import os
import csv
import io

from dataflows import Flow, validate, add_metadata, set_type, update_resource
import requests


def readme(fpath="README.md"):
    if os.path.exists(fpath):
        return open(fpath).read()


base_url = "https://fred.stlouisfed.org/graph/fredgraph.csv?id="
inverse = ["Australia", "Euro", "Ireland", "New Zealand", "United Kingdom"]
country_codes = {
    "Australia": {"daily": "DEXUSAL", "monthly": "EXUSAL", "annual": "AEXUSAL"},
    "Austria": {"daily": "", "monthly": "EXAUUS", "annual": ""},
    "Belgium": {"daily": "", "monthly": "EXBEUS", "annual": ""},
    "Brazil": {"daily": "DEXBZUS", "monthly": "EXBZUS", "annual": "AEXBZUS"},
    "Canada": {"daily": "DEXCAUS", "monthly": "EXCAUS", "annual": "AEXCAUS"},
    "China": {"daily": "DEXCHUS", "monthly": "EXCHUS", "annual": "AEXCHUS"},
    "Denmark": {"daily": "DEXDNUS", "monthly": "EXDNUS", "annual": "AEXDNUS"},
    "Euro": {"daily": "DEXUSEU", "monthly": "EXUSEU", "annual": "AEXUSEU"},
    "Finland": {"daily": "", "monthly": "EXFNUS", "annual": ""},
    "France": {"daily": "", "monthly": "EXFRUS", "annual": ""},
    "Germany": {"daily": "", "monthly": "EXGEUS", "annual": ""},
    "Greece": {"daily": "", "monthly": "EXGRUS", "annual": ""},
    "Hong Kong": {"daily": "DEXHKUS", "monthly": "EXHKUS", "annual": "AEXHKUS"},
    "India": {"daily": "DEXINUS", "monthly": "EXINUS", "annual": "AEXINUS"},
    "Ireland": {"daily": "", "monthly": "EXUSIR", "annual": ""},
    "Italy": {"daily": "", "monthly": "EXITUS", "annual": ""},
    "Japan": {"daily": "DEXJPUS", "monthly": "EXJPUS", "annual": "AEXJPUS"},
    "Malaysia": {"daily": "DEXMAUS", "monthly": "EXMAUS", "annual": "AEXMAUS"},
    "Mexico": {"daily": "DEXMXUS", "monthly": "EXMXUS", "annual": "AEXMXUS"},
    "Netherlands": {"daily": "", "monthly": "EXNEUS", "annual": ""},
    "New Zealand": {"daily": "DEXUSNZ", "monthly": "EXUSNZ", "annual": "AEXUSNZ"},
    "Norway": {"daily": "DEXNOUS", "monthly": "EXNOUS", "annual": "AEXNOUS"},
    "Portugal": {"daily": "", "monthly": "EXPOUS", "annual": ""},
    "Singapore": {"daily": "DEXSIUS", "monthly": "EXSIUS", "annual": "AEXSIUS"},
    "South Africa": {"daily": "DEXSFUS", "monthly": "EXSFUS", "annual": "AEXSFUS"},
    "South Korea": {"daily": "DEXKOUS", "monthly": "EXKOUS", "annual": "AEXKOUS"},
    "Spain": {"daily": "", "monthly": "EXSPUS", "annual": ""},
    "Sri Lanka": {"daily": "", "monthly": "EXSLUS", "annual": ""},
    "Sweden": {"daily": "DEXSDUS", "monthly": "EXSDUS", "annual": "AEXSDUS"},
    "Switzerland": {"daily": "DEXSZUS", "monthly": "EXSZUS", "annual": "AEXSZUS"},
    "Taiwan": {"daily": "DEXTAUS", "monthly": "EXTAUS", "annual": "AEXTAUS"},
    "Thailand": {"daily": "DEXTHUS", "monthly": "EXTHUS", "annual": "AEXTHUS"},
    "United Kingdom": {"daily": "DEXUSUK", "monthly": "EXUSUK", "annual": ""},
    "Venezuela": {"daily": "DEXVZUS", "monthly": "EXVZUS", "annual": "AEXVZUS"},
}


def extract_exchange_rates(frequency):
    for country in country_codes:
        country_frequency_ticker = country_codes[country][frequency]
        url = base_url + country_frequency_ticker
        if country_frequency_ticker:
            try:
                response = requests.get(url, timeout=60)
                response.raise_for_status()
                reader = csv.DictReader(io.StringIO(response.text))
                for row in reader:
                    date = (
                        row.get("DATE") or row.get("observation_date") or ""
                    ).strip()
                    value = (row.get(country_frequency_ticker) or "").strip()
                    if not date:
                        continue
                    if value == ".":
                        value = ""
                    if country in inverse and value != "":
                        try:
                            value = str(1 / float(value))
                        except ValueError:
                            value = ""

                    yield {"Date": date, "Country": country, "Exchange rate": value}
            except Exception:
                continue


exchange_rate_flow = Flow(
    add_metadata(
        name="us-euro-foreign-exchange-rate",
        title="USA / EUR Foreign Exchange Rate since 1999",
        homepage="https://fred.stlouisfed.org",
        sources=[
            {
                "name": "federal-reserve-bank-st-louis",
                "title": "Federal Reserve Bank of St. Louis",
                "path": "https://fred.stlouisfed.org/categories/158",
            }
        ],
        licenses=[
            {
                "id": "odc-pddl",
                "name": "public_domain_dedication_and_license",
                "version": "1.0",
                "url": "http://opendatacommons.org/licenses/pddl/1.0/",
            }
        ],
        views=[
            {
                "name": "us-to-uk-foreign-exchange-rate",
                "title": "USA / GBP Foreign Exchange Rate since 1971",
                "resources": [
                    {
                        "name": "daily",
                        "transform": [
                            {
                                "type": "filter",
                                "expression": "data['Country'] === 'United Kingdom'",
                            }
                        ],
                    }
                ],
                "specType": "simple",
                "spec": {"type": "line", "group": "Date", "series": ["Exchange rate"]},
            },
            {
                "name": "us-euro-foreign-exchange-rate",
                "title": "USA / EUR Foreign Exchange Rate since 1999",
                "resources": [
                    {
                        "name": "daily",
                        "transform": [
                            {
                                "type": "filter",
                                "expression": "data['Country'] === 'Euro'",
                            }
                        ],
                    }
                ],
                "specType": "simple",
                "spec": {"type": "line", "group": "Date", "series": ["Exchange rate"]},
            },
        ],
        version="0.2.0",
        readme=readme(),
    ),
    extract_exchange_rates("daily"),
    extract_exchange_rates("monthly"),
    extract_exchange_rates("annual"),
    update_resource(
        "res_1", **{"name": "daily", "path": "data/daily.csv", "dpp:streaming": True}
    ),
    update_resource(
        "res_2",
        **{"name": "monthly", "path": "data/monthly.csv", "dpp:streaming": True},
    ),
    update_resource(
        "res_3", **{"name": "annual", "path": "data/annual.csv", "dpp:streaming": True}
    ),
    set_type("Date", resources="daily", type="date", description="Date in ISO format"),
    set_type(
        "Country", resources="daily", type="string", description="Name of a country"
    ),
    set_type(
        "Exchange rate",
        resources="daily",
        type="number",
        description="Foreign Exchange Rate to USD. Only AUD, IEP, NZD, GBP and EUR to USD.",
    ),
    set_type(
        "Date", resources="monthly", type="date", description="Date in ISO format"
    ),
    set_type(
        "Country", resources="monthly", type="string", description="Name of a country"
    ),
    set_type(
        "Exchange rate",
        resources="monthly",
        type="number",
        description="Foreign Exchange Rate to USD. Only AUD, IEP, NZD, GBP and EUR to USD.",
    ),
    set_type("Date", resources="annual", type="date", description="Date in ISO format"),
    set_type(
        "Country", resources="annual", type="string", description="Name of a country"
    ),
    set_type(
        "Exchange rate",
        resources="annual",
        type="number",
        description="Foreign Exchange Rate to USD. Only AUD, IEP, NZD, GBP and EUR to USD.",
    ),
    validate(),
)


def flow(parameters, datapackage, resources, stats):
    return exchange_rate_flow


if __name__ == "__main__":
    exchange_rate_flow.process()