Bellhop/internal/config/config.go

package config

import (
	"fmt"
	"log/slog"
	"os"
	"regexp"

	"github.com/BurntSushi/toml"
)

var envBracketRe = regexp.MustCompile(`\$\{([^}]+)\}`)

type Config struct {
	Matrix   MatrixConfig   `toml:"matrix"`
	Services ServicesConfig `toml:"services"`
}

type MatrixConfig struct {
	Homeserver    string `toml:"homeserver"`
	UserID        string `toml:"user_id"`
	Password      string `toml:"password"`
	PickleKey     string `toml:"pickle_key"`
	DisplayName   string `toml:"display_name"`
	DataDir       string `toml:"data_dir"`
	CommandPrefix string `toml:"command_prefix"`
	// AllowedRooms is the set of room IDs the bot listens for commands in.
	// Messages in any other room are ignored.
	AllowedRooms []string `toml:"allowed_rooms"`
}

type ServicesConfig struct {
	Radarr *ArrConfig `toml:"radarr"`
	Sonarr *ArrConfig `toml:"sonarr"`
	Lidarr *ArrConfig `toml:"lidarr"`
}

type ArrConfig struct {
	URL              string `toml:"url"`
	APIKey           string `toml:"api_key"`
	QualityProfileID int    `toml:"quality_profile_id"`
	RootFolder       string `toml:"root_folder"`
	// MetadataProfileID is required by Lidarr; ignored by Radarr/Sonarr.
	MetadataProfileID int `toml:"metadata_profile_id"`
}

func Load(path string) (*Config, error) {
	data, err := os.ReadFile(path)
	if err != nil {
		return nil, fmt.Errorf("read config: %w", err)
	}

	expanded := envBracketRe.ReplaceAllStringFunc(string(data), func(match string) string {
		varName := match[2 : len(match)-1]
		val := os.Getenv(varName)
		if val == "" {
			slog.Warn("config: env var referenced but not set", "var", varName)
		}
		return val
	})

	var cfg Config
	if _, err := toml.Decode(expanded, &cfg); err != nil {
		return nil, fmt.Errorf("parse config: %w", err)
	}

	cfg.applyDefaults()

	if err := cfg.validate(); err != nil {
		return nil, fmt.Errorf("validate config: %w", err)
	}

	return &cfg, nil
}

func (c *Config) validate() error {
	if c.Matrix.Homeserver == "" {
		return fmt.Errorf("matrix.homeserver is required")
	}
	if c.Matrix.UserID == "" {
		return fmt.Errorf("matrix.user_id is required")
	}
	if c.Matrix.Password == "" {
		return fmt.Errorf("matrix.password is required")
	}
	if len(c.Matrix.AllowedRooms) == 0 {
		return fmt.Errorf("matrix.allowed_rooms must have at least one entry")
	}
	if c.Services.Radarr == nil && c.Services.Sonarr == nil && c.Services.Lidarr == nil {
		return fmt.Errorf("at least one of services.radarr/sonarr/lidarr must be configured")
	}
	for name, svc := range map[string]*ArrConfig{
		"radarr": c.Services.Radarr,
		"sonarr": c.Services.Sonarr,
		"lidarr": c.Services.Lidarr,
	} {
		if svc == nil {
			continue
		}
		if svc.URL == "" {
			return fmt.Errorf("services.%s.url is required when service is set", name)
		}
		if svc.APIKey == "" {
			return fmt.Errorf("services.%s.api_key is required when service is set", name)
		}
		if svc.RootFolder == "" {
			return fmt.Errorf("services.%s.root_folder is required when service is set", name)
		}
		if svc.QualityProfileID == 0 {
			return fmt.Errorf("services.%s.quality_profile_id is required when service is set", name)
		}
	}
	if c.Services.Lidarr != nil && c.Services.Lidarr.MetadataProfileID == 0 {
		return fmt.Errorf("services.lidarr.metadata_profile_id is required when lidarr is set")
	}
	return nil
}

func (c *Config) applyDefaults() {
	if c.Matrix.DataDir == "" {
		c.Matrix.DataDir = "./data"
	}
	if c.Matrix.DisplayName == "" {
		c.Matrix.DisplayName = "Bellhop"
	}
	if c.Matrix.PickleKey == "" {
		c.Matrix.PickleKey = "bellhop_pickle_key"
	}
	if c.Matrix.CommandPrefix == "" {
		c.Matrix.CommandPrefix = "!"
	}
}