package wrapper

import (
	"context"
	"fmt"
	"time"

	"go.unistack.org/micro/v3/logger"
	"go.unistack.org/micro/v3/meter"
	"go.unistack.org/micro/v3/tracer"
)

var (
	// DefaultMeterStatsInterval holds default stats interval
	DefaultMeterStatsInterval = 5 * time.Second
	// DefaultMeterMetricPrefix holds default metric prefix
	DefaultMeterMetricPrefix = "micro_sql_"
	// DefaultLoggerObserver used to prepare labels for logger
	DefaultLoggerObserver = func(ctx context.Context, method string, query string, td time.Duration, err error) []interface{} {
		labels := []interface{}{"db.method", method, "took", fmt.Sprintf("%v", td)}
		if err != nil {
			labels = append(labels, "error", err.Error())
		}
		if query != labelUnknown {
			labels = append(labels, "query", query)
		}
		return labels
	}
)

var (
	MaxOpenConnections = "max_open_conn"
	OpenConnections    = "open_conn"
	InuseConnections   = "inuse_conn"
	IdleConnections    = "idle_conn"
	WaitConnections    = "waited_conn"
	BlockedSeconds     = "blocked_seconds"
	MaxIdleClosed      = "max_idle_closed"
	MaxIdletimeClosed  = "closed_max_idle"
	MaxLifetimeClosed  = "closed_max_lifetime"

	meterRequestTotal               = "request_total"
	meterRequestLatencyMicroseconds = "latency_microseconds"
	meterRequestDurationSeconds     = "request_duration_seconds"

	labelUnknown  = "unknown"
	labelQuery    = "db.statement"
	labelMethod   = "db.method"
	labelStatus   = "status"
	labelSuccess  = "success"
	labelFailure  = "failure"
	labelHost     = "db.host"
	labelDatabase = "db.name"
)

// Options struct holds wrapper options
type Options struct {
	Logger             logger.Logger
	Meter              meter.Meter
	Tracer             tracer.Tracer
	DatabaseHost       string
	DatabaseName       string
	MeterMetricPrefix  string
	MeterStatsInterval time.Duration
	LoggerLevel        logger.Level
	LoggerEnabled      bool
	LoggerObserver     func(ctx context.Context, method string, name string, td time.Duration, err error) []interface{}
}

// Option func signature
type Option func(*Options)

// NewOptions create new Options struct from provided option slice
func NewOptions(opts ...Option) Options {
	options := Options{
		Logger:             logger.DefaultLogger,
		Meter:              meter.DefaultMeter,
		Tracer:             tracer.DefaultTracer,
		MeterStatsInterval: DefaultMeterStatsInterval,
		MeterMetricPrefix:  DefaultMeterMetricPrefix,
		LoggerLevel:        logger.ErrorLevel,
		LoggerObserver:     DefaultLoggerObserver,
	}
	for _, o := range opts {
		o(&options)
	}

	options.Meter = options.Meter.Clone(
		meter.MetricPrefix(options.MeterMetricPrefix),
		meter.Labels(
			labelHost, options.DatabaseHost,
			labelDatabase, options.DatabaseName,
		),
	)

	options.Logger = options.Logger.Clone(logger.WithCallerSkipCount(1))

	return options
}

// MetricInterval specifies stats interval for *sql.DB
func MetricInterval(td time.Duration) Option {
	return func(o *Options) {
		o.MeterStatsInterval = td
	}
}

// MetricPrefix specifies prefix for each metric
func MetricPrefix(pref string) Option {
	return func(o *Options) {
		o.MeterMetricPrefix = pref
	}
}

func DatabaseHost(host string) Option {
	return func(o *Options) {
		o.DatabaseHost = host
	}
}

func DatabaseName(name string) Option {
	return func(o *Options) {
		o.DatabaseName = name
	}
}

// Meter passes meter.Meter to wrapper
func Meter(m meter.Meter) Option {
	return func(o *Options) {
		o.Meter = m
	}
}

// Logger passes logger.Logger to wrapper
func Logger(l logger.Logger) Option {
	return func(o *Options) {
		o.Logger = l
	}
}

// LoggerEnabled enable sql logging
func LoggerEnabled(b bool) Option {
	return func(o *Options) {
		o.LoggerEnabled = b
	}
}

// LoggerLevel passes logger.Level option
func LoggerLevel(lvl logger.Level) Option {
	return func(o *Options) {
		o.LoggerLevel = lvl
	}
}

// LoggerObserver passes observer to fill logger fields
func LoggerObserver(obs func(context.Context, string, string, time.Duration, error) []interface{}) Option {
	return func(o *Options) {
		o.LoggerObserver = obs
	}
}

// Tracer passes tracer.Tracer to wrapper
func Tracer(t tracer.Tracer) Option {
	return func(o *Options) {
		o.Tracer = t
	}
}

type queryNameKey struct{}

// QueryName passes query name to wrapper func
func QueryName(ctx context.Context, name string) context.Context {
	if ctx == nil {
		ctx = context.Background()
	}
	return context.WithValue(ctx, queryNameKey{}, name)
}

func getQueryName(ctx context.Context) string {
	if v, ok := ctx.Value(queryNameKey{}).(string); ok && v != labelUnknown {
		return v
	}
	return getCallerName()
}