import { Injectable, Logger } from '@nestjs/common';
import sharp from 'sharp';
import { ProcessImageDto } from './dto';

interface WatermarkPosition {
  left: number;
  top: number;
}

@Injectable()
export class ImageProcessorService {
  private readonly logger = new Logger(ImageProcessorService.name);

  async processImage(
    inputBuffer: Buffer,
    options: ProcessImageDto,
  ): Promise<Buffer> {
    let pipeline = sharp(inputBuffer);

    if (options.width || options.height) {
      pipeline = pipeline.resize(options.width, options.height, {
        fit: (options.fit as any) || 'inside',
        withoutEnlargement: true,
      });
    }

    if (options.format) {
      pipeline = pipeline.toFormat(options.format, {
        quality: options.quality || 80,
      });
    } else if (options.quality) {
      const metadata = await sharp(inputBuffer).metadata();
      const format = metadata.format as keyof sharp.FormatEnum;
      if (format) {
        pipeline = pipeline.toFormat(format, {
          quality: options.quality,
        });
      }
    }

    if (options.watermarkText || options.watermarkImage) {
      pipeline = await this.applyWatermark(
        pipeline,
        inputBuffer,
        options as ProcessImageDto & { watermarkText?: string; watermarkImage?: string },
      );
    }

    return pipeline.toBuffer();
  }

  private async applyWatermark(
    pipeline: sharp.Sharp,
    originalBuffer: Buffer,
    options: ProcessImageDto & { watermarkText?: string; watermarkImage?: string },
  ): Promise<sharp.Sharp> {
    const metadata = await sharp(originalBuffer).metadata();
    const width = metadata.width || 0;
    const height = metadata.height || 0;

    let watermarkBuffer: Buffer;

    if (options.watermarkImage) {
      watermarkBuffer = Buffer.from(options.watermarkImage, 'base64');
    } else if (options.watermarkText) {
      watermarkBuffer = await this.createTextWatermark(
        options.watermarkText,
        width,
        height,
      );
    } else {
      return pipeline;
    }

    const position = this.calculatePosition(
      width,
      height,
      options.watermarkPosition || 'bottom-right',
    );

    return pipeline.composite([
      {
        input: watermarkBuffer,
        left: position.left,
        top: position.top,
        opacity: options.watermarkOpacity || 0.3,
      },
    ]);
  }

  private async createTextWatermark(
    text: string,
    _width: number,
    _height: number,
  ): Promise<Buffer> {
    const svg = `
      <svg width="300" height="100">
        <style>
          .watermark {
            fill: rgba(255, 255, 255, 0.8);
            font-size: 24px;
            font-family: Arial, sans-serif;
            font-weight: bold;
          }
        </style>
        <text x="150" y="60" text-anchor="middle" class="watermark">${text}</text>
      </svg>
    `;
    return sharp(Buffer.from(svg)).png().toBuffer();
  }

  private calculatePosition(
    imageWidth: number,
    imageHeight: number,
    position: string,
    watermarkWidth = 300,
    watermarkHeight = 100,
  ): WatermarkPosition {
    const padding = 20;

    switch (position) {
      case 'top-left':
        return { left: padding, top: padding };
      case 'top-right':
        return { left: imageWidth - watermarkWidth - padding, top: padding };
      case 'bottom-left':
        return { left: padding, top: imageHeight - watermarkHeight - padding };
      case 'center':
        return {
          left: (imageWidth - watermarkWidth) / 2,
          top: (imageHeight - watermarkHeight) / 2,
        };
      case 'bottom-right':
      default:
        return {
          left: imageWidth - watermarkWidth - padding,
          top: imageHeight - watermarkHeight - padding,
        };
    }
  }

  async getImageMetadata(buffer: Buffer): Promise<sharp.Metadata> {
    return sharp(buffer).metadata();
  }

  async generateThumbnail(
    buffer: Buffer,
    size = 200,
  ): Promise<Buffer> {
    return sharp(buffer)
      .resize(size, size, {
        fit: 'cover',
        withoutEnlargement: true,
      })
      .jpeg({ quality: 80 })
      .toBuffer();
  }

  async optimizeImage(
    buffer: Buffer,
    maxWidth = 1920,
    quality = 85,
  ): Promise<Buffer> {
    return sharp(buffer)
      .resize(maxWidth, null, {
        withoutEnlargement: true,
      })
      .jpeg({ quality })
      .toBuffer();
  }
}