUserId?: string },
  ): Promise<Contract> {
    const contract = await this.contractsService.findById(contractId);
    assertContractStatus(contract, ['SIGNED_CUSTOMER']);

    await this.applySignature(contract, dto, options);

    const now = new Date();
    const updates: Record<string, unknown> = {
      fullyExecutedAt: now,
      lockedAt: now,
    };

    // A clearance gate applies whenever a clearance doc set resolves — Path B
    // (customs) or Path A self-clearance (IMPORT/EXPORT without customs). DOMESTIC
    // resolves to null on both paths and skips straight to executed.
    const clearanceCode = contractClearanceSettingCode(
      contract.tradeDirection,
      contract.freightType,
      contract.customsClearingEnabled ?? false,
    );

    // GENERAL + customs (Path B) runs clearance PER BOOKING, not at the contract
    // level: there is no contract clearance cycle. The contract just becomes
    // active; the customer then files shipment requests and GL books + clears
    // each one. ONE_TIME customs and Path A self-clearance keep the contract
    // cycle below.
    const isGeneralCustoms =
      contract.contractKind === 'GENERAL' &&
      Boolean(contract.customsClearingEnabled);

    if (clearanceCode && !isGeneralCustoms) {
      // Open a clearance cycle, seed the pre-booking milestones, and route the
      // customer to upload. Path A is ops-reviewed; Path B is GL-reviewed — the
      // distinction is enforced at the review/finalize endpoints, not here.
      const cycleNumber = (contract.clearanceCycleNumber ?? 0) + 1;
      const cycle = await this.contractsRepository.openCycle(contractId, cycleNumber);
      await this.milestoneService.seedPreBookingMilestones(contract, cycle.id);
      updates.status = 'AWAITING_CLEARANCE_DOCUMENTS';
      updates.clearanceStatus = 'AWAITING_DOCUMENTS';
      updates.clearanceCycleNumber = cycleNumber;
    } else {
      // No contract-level clearance gate — DOMESTIC, or GENERAL+customs (which
      // clears per booking). Ready for shipment requests / direct booking.
      updates.status =
        contract.contractKind === 'GENERAL' ? 'CONTRACT_ACTIVE' : 'FULLY_EXECUTED';
      updates.clearanceStatus = 'NOT_APPLICABLE';
    }

    await this.contractsRepository.update(contractId, updates as never);
    await this.regenerateContractPdf(contractId, contract.reference);
    return this.contractsService.findById(contractId);
  }

  /** Customer requests renewal → RENEWAL_DRAFT linked via renewalOfId. */
  async renew(contractId: string, userId?: string): Promise<Contract> {
    const source = await this.contractsService.findById(contractId);

    const reference = await this.generateRenewalReference();
    const renewal = await this.contractsRepository.create({
      reference,
      companyId: source.companyId,
      companyProfileId: source.companyProfileId,
      isGovernment: source.isGovernment,
      governmentInstitution: source.governmentInstitution,
      contractKind: source.contractKind,
      renewalOfId: source.id,
      tradeDirection: source.tradeDirection,
      freightType: source.freightType,
      serviceTypeId: source.serviceTypeId,
      paymentCurrency: source.paymentCurrency,
      customsClearingEnabled: source.customsClearingEnabled,
      customsClearingAgent: source.customsClearingAgent,
      equipmentReturn: source.equipmentReturn,
      firstMilePickupAddress: source.firstMilePickupAddress,
      firstMilePickupLat: source.firstMilePickupLat,
      firstMilePickupLng: source.firstMilePickupLng,
      lastMileDeliveryAddress: source.lastMileDeliveryAddress,
      lastMileDeliveryLat: source.lastMileDeliveryLat,
      lastMileDeliveryLng: source.lastMileDeliveryLng,
      isHazardous: source.isHazardous,
      isReefer: source.isReefer,
      contractType: source.contractType,
      versionNumber: (source.versionNumber ?? 1) + 1,
      status: 'RENEWAL_DRAFT',
      clearanceStatus: 'NOT_APPLICABLE',
      clearanceCycleNumber: 0,
    } as never);

    void userId;
    return this.contractsService.findById(renewal.id);
  }

  private async generateRenewalReference(): Promise<string> {
    const year = new Date().getFullYear();
    const count = await this.contractsRepository.countByYear(year);
    return `CTR-${year}-${String(count + 1).padStart(5, '0')}`;
  }
}