package main

import (
	"fmt"
	"os"
	"strings"

	"gopkg.in/yaml.v3"
)

// CatalogConfig holds the configuration for a single catalog zone.
type CatalogConfig struct {
	Zone string `yaml:"zone"`
}

// SOAConfig holds the configurable SOA fields.
type SOAConfig struct {
	Mname string `yaml:"mname"`
	Rname string `yaml:"rname"`
}

// BindConfConfig holds BIND-specific configuration for domains.conf generation.
type BindConfConfig struct {
	AlsoNotify map[string][]string `yaml:"also-notify"`
}

// Config holds the parsed catz.yaml configuration.
type Config struct {
	Catalogs map[string]CatalogConfig `yaml:"catalogs"`
	SOA      SOAConfig                `yaml:"soa"`
	BindConf BindConfConfig           `yaml:"bind-conf"`
}

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

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

	if err := validateConfig(&cfg); err != nil {
		return nil, err
	}

	// Normalize zone FQDNs
	for name, cat := range cfg.Catalogs {
		cat.Zone = normalizeFQDN(cat.Zone)
		cfg.Catalogs[name] = cat
	}
	cfg.SOA.Mname = normalizeFQDN(cfg.SOA.Mname)
	cfg.SOA.Rname = normalizeFQDN(cfg.SOA.Rname)

	return &cfg, nil
}

func validateConfig(cfg *Config) error {
	if len(cfg.Catalogs) == 0 {
		return fmt.Errorf("config: no catalogs defined")
	}
	for name, cat := range cfg.Catalogs {
		if cat.Zone == "" {
			return fmt.Errorf("config: catalog %q has no zone defined", name)
		}
	}
	if cfg.SOA.Mname == "" {
		return fmt.Errorf("config: soa.mname is required")
	}
	if cfg.SOA.Rname == "" {
		return fmt.Errorf("config: soa.rname is required")
	}

	for catName := range cfg.BindConf.AlsoNotify {
		if _, ok := cfg.Catalogs[catName]; !ok {
			return fmt.Errorf("config: bind-conf.also-notify references unknown catalog %q", catName)
		}
	}

	return nil
}

func normalizeFQDN(name string) string {
	name = strings.ToLower(strings.TrimSpace(name))
	if name != "" && !strings.HasSuffix(name, ".") {
		name += "."
	}
	return name
}