extract.c

#include "htslib/sam.h"
#include "htslib/hts.h"
#include "htslib/faidx.h"
#include <getopt.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <inttypes.h>
#include <assert.h>
#include <errno.h>
#include <limits.h>
#include <math.h>
#include "MethylDackel.h"

void print_version(void);

inline double logit(double p) { 
    return(log(p) - log(1 - p)); 
}

//N.B., a tid of -1 means that the lastCall was written
struct lastCall{
    int32_t tid, pos;
    uint32_t nmethyl, nunmethyl;
};

void writeCall(FILE *of, Config *config, char *chrom, int32_t pos, int32_t width, uint32_t nmethyl, uint32_t nunmethyl, char base) { 
    char strand = (base=='C' || base=='c') ? 'F' : 'R';
    if(nmethyl+nunmethyl < config->minDepth) return;
    if (!config->fraction && !config->logit && !config->counts && !config->methylKit) {
        fprintf(of, \
            "%s\t%i\t%i\t%i\t%" PRIu32 "\t%" PRIu32 "\n", \
            chrom, \
            pos, \
            pos+width, \
            (int) (100.0*((double) nmethyl)/(nmethyl+nunmethyl)),\
            nmethyl, \
            nunmethyl);
    } else if(config->fraction) {
        fprintf(of, \
            "%s\t%i\t%i\t%f\n", \
            chrom, \
            pos, \
            pos+width, \
            ((double) nmethyl)/(nmethyl+nunmethyl));
    } else if(config->counts) {
        fprintf(of, \
            "%s\t%i\t%i\t%i\n", \
            chrom, \
            pos, \
            pos+width, \
            nmethyl+nunmethyl);
    } else if(config->logit) {
        fprintf(of, \
            "%s\t%i\t%i\t%f\n", \
            chrom, \
            pos, \
            pos+width, \
            logit(((double) nmethyl)/(nmethyl+nunmethyl)));
    } else if(config->methylKit) {
        fprintf(of, \
            "%s.%i\t%s\t%i\t%c\t%i\t%6.2f\t%6.2f\n", \
            chrom, \
            pos+1, \
            chrom, \
            pos+1, \
            strand, \
            nmethyl+nunmethyl, \
            100.0 * ((double) nmethyl)/(nmethyl+nunmethyl), \
            100.0 * ((double) nunmethyl)/(nmethyl+nunmethyl));
    }
}

void processLast(FILE *of, Config *config, struct lastCall *last, bam_hdr_t *hdr, int32_t tid, int32_t pos, int width, uint32_t nmethyl, uint32_t nunmethyl, char base) {
    if(last->tid == tid && last->pos == pos) {
        nmethyl += last->nmethyl;
        nunmethyl += last->nunmethyl;
        writeCall(of, config, hdr->target_name[tid], pos, width, nmethyl, nunmethyl, base);
        last->tid = -1;
    } else {
        if(last->tid != -1) {
            writeCall(of, config, hdr->target_name[last->tid], last->pos, width, last->nmethyl, last->nunmethyl, base);
        }
        last->tid = tid;
        last->pos = pos;
        last->nmethyl = nmethyl;
        last->nunmethyl = nunmethyl;
    }
}

void extractCalls(Config *config) {
    bam_hdr_t *hdr = sam_hdr_read(config->fp);
    bam_mplp_t iter;
    int ret, tid, pos, i, seqlen, type, rv, o = 0;
    int beg0 = 0, end0 = 1u<<29;
    int n_plp; //This will need to be modified for multiple input files
    int ctid = -1; //The tid of the contig whose sequence is stored in "seq"
    int idxBED = 0, strand;
    uint32_t nmethyl = 0, nunmethyl = 0;
    const bam_pileup1_t **plp = NULL;
    char *seq = NULL, base = 'A';
    mplp_data *data = NULL;
    struct lastCall *lastCpG = NULL;
    struct lastCall *lastCHG = NULL;

    if(config->merge) {
        if(config->keepCpG) {
            lastCpG = calloc(1, sizeof(struct lastCall));
            assert(lastCpG);
            lastCpG->tid = -1;
        }
        if(config->keepCHG) {
            lastCHG = calloc(1, sizeof(struct lastCall));
            assert(lastCHG);
            lastCHG->tid = -1;
        }
    }

    data = calloc(1,sizeof(mplp_data));
    if(data == NULL) {
        fprintf(stderr, "Couldn't allocate space for the data structure in extractCalls()!\n");
        return;
    }
    data->config = config;
    data->hdr = hdr;
    if (config->reg) {
        if((data->iter = sam_itr_querys(config->bai, hdr, config->reg)) == 0){
            fprintf(stderr, "failed to parse regions %s", config->reg);
            return;
        }
    }
    if(config->bedName) {
        config->bed = parseBED(config->bedName, hdr);
        if(config->bed == NULL) return;
    }

    plp = calloc(1, sizeof(bam_pileup1_t *)); //This will have to be modified for multiple input files
    if(plp == NULL) {
        fprintf(stderr, "Couldn't allocate space for the plp structure in extractCalls()!\n");
        return;
    }

    //Start the pileup
    iter = bam_mplp_init(1, filter_func, (void **) &data);
    bam_mplp_init_overlaps(iter);
    bam_mplp_set_maxcnt(iter, config->maxDepth);
    while((ret = cust_mplp_auto(iter, &tid, &pos, &n_plp, plp)) > 0) {
        //Do we need to process this position?
	if (config->reg){
	    beg0 = data->iter->beg, end0 = data->iter->end;
	    if ((pos < beg0 || pos >= end0)) continue; // out of the region requested
	}
        if(tid != ctid) {
            if(seq != NULL) free(seq);
            seq = faidx_fetch_seq(config->fai, hdr->target_name[tid], 0, faidx_seq_len(config->fai, hdr->target_name[tid]), &seqlen);
            if(seqlen < 0) {
                fprintf(stderr, "faidx_fetch_seq returned %i while trying to fetch the sequence for tid %i (%s)!\n",\
                    seqlen, tid, hdr->target_name[tid]);
                fprintf(stderr, "Note that the output will be truncated!\n");
                return;
            }
            ctid = tid;
        }

        if(config->bed) { //Handle -l
            while((o = posOverlapsBED(tid, pos, config->bed, idxBED)) == -1) idxBED++;
            if(o == 0) continue; //Wrong strand
        }

        if(isCpG(seq, pos, seqlen)) {
            if(!config->keepCpG) continue;
            type = 0;
        } else if(isCHG(seq, pos, seqlen)) {
            if(!config->keepCHG) continue;
            type = 1;
        } else if(isCHH(seq, pos, seqlen)) {
            if(!config->keepCHH) continue;
            type = 2;
        } else {
            continue;
        }

        nmethyl = nunmethyl = 0;
        base = *(seq+pos);
        for(i=0; i<n_plp; i++) {
            if(plp[0][i].is_del) continue;
            if(plp[0][i].is_refskip) continue;
            if(config->bed) if(!readStrandOverlapsBED(plp[0][i].b, config->bed->region[idxBED])) continue;
            strand = getStrand((plp[0]+i)->b);
            if(strand & 1) {
                if(base != 'C' && base != 'c') continue;
            } else {
                if(base != 'G' && base != 'g') continue;
            }
            rv = updateMetrics(config, plp[0]+i);
            if(rv > 0) nmethyl++;
            else if(rv<0) nunmethyl++;
        }

        if(nmethyl+nunmethyl==0) continue;
        if(!config->merge || type==2) {
            writeCall(config->output_fp[type], config, hdr->target_name[tid], pos, 1, nmethyl, nunmethyl, base);
        } else {
            //Merge into per-CpG/CHG metrics
            if(type==0) {
                if(base=='G' || base=='g') pos--;
                processLast(config->output_fp[0], config, lastCpG, hdr, tid, pos, 2, nmethyl, nunmethyl, base);
            } else {
                if(base=='G' || base=='g') pos-=2;
                processLast(config->output_fp[1], config, lastCHG, hdr, tid, pos, 3, nmethyl, nunmethyl, base);
            }
        }
    }

    //Don't forget the last CpG/CHG
    if(config->merge) {
        if(config->keepCpG && lastCpG->tid != -1) {
            processLast(config->output_fp[0], config, lastCpG, hdr, tid, pos, 2, nmethyl, nunmethyl, base);
        }
        if(config->keepCHG && lastCHG->tid != -1) {
            processLast(config->output_fp[1], config, lastCHG, hdr, tid, pos, 3, nmethyl, nunmethyl, base);
        }
    }

    bam_hdr_destroy(hdr);
    if(data->iter) hts_itr_destroy(data->iter);
    bam_mplp_destroy(iter);
    free(data);
    free(plp);
    if(seq != NULL) free(seq);
}

void parseBounds(char *s2, int *vals, int mult) {
    char *p, *s = strdup(s2), *end;
    int i, v;
    long tempV;

    p = strtok(s, ",");
    tempV = strtol(p, &end, 10);
    if((errno == ERANGE && (tempV == LONG_MAX || tempV == LONG_MIN)) || (errno != 0 && tempV == 0) || end == p) v = -1;
    else if(tempV > INT_MAX || tempV < LONG_MIN) v = -1;
    else v = tempV;

    if(v>=0) vals[4*mult] = v;
    else {
        fprintf(stderr, "Invalid bounds string, %s\n", s2);
        free(s);
        return;
    }
    for(i=1; i<4; i++) {
        p = strtok(NULL, ",");
        tempV = strtol(p, &end, 10);
        if((errno == ERANGE && (tempV == LONG_MAX || tempV == LONG_MIN)) || (errno != 0 && tempV == 0) || end == p) v = -1;
        else if(tempV > INT_MAX || tempV < LONG_MIN) v = -1;
        else v = tempV;

        if(v>=0) vals[4*mult+i] = v;
        else {
            fprintf(stderr, "Invalid bounds string, %s\n", s2);
            free(s);
            return;
        }
    }
    free(s);
}

void printHeader(FILE *of, char *context, char *opref, Config config) {
    fprintf(of, "track type=\"bedGraph\" description=\"%s %s", opref, context);
    if(config.merge) fprintf(of, " merged");
    if(config.fraction) fprintf(of, " methylation fractions\"\n");
    else if(config.counts) fprintf(of, " methylation counts\"\n");
    else if(config.logit) fprintf(of, " logit transformed methylation fractions\"\n");
    else fprintf(of, " methylation levels\"\n");
}

void extract_usage() {
    fprintf(stderr, "\nUsage: MethylDackel extract [OPTIONS] <ref.fa> <sorted_alignments.bam>\n");
    fprintf(stderr,
"\n"
"Options:\n"
" -q INT           Minimum MAPQ threshold to include an alignment (default 10)\n"
" -p INT           Minimum Phred threshold to include a base (default 5). This\n"
"                  must be >0.\n"
" -D INT           Maximum per-base depth (default 2000)\n"
" -d INT           Minimum per-base depth for reporting output. If you use\n"
"                  --mergeContext, this then applies to the merged CpG/CHG.\n"
"                  (default 1)\n"
" -r STR           Region string in which to extract methylation\n"
" -l FILE          A BED file listing regions for inclusion. Note that unlike\n"
"                  samtools mpileup, this option will utilize the strand column\n"
"                  (column 6) if present. Thus, if a region has a '+' in this\n"
"                  column, then only metrics from the top strand will be\n"
"                  output. Note that the -r option can be used to limit the\n"
"                  regions of -l.\n"
" --mergeContext   Merge per-Cytosine metrics from CpG and CHG contexts into\n"
"                  per-CPG or per-CHG metrics.\n"
" -o, --opref STR  Output filename prefix. CpG/CHG/CHH context metrics will be\n"
"                  output to STR_CpG.bedGraph and so on.\n"
" --keepDupes      By default, any alignment marked as a duplicate is ignored.\n"
"                  This option causes them to be incorporated.\n"
" --keepSingleton  By default, if only one read in a pair aligns (a singleton)\n"
"                  then it's ignored.\n"
" --keepDiscordant By default, paired-end alignments with the properly-paired bit\n"
"                  unset in the FLAG field are ignored. Note that the definition\n"
"                  of concordant and discordant is based on your aligner\n"
"                  settings.\n"
" -F, --ignoreFlags    By deault, any alignment marked as secondary (bit 0x100),\n"
"                  failing QC (bit 0x200), a PCR/optical duplicate (0x400) or\n"
"                  supplemental (0x800) is ignored. This equates to a value of\n"
"                  0xF00 or 3840 in decimal. If you would like to change that,\n"
"                  you can specify a new value here.\n"
"                  ignored. Specifying this causes them to be included.\n"
" -R, --requireFlags   Require each alignment to have all bits in this value\n"
"                  present, or else the alignment is ignored. This is equivalent\n"
"                  to the -f option in samtools. The default is 0, which\n"
"                  includes all alignments.\n"
" --noCpG          Do not output CpG context methylation metrics\n"
" --CHG            Output CHG context methylation metrics\n"
" --CHH            Output CHH context methylation metrics\n"
" --fraction       Extract fractional methylation (only) at each position. This\n"
"                  produces a file with a .meth.bedGraph extension.\n"
" --counts         Extract base counts (only) at each position. This produces a\n"
"                  file with a .counts.bedGraph extension.\n"
" --logit          Extract logit(M/(M+U)) (only) at each position. This produces\n"
"                  a file with a .logit.bedGraph extension.\n"
" --methylKit      Output in the format required by methylKit. Note that this is\n"
"                  incompatible with --mergeContext, --fraction and --counts.\n"
" --OT INT,INT,INT,INT Inclusion bounds for methylation calls from reads/pairs\n"
"                  origination from the original top strand. Suggested values can\n"
"                  be obtained from the MBias program. Each integer represents a\n"
"                  1-based position on a read. For example --OT A,B,C,D\n"
"                  translates to, \"Include calls at positions from A through B\n"
"                  on read #1 and C through D on read #2\". If a 0 is used a any\n"
"                  position then that is translated to mean start/end of the\n"
"                  alignment, as appropriate. For example, --OT 5,0,0,0 would\n"
"                  include all but the first 4 bases on read #1. Users are\n"
"                  strongly advised to consult a methylation bias plot, for\n"
"                  example by using the MBias program.\n"
" --OB INT,INT,INT,INT\n"
" --CTOT INT,INT,INT,INT\n"
" --CTOB INT,INT,INT,INT As with --OT, but for the original bottom, complementary\n"
"                  to the original top, and complementary to the original bottom\n"
"                  strands, respectively.\n"
" --nOT INT,INT,INT,INT Like --OT, but always exclude INT bases from a given end\n"
"                  from inclusion,regardless of the length of an alignment. This\n"
"                  is useful in cases where reads may have already been trimmed\n"
"                  to different lengths, but still none-the-less contain a\n"
"                  certain length bias at one or more ends.\n"
" --nOB INT,INT,INT,INT\n"
" --nCTOT INT,INT,INT,INT\n"
" --nCTOB INT,INT,INT,INT As with --nOT, but for the original bottom, complementary\n"
"                  to the original top, and complementary to the original bottom\n"
"                  strands, respectively.\n"
" --version        Print version and then quit.\n"
"\nNote that --fraction, --counts, and --logit are mutually exclusive!\n");
}

int extract_main(int argc, char *argv[]) {
    char *opref = NULL, *oname, *p;
    int c, i;
    Config config;

    //Defaults
    config.keepCpG = 1; config.keepCHG = 0; config.keepCHH = 0;
    config.minMapq = 10; config.minPhred = 5; config.keepDupes = 0;
    config.keepSingleton = 0, config.keepDiscordant = 0;
    config.minDepth = 1;
    config.methylKit = 0;
    config.merge = 0;
    config.maxDepth = 2000;
    config.fai = NULL;
    config.fp = NULL;
    config.bai = NULL;
    config.reg = NULL;
    config.bedName = NULL;
    config.bed = NULL;
    config.fraction = 0;
    config.counts = 0;
    config.logit = 0;
    config.ignoreFlags = 0xF00;
    config.requireFlags = 0;
    for(i=0; i<16; i++) config.bounds[i] = 0;
    for(i=0; i<16; i++) config.absoluteBounds[i] = 0;

    static struct option lopts[] = {
        {"opref",        1, NULL, 'o'},
        {"fraction",     0, NULL, 'f'},
        {"counts",       0, NULL, 'c'},
        {"logit",        0, NULL, 'm'},
        {"minDepth",     1, NULL, 'd'},
        {"noCpG",        0, NULL,   1},
        {"CHG",          0, NULL,   2},
        {"CHH",          0, NULL,   3},
        {"keepDupes",    0, NULL,   4},
        {"keepSingleton",0, NULL,   5},
        {"keepDiscordant",0,NULL,   6},
        {"OT",           1, NULL,   7},
        {"OB",           1, NULL,   8},
        {"CTOT",         1, NULL,   9},
        {"CTOB",         1, NULL,  10},
        {"mergeContext", 0, NULL,  11},
        {"methylKit",    0, NULL,  12},
        {"nOT",          1, NULL,  13},
        {"nOB",          1, NULL,  14},
        {"nCTOT",        1, NULL,  15},
        {"nCTOB",        1, NULL,  16},
        {"ignoreFlags",  1, NULL, 'F'},
        {"requireFlags", 1, NULL, 'R'},
        {"help",         0, NULL, 'h'},
        {"version",      0, NULL, 'v'},
        {0,              0, NULL,   0}
    };
    while((c = getopt_long(argc, argv, "hvq:p:r:l:o:D:f:c:m:d:F:R:", lopts,NULL)) >=0){
        switch(c) {
        case 'h' :
            extract_usage();
            return 0;
        case 'v' :
            print_version();
            return 0;
        case 'o' :
            opref = strdup(optarg);
            break;
        case 'D' :
            config.maxDepth = atoi(optarg);
            break;
        case 'd' :
            config.minDepth = atoi(optarg);
            if(config.minDepth < 1) {
                fprintf(stderr, "Error, the minimum depth must be at least 1!\n");
                return 1;
            }
            break;
	case 'r':
	    config.reg = strdup(optarg);
	    break;
        case 'l' :
            config.bedName = optarg;
            break;
        case 1 :
            config.keepCpG = 0;
            break;
        case 2 :
            config.keepCHG = 1;
            break;
        case 3 :
            config.keepCHH = 1;
            break;
        case 4 :
            config.keepDupes = 1;
            break;
        case 5 :
            config.keepSingleton = 1;
            break;
        case 6 :
            config.keepDiscordant = 1;
            break;
        case 7 :
            parseBounds(optarg, config.bounds, 0);
            break;
        case 8 :
            parseBounds(optarg, config.bounds, 1);
            break;
        case 9 :
            parseBounds(optarg, config.bounds, 2);
            break;
        case 10 :
            parseBounds(optarg, config.bounds, 3);
            break;
        case 11 :
            config.merge = 1;
            break;
        case 12 :
            config.methylKit = 1;
            break;
        case 13 :
            parseBounds(optarg, config.absoluteBounds, 0);
            break;
        case 14 :
            parseBounds(optarg, config.absoluteBounds, 1);
            break;
        case 15 :
            parseBounds(optarg, config.absoluteBounds, 2);
            break;
        case 16 :
            parseBounds(optarg, config.absoluteBounds, 3);
            break;
        case 'F' :
            config.ignoreFlags = atoi(optarg);
            break;
        case 'R':
            config.requireFlags = atoi(optarg);
            break;
        case 'q' :
            config.minMapq = atoi(optarg);
            break;
        case 'p' :
            config.minPhred = atoi(optarg);
            break;
        case 'm' :
            config.logit = 1;
            break;
        case 'f' :
            config.fraction = 1;
            break;
        case 'c' :
            config.counts = 1;
            break;
        case '?' :
        default :
            fprintf(stderr, "Invalid option '%c'\n", c);
            extract_usage();
            return 1;
        }
    }

    if(argc == 1) {
        extract_usage();
        return 0;
    }
    if(argc-optind != 2) {
        fprintf(stderr, "You must supply a reference genome in fasta format and an input BAM file!!!\n");
        extract_usage();
        return -1;
    }

    //Are the options reasonable?
    if(config.minPhred < 1) {
        fprintf(stderr, "-p %i is invalid. resetting to 1, which is the lowest possible value.\n", config.minPhred);
        config.minPhred = 1;
    }
    if(config.minMapq < 0) {
        fprintf(stderr, "-q %i is invalid. Resetting to 0, which is the lowest possible value.\n", config.minMapq);
        config.minMapq = 0;
    }
    if(config.fraction+config.counts+config.logit+config.methylKit > 1) {
        fprintf(stderr, "More than one of --fraction, --counts, --methylKit and --logit were specified. These are mutually exclusive.\n");
        extract_usage();
        return 1;
    }
    if(config.methylKit + config.merge == 2) {
        fprintf(stderr, "--mergeContext and --methylKit are mutually exclusive.\n");
        extract_usage();
        return 1;
    }

    //Has more than one output format been requested?
    if(config.fraction + config.counts + config.logit > 1) {
        fprintf(stderr, "You may specify AT MOST one of -c/--counts, -f/--fraction, or -m/--logit.\n");
        return -6;
    }

    //Is there still a metric to output?
    if(!(config.keepCpG + config.keepCHG + config.keepCHH)) {
        fprintf(stderr, "You haven't specified any metrics to output!\nEither don't use the --noCpG option or specify --CHG and/or --CHH.\n");
        return -1;
    }

    //Open the files
    if((config.fai = fai_load(argv[optind])) == NULL) {
        fprintf(stderr, "Couldn't open the index for %s!\n", argv[optind]);
        extract_usage();
        return -2;
    }
    if((config.fp = hts_open(argv[optind+1], "rb")) == NULL) {
        fprintf(stderr, "Couldn't open %s for reading!\n", argv[optind+1]);
        return -4;
    }
    if((config.bai = sam_index_load(config.fp, argv[optind+1])) == NULL) {
        fprintf(stderr, "Couldn't load the index for %s, will attempt to build it.\n", argv[optind+1]);
        if(bam_index_build(argv[optind+1], 0) < 0) {
            fprintf(stderr, "Couldn't build the index for %s! File corrupted?\n", argv[optind+1]);
            return -5;
        }
        if((config.bai = sam_index_load(config.fp, argv[optind+1])) == NULL) {
            fprintf(stderr, "Still couldn't load the index, quiting.\n");
            return -5;
        }
    }

    //Output files
    config.output_fp = malloc(sizeof(FILE *) * 3);
    assert(config.output_fp);
    if(opref == NULL) {
        opref = strdup(argv[optind+1]);
        assert(opref);
        p = strrchr(opref, '.');
        if(p != NULL) *p = '\0';
        fprintf(stderr, "writing to prefix:'%s'\n", opref);
    }
    if(config.fraction) { 
        oname = malloc(sizeof(char) * (strlen(opref)+19));
    } else if(config.counts) {
        oname = malloc(sizeof(char) * (strlen(opref)+21));
    } else if(config.logit) {
        oname = malloc(sizeof(char) * (strlen(opref)+20));
    } else if(config.methylKit) {
        oname = malloc(sizeof(char) * (strlen(opref)+15));
    } else { 
        oname = malloc(sizeof(char) * (strlen(opref)+14));
    }
    assert(oname);
    if(config.keepCpG) {
        if(config.fraction) { 
            sprintf(oname, "%s_CpG.meth.bedGraph", opref);
        } else if(config.counts) {
            sprintf(oname, "%s_CpG.counts.bedGraph", opref);
        } else if(config.logit) {
            sprintf(oname, "%s_CpG.logit.bedGraph", opref);
        } else if(config.methylKit) {
            sprintf(oname, "%s_CpG.methylKit", opref);
        } else { 
            sprintf(oname, "%s_CpG.bedGraph", opref);
        }
        config.output_fp[0] = fopen(oname, "w");
        if(config.output_fp[0] == NULL) {
            fprintf(stderr, "Couldn't open the output CpG metrics file for writing! Insufficient permissions?\n");
            return -3;
        }
        if(config.methylKit) {
            fprintf(config.output_fp[0], "chrBase\tchr\tbase\tstrand\tcoverage\tfreqC\tfreqT\n");
        } else {
            printHeader(config.output_fp[0], "CpG", opref, config);
        }
    }
    if(config.keepCHG) {
        if(config.fraction) { 
            sprintf(oname, "%s_CHG.meth.bedGraph", opref);
        } else if(config.counts) {
            sprintf(oname, "%s_CHG.counts.bedGraph", opref);
        } else if(config.logit) {
            sprintf(oname, "%s_CHG.logit.bedGraph", opref);
        } else if(config.methylKit) {
            sprintf(oname, "%s_CHG.methylKit", opref);
        } else { 
            sprintf(oname, "%s_CHG.bedGraph", opref);
        }
        config.output_fp[1] = fopen(oname, "w");
        if(config.output_fp[1] == NULL) {
            fprintf(stderr, "Couldn't open the output CHG metrics file for writing! Insufficient permissions?\n");
            return -3;
        }
        if(config.methylKit) {
            fprintf(config.output_fp[1], "chrBase\tchr\tbase\tstrand\tcoverage\tfreqC\tfreqT\n");
        } else {
            printHeader(config.output_fp[1], "CHG", opref, config);
        }
    }
    if(config.keepCHH) {
        if(config.fraction) { 
            sprintf(oname, "%s_CHH.meth.bedGraph", opref);
        } else if(config.counts) {
            sprintf(oname, "%s_CHH.counts.bedGraph", opref);
        } else if(config.logit) {
            sprintf(oname, "%s_CHH.logit.bedGraph", opref);
        } else if(config.methylKit) {
            sprintf(oname, "%s_CHH.methylKit", opref);
        } else { 
            sprintf(oname, "%s_CHH.bedGraph", opref);
        }
        config.output_fp[2] = fopen(oname, "w");
        if(config.output_fp[2] == NULL) {
            fprintf(stderr, "Couldn't open the output CHH metrics file for writing! Insufficient permissions?\n");
            return -3;
        }
        if(config.methylKit) {
            fprintf(config.output_fp[2], "chrBase\tchr\tbase\tstrand\tcoverage\tfreqC\tfreqT\n");
        } else {
            printHeader(config.output_fp[2], "CHH", opref, config);
        }
    }

    //Run the pileup
    extractCalls(&config);

    //Close things up
    hts_close(config.fp);
    fai_destroy(config.fai);
    if(config.keepCpG) fclose(config.output_fp[0]);
    if(config.keepCHG) fclose(config.output_fp[1]);
    if(config.keepCHH) fclose(config.output_fp[2]);
    hts_idx_destroy(config.bai);
    free(opref);
    if(config.reg) free(config.reg);
    if(config.bed) destroyBED(config.bed);
    free(oname);
    free(config.output_fp);

    return 0;
}