#Copyright (C) 2020 Inter-University Institute for Data Intensive Astronomy
#See processMeerKAT.py for license details.

#!/usr/bin/env python2.7

import os, sys
import argparse
import ConfigParser
import ast

from utils import globals
from utils import logger

# ========================================================================================================
# ========================================================================================================

def parse_args():
    """
        Parse the command line arguments
        """
    parser = argparse.ArgumentParser()
    parser.add_argument('-C','--config', default=globals.CONFIG, required=False, help='Name of the input config file')
    
    args, __ = parser.parse_known_args()
    
    return vars(args)

# ========================================================================================================

def parse_config(filename):
    """
        Given an input config file, parses it to extract key-value pairs that
        should represent task parameters and values respectively.
        """
    
    config = ConfigParser.SafeConfigParser(allow_no_value=True)
    config.read(filename)
    
    # Build a nested dictionary with tasknames at the top level
    # and parameter values one level down.
    taskvals = dict()
    for section in config.sections():
        
        if section not in taskvals:
            taskvals[section] = dict()
        
        for option in config.options(section):
            # Evaluate to the right type()
            try:
                taskvals[section][option] = ast.literal_eval(config.get(section, option))
            except (ValueError,SyntaxError):
                err = "Cannot format field '{0}' in config file '{1}'".format(option,filename)
                err += ", which is currently set to {0}. Ensure strings are in 'quotes'.".format(config.get(section, option))
                raise ValueError(err)

    return taskvals, config

# ========================================================================================================

def has_key(filename, section, key):
    config_dict,config = parse_config(filename)
    if has_section(filename, section) and key in config_dict[section]:
        return True
    return False


# ========================================================================================================

def has_section(filename, section):

    config_dict,config = parse_config(filename)
    return section in config_dict


# ========================================================================================================

def get_key(filename, section, key):
    config_dict,config = parse_config(filename)
    if has_key(filename, section, key):
        return config_dict[section][key]
    return ''


# ========================================================================================================

def remove_section(filename, section):

    config_dict,config = parse_config(filename)
    config.remove_section(section)
    config_file = open(filename, 'w')
    config.write(config_file)
    config_file.close()


# ========================================================================================================

def overwrite_config(filename, conf_dict={}, conf_sec='', sec_comment=''):

    config_dict,config = parse_config(filename)

    if conf_sec not in config.sections():
        logger.logger.debug('Writing [{0}] section in config file "{1}" with:\n{2}.'.format(conf_sec,filename,conf_dict))
        config.add_section(conf_sec)
    else:
        logger.logger.debug('Overwritting [{0}] section in config file "{1}" with:\n{2}.'.format(conf_sec,filename,conf_dict))

    if sec_comment != '':
        config.set(conf_sec, sec_comment)

    for key in conf_dict.keys():
        config.set(conf_sec, key, str(conf_dict[key]))

    config_file = open(filename, 'w')
    config.write(config_file)
    config_file.close()

# ========================================================================================================


def parse_spw(filename):

    config_dict,config = parse_config(filename)
    spw = config_dict['crosscal']['spw']
    nspw = config_dict['crosscal']['nspw']

    if ',' in spw:
        SPWs = spw.split(',')
        low,high,unit,dirs = [0]*len(SPWs),[0]*len(SPWs),['']*len(SPWs),['']*len(SPWs)
        for i,SPW in enumerate(SPWs):
            low[i],high[i],unit[i],func = processMeerKAT.get_spw_bounds(SPW)
            dirs[i] = '{0}~{1}{2}'.format(low[i],high[i],unit[i])

        lowest = min(low)
        highest = max(high)

        # Uncomment to use e.g. '*MHz'
        # if all([i == unit[0] for i in unit]):
        #     unit = unit[0]
        #     dirs = '*{0}'.format(unit)

    else:
        low,high,unit,func = processMeerKAT.get_spw_bounds(spw)
        dirs = []

    return low,high,unit,dirs


# ========================================================================================================

def validate_args(kwdict, section, key, dtype, default=None):
    """
        Validate the dictionary created by parse_config. Make sure
        that traling characters are removed, and the input types are correct.
        
        kwdict  The dictionary retured by config_parser.parse_config
        section The section in the config file to consider
        key     The specific keyword to validate
        dtype   The type the keyword should conform to.
        default If not none, if the keyword doesn't exist, assigns
        the variable this default value
        
        Valid types are:
        str, float, int, bool
        
        If str, the trailing '/' and trailing whitespaces are removed.
        An exception is raised if the validation fails.
        """
    
    # The input has already been parsed from the config file using
    # ast.literal_eval, so the dictionary values should have recognisable
    # python types.
    
    if default is not None:
        val = kwdict[section].pop(key, default)
    else:
        val = kwdict[section][key]
    
    if dtype is str:
        try:
            val = str(val).rstrip('/ ')
        except UnicodeError as err: # Pretty much the only error str() can raise
            raise
    elif dtype is int:
        try:
            val = int(val)
        except ValueError as err:
            raise
    elif dtype is float:
        try:
            val = float(val)
        except ValueError as err:
            raise
    elif dtype is bool:
        try:
            val = bool(val)
        except ValueError as err:
            raise
    else:
        raise NotImplementedError('Only str, int, bool, and float are valid types.')
    
    return val


# ========================================================================================================

def raise_error(config,msg,parser=None):
    
    """Raise error with specified message, either as parser error (when option passed in via command line),
        or ValueError (when option passed in via config file).
        
        Arguments:
        ----------
        config : str
        Path to config file.
        msg : str
        Error message to display.
        parser : class ``argparse.ArgumentParser``, optional
        If this is input, parser error will be raised."""
    
    if parser is None:
        raise ValueError("Bad input found in '{0}' -- {1}".format(config,msg))
    else:
        parser.error(msg)