#!/usr/bin/env python

"""
This script parses the given fan presence definition yaml file and generates
a header file based on the defined methods for determining when a fan is
present.
"""

import os
import sys
import yaml
from argparse import ArgumentParser
# TODO Convert to using a mako template


def get_filename():
    """
    Constructs and returns the fully qualified header filename.
    """
    script_dir = os.path.dirname(os.path.abspath(__file__))
    header_file = os.path.join(script_dir, "fan_detect_defs.cpp")

    return header_file


def create_and_add_header(header_file):
    """
    Creates the header file based on the header filename value given within.
    The associated fan presence detection application includes this header.

    Parameter descriptions:
    header_file           Header filename to create
    """
    with open(header_file, 'w') as ofile:
        ofile.write("/* WARNING: This header contains code generated ")
        ofile.write("by " + __file__ + " */\n")
        ofile.write("/* !!! DO NOT EDIT THIS FILE BY HAND !!! */\n")
        ofile.write("#include \"fan_detect_defs.hpp\"\n\n")
        ofile.write("const std::map<std::string, ")
        ofile.write("std::set<phosphor::fan::Properties>>")
        ofile.write("\nfanDetectMap = {\n")


def add_detect(header_fd, dmethod):
    """
    Adds the detection method map entry for listing the fan(s) that should be
    detected using the supported method.

    Parameter descriptions:
    header_fd           Header file to add the detection method to
    dmethod             The detection method to be added
    """
    header_fd.write("    {\"" + dmethod + "\",{\n")


def add_fan(header_fd, fan_info):
    """
    Adds each fan's yaml entry presence detection information to the
    corresponding header file for the defined detection method

    Parameter descriptions:
    header_fd           Header file to add fan information to
    fan_info            Fan presence detection information
    """
    tab = ' ' * 4
    header_fd.write(tab * 2 + "std::make_tuple(\"" +
                    fan_info['Inventory'] + "\",\n")
    header_fd.write(tab * 6 + "\"" +fan_info['Description'] + "\",\n")
    header_fd.write(tab * 6 + "std::vector<std::string>({")
    for sensors in fan_info['Sensors']:
        if sensors != fan_info['Sensors'][-1]:
            header_fd.write("\"" + sensors + "\",")
        else:
            header_fd.write("\"" + sensors + "\"})),\n")


def close_detect(header_fd):
    """
    Closes the current detection method map entry.

    Parameter descriptions:
    header_fd           Header file to add detection method closing to
    """
    header_fd.write("    }},\n")


def add_closing(header_fd):
    """
    Appends final closing tags to the header file given. This essentially
    ends writing to the header file generated.

    Parameter descriptions:
    header_fd           Header file to add closing tags to
    """
    header_fd.write("};\n")


def parse_yaml(yaml_file):
    """
    Parse the given yaml file, creating a header file for each 'Detection'
    types found to be included within the app supporting presence detection
    by that type.

    Parameter descriptions:
    yaml_file           File to be parsed for fan presences definitions
    """
    with open(yaml_file, 'r') as input_file:
        yaml_input = yaml.safe_load(input_file)
        header_file = get_filename()
        create_and_add_header(header_file)
        header_fd = open(header_file, 'a')
        if yaml_input:
            for detect in yaml_input:
                for dmethod in detect:
                    add_detect(header_fd, dmethod.replace(" ", "-").lower())
                    for fan in detect[dmethod]:
                        add_fan(header_fd, fan)
                    close_detect(header_fd)
        add_closing(header_fd)
        header_fd.close()


if __name__ == '__main__':
    parser = ArgumentParser()
    # Input yaml containing how each fan's presence detection should be done
    parser.add_argument("-y", "--yaml", dest="pres_yaml",
                        default=
                        "example/fan-detect.yaml",
                        help=
                        "Input fan presences definition yaml file to parse")
    args = parser.parse_args(sys.argv[1:])

    # Verify given yaml file exists
    yaml_file = os.path.abspath(args.pres_yaml)
    if not os.path.isfile(yaml_file):
        print "Unable to find input yaml file " + yaml_file
        exit(1)

    parse_yaml(yaml_file)