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

const WORD_MIME = 'application/vnd.openxmlformats-officedocument.wordprocessingml.document';

interface WordRow {
  id: string;
  code: string;
  title: string;
  executiveSummary: string | null;
  reportDescription: string | null;
  generatedAt: Date;
  frozenSha256: string;
  frozenSnapshot: Record<string, unknown>;
  wordStatus: 'PENDING' | 'READY' | 'FAILED';
  wordOriginalName: string | null;
  wordStoredName: string | null;
  wordMimeType: string | null;
  wordSizeBytes: number | null;
  wordSha256: string | null;
  generatedBy: string;
}

@Injectable()
export class InspectionReportWordService {
  private readonly root: string;

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

  async ensure(reportId: string): Promise<void> {
    const row = await this.load(reportId);
    if (row.wordStatus === 'READY' && row.wordStoredName) {
      try {
        await this.content(row.id);
        await this.ensureInitialRevision(row);
        return;
      } catch {}
    }
    try {
      const built = buildInspectionReportWord({
        code: row.code,
        title: row.title,
        generatedAt: new Date(row.generatedAt),
        frozenSha256: row.frozenSha256,
        frozenSnapshot: row.frozenSnapshot,
        executiveSummary: row.executiveSummary,
        reportDescription: row.reportDescription,
      });
      await mkdir(this.root, { recursive: true, mode: 0o700 });
      const storedName = `${row.id}-${built.sha256.slice(0, 16)}.docx`;
      const originalName = `${row.code}.docx`;
      const filePath = resolve(this.root, storedName);
      await writeFile(filePath, built.buffer, { mode: 0o600 });
      await this.dataSource.query(`
        UPDATE inspection_reports
        SET word_status='READY',
            word_original_name=$2,
            word_stored_name=$3,
            word_mime_type=$4,
            word_size_bytes=$5,
            word_sha256=$6,
            word_generated_at=CURRENT_TIMESTAMP,
            word_error=NULL,
            updated_at=CURRENT_TIMESTAMP
        WHERE id=$1
      `, [row.id, originalName, storedName, WORD_MIME, built.buffer.length, built.sha256]);
      await this.ensureInitialRevision(await this.load(row.id));
    } catch (error) {
      const message = error instanceof Error ? error.message.slice(0, 500) : 'Error desconocido';
      await this.dataSource.query(`
        UPDATE inspection_reports
        SET word_status='FAILED',word_error=$2,updated_at=CURRENT_TIMESTAMP
        WHERE id=$1
      `, [row.id, message]).catch(() => undefined);
    }
  }

  async content(reportId: string): Promise<{ filePath: string; originalName: string; mimeType: string }> {
    const row = await this.load(reportId);
    if (
      row.wordStatus !== 'READY'
      || !row.wordStoredName
      || !row.wordOriginalName
      || !row.wordSha256
      || !row.wordSizeBytes
    ) {
      throw new NotFoundException({
        code: 'INSPECTION_REPORT_WORD_NOT_READY',
        message: 'El archivo Word del informe todavía no está disponible',
      });
    }
    const filePath = resolve(this.root, row.wordStoredName);
    if (!filePath.startsWith(`${this.root}/`)) throw this.storageError();
    const fileStat = await stat(filePath).catch(() => null);
    if (!fileStat?.isFile() || fileStat.size !== row.wordSizeBytes) throw this.storageError();
    const buffer = await readFile(filePath);
    const sha256 = createHash('sha256').update(buffer).digest('hex');
    if (sha256 !== row.wordSha256) throw this.storageError();
    return {
      filePath,
      originalName: row.wordOriginalName,
      mimeType: row.wordMimeType ?? WORD_MIME,
    };
  }

  private async ensureInitialRevision(row: WordRow): Promise<void> {
    if (
      row.wordStatus !== 'READY'
      || !row.wordOriginalName
      || !row.wordStoredName
      || !row.wordMimeType
      || !row.wordSizeBytes
      || !row.wordSha256
    ) return;
    await this.dataSource.query(`
      INSERT INTO inspection_report_revisions (
        report_id,revision_number,source,original_name,stored_name,mime_type,
        size_bytes,sha256,change_summary,created_by,created_at
      ) VALUES (
        $1,1,'AUTO',$2,$3,$4,$5,$6,'Versión automática inicial editable',$7,
        COALESCE((SELECT word_generated_at FROM inspection_reports WHERE id=$1),CURRENT_TIMESTAMP)
      )
      ON CONFLICT (report_id,revision_number) DO NOTHING
    `, [
      row.id,
      row.wordOriginalName,
      row.wordStoredName,
      row.wordMimeType,
      row.wordSizeBytes,
      row.wordSha256,
      row.generatedBy,
    ]);
    await this.dataSource.query(`
      UPDATE inspection_reports
      SET current_revision_number=GREATEST(current_revision_number,1),updated_at=CURRENT_TIMESTAMP
      WHERE id=$1
    `, [row.id]);
  }

  private async load(reportId: string): Promise<WordRow> {
    const [row] = await this.dataSource.query(`
      SELECT id,code,title,
             executive_summary AS "executiveSummary",
             report_description AS "reportDescription",
             generated_at AS "generatedAt",
             frozen_sha256 AS "frozenSha256",
             frozen_snapshot AS "frozenSnapshot",
             word_status AS "wordStatus",
             word_original_name AS "wordOriginalName",
             word_stored_name AS "wordStoredName",
             word_mime_type AS "wordMimeType",
             word_size_bytes::integer AS "wordSizeBytes",
             word_sha256 AS "wordSha256",
             generated_by AS "generatedBy"
      FROM inspection_reports
      WHERE id=$1
    `, [reportId]) as WordRow[];
    if (!row) {
      throw new NotFoundException({
        code: 'INSPECTION_REPORT_NOT_FOUND',
        message: 'Informe de inspección no encontrado',
      });
    }
    return row;
  }

  private storageError(): InternalServerErrorException {
    return new InternalServerErrorException({
      code: 'INSPECTION_REPORT_WORD_STORAGE_ERROR',
      message: 'El archivo Word del informe no está disponible o no supera la validación de integridad',
    });
  }
}