#include <stdlib.h>
#include <map>
#include <string>
#include <iostream>
#include <sstream>
#include <fstream>
#include <iterator>
#include <math.h>
#include <algorithm>
#include <vector>
#include <unistd.h> 

#ifdef _OPENMP
#include <omp.h>
#else
#define omp_get_max_threads() 1
#define omp_get_num_threads() 1
#define omp_get_thread_num() 0
#endif

#include "IRKE.hpp"
#include "Fasta_reader.hpp"
#include "sequenceUtil.hpp"
#include "KmerCounter.hpp"
#include "stacktrace.hpp"
#include "irke_common.hpp"


const unsigned int MAX_RECURSION_HARD_STOP = 50;

struct iworm_tmp_file {  //FIXME: make a class for this
    ofstream* fh;
    char* tmp_filename;
};



IRKE::IRKE () {   // IRKE = Inchworm Recursive Kmer Extension

}

IRKE::IRKE (unsigned int kmer_length, unsigned int max_recursion, float min_seed_entropy, 
			unsigned int min_seed_coverage, float min_any_entropy, 
			bool pacman, bool crawl, unsigned int crawl_length, bool double_stranded) : kcounter(kmer_length, double_stranded) {
	
	MAX_RECURSION = max_recursion;
	MIN_SEED_ENTROPY = min_seed_entropy;
	MIN_SEED_COVERAGE = min_seed_coverage;
	MIN_ANY_ENTROPY = min_any_entropy;
	PACMAN = pacman;
	CRAWL = crawl;
	CRAWL_LENGTH = crawl_length;
	
	INCHWORM_ASSEMBLY_COUNTER = 0;
	
	DOUBLE_STRANDED_MODE = double_stranded;
	PRUNE_SINGLETON_READ_INTERVAL = 0;

    TWO_PHASE = true; // default
	
}


void IRKE::set_prune_singleton_read_interval (unsigned long interval) {
	
	this->PRUNE_SINGLETON_READ_INTERVAL = interval;
	
}


void IRKE::build_graph(const string& fasta_filename, bool, bool useKmers) {
	
	if (useKmers)
		populate_Kmers_from_kmers(fasta_filename);
	else
		populate_Kmers_from_fasta(fasta_filename);
	
}


void IRKE::populate_Kmers_from_kmers(const string& fasta_filename) {
	unsigned int kmer_length = kcounter.get_kmer_length();
	int i, myTid;
	unsigned long sum, 
                  *record_counter = new unsigned long[omp_get_max_threads()];
	unsigned long start, end;


    omp_set_num_threads(IRKE_COMMON::MAX_THREADS_READ_PARSING); // place limit here because performance deteriorates beyond this value.

  // init record counter
  for (int i = 0; i < omp_get_max_threads(); i++) {
  	record_counter[i] = 0;
  }

	cerr << "-reading Kmer occurrences..." << "\n";
	start = time(NULL);

	Fasta_reader fasta_reader(fasta_filename);

  #pragma omp parallel private (myTid)
	{
		myTid = omp_get_thread_num();
		record_counter[myTid] = 0;

		while (true) {
			Fasta_entry fe = fasta_reader.getNext();
			if (fe.get_sequence() == "") break;

            record_counter[myTid]++;
            
			if (IRKE_COMMON::MONITOR) {
				if (myTid == 0 && record_counter[myTid] % 100000 == 0)
					{
						sum = record_counter[0];
						for (i=1; i<omp_get_num_threads(); i++)
							sum+= record_counter[i];
						cerr << "\r [" << sum/1000000 << "M] Kmers parsed.     ";
                    }
			}


			string seq = fe.get_sequence();
			if (seq.length() != kmer_length) {
				continue;
			}

			kmer_int_type_t kmer = kcounter.get_kmer_intval(seq);
			unsigned int count = atoi(fe.get_header().c_str());
			kcounter.add_kmer(kmer, count);
		}
	}
	end = time(NULL);

	sum = record_counter[0];
	for (i=1; i<omp_get_max_threads(); i++)
		sum+= record_counter[i];
    delete [] record_counter;

	cerr << "\n" << " done parsing " << sum << " Kmers, " << kcounter.size() << " added, taking " << (end-start) << " seconds." << "\n";

    cerr << "\n" << "TIMING KMER_DB_BUILDING " << (end-start) << " s." << "\n";
    
    ofstream iworm_kmer_count_report_fh;
    iworm_kmer_count_report_fh.open("inchworm.kmer_count");
    iworm_kmer_count_report_fh << kcounter.size() << "\n";
    iworm_kmer_count_report_fh.close();
    

    // restore multithreading settings
    omp_set_num_threads(IRKE_COMMON::NUM_THREADS);
    
	return;
}


void IRKE::populate_Kmers_from_fasta(const string& fasta_filename, bool reassembleIworm) {
	
	unsigned int kmer_length = kcounter.get_kmer_length();
	int i, myTid;
	unsigned long sum, 
                  *record_counter = new unsigned long[omp_get_max_threads()];
	unsigned long start, end;
    
    // init record counter
    for (int i = 0; i < omp_get_max_threads(); i++) {
        record_counter[i] = 0;
    }

	
	cerr << "-storing Kmers..." << "\n";
	start = time(NULL);
	
	Fasta_reader fasta_reader(fasta_filename);

    unsigned int entry_num = 0;

    #pragma omp parallel private (myTid)
	{
		myTid = omp_get_thread_num();
		record_counter[myTid] = 0;
		
		while (fasta_reader.hasNext()) {
			Fasta_entry fe = fasta_reader.getNext();
            string accession = fe.get_accession();

            #pragma omp atomic            
            entry_num++;
            record_counter[myTid]++;
			
			if (IRKE_COMMON::MONITOR >= 4) {
				cerr << "[" << entry_num << "] acc: " << accession << ", by thread no: " << myTid << "\n";;
			}
			else if (IRKE_COMMON::MONITOR) {
				if (myTid == 0 && record_counter[myTid] % 1000 == 0)
					{
						sum = record_counter[0];
						for (i=1; i<omp_get_num_threads(); i++)
							sum+= record_counter[i];
						cerr << "\r [" << sum << "] sequences parsed.     ";
					}
			}
			
			
			string seq = fe.get_sequence();
			
			if (seq.length() < kmer_length) {
				continue;
			}
			
			if (reassembleIworm) {
				string accession = fe.get_accession();
				string header = fe.get_header();
				// get coverage value from iworm assembly
				vector<string> tokens;
				string_util::tokenize(accession, tokens, ";");
				if (tokens.size() < 2) {
					stringstream err;
					err << "Could not extract coverage value from accession: " << tokens[tokens.size()-1];
					throw(err.str());
				}
				string cov_s = tokens[tokens.size()-1];
				unsigned int cov_val = atoi(cov_s.c_str());
				
				// get Kmer value from header
				vector<string> header_toks;
				string_util::tokenize(header, header_toks, " ");
				if (header_toks.size() < 5) {
					stringstream err;
					err << "Fasta header: " << header << " lacks expected format including Kmer length from previous inchworm assembly run";
					throw(err.str());
				}
				
				unsigned int kmer_val = atoi(header_toks[2].c_str());
				
				unsigned int normalized_coverage_val = static_cast<unsigned int> (cov_val * kmer_val / 25.0 + 0.5);
				
				if (IRKE_COMMON::MONITOR >= 1) {
					cerr << "Adding inchworm assembly " << accession 
						 << " K: " << kmer_val << " Cov: " << cov_val 
						 << " with coverage: " << normalized_coverage_val << "\n";
				}
				if (cov_val < 1) {
					stringstream err;
					err << "error parsing coverage value from accession: " << accession;
					throw(err.str());
				}
				kcounter.add_sequence(seq, normalized_coverage_val);
			}
			else {
				kcounter.add_sequence(seq);
			}
			
			// remove singleton kmers at read interval to minimize memory requirements.
			if (PRUNE_SINGLETON_READ_INTERVAL > 0 
				&& 
				myTid == 0
				&&
				record_counter[myTid]/omp_get_num_threads() % PRUNE_SINGLETON_READ_INTERVAL == 0) {
				if (IRKE_COMMON::MONITOR >= 1) {
					cerr << "Reached singleton kmer pruning interval at read count: " << record_counter << "\n";
				}
				prune_kmers_min_count(1);
			}
			
			
		}
	}
	end = time(NULL);
	
	sum = record_counter[0];
	for (i=1; i<omp_get_max_threads(); i++)
		sum+= record_counter[i];
    delete [] record_counter;
	
	cerr << "\n" << " done parsing " << sum << " sequences, extracted " << kcounter.size() << " kmers, taking " << (end-start) << " seconds." << "\n";
	
	
	return;
}


void IRKE::prune_kmers_min_count(unsigned int min_count) {
	
	// proxy, sends message to kcounter member
	
	kcounter.prune_kmers_min_count(min_count);
}


void IRKE::prune_kmers_min_entropy(float min_entropy) {
	
	// proxy, send message to kcounter
	
	kcounter.prune_kmers_min_entropy(min_entropy);
	
	
}


bool IRKE::prune_kmer_extensions(float min_ratio_non_error) {
	
	// proxy, send message to kcounter
	
	return(kcounter.prune_kmer_extensions(min_ratio_non_error));
}


bool IRKE::prune_some_kmers(unsigned int min_count, float min_entropy, bool prune_error_kmers, float min_ratio_non_error) {

	return(kcounter.prune_some_kmers(min_count, min_entropy, prune_error_kmers, min_ratio_non_error));
}


unsigned long IRKE::get_graph_size() {
	
	// proxy call
	
	return(kcounter.size());
	
}


void IRKE::traverse_path(KmerCounter& kcounter, Kmer_Occurence_Pair seed_kmer, Kmer_visitor& visitor,
						 Kmer_visitor& place_holder, float MIN_CONNECTIVITY_RATIO, unsigned int depth) {
	
	if (IRKE_COMMON::MONITOR >= 3) {
		cerr << "traverse_path, depth: " << depth << ", kmer: " << kcounter.get_kmer_string(seed_kmer.first) <<  "\n";
	}
	
	
	// check to see if visited already
	if (visitor.exists(seed_kmer.first)) {
		// already visited
		if (IRKE_COMMON::MONITOR >= 3) {
			cout << "\talready visited " << kcounter.get_kmer_string(seed_kmer.first) << "\n";
		}
		
		return;
	}
	
	// check if at the end of the max recursion, and if so, don't visit it but set a placeholder.
	if (depth > MAX_RECURSION) {
		place_holder.add(seed_kmer.first);
		return;
	}
	
	visitor.add(seed_kmer.first);
    
	// try each of the forward paths from the kmer:  
	vector<Kmer_Occurence_Pair> forward_candidates = kcounter.get_forward_kmer_candidates(seed_kmer.first);
	
	for(unsigned int i = 0; i < forward_candidates.size(); i++) {
		Kmer_Occurence_Pair kmer = forward_candidates[i];
		
		if (kmer.second	&& exceeds_min_connectivity(kcounter, seed_kmer, kmer, MIN_CONNECTIVITY_RATIO)) {
			
			traverse_path(kcounter, kmer, visitor, place_holder, MIN_CONNECTIVITY_RATIO, depth + 1);
		}
	}
	
	// try each of the reverse paths from the kmer:
	vector<Kmer_Occurence_Pair> reverse_candidates = kcounter.get_reverse_kmer_candidates(seed_kmer.first);
	
	for (unsigned int i = 0; i < reverse_candidates.size(); i++) {
		Kmer_Occurence_Pair kmer = reverse_candidates[i];
		
		if (kmer.second	&& exceeds_min_connectivity(kcounter, seed_kmer, kmer, MIN_CONNECTIVITY_RATIO)) {
			
			traverse_path(kcounter, kmer, visitor, place_holder, MIN_CONNECTIVITY_RATIO, depth + 1);
		}
	}
	
	
	return;
	
}


string add_fasta_seq_line_breaks(string& sequence, int interval) {
    
    stringstream fasta_seq;
    
    int counter = 0;
    for (string::iterator it = sequence.begin(); it != sequence.end(); it++) {
        counter++;
        
        fasta_seq << *it;
        if (counter % interval == 0 && (it + 1) != sequence.end()) {
            fasta_seq << "\n";
        }
    }

    return(fasta_seq.str());
}



void IRKE::compute_sequence_assemblies(float min_connectivity, unsigned int MIN_ASSEMBLY_LENGTH, unsigned int MIN_ASSEMBLY_COVERAGE,
									   bool PARALLEL_IWORM, bool WRITE_COVERAGE, string COVERAGE_OUTPUT_FILENAME) {

	// use self kcounter
	compute_sequence_assemblies(kcounter, min_connectivity, MIN_ASSEMBLY_LENGTH, MIN_ASSEMBLY_COVERAGE, 
                                PARALLEL_IWORM, WRITE_COVERAGE, COVERAGE_OUTPUT_FILENAME);
	
	return;
	
}


void IRKE::compute_sequence_assemblies(KmerCounter& kcounter, float min_connectivity,
									   unsigned int MIN_ASSEMBLY_LENGTH, unsigned int MIN_ASSEMBLY_COVERAGE,
									   bool PARALLEL_IWORM, bool WRITE_COVERAGE, string COVERAGE_OUTPUT_FILENAME) {
	
    if (! got_sorted_kmers_flag) {
        stringstream error;
        error << stacktrace() << " Error, must populate_sorted_kmers_list() before computing sequence assemblies" << "\n";
        throw(error.str());
    }
    

	//vector<Kmer_counter_map_iterator>& kmers = sorted_kmers; 
    vector<Kmer_Occurence_Pair>& kmers = sorted_kmers;  // note, these are not actually sorted if PARALLEL_IWORM mode.
	
	unsigned long init_size = kcounter.size();
    
    cerr << "Total kcounter hash size: " << init_size << " vs. sorted list size: " << kmers.size() << "\n";

	unsigned int kmer_length = kcounter.get_kmer_length();
	ofstream coverage_writer;
	if (WRITE_COVERAGE) {
		coverage_writer.open(COVERAGE_OUTPUT_FILENAME.c_str());
	}
	    

	// string s = "before.kmers";
	// kcounter.dump_kmers_to_file(s);

    /* -----------------------------------------------------------
       Two reconstruction modes. (bhaas, Jan-4-2014)

       1.  Original (not setting PARALLEL_IWORM): kmer list is sorted descendingly by abundance.
       Seed kmer is chosen as most abundant, and contig construction extends from this seed.

       2.  PARALLEL_IWORM:  the kmer list is not sorted. A random kmer (just ordered by hash iterator, nothing special, probably not so random)
       is used as a seed for draft contig reconstruction.
       The most abundant kmer in the draft contig is chosen as a proper seed.
       An inchworm contig is then constructed using this new seed, and reported.
       So, in this case, the draft contig in the first phase is just used to find a better seed, from which the inchworm contig is then 
       properly reconstructed.

    --------------------------------------------------------------- */

    
    
    // try building an inchworm contig from each seed kmer
    int myTid;


    if (PARALLEL_IWORM) {
        omp_set_num_threads(IRKE_COMMON::NUM_THREADS);
    }
    else {
        omp_set_num_threads(1); // turn off multithreading for the contig building.
    }


    //-----------------------------------------------------------------
    // Prep writing to separate inchworm output files for each thread
    //-----------------------------------------------------------------
    
    vector<iworm_tmp_file> tmpfiles;
    int num_threads = omp_get_max_threads();
    cerr << "num threads set to: " << num_threads << "\n";
    
    for (int i =0; i < num_threads; i++) {
        iworm_tmp_file tmpfile_struct;
        tmpfiles.push_back(tmpfile_struct);
        iworm_tmp_file& itmp = tmpfiles[i];
        
        stringstream filename_constructor;
        filename_constructor << "tmp.iworm.fa.pid_" << getpid() << ".thread_" << i;
        
        itmp.tmp_filename = new char[100];
        strcpy(itmp.tmp_filename, filename_constructor.str().c_str());
        itmp.tmp_filename[filename_constructor.str().length()] = '\0';
        
        itmp.fh = new ofstream();
        itmp.fh->open(itmp.tmp_filename);
        cerr << "Done opening file. " << itmp.tmp_filename << "\n";
    }
    

    //-------------------
    // Build contigs.
    //-------------------
    
    #pragma omp parallel for private (myTid) schedule (dynamic, 1000) 
	for (unsigned int i = 0; i < kmers.size(); i++) {
		
		// cerr << "round: " << i << "\n";
	
        myTid = omp_get_thread_num();
	
		unsigned long kmer_counter_size = kcounter.size();
		if (kmer_counter_size > init_size) {
			
			// string s = "after.kmers";
			// kcounter.dump_kmers_to_file(s);
			
			stringstream error;
			error << stacktrace() << "Error, Kcounter size has grown from " << init_size
				  << " to " << kmer_counter_size << "\n";
			throw (error.str());
		}
		
		
		//kmer_int_type_t kmer = kmers[i]->first;
		//unsigned int kmer_count = kmers[i]->second;

        kmer_int_type_t kmer = kmers[i].first;
		// unsigned int kmer_count = kmers[i].second;  // NO!!!  Use for sorting, but likely zeroed out in the hashtable after contig construction
        unsigned int kmer_count = kcounter.get_kmer_count(kmer);

        if (! is_good_seed_kmer(kmer, kmer_count, kmer_length, min_connectivity)) {
            continue;
        }
        
        // cout << "SEED kmer: " << kcounter.get_kmer_string(kmer) << ", count: " << kmer_count << "\n";
        
        if (IRKE_COMMON::MONITOR >= 2) {
            cerr << "SEED kmer: " << kcounter.get_kmer_string(kmer) << ", count: " << kmer_count << "\n";
        }
                
        if (IRKE_COMMON::MONITOR >= 2) {
            #pragma omp critical
            cerr << "Seed for thread: " << myTid << " is " <<  kcounter.get_kmer_string(kmer) << " with count: " << kmer_count << "\n";
        }

		unsigned int total_counts;
        vector<kmer_int_type_t> joined_path = build_inchworm_contig_from_seed(kmer, kcounter, min_connectivity, total_counts, PARALLEL_IWORM);

        if (PARALLEL_IWORM && TWO_PHASE) {
            // get a new seed based on the draft contig
            // choose the 'good' kmer with highest abundance
            
            kmer_int_type_t new_seed = extract_best_seed(joined_path, kcounter, min_connectivity);
            
            if (kcounter.get_kmer_count(new_seed) == 0) {
                continue; // must have been zapped by another thread
            }
            
            joined_path = build_inchworm_contig_from_seed(new_seed, kcounter, min_connectivity, total_counts, PARALLEL_IWORM);
        }
        
		// report sequence reconstructed from path.
		
		vector<unsigned int> assembly_base_coverage;

        string sequence = reconstruct_path_sequence(kcounter, joined_path, assembly_base_coverage);
		
		unsigned int avg_cov =  static_cast<unsigned int> ( (float)total_counts/(sequence.length()-kcounter.get_kmer_length() +1) + 0.5);
		
		/*
		  cout << "Inchworm-reconstructed sequence, length: " << sequence.length() 
		  << ", avgCov: " << avg_cov
		  << " " << sequence << "\n";
		*/

        size_t contig_length = sequence.length();

	if (contig_length >= MIN_ASSEMBLY_LENGTH && avg_cov >= MIN_ASSEMBLY_COVERAGE) {


            *(tmpfiles[myTid].fh) << total_counts << "\n"
                                  << avg_cov << "\n"
                                  << kmer_count << "\n"
                                  << sequence << "\n";
		
        }
        
		// remove path
        
        if (IRKE_COMMON::__DEVEL_zero_kmer_on_use) { 
            
            // dont forget the seed. The forward/reverse path kmers already cleared.
            kcounter.clear_kmer(kmer);
            

        } else {
            
            for (unsigned int i = 0; i < joined_path.size(); i++) {
                
                kmer_int_type_t kmer = joined_path[i];
                kcounter.clear_kmer(kmer);
            }
                
        }

    }
	
	if (IRKE_COMMON::MONITOR) {
		cerr << "\n";
	}
	
	if (WRITE_COVERAGE) {
		coverage_writer.close();
	}
        
    // drop sorted kmer list as part of cleanup
    clear_sorted_kmers_list();
    

    //------------------------------------------------------------------------------      
    // examine the contigs generated by the individual threads, remove redundancies.
    //------------------------------------------------------------------------------
    
    map<unsigned long long, bool> seen_contig_already;

    for (unsigned int i=0; i < tmpfiles.size(); i++) {
        
        tmpfiles[i].fh->close();
        

        ifstream tmpreader(tmpfiles[i].tmp_filename);
        
        while (! tmpreader.eof()) {
            
            unsigned int total_counts;
            unsigned int avg_cov;
            unsigned int kmer_count;
            string sequence;
            
            tmpreader >> total_counts
                      >> avg_cov 
                      >> kmer_count
                      >> sequence;

            if (tmpreader.eof()) // apparently only happens on the read after the last line is read.
                break;
            
            //cerr << "Read sequence: " << sequence << "\n";
            
            unsigned int contig_hash = generateHash(sequence);
            
            if (! seen_contig_already[contig_hash]
                ) {
                
                seen_contig_already[contig_hash] = true;
                
                INCHWORM_ASSEMBLY_COUNTER++;
                
                stringstream headerstream;
                
                
                headerstream << ">a" << INCHWORM_ASSEMBLY_COUNTER << ";" << avg_cov 
                             << " total_counts: " <<  total_counts 
                    //<< " Fpath: " << selected_path_n_pair_forward.second << " Rpath: " << selected_path_n_pair_reverse.second 
                             << " Seed: " << kmer_count 
                             << " K: " << kmer_length
                             << " length: " << sequence.length();
                                
                string header = headerstream.str();
                
                sequence = add_fasta_seq_line_breaks(sequence, 60);
                
                cout << header << "\n" << sequence << "\n";      

                
            }
        }

        // cleanup from earlier dynamic allocation
        delete(tmpfiles[i].fh);
        if (! IRKE_COMMON::KEEP_TMP_FILES) {
            remove(tmpfiles[i].tmp_filename);
        }
        delete(tmpfiles[i].tmp_filename);
        
    }
    
    /*
      
                
                if (WRITE_COVERAGE) {
				
                    coverage_writer << header << "\n";
                    
                    for (unsigned int i = 0; i < assembly_base_coverage.size(); i++) {
                        coverage_writer << assembly_base_coverage[i];
                        if ( (i+1) % 30 == 0) {
                            coverage_writer << "\n";
                        }
                        else {
                            coverage_writer << " ";
                        }
                    }
                    coverage_writer << "\n";
                }
                
            }


        
    */

	
	return; // end of runIRKE
	
}


bool IRKE::is_good_seed_kmer(kmer_int_type_t kmer, unsigned int kmer_count, unsigned int kmer_length, 
                             float) {

    if (kmer_count == 0) {
        return(false);
    }
    
    if (kmer == revcomp_val(kmer, kmer_length)) {
        // palindromic kmer, avoid palindromes as seeds
		
        if (IRKE_COMMON::MONITOR >= 2) {
            cerr << "SEED kmer: " << kcounter.get_kmer_string(kmer) << " is palidnromic.  Skipping. " << "\n";
        }
        
        return(false);
    }
    
        
    if (kmer_count < MIN_SEED_COVERAGE) {
        if (IRKE_COMMON::MONITOR >= 2) {
            cerr << "-seed has insufficient coverage, skipping" << "\n";
        }
        
        return(false);
    }
    
    float entropy = compute_entropy(kmer, kmer_length);
	
	
    if (entropy < MIN_SEED_ENTROPY) {
        
        if (IRKE_COMMON::MONITOR >= 2) {
            cerr << "-skipping seed due to low entropy: " << entropy << "\n";
        }
        
        return(false);
    }
	

    // got this far, so kmer is fine as a seed
    return(true);
}



vector<kmer_int_type_t>  IRKE::build_inchworm_contig_from_seed(kmer_int_type_t kmer, KmerCounter& kcounter, 
                                                               float min_connectivity, unsigned int& total_counts,
                                                               bool) {
    	        
        unsigned int kmer_count = kcounter.get_kmer_count(kmer); 

		/* Extend to the right */
    
	    unsigned int kmer_length = kcounter.get_kmer_length();
	
		Kmer_visitor visitor(kmer_length, DOUBLE_STRANDED_MODE);
		Path_n_count_pair selected_path_n_pair_forward = inchworm(kcounter, 'F', kmer, visitor, min_connectivity); 
		
		visitor.clear();
		// add selected path to visitor
		
		vector<kmer_int_type_t>& forward_path = selected_path_n_pair_forward.first;

		if (IRKE_COMMON::MONITOR >= 2) {
            cerr << "Forward path contains: " << forward_path.size() << " kmers. " << "\n";
        }


        for (unsigned int i = 0; i < forward_path.size(); i++) {
			kmer_int_type_t kmer = forward_path[i];
			visitor.add(kmer);
            
            if (IRKE_COMMON::MONITOR >= 2) {
                cerr << "\tForward path kmer: " << kcounter.get_kmer_string(kmer) << "\n";
            }
            
		}
		
		
		/* Extend to the left */ 
		visitor.erase(kmer); // reset the seed
		
		Path_n_count_pair selected_path_n_pair_reverse = inchworm(kcounter, 'R', kmer, visitor, min_connectivity);
        if (IRKE_COMMON::MONITOR >= 2) {
            vector<kmer_int_type_t>& reverse_path = selected_path_n_pair_reverse.first;
            cerr << "Reverse path contains: " << reverse_path.size() << " kmers. " << "\n";
            for (unsigned int i = 0; i < reverse_path.size(); i++) {
                cerr  << "\tReverse path kmer: " << kcounter.get_kmer_string(reverse_path[i]) << "\n"; 
            }
        }
        
		
		total_counts = selected_path_n_pair_forward.second + selected_path_n_pair_reverse.second + kmer_count; 
		
		vector<kmer_int_type_t>& reverse_path = selected_path_n_pair_reverse.first;
		
		vector<kmer_int_type_t> joined_path = _join_forward_n_reverse_paths(reverse_path, kmer, forward_path);

        return(joined_path);
}
		

Path_n_count_pair IRKE::inchworm (KmerCounter& kcounter, char direction, kmer_int_type_t kmer, Kmer_visitor& visitor, float min_connectivity) {
	
	// cout << "inchworm" << "\n";
	
	Path_n_count_pair entire_path;
    entire_path.second = 0; // init cumulative path coverage

	unsigned int inchworm_round = 0;
	
	unsigned long num_total_kmers = kcounter.size();
	
	Kmer_visitor eliminator(kcounter.get_kmer_length(), DOUBLE_STRANDED_MODE);
	
	while (true) {


        if (IRKE_COMMON::__DEVEL_rand_fracture) {
            
            // terminate extension with probability of __DEVEL_rand_fracture_prob
            
            float prob_to_fracture = rand() / (float) RAND_MAX;
            //cerr << "prob: " << prob_to_fracture << "\n";
            
            if (prob_to_fracture <= IRKE_COMMON::__DEVEL_rand_fracture_prob) {
                
                // cerr << "Fracturing at iworm round: " << inchworm_round << " given P: " << prob_to_fracture << "\n";
                
                return(entire_path);
            }
        }
        		
		inchworm_round++;
		eliminator.clear();
		
		if (inchworm_round > num_total_kmers) {
			throw(string ("Error, inchworm rounds have exceeded the number of possible seed kmers"));
		}
		
		if (IRKE_COMMON::MONITOR >= 3) {
			cerr << "\n" << "Inchworm round(" << string(1,direction) << "): " << inchworm_round << " searching kmer: " << kmer << "\n";
			string kmer_str = kcounter.get_kmer_string(kmer);
			cerr << kcounter.describe_kmer(kmer_str) << "\n";
		}
		
		visitor.erase(kmer); // seed kmer must be not visited already.
		
		Kmer_Occurence_Pair kmer_pair(kmer, kcounter.get_kmer_count(kmer));
		Path_n_count_pair best_path = inchworm_step(kcounter, direction, kmer_pair, visitor, eliminator, inchworm_round, 0, min_connectivity, MAX_RECURSION);
		

        vector<kmer_int_type_t>& kmer_list = best_path.first;
        unsigned int num_kmers = kmer_list.size();

		if ( (IRKE_COMMON::__DEVEL_zero_kmer_on_use && num_kmers >= 1) || best_path.second > 0) {
			// append info to entire path in reverse order, so starts just after seed kmer
			
			int first_index = num_kmers - 1;
			int last_index = 0;
			if (CRAWL) {
				last_index = first_index - CRAWL_LENGTH + 1;
				if (last_index < 0) {
					last_index = 0;
				}
			}
			
			for (int i = first_index; i >= last_index; i--) {
				kmer_int_type_t kmer_extend = kmer_list[i];
				entire_path.first.push_back(kmer_extend);
				visitor.add(kmer_extend);
				//entire_path.second += kcounter.get_kmer_count(kmer_extend);

                // selected here, zero out:

                
                if (IRKE_COMMON::__DEVEL_zero_kmer_on_use) {
                    kcounter.clear_kmer(kmer_extend);
                }
                
			}
			
			kmer = entire_path.first[ entire_path.first.size() -1 ];
            
            entire_path.second += best_path.second;
            

		}
		else {
			// no extension possible
			break;
		}
	}
	
	if (IRKE_COMMON::MONITOR >= 3) 
		cerr << "No extension possible." << "\n" << "\n";
	
	
	return(entire_path);
}


bool compare (const Path_n_count_pair& valA, const Path_n_count_pair& valB) {
	
#ifdef _DEBUG
    if (valA.second == valB.second)
        return (valA.first > valB.first);
	else
#endif
		return(valA.second > valB.second); // reverse sort.
}



Path_n_count_pair IRKE::inchworm_step (KmerCounter& kcounter, char direction, Kmer_Occurence_Pair kmer, Kmer_visitor& visitor,
									   Kmer_visitor& eliminator, unsigned int inchworm_round, unsigned int depth, 
									   float MIN_CONNECTIVITY_RATIO, unsigned int max_recurse) {
	
	// cout << "inchworm_step" << "\n";
	
	if (IRKE_COMMON::MONITOR >= 2) {
		cerr << "\rinchworm: " << string(1,direction) 
			 << " A:" << INCHWORM_ASSEMBLY_COUNTER << " "
			 << " rnd:" << inchworm_round << " D:" << depth << "         "; 
	}
	
	// check to see if kmer exists.  If not, return empty container
	Path_n_count_pair best_path_n_pair;
	best_path_n_pair.second = 0; // init
		
	if ( // !kmer.second || 
        
        visitor.exists(kmer.first) // visited
        || eliminator.exists(kmer.first) // eliminated
		
		 ) {
        
        if (IRKE_COMMON::MONITOR >= 3) {
            cerr << "base case, already visited or kmer doesn't exist." << "\n";
            cerr << kmer.first << " already visited or doesn't exist.  ending recursion at depth: " << depth << "\n";
        }
		
        return(best_path_n_pair);
		
	}
	
	visitor.add(kmer.first);
	
	if (PACMAN && depth > 0) {
		// cerr << "pacman eliminated kmer: " << kmer << "\n";
		eliminator.add(kmer.first);
	}
	
	
	if (depth < max_recurse) {
		
		vector<Kmer_Occurence_Pair> kmer_candidates;
		if (direction == 'F') {
			// forward search
			kmer_candidates = kcounter.get_forward_kmer_candidates(kmer.first);
		}
		else {
			// reverse search
			kmer_candidates = kcounter.get_reverse_kmer_candidates(kmer.first);
		}
		
        if (IRKE_COMMON::MONITOR >= 3) {
            cerr << "Got " << kmer_candidates.size() << " kmer extension candidates." << "\n";
        }
        
		bool tie = true;
		unsigned int recurse_cap = max_recurse;
		unsigned int best_path_length = 0;
		while (tie) {

            // keep trying to break ties if ties encountered.
            // this is done by increasing the allowed recursion depth until the tie is broken.
            //  Recursion depth set via: recurse_cap and incremented if tie is found
            

			vector<Path_n_count_pair> paths;
			
			for (unsigned int i = 0; i < kmer_candidates.size(); i++) {
				Kmer_Occurence_Pair kmer_candidate = kmer_candidates[i];
				
				if ( kmer_candidate.second &&
				    
                    !visitor.exists(kmer_candidate.first)  // avoid creating already visited kmers since they're unvisited below...
					&& exceeds_min_connectivity(kcounter, kmer, kmer_candidate, MIN_CONNECTIVITY_RATIO) ) {
					//cout << "\n" << "\ttrying " << kmer_candidate << "\n";
					

                    // recursive call here for extension
					Path_n_count_pair p = inchworm_step(kcounter, direction, kmer_candidate, visitor, eliminator, inchworm_round, depth+1, MIN_CONNECTIVITY_RATIO, recurse_cap);
					
                    if (p.first.size() >= 1) {
                        // only retain paths that include visited nodes.
                        paths.push_back(p);
                    }
					visitor.erase(kmer_candidate.first); // un-visiting
					
                }
				
			} // end for kmer
			
			
			if (paths.size() > 1) {

                sort(paths.begin(), paths.end(), compare);
				
                if (IRKE_COMMON::__DEVEL_no_greedy_extend) {
                    // pick a path at random
                    int rand_index = rand() % paths.size();
                    tie = false;
                    if (IRKE_COMMON::MONITOR) {
                        cerr << "IRKE_COMMON::__DEVEL_no_greedy_extend -- picking random path index: " << rand_index << " from size(): " << paths.size() << "\n";
                    }
                    best_path_n_pair = paths[rand_index];
                }
				
                else if (paths[0].second == paths[1].second   // same cumulative coverage values for both paths.
					&&
					// check last kmer to be sure they're different. 
					// Not interested in breaking ties between identically scoring paths that end up at the same kmer.
					paths[0].first[0] != paths[1].first[0]
					
					) {
					
					// got tie, two different paths and two different endpoints:
					if (IRKE_COMMON::MONITOR >= 3) {
												
						cerr << "Got tie! " << ", score: " << paths[0].second << ", recurse at: " << recurse_cap << "\n";
						vector<unsigned int> v;
						cerr << reconstruct_path_sequence(kcounter, paths[0].first, v) << "\n";
						cerr << reconstruct_path_sequence(kcounter, paths[1].first, v) << "\n";
												
					}
                    
                    if (IRKE_COMMON::__DEVEL_no_tie_breaking || recurse_cap >= MAX_RECURSION_HARD_STOP) {
                        tie = false;
                        
                        int rand_index = rand() % 2;

                        if (IRKE_COMMON::MONITOR >= 2) {
                            cerr << "IRKE_COMMON::__DEVEL_no_tie_breaking, so picking path: " << rand_index << " at random." << "\n";
                        }
                        
                        best_path_n_pair = paths[rand_index];
                    }
                    
                    else if (paths[0].first.size() > best_path_length) {
                        // still making progress in extending to try to break the tie.  Keep going.
                        // note, this is the only test that keeps us in this while loop. (tie stays true)
                        recurse_cap++;
						best_path_length = paths[0].first.size();
					}
					else {
						// cerr << "not able to delve further into the graph, though...  Stopping here." << "\n";
						tie = false;
                        best_path_n_pair = paths[0]; // pick one
					}
				}
				
				else if ((paths[0].second == paths[1].second   // same cumulative coverage values for both paths.
						  &&
						  paths[0].first[0] == paths[1].first[0] ) // same endpoint
						 ) {
					
					if (IRKE_COMMON::MONITOR >= 3) {
						cerr << "Tied, but two different paths join to the same kmer.  Choosing first path arbitrarily." << "\n";
					}
					tie = false;
					best_path_n_pair = paths[0];
				}
				
				else {
					// no tie.
					tie = false;
					best_path_n_pair = paths[0];
				}
				
				
			}
			else if (paths.size() == 1) {
				tie = false;
				best_path_n_pair = paths[0];
			}
			else {
				// no extensions possible.
				tie = false;
			}
			
			
		} // end while tie
	}
	
	// add current kmer to path, as long as not the original seed kmer!
	if (depth > 0) {
		best_path_n_pair.first.push_back(kmer.first);
		best_path_n_pair.second += kmer.second;
        
    }
	
	return(best_path_n_pair);
	
	
}


vector<kmer_int_type_t> IRKE::_join_forward_n_reverse_paths(vector<kmer_int_type_t>& reverse_path, 
															kmer_int_type_t seed_kmer_val, 
															vector<kmer_int_type_t>& forward_path) {
	
	vector<kmer_int_type_t> joined_path;
	
	// want reverse path in reverse order
	
	for (int i = reverse_path.size()-1; i >= 0; i--) {
		joined_path.push_back( reverse_path[i] );
	}
	
	// add seed kmer
	joined_path.push_back(seed_kmer_val);
	
	// tack on the entire forward path.
	
	for (unsigned int i = 0; i < forward_path.size(); i++) {
		joined_path.push_back( forward_path[i] );
	}
	
	return(joined_path);
}


string IRKE::reconstruct_path_sequence(vector<kmer_int_type_t>& path, vector<unsigned int>& cov_counter) {
	// use kcounter member
	return(reconstruct_path_sequence(kcounter, path, cov_counter));
}


string IRKE::reconstruct_path_sequence(KmerCounter& kcounter, vector<kmer_int_type_t>& path, vector<unsigned int>& cov_counter) {
	
	if (path.size() == 0) {
		return("");
	}
	
	string seq = kcounter.get_kmer_string(path[0]);
	cov_counter.push_back( kcounter.get_kmer_count(path[0]) );
	
	for (unsigned int i = 1; i < path.size(); i++) {
		string kmer = kcounter.get_kmer_string(path[i]);
		seq += kmer.substr(kmer.length()-1, 1);
		
		cov_counter.push_back( kcounter.get_kmer_count(path[i]) );
	}
	
	return(seq);
}


bool IRKE::exceeds_min_connectivity (KmerCounter&, Kmer_Occurence_Pair kmerA, Kmer_Occurence_Pair kmerB, float min_connectivity) {
	
    if (min_connectivity < 1e5) {
        return(true); // consider test off
    }
    
	
	unsigned int kmerA_count = kmerA.second;
	if (kmerA_count == 0)
		return(false);
	unsigned int kmerB_count = kmerB.second;
	if (kmerB_count == 0)
		return(false);
	
	unsigned int minVal;
	unsigned int maxVal;
	
	if (kmerA_count < kmerB_count) {
		minVal = kmerA_count;
		maxVal = kmerB_count;
	}
	else {
		minVal = kmerB_count;
		maxVal = kmerA_count;
	}
	
	float connectivity_ratio = (float) minVal/maxVal;
	
	if (connectivity_ratio >= min_connectivity) {
		return(true);
	}
	else {
		return(false);
	}
}


bool IRKE::exceeds_min_connectivity (KmerCounter& kcounter, string kmerA, string kmerB, float min_connectivity) {

	kmer_int_type_t valA = kmer_to_intval(kmerA);
	kmer_int_type_t valB = kmer_to_intval(kmerB);

	Kmer_Occurence_Pair pairA(valA, kcounter.get_kmer_count(valA));
	Kmer_Occurence_Pair pairB(valB, kcounter.get_kmer_count(valB));

	return exceeds_min_connectivity(kcounter, pairA, pairB, min_connectivity);

}



string IRKE::thread_sequence_through_graph(string& sequence) {
	
	// describe each of the ordered kmers in the input sequence as they exist in the graph.
	
	unsigned int kmer_length = kcounter.get_kmer_length();
	
	if (sequence.length() < kmer_length) {
		cerr << "Sequence length: " << sequence.length() << " is too short to contain any kmers." << "\n";
		return("");
	}
	
	stringstream s;
	
	for (unsigned int i=0; i <= sequence.length() - kmer_length; i++) {
		
		string kmer = sequence.substr(i, kmer_length);
		
		s << kcounter.describe_kmer(kmer) << "\n";
	}
	
	return(s.str());
	
	
}



bool IRKE::sequence_path_exists(string& sequence, unsigned int min_coverage, float min_entropy, float min_connectivity, 
								vector<unsigned int>& coverage_counter) {
	
	unsigned int kmer_length = kcounter.get_kmer_length();
	
	if (sequence.length() < kmer_length) {
		return(false);
	}
	
	bool path_exists = true;
	
	string prev_kmer = sequence.substr(0, kmer_length);
	if (contains_non_gatc(prev_kmer) || ! kcounter.kmer_exists(prev_kmer)) {
		path_exists = false;
		coverage_counter.push_back(0);
	}
	else {
		unsigned int kmer_count = kcounter.get_kmer_count(prev_kmer);
		coverage_counter.push_back(kmer_count);

		float entropy = compute_entropy(prev_kmer);

		if (kmer_count < min_coverage || entropy < min_entropy) {
			path_exists = false;
		}
	}
	
	
	for (unsigned int i=1; i <= sequence.length() - kmer_length; i++) {
		
		string kmer = sequence.substr(i, kmer_length);
		
		if (contains_non_gatc(kmer) || ! kcounter.kmer_exists(kmer)) {
			path_exists = false;
			coverage_counter.push_back(0);
		}
		else {
			unsigned int kmer_count = kcounter.get_kmer_count(kmer);
			coverage_counter.push_back(kmer_count);

			float entropy = compute_entropy(kmer);

			if (kmer_count < min_coverage || entropy < min_entropy) {
				path_exists = false;
			}
		}

		
		if (path_exists && ! exceeds_min_connectivity(kcounter, prev_kmer, kmer, min_connectivity)) {
			path_exists = false;
		}
		
		prev_kmer = kmer;
		
	}
	
	return(path_exists);
}



void IRKE::describe_kmers() {
	
	return(describe_kmers(kcounter));
}

void IRKE::describe_kmers(KmerCounter& kcounter) {
	
	// proxy call to Kcounter method.
	
	kcounter.describe_kmers();
	
	return;
}

void IRKE::populate_sorted_kmers_list() {
    
    sorted_kmers = kcounter.get_kmers_sort_descending_counts();
    got_sorted_kmers_flag = true;

    return;
}

void IRKE::clear_sorted_kmers_list() {

    sorted_kmers.clear();
    got_sorted_kmers_flag = false;
    
    return;
}

kmer_int_type_t IRKE::extract_best_seed(vector<kmer_int_type_t>& kmer_vec, KmerCounter& kcounter, float min_connectivity) {

    unsigned int kmer_length = kcounter.get_kmer_length();
    
    unsigned int best_kmer_count = 0;
    kmer_int_type_t best_seed = 0;
    
    for (unsigned int i = 0; i < kmer_vec.size(); i++) {
        
        kmer_int_type_t kmer = kmer_vec[i];
        unsigned int count = kcounter.get_kmer_count(kmer);
        
        if (count > best_kmer_count && is_good_seed_kmer(kmer, count, kmer_length, min_connectivity)) {
            best_kmer_count = count;
            best_seed = kmer;
        }
    }
    
    if (IRKE_COMMON::MONITOR >= 2) {
        cerr << "Parallel method found better seed: " << kcounter.get_kmer_string(best_seed) << " with count: " << best_kmer_count << "\n";
    }

    return(best_seed);
}