package config

import (
	"errors"
	"fmt"
	"th7/data/config"
	"th7/data/temperature"
	"th7/data/thermocouple"

	"github.com/spf13/viper"
)

var (
	ErrConfigBadThermocoupleType = errors.New("unrecognised thermocouple type")
	ErrConfigBadTemperatureUnit  = errors.New("unrecognised temperature unit")
)

var (
	thermocoupleTypes = map[string]thermocouple.Type{
		"B":  thermocouple.B,
		"E":  thermocouple.E,
		"J":  thermocouple.J,
		"K":  thermocouple.K,
		"N":  thermocouple.N,
		"R":  thermocouple.R,
		"S":  thermocouple.S,
		"T":  thermocouple.T,
		"UV": thermocouple.None,
	}
	temperatureUnits = map[string]temperature.Unit{
		"C":  temperature.C,
		"F":  temperature.F,
		"K":  temperature.K,
		"UV": temperature.None,
	}
)

func getThermocoupleType(t string) (thermocouple.Type, error) {
	if val, ok := thermocoupleTypes[t]; ok {
		return val, nil
	} else {
		return thermocouple.None, ErrConfigBadThermocoupleType
	}
}

func getTemperatureUnit(u string) (temperature.Unit, error) {
	if val, ok := temperatureUnits[u]; ok {
		return val, nil
	} else {
		return temperature.None, ErrConfigBadTemperatureUnit
	}
}

func Load() (config.Config, error) {

	var cfg config.Config
	var err error

	v := viper.New()
	v.AddConfigPath(".")
	v.SetConfigFile("config.toml")

	err = v.ReadInConfig()
	if err != nil {
		return cfg, err
	}

	v.SetDefault("TH7.port", 8080)
	v.SetDefault("TH7.cache", true)
	v.SetDefault("TH7.LED", true)
	v.SetDefault("TH7.logfreq", 60)
	v.SetDefault("TH7.debug", false)

	cfg.Board.Port = v.GetInt("TH7.port")
	cfg.Board.Cache = v.GetBool("TH7.cache")
	cfg.Board.Led = v.GetBool("TH7.LED")
	cfg.Board.Logfreq = v.GetInt("TH7.logfreq")
	cfg.Board.Debug = v.GetBool("TH7.debug")

	cfg.Channels = make([]config.Channel, 0)
	var c config.Channel

	// set defaults for channels
	for i := 1; i < 8; i++ {
		var head = fmt.Sprintf("Channel_%d", i)
		v.SetDefault(head+".gain", 106.8)
		v.SetDefault(head+".offset", 0.0)
		v.SetDefault(head+".unit", "UV")
	}

	for i := 1; i < 8; i++ {
		var head = fmt.Sprintf("Channel_%d", i)

		tc := v.GetString(head + ".type")
		// thermocouple type is non-optional, so if it doesnt exist
		// then the entry does not exist.
		if tc == "" {
			continue
		}

		c.Id = i
		c.Gain = v.GetFloat64(head + ".gain")
		c.Offset = v.GetFloat64(head + ".offset")

		tctype, err := getThermocoupleType(tc)
		if err != nil {
			return cfg, err
		}
		c.Thermo = tctype

		unit, err := getTemperatureUnit(v.GetString(head + ".unit"))
		if err != nil {
			fmt.Printf("%s.unit=%c\n", head, v.GetInt(head+".unit"))
			return cfg, err
		}
		c.Unit = unit

		cfg.Channels = append(cfg.Channels, c)
	}

	cfg.DB = v.GetStringMap("DB")

	return cfg, nil
}