package server

import (
	"fmt"
	"io"
	"io/ioutil"
	"os"
	"path/filepath"
	"strconv"
	"strings"
	"time"

	log "github.com/mgutz/logxi/v1"

	"github.com/hashicorp/go-multierror"
	"github.com/hashicorp/hcl"
	"github.com/hashicorp/hcl/hcl/ast"
)

// ReloadFunc are functions that are called when a reload is requested.
type ReloadFunc func(map[string]string) error

// Config is the configuration for the vault server.
type Config struct {
	Listeners []*Listener `hcl:"-"`
	Backend   *Backend    `hcl:"-"`
	HABackend *Backend    `hcl:"-"`

	DisableCache bool `hcl:"disable_cache"`
	DisableMlock bool `hcl:"disable_mlock"`

	Telemetry *Telemetry `hcl:"telemetry"`

	MaxLeaseTTL        time.Duration `hcl:"-"`
	MaxLeaseTTLRaw     string        `hcl:"max_lease_ttl"`
	DefaultLeaseTTL    time.Duration `hcl:"-"`
	DefaultLeaseTTLRaw string        `hcl:"default_lease_ttl"`

	ClusterName string `hcl:"cluster_name"`
}

// DevConfig is a Config that is used for dev mode of Vault.
func DevConfig(ha bool) *Config {
	ret := &Config{
		DisableCache: false,
		DisableMlock: true,

		Backend: &Backend{
			Type: "inmem",
		},

		Listeners: []*Listener{
			&Listener{
				Type: "tcp",
				Config: map[string]string{
					"address":     "127.0.0.1:8200",
					"tls_disable": "1",
				},
			},
		},

		Telemetry: &Telemetry{},

		MaxLeaseTTL:     30 * 24 * time.Hour,
		DefaultLeaseTTL: 30 * 24 * time.Hour,
	}

	if ha {
		ret.Backend.Type = "inmem_ha"
	}

	return ret
}

// Listener is the listener configuration for the server.
type Listener struct {
	Type   string
	Config map[string]string
}

func (l *Listener) GoString() string {
	return fmt.Sprintf("*%#v", *l)
}

// Backend is the backend configuration for the server.
type Backend struct {
	Type              string
	RedirectAddr      string
	ClusterAddr       string
	DisableClustering bool
	Config            map[string]string
}

func (b *Backend) GoString() string {
	return fmt.Sprintf("*%#v", *b)
}

// Telemetry is the telemetry configuration for the server
type Telemetry struct {
	StatsiteAddr string `hcl:"statsite_address"`
	StatsdAddr   string `hcl:"statsd_address"`

	DisableHostname bool `hcl:"disable_hostname"`

	// Circonus: see https://github.com/circonus-labs/circonus-gometrics
	// for more details on the various configuration options.
	// Valid configuration combinations:
	//    - CirconusAPIToken
	//      metric management enabled (search for existing check or create a new one)
	//    - CirconusSubmissionUrl
	//      metric management disabled (use check with specified submission_url,
	//      broker must be using a public SSL certificate)
	//    - CirconusAPIToken + CirconusCheckSubmissionURL
	//      metric management enabled (use check with specified submission_url)
	//    - CirconusAPIToken + CirconusCheckID
	//      metric management enabled (use check with specified id)

	// CirconusAPIToken is a valid API Token used to create/manage check. If provided,
	// metric management is enabled.
	// Default: none
	CirconusAPIToken string `hcl:"circonus_api_token"`
	// CirconusAPIApp is an app name associated with API token.
	// Default: "consul"
	CirconusAPIApp string `hcl:"circonus_api_app"`
	// CirconusAPIURL is the base URL to use for contacting the Circonus API.
	// Default: "https://api.circonus.com/v2"
	CirconusAPIURL string `hcl:"circonus_api_url"`
	// CirconusSubmissionInterval is the interval at which metrics are submitted to Circonus.
	// Default: 10s
	CirconusSubmissionInterval string `hcl:"circonus_submission_interval"`
	// CirconusCheckSubmissionURL is the check.config.submission_url field from a
	// previously created HTTPTRAP check.
	// Default: none
	CirconusCheckSubmissionURL string `hcl:"circonus_submission_url"`
	// CirconusCheckID is the check id (not check bundle id) from a previously created
	// HTTPTRAP check. The numeric portion of the check._cid field.
	// Default: none
	CirconusCheckID string `hcl:"circonus_check_id"`
	// CirconusCheckForceMetricActivation will force enabling metrics, as they are encountered,
	// if the metric already exists and is NOT active. If check management is enabled, the default
	// behavior is to add new metrics as they are encoutered. If the metric already exists in the
	// check, it will *NOT* be activated. This setting overrides that behavior.
	// Default: "false"
	CirconusCheckForceMetricActivation string `hcl:"circonus_check_force_metric_activation"`
	// CirconusCheckInstanceID serves to uniquely identify the metrics comming from this "instance".
	// It can be used to maintain metric continuity with transient or ephemeral instances as
	// they move around within an infrastructure.
	// Default: hostname:app
	CirconusCheckInstanceID string `hcl:"circonus_check_instance_id"`
	// CirconusCheckSearchTag is a special tag which, when coupled with the instance id, helps to
	// narrow down the search results when neither a Submission URL or Check ID is provided.
	// Default: service:app (e.g. service:consul)
	CirconusCheckSearchTag string `hcl:"circonus_check_search_tag"`
	// CirconusBrokerID is an explicit broker to use when creating a new check. The numeric portion
	// of broker._cid. If metric management is enabled and neither a Submission URL nor Check ID
	// is provided, an attempt will be made to search for an existing check using Instance ID and
	// Search Tag. If one is not found, a new HTTPTRAP check will be created.
	// Default: use Select Tag if provided, otherwise, a random Enterprise Broker associated
	// with the specified API token or the default Circonus Broker.
	// Default: none
	CirconusBrokerID string `hcl:"circonus_broker_id"`
	// CirconusBrokerSelectTag is a special tag which will be used to select a broker when
	// a Broker ID is not provided. The best use of this is to as a hint for which broker
	// should be used based on *where* this particular instance is running.
	// (e.g. a specific geo location or datacenter, dc:sfo)
	// Default: none
	CirconusBrokerSelectTag string `hcl:"circonus_broker_select_tag"`
}

func (s *Telemetry) GoString() string {
	return fmt.Sprintf("*%#v", *s)
}

// Merge merges two configurations.
func (c *Config) Merge(c2 *Config) *Config {
	if c2 == nil {
		return c
	}

	result := new(Config)
	for _, l := range c.Listeners {
		result.Listeners = append(result.Listeners, l)
	}
	for _, l := range c2.Listeners {
		result.Listeners = append(result.Listeners, l)
	}

	result.Backend = c.Backend
	if c2.Backend != nil {
		result.Backend = c2.Backend
	}

	result.HABackend = c.HABackend
	if c2.HABackend != nil {
		result.HABackend = c2.HABackend
	}

	result.Telemetry = c.Telemetry
	if c2.Telemetry != nil {
		result.Telemetry = c2.Telemetry
	}

	// merging these booleans via an OR operation
	result.DisableCache = c.DisableCache
	if c2.DisableCache {
		result.DisableCache = c2.DisableCache
	}

	result.DisableMlock = c.DisableMlock
	if c2.DisableMlock {
		result.DisableMlock = c2.DisableMlock
	}

	// merge these integers via a MAX operation
	result.MaxLeaseTTL = c.MaxLeaseTTL
	if c2.MaxLeaseTTL > result.MaxLeaseTTL {
		result.MaxLeaseTTL = c2.MaxLeaseTTL
	}

	result.DefaultLeaseTTL = c.DefaultLeaseTTL
	if c2.DefaultLeaseTTL > result.DefaultLeaseTTL {
		result.DefaultLeaseTTL = c2.DefaultLeaseTTL
	}

	result.ClusterName = c.ClusterName
	if c2.ClusterName != "" {
		result.ClusterName = c2.ClusterName
	}

	return result
}

// LoadConfig loads the configuration at the given path, regardless if
// its a file or directory.
func LoadConfig(path string, logger log.Logger) (*Config, error) {
	fi, err := os.Stat(path)
	if err != nil {
		return nil, err
	}

	if fi.IsDir() {
		return LoadConfigDir(path, logger)
	} else {
		return LoadConfigFile(path, logger)
	}
}

// LoadConfigFile loads the configuration from the given file.
func LoadConfigFile(path string, logger log.Logger) (*Config, error) {
	// Read the file
	d, err := ioutil.ReadFile(path)
	if err != nil {
		return nil, err
	}
	return ParseConfig(string(d), logger)
}

func ParseConfig(d string, logger log.Logger) (*Config, error) {
	// Parse!
	obj, err := hcl.Parse(d)
	if err != nil {
		return nil, err
	}

	// Start building the result
	var result Config
	if err := hcl.DecodeObject(&result, obj); err != nil {
		return nil, err
	}

	if result.MaxLeaseTTLRaw != "" {
		if result.MaxLeaseTTL, err = time.ParseDuration(result.MaxLeaseTTLRaw); err != nil {
			return nil, err
		}
	}
	if result.DefaultLeaseTTLRaw != "" {
		if result.DefaultLeaseTTL, err = time.ParseDuration(result.DefaultLeaseTTLRaw); err != nil {
			return nil, err
		}
	}

	list, ok := obj.Node.(*ast.ObjectList)
	if !ok {
		return nil, fmt.Errorf("error parsing: file doesn't contain a root object")
	}

	valid := []string{
		"atlas",
		"backend",
		"ha_backend",
		"listener",
		"disable_cache",
		"disable_mlock",
		"telemetry",
		"default_lease_ttl",
		"max_lease_ttl",
		"cluster_name",
	}
	if err := checkHCLKeys(list, valid); err != nil {
		return nil, err
	}

	if o := list.Filter("backend"); len(o.Items) > 0 {
		if err := parseBackends(&result, o); err != nil {
			return nil, fmt.Errorf("error parsing 'backend': %s", err)
		}
	}

	if o := list.Filter("ha_backend"); len(o.Items) > 0 {
		if err := parseHABackends(&result, o); err != nil {
			return nil, fmt.Errorf("error parsing 'ha_backend': %s", err)
		}
	}

	if o := list.Filter("listener"); len(o.Items) > 0 {
		if err := parseListeners(&result, o); err != nil {
			return nil, fmt.Errorf("error parsing 'listener': %s", err)
		}
	}

	if o := list.Filter("telemetry"); len(o.Items) > 0 {
		if err := parseTelemetry(&result, o); err != nil {
			return nil, fmt.Errorf("error parsing 'telemetry': %s", err)
		}
	}

	return &result, nil
}

// LoadConfigDir loads all the configurations in the given directory
// in alphabetical order.
func LoadConfigDir(dir string, logger log.Logger) (*Config, error) {
	f, err := os.Open(dir)
	if err != nil {
		return nil, err
	}
	defer f.Close()

	fi, err := f.Stat()
	if err != nil {
		return nil, err
	}
	if !fi.IsDir() {
		return nil, fmt.Errorf(
			"configuration path must be a directory: %s",
			dir)
	}

	var files []string
	err = nil
	for err != io.EOF {
		var fis []os.FileInfo
		fis, err = f.Readdir(128)
		if err != nil && err != io.EOF {
			return nil, err
		}

		for _, fi := range fis {
			// Ignore directories
			if fi.IsDir() {
				continue
			}

			// Only care about files that are valid to load.
			name := fi.Name()
			skip := true
			if strings.HasSuffix(name, ".hcl") {
				skip = false
			} else if strings.HasSuffix(name, ".json") {
				skip = false
			}
			if skip || isTemporaryFile(name) {
				continue
			}

			path := filepath.Join(dir, name)
			files = append(files, path)
		}
	}

	var result *Config
	for _, f := range files {
		config, err := LoadConfigFile(f, logger)
		if err != nil {
			return nil, fmt.Errorf("Error loading %s: %s", f, err)
		}

		if result == nil {
			result = config
		} else {
			result = result.Merge(config)
		}
	}

	return result, nil
}

// isTemporaryFile returns true or false depending on whether the
// provided file name is a temporary file for the following editors:
// emacs or vim.
func isTemporaryFile(name string) bool {
	return strings.HasSuffix(name, "~") || // vim
		strings.HasPrefix(name, ".#") || // emacs
		(strings.HasPrefix(name, "#") && strings.HasSuffix(name, "#")) // emacs
}

func parseBackends(result *Config, list *ast.ObjectList) error {
	if len(list.Items) > 1 {
		return fmt.Errorf("only one 'backend' block is permitted")
	}

	// Get our item
	item := list.Items[0]

	key := "backend"
	if len(item.Keys) > 0 {
		key = item.Keys[0].Token.Value().(string)
	}

	var m map[string]string
	if err := hcl.DecodeObject(&m, item.Val); err != nil {
		return multierror.Prefix(err, fmt.Sprintf("backend.%s:", key))
	}

	// Pull out the redirect address since it's common to all backends
	var redirectAddr string
	if v, ok := m["redirect_addr"]; ok {
		redirectAddr = v
		delete(m, "redirect_addr")
	} else if v, ok := m["advertise_addr"]; ok {
		redirectAddr = v
		delete(m, "advertise_addr")
	}

	// Pull out the cluster address since it's common to all backends
	var clusterAddr string
	if v, ok := m["cluster_addr"]; ok {
		clusterAddr = v
		delete(m, "cluster_addr")
	}

	//TODO: Change this in the future
	disableClustering := true
	var err error
	if v, ok := m["disable_clustering"]; ok {
		disableClustering, err = strconv.ParseBool(v)
		if err != nil {
			return multierror.Prefix(err, fmt.Sprintf("backend.%s:", key))
		}
		delete(m, "disable_clustering")
	}

	result.Backend = &Backend{
		RedirectAddr:      redirectAddr,
		ClusterAddr:       clusterAddr,
		DisableClustering: disableClustering,
		Type:              strings.ToLower(key),
		Config:            m,
	}
	return nil
}

func parseHABackends(result *Config, list *ast.ObjectList) error {
	if len(list.Items) > 1 {
		return fmt.Errorf("only one 'ha_backend' block is permitted")
	}

	// Get our item
	item := list.Items[0]

	key := "backend"
	if len(item.Keys) > 0 {
		key = item.Keys[0].Token.Value().(string)
	}

	var m map[string]string
	if err := hcl.DecodeObject(&m, item.Val); err != nil {
		return multierror.Prefix(err, fmt.Sprintf("ha_backend.%s:", key))
	}

	// Pull out the redirect address since it's common to all backends
	var redirectAddr string
	if v, ok := m["redirect_addr"]; ok {
		redirectAddr = v
		delete(m, "redirect_addr")
	} else if v, ok := m["advertise_addr"]; ok {
		redirectAddr = v
		delete(m, "advertise_addr")
	}

	// Pull out the cluster address since it's common to all backends
	var clusterAddr string
	if v, ok := m["cluster_addr"]; ok {
		clusterAddr = v
		delete(m, "cluster_addr")
	}

	//TODO: Change this in the future
	disableClustering := true
	var err error
	if v, ok := m["disable_clustering"]; ok {
		disableClustering, err = strconv.ParseBool(v)
		if err != nil {
			return multierror.Prefix(err, fmt.Sprintf("backend.%s:", key))
		}
		delete(m, "disable_clustering")
	}

	result.HABackend = &Backend{
		RedirectAddr:      redirectAddr,
		ClusterAddr:       clusterAddr,
		DisableClustering: disableClustering,
		Type:              strings.ToLower(key),
		Config:            m,
	}
	return nil
}

func parseListeners(result *Config, list *ast.ObjectList) error {
	var foundAtlas bool

	listeners := make([]*Listener, 0, len(list.Items))
	for _, item := range list.Items {
		key := "listener"
		if len(item.Keys) > 0 {
			key = item.Keys[0].Token.Value().(string)
		}

		valid := []string{
			"address",
			"cluster_address",
			"endpoint",
			"infrastructure",
			"node_id",
			"tls_disable",
			"tls_cert_file",
			"tls_key_file",
			"tls_min_version",
			"token",
		}
		if err := checkHCLKeys(item.Val, valid); err != nil {
			return multierror.Prefix(err, fmt.Sprintf("listeners.%s:", key))
		}

		var m map[string]string
		if err := hcl.DecodeObject(&m, item.Val); err != nil {
			return multierror.Prefix(err, fmt.Sprintf("listeners.%s:", key))
		}

		lnType := strings.ToLower(key)

		if lnType == "atlas" {
			if foundAtlas {
				return multierror.Prefix(fmt.Errorf("only one listener of type 'atlas' is permitted"), fmt.Sprintf("listeners.%s", key))
			}

			foundAtlas = true
			if m["token"] == "" {
				return multierror.Prefix(fmt.Errorf("'token' must be specified for an Atlas listener"), fmt.Sprintf("listeners.%s", key))
			}
			if m["infrastructure"] == "" {
				return multierror.Prefix(fmt.Errorf("'infrastructure' must be specified for an Atlas listener"), fmt.Sprintf("listeners.%s", key))
			}
			if m["node_id"] == "" {
				return multierror.Prefix(fmt.Errorf("'node_id' must be specified for an Atlas listener"), fmt.Sprintf("listeners.%s", key))
			}
		}

		listeners = append(listeners, &Listener{
			Type:   lnType,
			Config: m,
		})
	}

	result.Listeners = listeners
	return nil
}

func parseTelemetry(result *Config, list *ast.ObjectList) error {
	if len(list.Items) > 1 {
		return fmt.Errorf("only one 'telemetry' block is permitted")
	}

	// Get our one item
	item := list.Items[0]

	// Check for invalid keys
	valid := []string{
		"circonus_api_token",
		"circonus_api_app",
		"circonus_api_url",
		"circonus_submission_interval",
		"circonus_submission_url",
		"circonus_check_id",
		"circonus_check_force_metric_activation",
		"circonus_check_instance_id",
		"circonus_check_search_tag",
		"circonus_broker_id",
		"circonus_broker_select_tag",
		"disable_hostname",
		"statsd_address",
		"statsite_address",
	}
	if err := checkHCLKeys(item.Val, valid); err != nil {
		return multierror.Prefix(err, "telemetry:")
	}

	var t Telemetry
	if err := hcl.DecodeObject(&t, item.Val); err != nil {
		return multierror.Prefix(err, "telemetry:")
	}

	if result.Telemetry == nil {
		result.Telemetry = &Telemetry{}
	}

	if err := hcl.DecodeObject(&result.Telemetry, item.Val); err != nil {
		return multierror.Prefix(err, "telemetry:")
	}
	return nil
}

func checkHCLKeys(node ast.Node, valid []string) error {
	var list *ast.ObjectList
	switch n := node.(type) {
	case *ast.ObjectList:
		list = n
	case *ast.ObjectType:
		list = n.List
	default:
		return fmt.Errorf("cannot check HCL keys of type %T", n)
	}

	validMap := make(map[string]struct{}, len(valid))
	for _, v := range valid {
		validMap[v] = struct{}{}
	}

	var result error
	for _, item := range list.Items {
		key := item.Keys[0].Token.Value().(string)
		if _, ok := validMap[key]; !ok {
			result = multierror.Append(result, fmt.Errorf(
				"invalid key '%s' on line %d", key, item.Assign.Line))
		}
	}

	return result
}