// Package config provides the winlogbeat specific configuration options.
package config

import (
	"fmt"
	"net"
	"sort"
	"strconv"
	"strings"

	"github.com/joeshaw/multierror"
)

const (
	// DefaultRegistryFile specifies the default filename of the registry file.
	DefaultRegistryFile = ".winlogbeat.yml"
)

// Validator is the interface for configuration data that can be validating.
//
// Validate reads the configuration and validates all fields. An error
// describing all problems is returned (versus returning an error only for the
// first problem encountered).
type Validator interface {
	Validate() error
}

// Settings is the root of the Winlogbeat configuration data hierarchy.
type Settings struct {
	Winlogbeat WinlogbeatConfig       `config:"winlogbeat"`
	Raw        map[string]interface{} `config:",inline"`
}

// Validate validates the Settings data and returns an error describing
// all problems or nil if there are none.
func (s Settings) Validate() error {
	validKeys := []string{"filters", "logging", "output", "shipper", "winlogbeat"}
	sort.Strings(validKeys)

	// Check for invalid top-level keys.
	var errs multierror.Errors
	for k := range s.Raw {
		k = strings.ToLower(k)
		i := sort.SearchStrings(validKeys, k)
		if i >= len(validKeys) || validKeys[i] != k {
			errs = append(errs, fmt.Errorf("Invalid top-level key '%s' "+
				"found. Valid keys are %s", k, strings.Join(validKeys, ", ")))
		}
	}

	err := s.Winlogbeat.Validate()
	if err != nil {
		errs = append(errs, err)
	}

	return errs.Err()
}

// WinlogbeatConfig contains all of Winlogbeat configuration data.
type WinlogbeatConfig struct {
	EventLogs    []map[string]interface{} `config:"event_logs"`
	Metrics      MetricsConfig            `config:"metrics"`
	RegistryFile string                   `config:"registry_file"`
}

// Validate validates the WinlogbeatConfig data and returns an error describing
// all problems or nil if there are none.
func (ebc WinlogbeatConfig) Validate() error {
	var errs multierror.Errors

	if len(ebc.EventLogs) == 0 {
		errs = append(errs, fmt.Errorf("At least one event log must be "+
			"configured as part of event_logs"))
	}

	if err := ebc.Metrics.Validate(); err != nil {
		errs = append(errs, err)
	}

	return errs.Err()
}

// MetricsConfig holds the configuration data for the HTTP metric service.
type MetricsConfig struct {
	BindAddress string // Bind address for the metric service. Format is host:port.
}

// Validate validates the MetricsConfig data and returns an error describing any
// problems or nil.
func (mc MetricsConfig) Validate() error {
	if mc.BindAddress == "" {
		return nil
	}

	host, portStr, err := net.SplitHostPort(mc.BindAddress)
	if err != nil {
		return fmt.Errorf("bind_address must be formatted as host:port but "+
			"was '%s' (%v)", mc.BindAddress, err)
	}

	if len(host) == 0 {
		return fmt.Errorf("bind_address value ('%s') is missing a host",
			mc.BindAddress)
	}

	port, err := strconv.Atoi(portStr)
	if err != nil {
		return fmt.Errorf("bind_address port value ('%s') must be a number "+
			"(%v)", portStr, err)
	}

	if port < 1 || port > 65535 {
		return fmt.Errorf("bind_address port must be within [1-65535] but "+
			"was '%d'", port)
	}

	return nil
}