import { HttpStatus, Injectable } from '@nestjs/common';
import { ConfigService } from '@nestjs/config';
import type { ToolArtifact } from '@prisma/client';
import { createReadStream, existsSync } from 'fs';
import { mkdir, writeFile } from 'fs/promises';
import { dirname, resolve } from 'path';
import { Readable } from 'stream';
import { ERROR_CODES } from '../../common/constants/error-codes';
import { AppException } from '../../common/exceptions/app.exception';

export interface ArtifactDownloadStream {
  stream: NodeJS.ReadableStream;
  fileName: string;
  mimeType?: string;
  fileSize: number;
}

export interface ArtifactUploadInput {
  toolId: string;
  version: string;
  fileName: string;
  mimeType?: string;
  buffer: Buffer;
}

export interface ArtifactUploadResult {
  gitlabProjectId: number;
  gitlabPackageName: string;
  gitlabPackageVersion: string;
  gitlabFilePath: string;
}

@Injectable()
export class GitlabStorageService {
  constructor(private readonly configService: ConfigService) {}

  async getArtifactStream(artifact: ToolArtifact): Promise<ArtifactDownloadStream> {
    const gitlabApiBase = this.configService.get<string>('GITLAB_API_BASE');
    const gitlabToken = this.configService.get<string>('GITLAB_TOKEN');

    if (gitlabApiBase && gitlabToken && artifact.gitlabProjectId > 0) {
      return this.downloadFromGitlab(artifact, gitlabApiBase, gitlabToken);
    }

    return this.readFromLocalStorage(artifact);
  }

  async uploadArtifact(input: ArtifactUploadInput): Promise<ArtifactUploadResult> {
    const gitlabApiBase = this.configService.get<string>('GITLAB_API_BASE');
    const gitlabToken = this.configService.get<string>('GITLAB_TOKEN');
    const projectId = Number(this.configService.get<string>('GITLAB_PROJECT_ID', '0'));
    const packagePrefix = this.configService.get<string>('GITLAB_PACKAGE_NAME_PREFIX', 'toolsshow');
    const packageName = `${packagePrefix}/${input.toolId}`;

    if (gitlabApiBase && gitlabToken && projectId > 0) {
      const url = `${gitlabApiBase}/projects/${encodeURIComponent(
        String(projectId),
      )}/packages/generic/${encodeURIComponent(packageName)}/${encodeURIComponent(
        input.version,
      )}/${encodeURIComponent(input.fileName)}`;

      const response = await fetch(url, {
        method: 'PUT',
        headers: {
          'PRIVATE-TOKEN': gitlabToken,
          'Content-Type': input.mimeType ?? 'application/octet-stream',
        },
        body: input.buffer as unknown as BodyInit,
      });

      if (!response.ok) {
        throw new AppException(
          ERROR_CODES.GITLAB_UPLOAD_FAILED,
          'failed to upload artifact to GitLab',
          HttpStatus.BAD_GATEWAY,
        );
      }

      return {
        gitlabProjectId: projectId,
        gitlabPackageName: packageName,
        gitlabPackageVersion: input.version,
        gitlabFilePath: `${packageName}/${input.version}/${input.fileName}`,
      };
    }

    const localRelativePath = `storage/uploads/${input.toolId}/${input.version}/${input.fileName}`;
    const localAbsolutePath = resolve(process.cwd(), localRelativePath);
    await mkdir(dirname(localAbsolutePath), { recursive: true });
    await writeFile(localAbsolutePath, input.buffer);

    return {
      gitlabProjectId: 0,
      gitlabPackageName: packageName,
      gitlabPackageVersion: input.version,
      gitlabFilePath: localRelativePath.replace(/\\/g, '/'),
    };
  }

  private async downloadFromGitlab(
    artifact: ToolArtifact,
    gitlabApiBase: string,
    gitlabToken: string,
  ): Promise<ArtifactDownloadStream> {
    const url = `${gitlabApiBase}/projects/${encodeURIComponent(
      String(artifact.gitlabProjectId),
    )}/packages/generic/${encodeURIComponent(artifact.gitlabPackageName)}/${encodeURIComponent(
      artifact.gitlabPackageVersion,
    )}/${encodeURIComponent(artifact.fileName)}`;

    const response = await fetch(url, {
      headers: {
        'PRIVATE-TOKEN': gitlabToken,
      },
    });

    if (!response.ok || !response.body) {
      throw new AppException(
        ERROR_CODES.GITLAB_DOWNLOAD_FAILED,
        'failed to download artifact from GitLab',
        HttpStatus.BAD_GATEWAY,
      );
    }

    return {
      stream: Readable.fromWeb(response.body as any),
      fileName: artifact.fileName,
      mimeType: artifact.mimeType ?? undefined,
      fileSize: artifact.fileSizeBytes,
    };
  }

  private readFromLocalStorage(artifact: ToolArtifact): ArtifactDownloadStream {
    const filePath = resolve(process.cwd(), artifact.gitlabFilePath);
    if (!existsSync(filePath)) {
      throw new AppException(
        ERROR_CODES.GITLAB_DOWNLOAD_FAILED,
        `artifact file not found: ${artifact.gitlabFilePath}`,
        HttpStatus.NOT_FOUND,
      );
    }

    return {
      stream: createReadStream(filePath),
      fileName: artifact.fileName,
      mimeType: artifact.mimeType ?? undefined,
      fileSize: artifact.fileSizeBytes,
    };
  }
}