import { createHash } from 'node:crypto';
import { mkdir, readFile, stat, writeFile } from 'node:fs/promises';
import { isAbsolute, parse, resolve } from 'node:path';
import { ConfigService } from '@nestjs/config';
import { Injectable, InternalServerErrorException, NotFoundException } from '@nestjs/common';
import { DataSource } from 'typeorm';
import { buildInspectionActPdf } from './inspection-act-pdf-builder';

@Injectable()
export class InspectionActPdfService {
  private readonly root:string;
  constructor(private readonly dataSource:DataSource, config:ConfigService){ const configured=config.get<string>('INSPECTION_ACT_PDF_ROOT')??'/app/storage/asset-media/inspection-acts-pdf'; if(!isAbsolute(configured))throw new Error('INSPECTION_ACT_PDF_ROOT must be an absolute path'); this.root=resolve(configured); if(this.root===parse(this.root).root)throw new Error('INSPECTION_ACT_PDF_ROOT cannot be the filesystem root'); }

  async ensure(actId:string):Promise<void>{
    const [row]=await this.dataSource.query(`SELECT a.id,a.code,a.closure_sha256 AS "closureSha256",c.final_snapshot AS "finalSnapshot",p.status,p.stored_name AS "storedName" FROM inspection_acts a JOIN inspection_act_closures c ON c.act_id=a.id LEFT JOIN inspection_act_pdf_artifacts p ON p.act_id=a.id WHERE a.id=$1 AND a.status='CLOSED'`,[actId]) as Array<{id:string;code:string;closureSha256:string;finalSnapshot:Record<string,unknown>;status:string|null;storedName:string|null}>;
    if(!row)throw new NotFoundException({code:'INSPECTION_ACT_NOT_CLOSED',message:'El acta cerrada no está disponible'});
    if(row.status==='READY'&&row.storedName){ try{ await this.content(actId); return; }catch{} }
    await this.dataSource.query(`INSERT INTO inspection_act_pdf_artifacts (act_id,status) VALUES ($1,'PENDING') ON CONFLICT (act_id) DO UPDATE SET status='PENDING',error=NULL,updated_at=CURRENT_TIMESTAMP`,[actId]);
    try{
      const snapshot={...row.finalSnapshot,finalSha256:row.closureSha256}; const built=buildInspectionActPdf(snapshot); await mkdir(this.root,{recursive:true,mode:0o700}); const storedName=`${actId}.pdf`; const originalName=`${row.code}.pdf`; const filePath=resolve(this.root,storedName); await writeFile(filePath,built.buffer,{mode:0o600});
      await this.dataSource.query(`UPDATE inspection_act_pdf_artifacts SET status='READY',original_name=$2,stored_name=$3,mime_type='application/pdf',size_bytes=$4,sha256=$5,generated_at=CURRENT_TIMESTAMP,error=NULL,updated_at=CURRENT_TIMESTAMP WHERE act_id=$1`,[actId,originalName,storedName,built.buffer.length,built.sha256]);
    }catch(error){ const message=error instanceof Error?error.message.slice(0,500):'Error desconocido'; await this.dataSource.query(`UPDATE inspection_act_pdf_artifacts SET status='FAILED',error=$2,updated_at=CURRENT_TIMESTAMP WHERE act_id=$1`,[actId,message]).catch(()=>undefined); }
  }

  async content(actId:string):Promise<{buffer:Buffer;originalName:string;mimeType:string}>{ const [row]=await this.dataSource.query(`SELECT original_name AS "originalName",stored_name AS "storedName",mime_type AS "mimeType",size_bytes::integer AS "sizeBytes",sha256 FROM inspection_act_pdf_artifacts WHERE act_id=$1 AND status='READY'`,[actId]) as Array<{originalName:string;storedName:string;mimeType:string;sizeBytes:number;sha256:string}>; if(!row)throw new NotFoundException({code:'INSPECTION_ACT_PDF_NOT_READY',message:'El PDF del acta todavía no está disponible'}); const filePath=resolve(this.root,row.storedName); if(!filePath.startsWith(`${this.root}/`))throw this.storageError(); const st=await stat(filePath).catch(()=>null); if(!st?.isFile()||st.size!==row.sizeBytes)throw this.storageError(); const buffer=await readFile(filePath); if(createHash('sha256').update(buffer).digest('hex')!==row.sha256)throw this.storageError(); return {buffer,originalName:row.originalName,mimeType:row.mimeType}; }
  private storageError(){return new InternalServerErrorException({code:'INSPECTION_ACT_PDF_STORAGE_ERROR',message:'El PDF del acta no está disponible o no supera la validación de integridad'});}
}