#
# psuutil.py
# Platform-specific PSU status interface for SONiC
#


import os.path

try:
    from sonic_psu.psu_base import PsuBase
except ImportError as e:
    raise ImportError(str(e) + "- required module not found")


class PsuUtil(PsuBase):
    """Platform-specific PSUutil class"""

    SYSFS_PSU_DIR = ["/sys/bus/i2c/devices/i2c-3/3-0051",
                     "/sys/bus/i2c/devices/i2c-4/4-0051"]

    def __init__(self):
        PsuBase.__init__(self)
    
             
    # Get sysfs attribute
    def get_attr_value(self, attr_path):
        
        retval = 'ERR'        
        if (not os.path.isfile(attr_path)):
            return retval

        try:
            with open(attr_path, 'r') as fd:
                retval = fd.read()
        except Exception as error:
            logging.error("Unable to open ", attr_path, " file !")

        retval = retval.rstrip('\r\n')
        return retval

    def get_num_psus(self):
        """
        Retrieves the number of PSUs available on the device
        :return: An integer, the number of PSUs available on the device
         """
        MAX_PSUS = 2
        return MAX_PSUS

    def get_psu_status(self, index):
        """
        Retrieves the oprational status of power supply unit (PSU) defined
                by index <index>
        :param index: An integer, index of the PSU of which to query status
        :return: Boolean, True if PSU is operating properly, False if PSU is\
        faulty
        """
        status = 0
        attr_file = 'psu_pg'        
        attr_path = self.SYSFS_PSU_DIR[index-1] +'/' + attr_file
                  
        attr_value = self.get_attr_value(attr_path)
        
        if (attr_value != 'ERR'):
            attr_value = int(attr_value, 16)
            # Check for PSU status
            if (attr_value == 1):
                    status = 1

        return status

    def get_psu_presence(self, index):
        """
        Retrieves the presence status of power supply unit (PSU) defined
                by index <index>
        :param index: An integer, index of the PSU of which to query status
        :return: Boolean, True if PSU is plugged, False if not
        """
        status = 0
        psu_absent = 0
        attr_file ='psu_abs'
        attr_path = self.SYSFS_PSU_DIR[index-1] +'/' + attr_file
        
        attr_value = self.get_attr_value(attr_path)

        if (attr_value != 'ERR'):
            attr_value = int(attr_value, 16)
            # Check for PSU presence
            if (attr_value == 0):
                    status = 1

        return status