import { Injectable } from '@nestjs/common';
import { mkdir, access } from 'node:fs/promises';
import { constants } from 'node:fs';
import { dirname, join } from 'node:path';
import { AppConfigService } from '../config/config.service';

export interface StorageStatus {
  root: string;
  writable: boolean;
}

@Injectable()
export class LocalFilesystemStorageService {
  constructor(private readonly configService: AppConfigService) {}

  get root(): string {
    return this.configService.storageRoot;
  }

  resolve(relativePath: string): string {
    return join(this.root, relativePath);
  }

  userAudioAssetStorageKey(userId: string, sha256: string): string {
    return join('users', userId, 'audio', `${sha256}.mp3`);
  }

  userAudioAssetPath(userId: string, sha256: string): string {
    return this.resolve(this.userAudioAssetStorageKey(userId, sha256));
  }

  userArtworkAssetStorageKey(
    userId: string,
    sha256: string,
    fileExtension: string,
  ): string {
    return join('users', userId, 'artwork', `${sha256}.${fileExtension}`);
  }

  userArtworkAssetPath(
    userId: string,
    sha256: string,
    fileExtension: string,
  ): string {
    return this.resolve(
      this.userArtworkAssetStorageKey(userId, sha256, fileExtension),
    );
  }

  tempUploadStorageKey(uploadId: string): string {
    return join('temp', 'uploads', `${uploadId}.part`);
  }

  tempUploadPath(uploadId: string): string {
    return this.resolve(this.tempUploadStorageKey(uploadId));
  }

  async ensureDirectory(path: string): Promise<void> {
    await mkdir(path, { recursive: true });
  }

  async ensureParentDirectory(path: string): Promise<void> {
    await this.ensureDirectory(dirname(path));
  }

  async checkReadiness(): Promise<StorageStatus> {
    const paths = [
      this.root,
      join(this.root, 'users'),
      join(this.root, 'temp'),
      join(this.root, 'temp', 'uploads'),
      join(this.root, 'incoming'),
      join(this.root, 'quarantine'),
      join(this.root, 'library', 'audio'),
      join(this.root, 'library', 'artwork'),
    ];

    for (const path of paths) {
      await mkdir(path, { recursive: true });
      await access(path, constants.R_OK | constants.W_OK);
    }

    return {
      root: this.root,
      writable: true,
    };
  }
}