package config

import (
	"encoding/json"
	"errors"
	"fmt"
	"net/netip"
	"os"
)

type HealthchecksConfig struct {
	Enabled     bool   `json:"enabled"`
	HostPingAPI string `json:"host_ping_api"`
	PingKey     string `json:"ping_key"`
}

type DNSMasqConfig struct {
	DHCPRangeStart netip.Addr
	DHCPRangeEnd   netip.Addr
	LeasesPath     string
}

type NetboxConfig struct {
	Host    string `json:"host"`
	APIKey  string `json:"api_key"`
	VRFName string `json:"vrf"`
}

type Config struct {
	HealthchecksConfig `json:"healthchecks"`
	DNSMasqConfigFile  string `json:"dnsmasq_config"`
	DNSMasqConfig
	NetboxConfig `json:"netbox"`
}

func (c *Config) parseDNSMasqConf() error {
	dnsMasqRootContent, err := os.ReadFile(c.DNSMasqConfigFile)
	if err != nil {
		return fmt.Errorf("failed to read dnsmasq config: %w", err)
	}

	dnsmasqRawConf, err := parseDNSMasqOptions(string(dnsMasqRootContent))
	if err != nil {
		return fmt.Errorf("failed to parse dnsmasq config: %w", err)
	}
	c.LeasesPath = dnsmasqRawConf.leaseFile
	c.DHCPRangeStart, err = netip.ParseAddr(dnsmasqRawConf.rangeStart)
	if err != nil {
		return fmt.Errorf("failed to parse dhcp range start: %w", err)
	}
	c.DHCPRangeEnd, err = netip.ParseAddr(dnsmasqRawConf.rangeEnd)
	if err != nil {
		return fmt.Errorf("failed to parse dhcp range end: %w", err)
	}

	return nil
}

func defaultConfig() *Config {
	return &Config{
		HealthchecksConfig: HealthchecksConfig{
			Enabled: false,
		},
		DNSMasqConfigFile: "etc/dnsmasq.conf",
	}
}

func New(path string) (*Config, error) {
	fileContent, err := os.ReadFile(path)
	if err != nil {
		if errors.Is(err, os.ErrNotExist) {
			conf := defaultConfig()
			return conf, conf.parseDNSMasqConf()
		}
		return nil, fmt.Errorf("failed to read config file %w", err)
	}

	var c Config
	if err := json.Unmarshal(fileContent, &c); err != nil {
		return nil, fmt.Errorf("failed to parse config file: %w", err)
	}
	return &c, c.parseDNSMasqConf()
}