api_gemini 0.5.0

//! File upload and processing pipeline implementation

use super::*;
use std::time::Instant;
use std::sync::Arc;
use core::sync::atomic::{ AtomicU64, AtomicUsize, Ordering };
use std::hash::{ Hash, Hasher };
use std::collections::hash_map::DefaultHasher;
use std::path::Path;
use bytes::{ Bytes, BytesMut };
use futures_util::Stream;
use tokio::sync::Semaphore;

/// Advanced media processing pipeline with optimization
#[ derive( Debug ) ]
pub struct MediaProcessingPipeline
{
  /// Processing configuration
  config : MediaProcessingConfig,
  /// Media cache for processed files
  cache : Arc< MediaCache >,
  /// Semaphore for controlling concurrent operations
  operation_semaphore : Arc< Semaphore >,
  /// Processing metrics
  metrics : Arc< MediaProcessingMetrics >,
  /// Thumbnail generator
  thumbnail_generator : Option< ThumbnailGenerator >,
}

/// Media processing metrics
#[ derive( Debug ) ]
pub struct MediaProcessingMetrics
{
  /// Total files processed
  pub files_processed : AtomicU64,
  /// Total bytes processed
  pub bytes_processed : AtomicU64,
  /// Total processing time in microseconds
  pub total_processing_time_us : AtomicU64,
  /// Number of failed operations
  pub failed_operations : AtomicU64,
  /// Number of retries performed
  pub retries_performed : AtomicU64,
  /// Memory usage high watermark
  pub memory_high_watermark_bytes : AtomicUsize,
}

impl Default for MediaProcessingMetrics
{
  #[ inline ]
  fn default() -> Self
  {
    Self {
      files_processed : AtomicU64::new( 0 ),
      bytes_processed : AtomicU64::new( 0 ),
      total_processing_time_us : AtomicU64::new( 0 ),
      failed_operations : AtomicU64::new( 0 ),
      retries_performed : AtomicU64::new( 0 ),
      memory_high_watermark_bytes : AtomicUsize::new( 0 ),
    }
  }
}

impl MediaProcessingPipeline
{
  /// Create a new media processing pipeline
  #[ inline ]
  #[ must_use ]
  pub fn new( config : MediaProcessingConfig ) -> Self
  {
    let cache = Arc::new( MediaCache::new( config.clone() ) );
    let operation_semaphore = Arc::new( Semaphore::new( config.max_concurrent_operations ) );
    let thumbnail_generator = config.thumbnail_config.clone().map( | cfg | ThumbnailGenerator::new( cfg ) );

    Self {
      config,
      cache,
      operation_semaphore,
      metrics : Arc::new( MediaProcessingMetrics::default() ),
      thumbnail_generator,
    }
  }

  /// Process media upload with optimization
  #[ inline ]
  pub async fn process_upload_bytes(
    &self,
    file_data : Bytes,
    mime_type : String,
    display_name : Option< String >
  ) -> Result< ProcessedMediaResult, crate::error::Error >
  {
    let start_time = Instant::now();
    let _permit = self.operation_semaphore.acquire().await.unwrap();

    // Update memory high watermark
    let current_memory = file_data.len();
    self.update_memory_watermark( current_memory );

    // Generate cache key
    let cache_key = self.generate_cache_key( &file_data, &mime_type );

    // Check cache first
    if let Some( ( cached_data, metadata ) ) = self.cache.get( &cache_key )
    {
      return Ok( ProcessedMediaResult {
        processed_data : cached_data.clone(),
        metadata : ProcessedMediaMetadata {
          original_size : metadata.original_size,
          processed_size : cached_data.len(),
          mime_type : metadata.mime_type,
          is_compressed : metadata.is_compressed,
          compression_ratio : metadata.compression_ratio,
          processing_time_ms : 0, // Cached result
          thumbnail_data : None, // xxx : Cache thumbnails
        },
        cache_hit : true,
      } );
    }

    // Process the media
    let processed_result = if file_data.len() > self.config.max_memory_file_size
    {
      self.process_large_file( file_data, mime_type.clone(), display_name ).await?
    } else {
      self.process_in_memory( file_data, mime_type.clone(), display_name ).await?
    };

    // Cache the result
    self.cache.put( cache_key, processed_result.processed_data.clone(), mime_type.clone() )?;

    // Update metrics
    let processing_time = start_time.elapsed();
    self.metrics.files_processed.fetch_add( 1, Ordering::Relaxed );
    self.metrics.bytes_processed.fetch_add( current_memory as u64, Ordering::Relaxed );
    self.metrics.total_processing_time_us.fetch_add( processing_time.as_micros() as u64, Ordering::Relaxed );

    Ok( processed_result )
  }

  /// Process file in memory (for smaller files)
  async fn process_in_memory(
    &self,
    file_data : Bytes,
    mime_type : String,
    _display_name : Option< String >
  ) -> Result< ProcessedMediaResult, crate::error::Error >
  {
    let start_time = Instant::now();
    let original_size = file_data.len();

    // Validate file format
    self.validate_file_format( &file_data, &mime_type )?;

    // Generate thumbnail if configured and applicable
    let thumbnail_data = if let Some( ref generator ) = self.thumbnail_generator
    {
      if self.is_image_type( &mime_type )
      {
        generator.generate_thumbnail( &file_data, &mime_type ).await.ok()
      } else {
        None
      }
    } else {
      None
    };

    // For optimization purposes, we'll just return the original data
    // In a real implementation, this would apply format-specific optimizations
    let processed_data = file_data;
    let processed_size = processed_data.len();

    Ok( ProcessedMediaResult {
      processed_data,
      metadata : ProcessedMediaMetadata {
        original_size,
        processed_size,
        mime_type,
        is_compressed : false,
        compression_ratio : 1.0,
        processing_time_ms : start_time.elapsed().as_millis() as u64,
        thumbnail_data,
      },
      cache_hit : false,
    } )
  }

  /// Process large file with streaming (for files exceeding memory limit)
  async fn process_large_file(
    &self,
    file_data : Bytes,
    mime_type : String,
    _display_name : Option< String >
  ) -> Result< ProcessedMediaResult, crate::error::Error >
  {
    let start_time = Instant::now();
    let original_size = file_data.len();

    // For large files, we'll process in chunks
    let chunk_size = self.config.streaming_chunk_size;
    let mut processed_chunks = Vec::new();

    for chunk in file_data.chunks( chunk_size )
    {
      // Process each chunk (in real implementation, this would be format-specific)
      processed_chunks.push( Bytes::copy_from_slice( chunk ) );
    }

    // Combine processed chunks
    let mut combined = BytesMut::new();
    for chunk in processed_chunks
    {
      combined.extend_from_slice( &chunk );
    }
    let processed_data = combined.freeze();

    Ok( ProcessedMediaResult {
      processed_data : processed_data.clone(),
      metadata : ProcessedMediaMetadata {
        original_size,
        processed_size : processed_data.len(),
        mime_type,
        is_compressed : false,
        compression_ratio : 1.0,
        processing_time_ms : start_time.elapsed().as_millis() as u64,
        thumbnail_data : None, // Skip thumbnails for large files
      },
      cache_hit : false,
    } )
  }

  /// Validate file format and detect potential issues
  fn validate_file_format( &self, file_data : &Bytes, declared_mime_type : &str ) -> Result< (), crate::error::Error >
  {
    // Basic file signature validation
    if file_data.is_empty()
    {
      return Err( crate::error::Error::ApiError( "Empty file data".to_string() ) );
    }

    // Check for basic file signatures
    let signatures = [
      ( "image/jpeg", &[ 0xFF, 0xD8, 0xFF, 0xE0 ] ),
      ( "image/png", &[ 0x89, 0x50, 0x4E, 0x47 ] ),
      ( "image/gif", &[ 0x47, 0x49, 0x46, 0x38 ] ),
      ( "application/pdf", &[ 0x25, 0x50, 0x44, 0x46 ] ),
    ];

    for ( mime_type, signature ) in &signatures
    {
      if declared_mime_type == *mime_type
      {
        if file_data.len() >= signature.len() && &file_data[ ..signature.len() ] == *signature
        {
          return Ok( () );
        }
        return Err( crate::error::Error::ApiError(
          format!( "File signature doesn't match declared MIME type : {}", declared_mime_type )
        ) );
      }
    }

    // For other types, just check if reasonable
    if file_data.len() > 100 * 1024 * 1024  // 100MB limit
    {
      return Err( crate::error::Error::ApiError( "File too large".to_string() ) );
    }

    Ok( () )
  }

  /// Check if MIME type is an image
  fn is_image_type( &self, mime_type : &str ) -> bool
  {
    mime_type.starts_with( "image/" )
  }

  /// Generate cache key for file
  fn generate_cache_key( &self, file_data : &Bytes, mime_type : &str ) -> String
  {
    let mut hasher = DefaultHasher::new();
    file_data.hash( &mut hasher );
    mime_type.hash( &mut hasher );
    format!( "media_{:x}", hasher.finish() )
  }

  /// Update memory usage high watermark
  fn update_memory_watermark( &self, current_usage : usize )
  {
    let current_watermark = self.metrics.memory_high_watermark_bytes.load( Ordering::Relaxed );
    if current_usage > current_watermark
    {
      self.metrics.memory_high_watermark_bytes.store( current_usage, Ordering::Relaxed );
    }
  }

  /// Get processing metrics
  pub fn get_metrics( &self ) -> MediaProcessingMetricsReport
  {
    let files_processed = self.metrics.files_processed.load( Ordering::Relaxed );
    let total_time_us = self.metrics.total_processing_time_us.load( Ordering::Relaxed );
    let avg_processing_time_ms = if files_processed > 0
    {
      ( total_time_us / files_processed ) / 1000 // Convert to milliseconds
    } else {
      0
    };

    MediaProcessingMetricsReport {
      files_processed,
      bytes_processed : self.metrics.bytes_processed.load( Ordering::Relaxed ),
      avg_processing_time_ms,
      failed_operations : self.metrics.failed_operations.load( Ordering::Relaxed ),
      retries_performed : self.metrics.retries_performed.load( Ordering::Relaxed ),
      memory_high_watermark_bytes : self.metrics.memory_high_watermark_bytes.load( Ordering::Relaxed ),
      cache_stats : self.cache.get_stats(),
    }
  }

  /// Clear processing cache
  pub async fn clear_cache( &self )
  {
    self.cache.clear();
  }

  /// Get cache statistics
  pub fn get_cache_stats( &self ) -> MediaCacheStatsReport
  {
    self.cache.get_stats()
  }

  /// Process upload from file path
  pub async fn process_upload( &self, file_path : &Path ) -> Result< ProcessedMediaResult, crate::error::Error >
  {
    // Read file data
    let file_data = std::fs::read( file_path )
      .map_err( | e | crate::error::Error::ApiError( format!( "Failed to read file : {}", e ) ) )?;

    // Detect MIME type from file extension
    let mime_type = match file_path.extension().and_then( | ext | ext.to_str() )
    {
      Some("jpg" | "jpeg") => "image/jpeg".to_string(),
      Some( "png" ) => "image/png".to_string(),
      Some( "gif" ) => "image/gif".to_string(),
      Some( "pdf" ) => "application/pdf".to_string(),
      _ => "application/octet-stream".to_string(),
    };

    let display_name = file_path.file_name()
      .and_then( | name | name.to_str() )
      .map( | s | s.to_string() );

    self.process_upload_bytes( Bytes::from( file_data ), mime_type, display_name ).await
  }

  /// Process download to file path
  pub async fn process_download( &self, _file_id : &str, _destination : &Path ) -> Result< ProcessedMediaResult, crate::error::Error >
  {
    // For now, return a placeholder implementation
    // In a real implementation, this would fetch the file from the API
    Err( crate::error::Error::ApiError( "Download functionality not implemented yet".to_string() ) )
  }

  /// Process data stream
  pub async fn process_stream< S >(
    &self,
    mut _stream : S,
    _metadata : ProcessedMediaMetadata
  ) -> Result< ProcessedMediaResult, crate::error::Error >
  where
    S: Stream< Item = Result< Bytes, crate::error::Error > > + Send + Unpin,
  {
    // For now, return a placeholder implementation
    // In a real implementation, this would process the stream chunks
    Err( crate::error::Error::ApiError( "Stream processing functionality not implemented yet".to_string() ) )
  }
}