import os
from csv import writer
from artifice import sales_order
# from artifice import clerk_mixins
from decimal import *


class Csv(sales_order.RatesFileMixin, sales_order.SalesOrder):

    def __init__(self, start, end, config):
        super(Csv, self).__init__(start, end, config)
        self.lines = {}
        self.total = Decimal(0.0)
        self.tenant = None

    def _bill(self, tenant):
        """Generates the lines for a sales order for the tenant."""

        if self.tenant is not None:
            raise AttributeError("Sales order already has a tenant.")

        # Usage is one of VMs, Storage, or Volumes.
        for resource in tenant.resources.values():
            print " * " + resource.metadata['type']

            print "   - resource id: " + str(resource.id)
            self.add_line(resource.metadata['type'], [resource.id])

            headers = []
            values = []
            for key, value in resource.metadata.iteritems():
                print "   - " + key + ": " + str(value)
                headers.append(key + str(":"))
                values.append(value)

            self.add_line(resource.metadata['type'], headers)
            self.add_line(resource.metadata['type'], values)

            headers = ["service:", "usage:", "rate:", "cost:"]
            self.add_line(resource.metadata['type'], headers)

            total_cost = Decimal(0.0)

            for service in resource.services.values():
                appendee = []
                cost = Decimal(0.0)
                usage = Decimal(service.volume)

                # GET REGION FROM CONFIG:
                region = 'wellington'

                rate = self.rate(service.name, region)
                cost = usage * rate
                total_cost += cost
                appendee.append(service.name)
                appendee.append(usage)
                appendee.append(rate)
                appendee.append(round(cost, 2))
                print "   - " + service.name + ": " + str(usage)
                print "     - rate: " + str(rate)
                print "     - cost: " + str(round(cost))
                self.add_line(resource.metadata['type'], appendee)

            appendee = ["total cost:", round(total_cost, 2)]
            self.add_line(resource.metadata['type'], appendee)
            print "   - total cost: " + str(round(total_cost))

            self.add_line(resource.metadata['type'], [])

            # adds resource total to sales-order total.
            self.total += total_cost
        self.tenant = tenant

    def add_line(self, res_type, line):
        """Adds a line to the given resource type list."""
        try:
            self.lines[res_type].append(line)
        except KeyError:
            self.lines[res_type] = [line]

    @property
    def filename(self):
        fn_dict = dict(tenant=self.tenant.name, start=self.start,
                       end=self.end)

        fn = os.path.join(
            self.config["output_path"],
            self.config["output_file"] % fn_dict
        )
        return fn

    def close(self):
        """Closes the sales order, and exports the lines to a csv file."""

        try:
            with open(self.filename) as temp_fh:
                pass
            raise RuntimeError("Can't write to an existing file!")
        except IOError:
            pass
        with open(self.filename, "w") as fh:
            csvwriter = writer(fh, dialect='excel', delimiter=',')

            csvwriter.writerow(["", "from", "until"])
            csvwriter.writerow(["usage range: ", str(self.start),
                                str(self.end)])
            csvwriter.writerow([])

            # write types in given order
            for key in self.config["type_order"]:
                try:
                    for line in self.lines[key]:
                        csvwriter.writerow(line)
                    csvwriter.writerow([])
                except KeyError:
                    # not a problem, no resources of that type present
                    pass

            # write remaining types if any:
            keys = list(set(self.lines) - set(self.config["type_order"]))
            for key in keys:
                for line in self.lines[key]:
                    csvwriter.writerow(line)
                csvwriter.writerow([])

            # write a blank line
            csvwriter.writerow([])
            # write total
            csvwriter.writerow(["invoice total cost: ", round(self.total, 2)])