package main

import (
  "fmt"
  "io/ioutil"

  yaml "gopkg.in/yaml.v2"
)

type Config struct {
  InfluxDB struct {
    URL         string   `yaml:"url"`
    Database    string   `yaml:"database"`
    Measurement string   `yaml:"measurement"`
    Username    string   `yaml:"username"`
    Password    string   `yaml:"password"`
  }                      `yaml:"influxdb"`
  OpenWeatherMap struct {
    ApiKey      string   `yaml:"api_key"`
    Units       string   `yaml:"units"`
  }                      `yaml:"openweathermap"`
  Cities        []string `yaml:"cities"`
  Interval      int64    `yaml:"interval"`
}

func (c *Config) Load(path string) error {
  data, err := ioutil.ReadFile(path)
  if err != nil {
    return err
  }

  err = yaml.Unmarshal(data, &c)
  if err != nil {
    return err
  }

  c.Defaults()
  err = c.Check()
  if err != nil {
    return err
  }

  return nil
}

func (c *Config) Defaults() {
  if c.OpenWeatherMap.Units == "" {
    c.OpenWeatherMap.Units = "metric"
  }

  if c.Interval == 0 {
    c.Interval = 600
  }

  if c.InfluxDB.URL == "" {
    c.InfluxDB.URL = "http://127.0.0.1:8086"
  }

  if c.InfluxDB.Measurement == "" {
    c.InfluxDB.Measurement = "weather"
  }
}

func (c *Config) Check() error {
  if c.InfluxDB.Database == "" {
    return fmt.Errorf("you must specify influxdb.database in config file")
  }

  if c.OpenWeatherMap.ApiKey == "" {
    return fmt.Errorf("you must specify api_key in config file")
  }

  return nil
}