import { Injectable, Logger, NotFoundException, BadRequestException } from '@nestjs/common';
import { InjectRepository } from '@nestjs/typeorm';
import { Repository, LessThan, IsNull } from 'typeorm';
import { Subject, Observable } from 'rxjs';
import { LabelPrintJob } from '../database/entities/label-print-job.entity';
import { BarcodeTemplate } from '../database/entities/barcode-template.entity';
import { LabelRendererService } from './label-renderer.service';

function isSafeUrl(url: string): boolean {
  try {
    const parsed = new URL(url);
    return parsed.protocol === 'http:' || parsed.protocol === 'https:';
  } catch {
    return false;
  }
}

function applyVars(template: string, vars: Record<string, string>): string {
  return template.replace(/\{([^}]+)\}/g, (_, key: string) => {
    const colonIdx = key.indexOf(':');
    if (colonIdx !== -1) {
      const varName = key.slice(0, colonIdx);
      const width = parseInt(key.slice(colonIdx + 1), 10);
      if (!isNaN(width) && varName in vars) {
        return vars[varName].padStart(width, '0');
      }
    }
    return vars[key] ?? '';
  });
}

function lockExpiry(): Date {
  const d = new Date();
  d.setMinutes(d.getMinutes() - 5);
  return d;
}

@Injectable()
export class LabelPrintAgentService {
  private readonly logger = new Logger(LabelPrintAgentService.name);
  private readonly jobCreated$ = new Subject<void>();

  get newJob$(): Observable<void> {
    return this.jobCreated$.asObservable();
  }

  constructor(
    @InjectRepository(LabelPrintJob)
    private readonly jobRepo: Repository<LabelPrintJob>,
    @InjectRepository(BarcodeTemplate)
    private readonly templateRepo: Repository<BarcodeTemplate>,
    private readonly renderer: LabelRendererService,
  ) {}

  async createJob(
    templateId: number,
    fieldValues: Record<string, string>,
  ): Promise<LabelPrintJob> {
    const template = await this.templateRepo.findOne({ where: { Id: templateId } });
    if (!template) throw new NotFoundException('Template nicht gefunden');
    if (!template.LabelEnabled) throw new BadRequestException('Etikett-Druck für dieses Template nicht aktiviert');

    // Variablen aufbauen
    const vars: Record<string, string> = { ...fieldValues };

    // Datum-Felder: year/month/day separat ablegen
    for (const field of template.LabelInputFields ?? []) {
      if (field.type === 'date' && fieldValues[field.name]) {
        const raw = fieldValues[field.name]; // erwartet YYYY-MM-DD
        const parts = raw.split('-');
        if (parts.length === 3) {
          vars[field.name] = `${parts[2]}.${parts[1]}.${parts[0]}`; // dd.MM.yyyy
          vars[`${field.name}.year`] = parts[0];
          vars[`${field.name}.month`] = parts[1];
          vars[`${field.name}.day`] = parts[2];
        }
      }
    }

    // GET-URL aufrufen → {number}
    if (template.LabelGetUrl) {
      const url = applyVars(template.LabelGetUrl, vars);
      if (isSafeUrl(url)) {
        try {
          const res = await fetch(url);
          const text = (await res.text()).trim();
          vars['number'] = text;
        } catch (err: any) {
          this.logger.warn(`GET-URL fehlgeschlagen (${url}): ${err.message}`);
        }
      } else {
        this.logger.warn(`GET-URL übersprungen (ungültiges Protokoll): ${url}`);
      }
    }

    const job = this.jobRepo.create({
      Status: 'pending',
      LabelImageData: null,
      LabelWidthMm: template.LabelWidthMm ?? 57,
      LabelHeightMm: template.LabelHeightMm ?? 32,
      BarcodeTemplateId: template.Id,
      LabelVariables: vars,
      LockedAt: null,
      LockedByAgent: null,
    });

    const saved = await this.jobRepo.save(job);
    this.jobCreated$.next();
    return saved;
  }

  async claimNextJob(agentId: string): Promise<LabelPrintJob | null> {
    // Kandidat: pending und kein Lock oder Lock abgelaufen (> 5 Min)
    const candidate = await this.jobRepo.findOne({
      where: [
        { Status: 'pending', LockedAt: IsNull() },
        { Status: 'pending', LockedAt: LessThan(lockExpiry()) },
      ],
      order: { CreatedAt: 'ASC' },
    });
    if (!candidate) return null;

    // Lock setzen
    candidate.LockedAt = new Date();
    candidate.LockedByAgent = agentId;
    await this.jobRepo.save(candidate);

    // Lazy render
    if (!candidate.LabelImageData) {
      const template = await this.templateRepo.findOne({ where: { Id: candidate.BarcodeTemplateId ?? undefined } });
      if (template?.LabelLayout?.length) {
        try {
          candidate.LabelImageData = await this.renderer.render(
            template.LabelLayout,
            candidate.LabelWidthMm,
            candidate.LabelHeightMm,
            candidate.LabelVariables ?? {},
          );
          await this.jobRepo.save(candidate);
        } catch (err: any) {
          this.logger.error(`Label-Rendering fehlgeschlagen für Job ${candidate.Id}: ${err.message}`);
        }
      }
    }

    return candidate;
  }

  async getJobImage(jobId: number): Promise<Buffer | null> {
    const job = await this.jobRepo.findOne({ where: { Id: jobId } });
    return job?.LabelImageData ?? null;
  }

  async markPrinted(jobId: number, agentId: string, printerName: string): Promise<void> {
    const job = await this.jobRepo.findOne({ where: { Id: jobId } });
    if (!job) throw new NotFoundException('Job nicht gefunden');

    job.Status = 'printed';
    job.PrintedAt = new Date();
    job.PrintedByAgent = agentId;
    job.PrinterName = printerName;
    await this.jobRepo.save(job);

    await this.callUrl('PRINTED', job);
  }

  async markError(jobId: number, agentId: string, printerName: string, errorMessage: string): Promise<void> {
    const job = await this.jobRepo.findOne({ where: { Id: jobId } });
    if (!job) throw new NotFoundException('Job nicht gefunden');

    job.Status = 'error';
    job.PrintedByAgent = agentId;
    job.PrinterName = printerName;
    job.ErrorMessage = errorMessage;
    await this.jobRepo.save(job);

    await this.callUrl('RELEASE', job);
  }

  async renderPreview(templateId: number, fieldValues: Record<string, string>): Promise<Buffer> {
    const template = await this.templateRepo.findOne({ where: { Id: templateId } });
    if (!template) throw new NotFoundException('Template nicht gefunden');
    if (!template.LabelLayout?.length) throw new BadRequestException('Kein Layout definiert');

    const vars: Record<string, string> = { ...fieldValues };
    for (const field of template.LabelInputFields ?? []) {
      if (field.type === 'date' && fieldValues[field.name]) {
        const parts = fieldValues[field.name].split('-');
        if (parts.length === 3) {
          vars[field.name] = `${parts[2]}.${parts[1]}.${parts[0]}`; // dd.MM.yyyy
          vars[`${field.name}.year`] = parts[0];
          vars[`${field.name}.month`] = parts[1];
          vars[`${field.name}.day`] = parts[2];
        }
      }
    }
    vars['number'] = '1';

    return this.renderer.render(
      template.LabelLayout,
      template.LabelWidthMm ?? 57,
      template.LabelHeightMm ?? 32,
      vars,
    );
  }

  private async callUrl(type: 'PRINTED' | 'RELEASE', job: LabelPrintJob): Promise<void> {
    const template = job.BarcodeTemplateId
      ? await this.templateRepo.findOne({ where: { Id: job.BarcodeTemplateId } })
      : null;
    if (!template) return;

    const urlTemplate = type === 'PRINTED' ? template.LabelPrintedUrl : template.LabelReleaseUrl;
    if (!urlTemplate) return;

    const url = applyVars(urlTemplate, job.LabelVariables ?? {});
    if (!isSafeUrl(url)) {
      this.logger.warn(`${type}-URL übersprungen (ungültiges Protokoll): ${url}`);
      return;
    }
    try {
      await fetch(url, { method: 'POST' });
    } catch (err: any) {
      this.logger.warn(`${type}-URL fehlgeschlagen (${url}): ${err.message}`);
    }
  }
}