package config

import (
	"errors"
	"os"
	"time"

	"gopkg.in/yaml.v3"
)

type Config struct {
	LogLevel string `yaml:"log_level"`

	MQTT struct {
		Broker   string `yaml:"broker"`
		ClientID string `yaml:"client_id"`
		Username string `yaml:"username"`
		Password string `yaml:"password"`
		Topic    string `yaml:"topic"`
		QoS      byte   `yaml:"qos"`
	} `yaml:"mqtt"`

	DB struct {
		ConnString string `yaml:"conn_string"`
	} `yaml:"db"`

	Site struct {
		Name       string  `yaml:"name"`
		Latitude   float64 `yaml:"latitude"`
		Longitude  float64 `yaml:"longitude"`
		ElevationM float64 `yaml:"elevation_m"`
	} `yaml:"site"`

	Pollers struct {
		OpenMeteo struct {
			Enabled  bool          `yaml:"enabled"`
			Interval time.Duration `yaml:"interval"`
			Model    string        `yaml:"model"`
		} `yaml:"open_meteo"`
	} `yaml:"pollers"`

	Wunderground struct {
		Enabled    bool          `yaml:"enabled"`
		StationID  string        `yaml:"station_id"`
		StationKey string        `yaml:"station_key"`
		Interval   time.Duration `yaml:"interval"`
	} `yaml:"wunderground"`
}

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

	var c Config
	if err := yaml.Unmarshal(b, &c); err != nil {
		return nil, err
	}

	// Minimal validation
	if c.MQTT.Broker == "" || c.MQTT.Topic == "" {
		return nil, errors.New("mqtt broker and topic are required")
	}
	if c.DB.ConnString == "" {
		return nil, errors.New("db conn_string is required")
	}
	if c.Site.Name == "" {
		c.Site.Name = "default"
	}
	if c.Pollers.OpenMeteo.Model == "" {
		c.Pollers.OpenMeteo.Model = "ecmwf"
	}
	if c.Pollers.OpenMeteo.Interval == 0 {
		c.Pollers.OpenMeteo.Interval = 30 * time.Minute
	}
	if c.Wunderground.Interval == 0 {
		c.Wunderground.Interval = 60 * time.Second
	}
	// If enabled, require creds
	if c.Wunderground.Enabled && (c.Wunderground.StationID == "" || c.Wunderground.StationKey == "") {
		return nil, errors.New("wunderground enabled but station_id/station_key not set")
	}

	return &c, nil
}