#!/usr/bin/env python3
"""Prefer existing physical highway ways as native hiking-route relation members.
Never invent highway=path. Only attach where exact coordinate-node edge coverage >=90%
and physical-way overrun <=10%; otherwise preserve original overlay member.
"""
import argparse,collections,json,pathlib,xml.etree.ElementTree as ET
from native_translate import mapping,tagdict,top_level_elements

def edges(refs):
 for a,b in zip(refs,refs[1:]):
  if a!=b:yield (a,b) if a<b else (b,a)

def match(src,dst,line_cfg,report):
 candidates={c for c,r in mapping(line_cfg).items() if r.get('route_mode')=='relation'}
 overlay_refs={};lookup=collections.defaultdict(set)
 with open(src,'rb') as f:
  for e in top_level_elements(f):
   if e.tag=='way':
    t=tagdict(e)
    if t.get('garmin:type') in candidates and t.get('garmin:feature')=='extended_polyline':
     oid=int(e.get('id'))
     ns=[int(n.get('ref')) for n in e.findall('nd')]
     if len(ns)>=2:
      overlay_refs[oid]=ns
      for edge in edges(ns):lookup[edge].add(oid)
    e.clear()
   elif e.tag in ('node','relation'):e.clear()
 matches=collections.defaultdict(collections.Counter);physical_len={};written=0
 with open(src,'rb') as f,open(dst,'w',encoding='utf-8') as out:
  out.write('<?xml version="1.0" encoding="UTF-8"?>\n<osm version="0.6" generator="garmin2osm-v0.92" upload="never">\n')
  replaced={}; relations=0
  for e in top_level_elements(f):
   if e.tag=='way':
    t=tagdict(e)
    if 'highway' in t:
     pid=int(e.get('id'));ns=[int(n.get('ref')) for n in e.findall('nd')]
     physical_len[pid]=max(0,len(ns)-1)
     for edge in edges(ns):
      for oid in lookup.get(edge,()):matches[oid][pid]+=1
   elif e.tag=='relation':
    if not replaced:
     for oid,refs in overlay_refs.items():
      nseg=max(1,len(refs)-1)
      for pid,matched in matches.get(oid,{}).most_common():
       # Not allowed to extend a colored marking beyond its actual physical segment.
       if matched/nseg>=0.9 and physical_len.get(pid,10**9)<=nseg*1.1:
        replaced[oid]=pid;break
    tt=tagdict(e)
    if tt.get('route')=='hiking' and tt.get('bgm:source_feature')=='extended_polyline':
     seen=set();relations+=1
     for m in list(e.findall('member')):
      val=int(m.get('ref'))
      ref=str(replaced.get(val,val))
      if ref in seen:e.remove(m)
      else:m.set('ref',ref);seen.add(ref)
   out.write(ET.tostring(e,encoding='unicode')+'\n');written+=1;e.clear()
  out.write('</osm>\n')
  summary={'candidate_overlay_ways':len(overlay_refs),'attached_to_existing_highway':len(replaced),
   'unmatched_overlay_members':len(overlay_refs)-len(replaced),'hiking_relations':relations,
   'policy':'Attach only with >=90% shared physical segments and <=10% physical overrun. No invented routable ways.'}
 pathlib.Path(report).write_text(json.dumps(summary,ensure_ascii=False,indent=2)+'\n',encoding='utf-8')
 return summary

def main():
 p=argparse.ArgumentParser(description=__doc__)
 p.add_argument('--osm',required=True);p.add_argument('--out',required=True);p.add_argument('--lines',required=True);p.add_argument('--report',required=True)
 a=p.parse_args();print(json.dumps(match(a.osm,a.out,a.lines,a.report),ensure_ascii=False,indent=2))
if __name__=='__main__':main()