diff --git a/pip-requirements.txt b/pip-requirements.txt
index 26f0adc..87bf947 100644
--- a/pip-requirements.txt
+++ b/pip-requirements.txt
@@ -1,3 +1,4 @@
 toolz
 biopython
 PyVCF
+pysam
diff --git a/vartable/primers.py b/vartable/primers.py
new file mode 100644
index 0000000..6e9371b
--- /dev/null
+++ b/vartable/primers.py
@@ -0,0 +1,248 @@
+from dataclasses import dataclass
+import pysam
+import os
+from typing import Iterator, Any, List, Optional, NamedTuple
+import vcf
+from functools import partial
+import itertools
+# from vartable.types import find
+import sys
+from typing import Sequence, Iterable
+
+debug_log = sys.stderr.write
+TESTING = True
+def first(seq):
+    '''@Warning: mutates seq'''
+    if isinstance(seq, Sequence):
+        ret = None if len(seq) == 0 else seq[0]
+    else:
+        try:
+            ret = next(seq)
+        except StopIteration:
+            ret = None
+    return ret
+
+def find(p, seq):
+    return first(filter(p, seq))
+
+class Alt(NamedTuple):
+    position: int
+    base: str
+
+class MappingCoordinate(NamedTuple):
+    reference_start: int
+    reference_end: int
+    query_alignment_sequence: str
+    query_alignment_start: int
+
+class BamRead(NamedTuple):
+    referenceEnd: int
+    referenceStart: int
+    queryStart: int
+    queryEnd: int
+    querySequence: str # without soft clipping
+    querySequenceSoftClipped: str 
+  #  def query_base_at_reference_position(position: int) -> str: ....
+# drawing from https://pysam.readthedocs.io/en/latest/api.html#pysam.AlignedSegment
+import abc
+@dataclass
+class PrimerResult(metaclass=abc.ABCMeta):
+    @property
+    @abc.abstractmethod
+    def outsidePrimer(self) -> bool: ...
+
+@dataclass
+class PrimerCount(PrimerResult):
+   position: int
+   alt: Alt # position and alternate where this count came from. the alt call is obtained from the VCF file.
+   total: int
+   totalWithinEnd : int
+   supportsAltTotal: int # won't have this information for non-primer regions
+   supportsAltWithinEnd: int
+   primer_base: str
+
+   @property
+   def outsidePrimer(self) -> bool:
+       return False
+
+class OutsidePrimer(PrimerResult):
+   @property
+   def outsidePrimer(self) -> bool:
+       return True
+
+@dataclass
+class BamRowInfo:
+    queryBase: str
+    withinEnd: bool
+
+  # alnfile = pysam.AlignmentFile('testdata/fullsample.bam')
+AlignedSegment = AlignmentFile = Any
+
+def calc_query_position(row: Any, alt_position :int) -> Optional[int]: #, query_start: int ): 
+  query_pos_and_ref_pos = find(lambda x: x[1] == alt_position, row.get_aligned_pairs())
+  if query_pos_and_ref_pos and query_pos_and_ref_pos[0]:
+      assert query_pos_and_ref_pos[1] in (alt_position, None)
+      return query_pos_and_ref_pos[0] - row.query_alignment_start
+def single_bam_row_info(alt_position: int, thresh: int, row: AlignedSegment) -> Optional[BamRowInfo]:
+  # get query position
+        
+    # return alt_position - ref_start
+# (Pdb) row.get_aligned_pairs()
+  query_position = calc_query_position(row, alt_position) # , row.reference_start) # , row.query_alignment_start)
+  if not query_position: # the query may be deleted or something at that position
+      return None
+  base_at_alt_position = row.query_alignment_sequence[query_position]
+  # NOTE: Not worrying if soft-clipping would interfere because it's not part of manual process
+
+  # could check for soft clipping by looking at the first/last entry of the cigar string
+  not_primer_start = thresh
+  not_primer_end = len(row.query_alignment_sequence) - thresh
+  is_within_end = (query_position < not_primer_start) or (query_position > not_primer_end)
+  return BamRowInfo(base_at_alt_position, is_within_end)
+
+import functools 
+def primer_count_at_position(thresh: int, primerCoords: List[MappingCoordinate], sampleBamFile: str, reference_id: str, alt: Alt) -> PrimerResult: 
+# , rows: Iterator[AlignedSegment]) -> PrimerCount:
+# TODO1 : Could have more than one primer overlapping, which would be a problem.
+  def overlaps(coord: MappingCoordinate) -> bool: 
+    return (coord.reference_start <= alt.position) and (alt.position <= coord.reference_end)
+
+  overlapped_primers: Optional[MappingCoordinate] = filter(overlaps, primerCoords)
+  if not overlapped_primers:
+    return OutsidePrimer()
+  def get_base_of_primer_at_position(coord: MappingCoordinate) -> str:
+      query_position = calc_query_position(coord, alt.position)
+      if not query_position:
+          return '*' # or should it be a? IDK
+      return coord.query_alignment_sequence[ query_position ] 
+  from collections import Counter
+  primer_cnt = Counter(map(get_base_of_primer_at_position, overlapped_primers))
+  primer_base = primer_cnt.most_common()[0] # could log here
+  # import pdb; pdb.set_trace()
+  with pysam.AlignmentFile(sampleBamFile) as alnfile:
+    bam_rows = alnfile.fetch(reference=reference_id, start=alt.position, stop=alt.position+1)
+    single_info = functools.partial(single_bam_row_info,alt.position, thresh)
+    row_infos = filter(bool, map(single_info, bam_rows))
+  # TODO: Does this assume that the base
+    total = totalWithinEnd = supportsAltWithinEnd = supportsAltTotal = 0
+    for bri in row_infos:
+        isAlt = bri.queryBase == alt.base
+        total += 1
+        totalWithinEnd += int(bri.withinEnd)
+        supportsAltTotal += int(isAlt)
+        supportsAltWithinEnd += int(bri.withinEnd and isAlt)
+    pc = PrimerCount(alt.position, alt, total, totalWithinEnd, supportsAltTotal, supportsAltWithinEnd, primer_base)
+    return pc
+
+def primer_count_all_reference(thresh: int, primerCoords: List[MappingCoordinate], sampleBamFile: str, reference_id: str, alts: Iterable[Alt]) -> Iterator[PrimerResult]:
+  primer_single_position = partial(primer_count_at_position, thresh, primerCoords, sampleBamFile, reference_id)
+  return map(primer_single_position, alts)
+
+def main(thresh: int, primerFile: str, sampleBam: str, alts: Iterable[Alt], reference_file: str, reference_id: str) -> Iterator[PrimerResult]:
+  primer_bam_name = f'{primerFile}.sam'
+  if not TESTING: bwa_map(primerFile, reference_file, primer_bam_name)
+  primer_coords =  get_coordinates_from_bam(reference_id, primer_bam_name)
+  result = primer_count_all_reference(thresh, primer_coords, sampleBam, reference_id, alts)
+  return result
+  
+def reduce_bamRowInfo(infos: Iterable[BamRowInfo], alt: str, primer_base: str, alt_position: int, alt_primer_base: str) -> PrimerResult:
+  total, altTotal, totalWithinEnd, supportsAltWithinEnd = 0, 0, 0, 0
+  for x in infos:
+    total += 1
+    if x.queryBase == alt:
+       altTotal += 1
+       if x.withinEnd: 
+         supportsAltWithinEnd += 1
+    elif x.withinEnd:
+       totalWithinEnd += 1
+  return PrimerCount(alt_position, alt, total, totalWithinEnd, altTotal, supportsAltWithinEnd, primer_base)
+      
+      
+  # query_alignment_sequence starts at query_start [query_sequence does not]
+
+import os
+import sys
+import subprocess
+
+
+def bwa_map(query_file: str, ref_file: str, out_sam: str) -> None:
+  # @Side-effect: produce index files for ref_file if they don't exist
+  # @Side-effect: produces SAM file as out_file
+  index_files = f'{ref_file}.amb' , f'{ref_file}.bwt' , f'{ref_file}.pac' ,f'{ref_file}.ann' , f'{ref_file}.sa'
+  if not all(map(os.path.exists, index_files)):
+     debug_log(f"could not find all required index files: {index_files}\nRuning BWA index on {ref_file}")
+     subprocess.check_call(['bwa', 'index', ref_file])
+     #index_proc_out = subprocess.check_output(['bwa', 'index', ref_file]); #sys.stderr.write(index_proc_out)
+  # bwa is okay with fasta query inputs it seems 
+  with open(out_sam, 'w') as out:
+     debug_log(f"Runing BWA mem on {ref_file}")
+     debug_log(f"Running [bwa mem {ref_file} {query_file} > {out}")
+     subprocess.check_call(['bwa', 'mem', ref_file, query_file], stdout=out)
+     debug_log(f"bwa mem finished.\n")
+  return None
+
+#  for idx in index_files:
+#    assert os.path.exists(idx), 
+def get_coordinates_from_bam(refid: str, bamfile: str) -> List[MappingCoordinate]:
+  with pysam.AlignmentFile(bamfile) as alnfile:
+    coordinates = [ aln for aln in alnfile if aln.reference_name == refid]
+    # coordinates = [ MappingCoordinate(aln.reference_start, aln.reference_end, aln.query_alignment_sequence, aln.query_alignment_start) for aln in alnfile if aln.reference_name == refid]
+  return coordinates
+
+
+ #  query_sequence read sequence bases, including soft clipped bases (None if not present).
+
+def base_caller_process(vcf_path, min_percent, min_depth, out_path):
+  def passes(rec):
+    # VCFRow -> Bool
+    #ValueError: dict contains fields not in fieldnames:
+    # with base_caller, check rec.ALT[0] because we want to skip those which
+    # have no alts and are jus the ref; it's rec.ALT=[None] in that case.
+    return rec.ALT[0] and rec.INFO['DP'] >= min_depth and max(rec.INFO['PAC']) >= min_percent
+  with open(vcf_path, 'r') as vcf_handle:
+    HEADERS = ['Reference ID', 'Position', 'Total Depth', 'Ref Base', 'Alt Base', 'Ref Frequency', 'Alt Frequency', 'Codon', 'Codon Type']
+
+    #TODO: filter on individual alts, so after flattening (I guess as dicts var, in dicts form)
+    muts = filter(passes, vcf.Reader(vcf_handle))
+  #  def to_dict(rec):
+  #    return dict(zip(HEADERS[:-2], [rec.CHROM, rec.POS, rec.REF, rec.ALT, rec.INFO['PRC'], rec.INFO['PAC'], 'Unavailable', 'Unavailable']))
+    def to_dict_single(rec, alt, pac):
+      return dict(zip(HEADERS[:-2], [rec.CHROM, rec.POS, rec.INFO['DP'], rec.REF, alt, rec.INFO['PRC'], pac, 'Unavailable', 'Unavailable']))
+    def to_dict(rec):
+      return map(partial(to_dict_single, rec), rec.ALT, rec.INFO['PAC'])
+    #dicts = map(to_dict, muts)
+    def passes2(dict):
+      return (dict['Total Depth'] >= min_depth) and (dict['Alt Frequency'] >= min_percent)
+    raw_dicts = itertools.chain(*map(to_dict, muts))
+    dicts = filter(passes2, raw_dicts)
+    return dicts
+# global res
+# from vartable import base_caller_process
+if __name__ == '__main__':
+  refid = 'Den1/U88535_1/WestPac/1997/Den1_1' 
+  primer_sam = 'testdata/primers.sam'
+  # print(res)
+  ref = 'testdata/Den1__WestPac__1997.fasta'
+  primer_fasta = 'testdata/read1.fasta'
+  # if not os.path.exists(primer_sam): bwa_map(primer_fasta, ref, primer_sam)
+  res = get_coordinates_from_bam(refid, 'testdata/primers.sam')
+  # primer_sa_print(res)
+  bam = 'testdata/fullsample.bam'
+  vcf_path = 'testdata/fullsample.bam.vcf'
+  # reference_id = 'JF915894.1'
+  reference_id = 'Den1/U88535_1/WestPac/1997/Den1_1'
+  dicts = base_caller_process(vcf_path, 10, 10, '')
+  raw_alts_ = list((d for d in dicts if d['Alt Base'] != '*'))
+  ref_id_ = raw_alts_[0]['Reference ID'] # TODO: multiple refs in a single vcf
+  alts_ = [Alt(d['Position'], d['Alt Base']) for d in raw_alts_]
+  results = main(20, 'testdata/primers', bam, alts_, ref, ref_id_)
+  print(list(results))
+  # main(thresh: int, primerFile: str, sampleBam: str, alts: Iterable[Alt], reference_file: str, reference_id: str) -> Iterator[PimerResult]: 
+
+
+# def match_primers(primers: List[MappingCoordinate], alts: List[Alt], bamReads: Iterator[BamRead], thresh: int) -> List[PrimerCount]: 
+#     pass 
+# 
+#     with pysam.AlignmentFile(bampath) as bam:
+#         for ref in bam.references:
+#             pileupgen = pileup(bam, ref, 0, bam.get_reference_length(ref), opts)