import numpy as np
import yaml 
import os
import datetime 
import epics

# things to do:
# 1. Read a snapshot file (not request file)
# 2. add parameters and performance channels (e.g. AT photon energies)

def parseSnapShotReqYAML(filename):
# read the snapshot request file
# returns a list of PV names
    if not filename:
        filename =  '/sf/data/applications/snapshot/req/op/SF_settings.yaml'
    pvs = []
    path = os.path.dirname(filename)
    with open(filename) as f:
        try:
            content = yaml.load(f, Loader=yaml.SafeLoader)
            if 'include' in content.keys():
                if len(content['include']) > 0:
                    for cont in content['include']:
                        retpv = parseSnapShotReqYAML(path+'/'+cont['name'])
                        if 'macros' in cont.keys():
                            retpv = applyReqMacro(retpv,cont['macros'])
                        pvs =  pvs + retpv
            if 'pvs' in content.keys():
                if 'list' in content['pvs']:
                    for pv in content['pvs']['list']:
                        pvs.append(pv['name'])
                return pvs
            return None
        except yaml.YAMLError as e:
            print(e)
            return None
    return None

def applyReqMacro(pvs_in,macros):    
    pvs = []
    for macro in macros:
        for key in macro:
            tag='$('+key+')'
            for pv in pvs_in:
                if tag in pv:
                    pvs.append(pv.replace(tag,macro[key]))
    for pv in pvs_in:   # copy the ones without macro
        if not '$(' in pv:
            pvs.append(pv)
    return pvs

def getSnap(pvs=None):  
    if not isinstance(pvs,list):
        pvs = parseSnapShotReqYAML(pvs)
    if not pvs:
        return
    ret={}
    val = epics.caget_many(pvs)
    for i,pv in enumerate(pvs):
        if val[i]:      # filter out None values
            ret[pv]=float(val[i]) 
    epics.ca.clear_cache()
    return ret

def saveSnap(pvs={},label="", comment = "generated by application"):
    filename = datetime.datetime.now().strftime('/sf/data/applications/snapshot/SF_settings_%Y%m%d_%H%M%S.snap')
    with open(filename,'w') as fid:
        fid.write('#{"labels":["%s"],"comment":"%s", "machine_parms":{}, "save_time": 0.0, "req_file_name": "SF_settings.yaml"}\n'  % (label,comment))
        for key in pvs.keys():
            if isinstance(pvs[key],int):
                fid.write('%s,{"val": %d}\n' % (key,pvs[key]))
            elif isinstance(pvs[key],float):
                fid.write('%s,{"val": %f}\n' % (key,pvs[key]))
            elif isinstance(pvs[key],str):
                fid.write('%s,{"val": %s}\n' % (key,pvs[key]))