package config

import (
	"fmt"

	"github.com/joho/godotenv"
	"github.com/spf13/viper"
)

type Config struct {
	Host     string `mapstructure:"host"`
	Port     int    `mapstructure:"port"`
	LogLevel string `mapstructure:"log_level"`

	NetBoxURL            string `mapstructure:"netbox_url"`
	NetBoxToken          string `mapstructure:"netbox_token"`
	NetBoxTimeoutSeconds int    `mapstructure:"netbox_timeout_seconds"`

	DragonflyURL            string `mapstructure:"dragonfly_url"`
	WAQRetryIntervalSeconds int    `mapstructure:"waq_retry_interval_seconds"`
	WAQMaxAttempts          int    `mapstructure:"waq_max_attempts"`

	QualityGateConfidenceThreshold float64 `mapstructure:"quality_gate_confidence_threshold"`
}

func Load() (*Config, error) {
	// Load .env file if present (ignore error — .env is optional in production)
	_ = godotenv.Load()

	v := viper.New()

	// Set defaults
	v.SetDefault("host", "0.0.0.0")
	v.SetDefault("port", 8080)
	v.SetDefault("log_level", "info")
	v.SetDefault("netbox_timeout_seconds", 10)
	v.SetDefault("waq_retry_interval_seconds", 30)
	v.SetDefault("waq_max_attempts", 5)
	v.SetDefault("quality_gate_confidence_threshold", 0.75)

	// Config file
	v.SetConfigName("config")
	v.SetConfigType("json")
	v.AddConfigPath(".")
	v.AddConfigPath("/etc/hwlab")

	// Environment variables: HWLAB_PORT -> port, HWLAB_NETBOX_URL -> netbox_url, etc.
	v.SetEnvPrefix("HWLAB")
	v.AutomaticEnv()

	// Explicit bindings ensure AutomaticEnv works correctly with mapstructure v2 unmarshalling.
	// Format: key name -> env var (without prefix, viper adds HWLAB_ automatically).
	_ = v.BindEnv("host", "HWLAB_HOST")
	_ = v.BindEnv("port", "HWLAB_PORT")
	_ = v.BindEnv("log_level", "HWLAB_LOG_LEVEL")
	_ = v.BindEnv("netbox_url", "HWLAB_NETBOX_URL")
	_ = v.BindEnv("netbox_token", "HWLAB_NETBOX_TOKEN")
	_ = v.BindEnv("netbox_timeout_seconds", "HWLAB_NETBOX_TIMEOUT_SECONDS")
	_ = v.BindEnv("dragonfly_url", "HWLAB_DRAGONFLY_URL")
	_ = v.BindEnv("waq_retry_interval_seconds", "HWLAB_WAQ_RETRY_INTERVAL_SECONDS")
	_ = v.BindEnv("waq_max_attempts", "HWLAB_WAQ_MAX_ATTEMPTS")
	_ = v.BindEnv("quality_gate_confidence_threshold", "HWLAB_QUALITY_GATE_CONFIDENCE_THRESHOLD")

	// Read config file (non-fatal if missing)
	if err := v.ReadInConfig(); err != nil {
		if _, ok := err.(viper.ConfigFileNotFoundError); !ok {
			return nil, fmt.Errorf("config file: %w", err)
		}
	}

	var cfg Config
	if err := v.Unmarshal(&cfg); err != nil {
		return nil, fmt.Errorf("unmarshal config: %w", err)
	}

	return &cfg, nil
}