#!/usr/bin/env python
"""
run megablast for metagenomics data

usage: %prog [options]
   -d, --db_build=d: The database to use
   -i, --input=i: Input FASTQ candidate file
   -w, --word_size=w: Size of best perfect match
   -c, --identity_cutoff=c: Report hits at or above this identity
   -e, --eval_cutoff=e: Expectation value cutoff
   -f, --filter_query=f: Filter out low complexity regions
   -x, --index_dir=x: Data index directory
   -o, --output=o: Output file
   
usage: %prog db_build input_file word_size identity_cutoff eval_cutoff filter_query index_dir output_file
"""

# This version (April 26, 2012) replaces megablast with blast+ blastn
# There is now no need to augment NCBI-formatted databases and these can be
# directly downloaded from NCBI ftp site

import os, subprocess, sys, tempfile
from bx.cookbook import doc_optparse

assert sys.version_info[:2] >= ( 2, 4 )

def stop_err( msg ):
    sys.stderr.write( "%s\n" % msg )
    sys.exit()

def __main__():
    #Parse Command Line
    options, args = doc_optparse.parse( __doc__ )
    query_filename = options.input.strip() # -query
    output_filename = options.output.strip() # -out
    mega_word_size = options.word_size        # -word_size
    mega_iden_cutoff = options.identity_cutoff      # -perc_identity
    mega_evalue_cutoff = options.eval_cutoff      # -evalue
    mega_temp_output = tempfile.NamedTemporaryFile().name
    GALAXY_DATA_INDEX_DIR = options.index_dir
    DB_LOC = "%s/blastdb.loc" % GALAXY_DATA_INDEX_DIR

    # megablast parameters
    try:
        int( mega_word_size )    
    except:
        stop_err( 'Invalid value for word size' )
    try:
        float( mega_iden_cutoff )
    except:
        stop_err( 'Invalid value for identity cut-off' )
    try:
        float( mega_evalue_cutoff )
    except:
        stop_err( 'Invalid value for Expectation value' )

    if not os.path.exists( os.path.split( options.db_build )[0] ):
        stop_err( 'Cannot locate the target database directory. Please check your location file.' )

    try:
        threads = int( os.environ['GALAXY_SLOTS'])
    except Exception:
        threads = 8
    # arguments for megablast
    megablast_command = "blastn -task megablast -db %s -query %s -out %s -outfmt '6 qseqid sgi slen ppos length mismatch gaps qstart qend sstart send evalue bitscore' -num_threads %d -word_size %s -perc_identity %s -evalue %s -dust %s > /dev/null" \
        % ( options.db_build, query_filename, mega_temp_output, threads, mega_word_size, mega_iden_cutoff, mega_evalue_cutoff, options.filter_query ) 

    print megablast_command

    tmp = tempfile.NamedTemporaryFile().name
    try:
        tmp_stderr = open( tmp, 'wb' )
        proc = subprocess.Popen( args=megablast_command, shell=True, stderr=tmp_stderr.fileno() )
        returncode = proc.wait()
        tmp_stderr.close()
        # get stderr, allowing for case where it's very large
        tmp_stderr = open( tmp, 'rb' )
        stderr = ''
        buffsize = 1048576
        try:
            while True:
                stderr += tmp_stderr.read( buffsize )
                if not stderr or len( stderr ) % buffsize != 0:
                    break
        except OverflowError:
            pass
        tmp_stderr.close()
        if returncode != 0:
            raise Exception, stderr
        if os.path.exists( tmp ):
            os.unlink( tmp )
    except Exception, e:
        if os.path.exists( mega_temp_output ):
            os.unlink( mega_temp_output )
        if os.path.exists( tmp ):
            os.unlink( tmp )
        stop_err( 'Cannot execute megaablast. ' + str( e ) )

    output = open( output_filename, 'w' )
    invalid_lines = 0
    for i, line in enumerate( file( mega_temp_output ) ):
        line = line.rstrip( '\r\n' )
        fields = line.split()
        try:
            # convert the last column (bit-score as this is causing problem in filter tool) to float
            fields[-1] = float( fields[-1] )
            new_line = "%s\t%0.1f" % ( '\t'.join( fields[:-1] ), fields[-1] )
        except:
            new_line = line
            invalid_lines += 1
        output.write( "%s\n" % new_line )
    output.close()

    if os.path.exists( mega_temp_output ):
        os.unlink( mega_temp_output ) #remove the tempfile that we just reformatted the contents of

    if invalid_lines:
        print "Unable to parse %d lines. Keep the default format." % invalid_lines

    # megablast generates a file called error.log, if empty, delete it, if not, show the contents
    if os.path.exists( './error.log' ):
        for i, line in enumerate( file( './error.log' ) ):
            line = line.rstrip( '\r\n' )
            print line
        os.remove( './error.log' )

if __name__ == "__main__" : __main__()