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"`
}

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

// 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"`
}

// ScannerConfig holds scanner engine parameters.
type ScannerConfig struct {
	FuzzyThreshold      float64 `yaml:"fuzzy_threshold"`
	IgnoreBootlegs      bool    `yaml:"ignore_bootlegs"`
	IncludeCompilations bool    `yaml:"include_compilations"`
}

// 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
	}
}

// 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")
	}
	return nil
}