# Optional loopback-only teaching server. Never installed on the PHP hosting.
import argparse,json,math
from pathlib import Path
from http.server import BaseHTTPRequestHandler,HTTPServer
from worked_lab import predict_payload

def main():
    p=argparse.ArgumentParser();p.add_argument('--model',required=True);p.add_argument('--port',type=int,default=10080);args=p.parse_args()
    model=json.loads(Path(args.model).read_text())
    if model.get('schema_version')!=1 or model.get('features')!=['distance_km','load_ratio'] or len(model.get('coefficients',[]))!=3: raise ValueError('Unsupported model schema')
    if not all(isinstance(x,(int,float)) and not isinstance(x,bool) and math.isfinite(x) for x in model['coefficients']): raise ValueError('Invalid coefficients')
    if model.get('bounds')!={'distance_km':[0,250],'load_ratio':[0,1.2]}: raise ValueError('Unsupported bounds')
    class Handler(BaseHTTPRequestHandler):
        def log_message(self,*args): pass # Do not log payloads.
        def reply(self,status,value):
            body=json.dumps(value,allow_nan=False).encode();self.send_response(status);self.send_header('Content-Type','application/json');self.send_header('Content-Length',str(len(body)));self.end_headers();self.wfile.write(body)
        def do_GET(self):
            self.reply(200,{'status':'learning-only','model_id':model['model_id']}) if self.path=='/health' else self.reply(404,{'error':'Not found'})
        def do_POST(self):
            if self.path!='/predict':return self.reply(404,{'error':'Not found'})
            try:
                size=int(self.headers.get('Content-Length','0'))
                if not 0<size<=1024:raise ValueError('Invalid body size')
                payload=json.loads(self.rfile.read(size));result=predict_payload(payload,model)
            except (ValueError,TypeError,KeyError):return self.reply(400,{'error':'Invalid prediction request'})
            self.reply(200,result)
    HTTPServer(('127.0.0.1',args.port),Handler).serve_forever()
if __name__=='__main__':main()