package isoclient

import (
	"encoding/json"
	"errors"
	"fmt"
	"io/ioutil"
	"log"
	"net/http"
	"os"
	"strings"
	"time"

	"github.com/amigan/energyd/internal/config"
)

type Client interface {
	GetCurrentLoad() (*FiveMinSystemLoad, error)
	GetHourlyLoadForecast() (*HourlyLoadForecasts, error)
	GetGenFuelMixes() (GenFuelMixes, error)
}

type client struct {
	user   string
	passwd string
	Debug  bool
}

func New(cfg *config.Conf) Client {
	c := &client{
		user:   cfg.ISOUser,
		passwd: cfg.ISOPassword,
		Debug:  os.Getenv("DEBUG") == "true",
	}

	return c
}

const BASEURL = "https://webservices.iso-ne.com/api/v1.1"

const GETCURRENTLOADEP = "/fiveminutesystemload/current"

func (c *client) makeRequest(endpoint string, into interface{}) error {
	req, err := http.NewRequest(http.MethodGet, BASEURL+endpoint, nil)
	if err != nil {
		return err
	}

	req.SetBasicAuth(c.user, c.passwd)
	req.Header.Add("Accept", "application/json")
	req.Header.Add("Content-Type", "application/json")

	client := http.Client{}
	resp, err := client.Do(req)

	if resp.StatusCode != http.StatusOK {
		return errors.New("non 2xx response")
	}

	defer resp.Body.Close()

	body, err := ioutil.ReadAll(resp.Body)
	if err != nil {
		return err
	}

	if c.Debug {
		log.Println(string(body))
	}

	return json.Unmarshal(body, into)
}

type FiveMinSystemLoad struct {
	BeginDate       time.Time `json:"BeginDate"`
	LoadMW          float32   `json:"LoadMw"`
	NativeLoad      float32   `json:"NativeLoad"`
	ArdDemand       float32   `json:"ArdDemand"`
	SystemLoadBtmPv float32   `json:"SystemLoadBtmPv"`
	NativeLoadBtmPv float32   `json:"NativeLoadBtmPv"`
}

func (c *client) GetCurrentLoad() (*FiveMinSystemLoad, error) {
	fms := struct {
		FiveMinSystemLoad []*FiveMinSystemLoad
	}{}

	err := c.makeRequest(GETCURRENTLOADEP, &fms)
	if err != nil {
		return nil, err
	}

	if len(fms.FiveMinSystemLoad) < 1 {
		return nil, errors.New("less than one element")
	}

	return fms.FiveMinSystemLoad[0], nil
}

const GETHOURLYFORECASTEP = "/hourlyloadforecast/day/"

type HourlyLoadForecast struct {
	BeginDate        time.Time `json:"BeginDate"`
	CreationDate     time.Time `json:"CreationDate"`
	LoadMW           float32   `json:"LoadMw"`
	LoadAdjustmentMW *float32  `json:"LoadAdjustmentMw"`
	NetLoadMW        float32   `json:"NetLoadMw"`
}

type HourlyLoadForecasts struct {
	HourlyLoadForecast [23]HourlyLoadForecast `json:"HourlyLoadForecast"`
}

func (c *client) GetHourlyLoadForecast() (*HourlyLoadForecasts, error) {
	hlfc := struct {
		HourlyLoadForecasts HourlyLoadForecasts
	}{}

	year, month, day := time.Now().Date()
	endpoint := fmt.Sprintf("%s%04d%02d%02d", GETHOURLYFORECASTEP, year, month, day)

	err := c.makeRequest(endpoint, &hlfc)
	if err != nil {
		return nil, err
	}

	return &hlfc.HourlyLoadForecasts, nil
}

type GenFuelMix struct {
	BeginDate          time.Time `json:"BeginDate"`
	GenMW              float32   `json:"GenMW"`
	FuelCategoryRollup string    `json:"FuelCategoryRollup"`
	FuelCategory       string    `json:"FuelCategory"`
	Marginal           YNFlag    `json:"MarginalFlag"`
}

type YNFlag bool

func (ynf *YNFlag) UnmarshalJSON(b []byte) error {
	var s string
	err := json.Unmarshal(b, &s)
	if err != nil {
		return err
	}

	switch strings.ToLower(s) {
	case "y":
		*ynf = true
	case "n":
		*ynf = false
	}

	return nil
}

type GenFuelMixes []GenFuelMix

const GETGENFUELMIXES = "/genfuelmix/current"

func (c *client) GetGenFuelMixes() (GenFuelMixes, error) {
	var fm struct {
		GenFuelMixes struct {
			GenFuelMix GenFuelMixes `json:"GenFuelMix"`
		} `json:"GenFuelMixes"`
	}
	err := c.makeRequest(GETGENFUELMIXES, &fm)
	if err != nil {
		return nil, err
	}

	return fm.GenFuelMixes.GenFuelMix, nil

}