#include "common/ReadMicroCT.h"
#include "common/Utilities.h"

#include "zlib.h"

#include <cstring>


// Read a file into memory
std::vector<char> readFile( const std::string& filename )
{
    auto fid = fopen( filename.c_str(), "rb" );
    INSIST( fid, "File does not exist: " + filename );
    fseek( fid, 0, SEEK_END );
    size_t bytes = ftell(fid);
    fseek( fid, 0, SEEK_SET );
    std::vector<char> data( bytes );
    size_t bytes2 = fread( data.data(), 1, bytes, fid );
    ASSERT( bytes == bytes2 );
    fclose( fid );
    return data;
}


// Decompress a gzip buffer
std::vector<char> gunzip( const std::vector<char>& in )
{
    z_stream stream;
    std::vector<char> out( 1000000 );
    stream.next_in = (Bytef*) in.data();
    stream.avail_in = in.size();
    stream.total_in = 0;
    stream.zalloc = Z_NULL;
    stream.zfree = Z_NULL;
    stream.opaque = Z_NULL;
    stream.next_out = (Bytef*) out.data();
    stream.avail_out = out.size();
    stream.total_out = 0;
    ASSERT( inflateInit2(&stream, 16+MAX_WBITS) == Z_OK );
    bool finished = inflate(&stream, Z_SYNC_FLUSH) == Z_STREAM_END;
    while ( !finished && stream.msg == Z_NULL ) {
        out.resize( 2 * out.size() );
        stream.next_out = (Bytef*) &out[stream.total_out];
        stream.avail_out = out.size() - stream.total_out;
        finished = inflate(&stream, Z_SYNC_FLUSH) == Z_STREAM_END;
    }
    ASSERT( stream.msg == Z_NULL );
    out.resize( stream.total_out );
    inflateEnd(&stream);
    return out;
}


// Read the compressed micro CT data
Array<uint8_t> readMicroCT( const std::string& filename )
{
    auto in  = readFile( filename );
    auto out = gunzip( in );
    ASSERT( out.size() == 1024*1024*1024 );
    Array<uint8_t> data( 1024, 1024, 1024 );
    memcpy( data.data(), out.data(), data.length() );
    return data;
}


// Read the compressed micro CT data and distribute
Array<uint8_t> readMicroCT( const Database& domain, const Utilities::MPI& comm )
{
    // Get the local problem info
    auto n = domain.getVector<int>( "n" );
    int rank = comm.getRank();
    auto nproc = domain.getVector<int>( "nproc" );
    RankInfoStruct rankInfo( rank, nproc[0], nproc[1], nproc[2] );
    
    // Determine the largest file number to get
    int Nfx = ( n[0] * rankInfo.nx + 1023 ) / 1024;
    int Nfy = ( n[1] * rankInfo.ny + 1023 ) / 1024;
    int Nfz = ( n[2] * rankInfo.nz + 1023 ) / 1024;

    // Load one of the files if rank < largest file
    Array<uint8_t> data;
    RankInfoStruct srcRankInfo( rank, Nfx, Nfy, Nfz );
    if ( srcRankInfo.ix >= 0 ) {
    	auto filename = domain.getScalar<std::string>( "Filename" );
    	char tmp[100];
    	if ( filename.find( "0x_0y_0z.gbd.gz" ) != std::string::npos ) {
    		sprintf( tmp, "%ix_%iy_%iz.gbd.gz", srcRankInfo.ix, srcRankInfo.jy, srcRankInfo.kz );
    		filename = filename.replace( filename.find( "0x_0y_0z.gbd.gz" ), 15, std::string( tmp ) );
    	} else if ( filename.find( "x0_y0_z0.gbd.gz" ) != std::string::npos ) {
    		sprintf( tmp, "x%i_y%i_z%i.gbd.gz", srcRankInfo.ix, srcRankInfo.jy, srcRankInfo.kz );
    		filename = filename.replace( filename.find( "x0_y0_z0.gbd.gz" ), 15, std::string( tmp ) );
    	} else {
    		ERROR( "Invalid name for first file" );
    	}
    	data = readMicroCT( filename );
    }

    // Redistribute the data
    data = redistribute( srcRankInfo, data, rankInfo, { n[0], n[1], n[2] }, comm );

	// Relabel the data
    auto ReadValues = domain.getVector<int>( "ReadValues" );
    auto WriteValues = domain.getVector<int>( "WriteValues" );
    ASSERT( ReadValues.size() == WriteValues.size() );
    int readMaxValue = 0;
    for ( auto v : ReadValues )
        readMaxValue = std::max( data.max()+1, v );
    std::vector<int> map( readMaxValue + 1, -1 );
    for ( size_t i=0; i<ReadValues.size(); i++ )
        map[ReadValues[i]] = WriteValues[i];
    for ( size_t i=0; i<data.length(); i++ ) {
        int t = data(i);
        ASSERT( t >= 0 && t <= readMaxValue );
        data(i) = map[t];
    }

    return data;
}