import { Injectable, Logger } from '@nestjs/common';
import { spawn } from 'child_process';
import * as path from 'path';
import { config } from '../config';

const PYTHON_DIR = path.resolve(__dirname, '..', '..', 'python');

export interface CloudStats {
  count: number;
  mean_nn: number;
  median_nn: number;
  std_nn: number;
  bbox: { xmin: number; xmax: number; ymin: number; ymax: number; zmin: number; zmax: number };
  /** 0.1e et 1er percentile de Z : estimateurs robustes du plan de reference, voir CONCEPT.md §7.7 */
  z_p01: number;
  z_p1: number;
  approximate: boolean;
}

/** Wrapper autour des scripts python/*.py (statistiques + generation d'images). */
@Injectable()
export class PyHelperService {
  private readonly logger = new Logger(PyHelperService.name);

  private async runJson(scriptRelPath: string, args: string[]): Promise<any> {
    const scriptPath = path.join(PYTHON_DIR, scriptRelPath);
    return new Promise((resolve, reject) => {
      const child = spawn(config.pythonBin, [scriptPath, ...args], { windowsHide: true });
      let stdout = '';
      let stderr = '';
      child.stdout.on('data', (d) => (stdout += d.toString()));
      child.stderr.on('data', (d) => (stderr += d.toString()));
      child.on('error', (err) => reject(new Error(`Impossible de lancer python (${config.pythonBin}): ${err.message}`)));
      child.on('close', (code) => {
        if (stderr) this.logger.warn(`${scriptRelPath} stderr: ${stderr.trim()}`);
        const trimmed = stdout.trim();
        if (!trimmed) {
          reject(new Error(`${scriptRelPath} n'a produit aucune sortie (code ${code}). stderr: ${stderr}`));
          return;
        }
        let parsed: any;
        try {
          parsed = JSON.parse(trimmed.split('\n').pop()!);
        } catch {
          reject(new Error(`Sortie JSON invalide de ${scriptRelPath}: ${trimmed}`));
          return;
        }
        if (parsed.error) {
          reject(new Error(`${scriptRelPath}: ${parsed.error}`));
          return;
        }
        resolve(parsed);
      });
    });
  }

  computeStats(xyzSamplePath: string): Promise<CloudStats> {
    return this.runJson('stats_helper.py', ['--input', xyzSamplePath]);
  }

  /**
   * Carte de comparaison unique (bleu->rouge) entre le nuage du dessus (ceil) et soit un plan Z
   * constant (mode const_height, groundXyzPath=null), soit le nuage du dessous (mode
   * cloud_compare, constHeight=null). Remplace les cartes de hauteur separees par nuage.
   */
  renderDiffmap(
    ceilXyzPath: string,
    groundXyzPath: string | null,
    constHeight: number | null,
    gridStep: number,
    outputPngPath: string,
    title: string,
  ): Promise<void> {
    const args = ['diffmap', '--ceil', ceilXyzPath, '--gridstep', String(gridStep), '--output', outputPngPath, '--title', title];
    if (groundXyzPath) args.push('--ground', groundXyzPath);
    if (constHeight !== null) args.push('--const-height', String(constHeight));
    return this.runJson('render_images.py', args);
  }

  renderSummary(reportJsonPath: string, outDir: string): Promise<void> {
    return this.runJson('render_images.py', ['summary', '--report', reportJsonPath, '--outdir', outDir]);
  }

  /**
   * Le paquet apt CloudCompare (Debian) ne fournit pas le plugin LAS/LAZ (seulement "Core I/O").
   * On convertit donc les entrees LAS/LAZ/COPC en ASCII XYZ via laspy avant de les transmettre
   * a CloudCompare, qui lit nativement le format ASCII sans plugin.
   */
  /**
   * offsetX/offsetY : decalage (en metres, arrondi au metre) soustrait de X/Y avant ecriture, voir
   * CONCEPT.md §7.2. Necessaire en coordonnees projetees (ex. Lambert-93, X/Y ~ 10^6-10^7 m) ou la
   * precision float32 interne de CloudCompare degraderait sinon la position des points a l'echelle
   * du decimetre. Le volume 2.5D etant invariant par translation, ce decalage n'affecte pas le
   * resultat - seul zref (mode const_height) reste en coordonnees Z non decalees.
   */
  async convertLasToXyz(inputPath: string, outputXyzPath: string): Promise<{ count: number; offsetX: number; offsetY: number }> {
    return this.runJson('las_to_xyz.py', ['--input', inputPath, '--output', outputXyzPath]);
  }
}