NaviWatcher/internal/config/config.go

package config

import (
	"fmt"
	"os"
	"time"

	"gopkg.in/yaml.v3"
)

// Config represents the top-level configuration for NaviWatcher.
type Config struct {
	Server      ServerConfig      `yaml:"server"`
	Navidrome   NavidromeConfig   `yaml:"navidrome"`
	MusicBrainz MusicBrainzConfig `yaml:"musicbrainz"`
	Telegram    TelegramConfig    `yaml:"telegram"`
	Scanner     ScannerConfig     `yaml:"scanner"`
	Sync        SyncConfig        `yaml:"sync"`
}

// ServerConfig holds HTTP server settings.
type ServerConfig struct {
	Host      string `yaml:"host"`
	Port      int    `yaml:"port"`
	Username  string `yaml:"username"`
	Password  string `yaml:"password"`
	PublicURL string `yaml:"public_url"`
}

// NavidromeConfig holds Subsonic API connection details.
type NavidromeConfig struct {
	URL      string `yaml:"url"`
	User     string `yaml:"user"`
	Password string `yaml:"password"`
}

// MusicBrainzConfig holds MusicBrainz API settings.
type MusicBrainzConfig struct {
	UserAgent string        `yaml:"user_agent"`
	CacheTTL  time.Duration `yaml:"cache_ttl"`
}

// TelegramConfig holds Telegram bot notification settings.
type TelegramConfig struct {
	Enabled      bool   `yaml:"enabled"`
	Token        string `yaml:"token"`
	ChatID       string `yaml:"chat_id"`
	CronSchedule string `yaml:"cron_schedule"`
}

// SyncConfig holds periodic sync pipeline settings.
type SyncConfig struct {
	Interval time.Duration `yaml:"interval"`
}

// DefaultSyncInterval is the default period between full sync+scan runs when
// sync.interval is not specified in the config file.
const DefaultSyncInterval = 6 * time.Hour

// ScannerConfig holds scanner engine parameters.
//
// Type filtering is handled in musicbrainz/api.go, not here: only Album/Single/EP
// primary types (and release groups whose secondary types include Single/EP/Compilation)
// are included. Bootlegs are not explicitly excluded — a release group whose primary
// type is an included type but whose secondary types include "Bootleg" will still pass
// through and may be reported as missing. Compilations are included by default but can
// be excluded per-artist via artist_settings.ignore_compilations. These behaviours are
// not user-toggleable at the global config level, so there are no corresponding config fields.
type ScannerConfig struct {
	FuzzyThreshold float64 `yaml:"fuzzy_threshold"`
}

// LoadConfig reads a YAML file from path, parses it, applies defaults,
// and validates the configuration.
func LoadConfig(path string) (*Config, error) {
	data, err := os.ReadFile(path)
	if err != nil {
		return nil, fmt.Errorf("read config file: %w", err)
	}

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

	applyDefaults(&cfg)

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

	return &cfg, nil
}

// applyDefaults sets zero-value defaults for optional fields.
func applyDefaults(cfg *Config) {
	if cfg.Server.Host == "" {
		cfg.Server.Host = "0.0.0.0"
	}
	if cfg.Server.Port == 0 {
		cfg.Server.Port = 8080
	}
	if cfg.Scanner.FuzzyThreshold == 0 {
		cfg.Scanner.FuzzyThreshold = 0.85
	}
	if cfg.MusicBrainz.CacheTTL == 0 {
		cfg.MusicBrainz.CacheTTL = 24 * time.Hour
	}
	if cfg.Sync.Interval == 0 {
		cfg.Sync.Interval = DefaultSyncInterval
	}
}

// validate checks that required fields are set and values are within acceptable ranges.
func validate(cfg *Config) error {
	if cfg.Navidrome.URL == "" {
		return fmt.Errorf("navidrome.url is required")
	}
	if cfg.Navidrome.User == "" {
		return fmt.Errorf("navidrome.user is required")
	}
	if cfg.Navidrome.Password == "" {
		return fmt.Errorf("navidrome.password is required")
	}
	if cfg.Server.Port < 1 || cfg.Server.Port > 65535 {
		return fmt.Errorf("server.port must be between 1 and 65535, got %d", cfg.Server.Port)
	}
	if cfg.Scanner.FuzzyThreshold < 0.0 || cfg.Scanner.FuzzyThreshold > 1.0 {
		return fmt.Errorf("scanner.fuzzy_threshold must be between 0.0 and 1.0, got %f", cfg.Scanner.FuzzyThreshold)
	}
	if cfg.MusicBrainz.UserAgent == "" {
		return fmt.Errorf("musicbrainz.user_agent is required")
	}
	if cfg.Sync.Interval <= 0 {
		return fmt.Errorf("sync.interval must be positive, got %v", cfg.Sync.Interval)
	}
	if cfg.Telegram.Enabled {
		if cfg.Telegram.Token == "" {
			return fmt.Errorf("telegram.token is required when telegram.enabled is true")
		}
		if cfg.Telegram.ChatID == "" {
			return fmt.Errorf("telegram.chat_id is required when telegram.enabled is true")
		}
		if cfg.Telegram.CronSchedule == "" {
			return fmt.Errorf("telegram.cron_schedule is required when telegram.enabled is true")
		}
	}
	return nil
}