package db

import (
	"context"
	"database/sql"
	"fmt"
	"path/filepath"
	"sort"
	"strings"

	"github.com/Masterminds/semver"

	"github.com/go-flucky/flucky/pkg/types"

	// PostgreSQL lib
	_ "github.com/lib/pq"
)

var (
	postgresAssetPath = "pkg/storage/db/sql/psql"
)

// Postgres provide functions to interact with a postgres database
type Postgres struct {
	dbo *sql.DB
}

// Close the database connection
func (p *Postgres) Close() error {
	return p.dbo.Close()
}

// Schema create or updates the database schema to a given version. Normally the
// version is the same as the flucky binary version.
func (p *Postgres) Schema(ctx context.Context, version *semver.Version) error {
	schemaFunc := func(ctx context.Context, fromVersion *semver.Version, toVersion *semver.Version) error {

		assetPath := fmt.Sprintf("%v/schema", postgresAssetPath)
		sqlAssetFiles, err := AssetDir(assetPath)
		if err != nil {
			return fmt.Errorf("Can not restore asset directory %v: %v", assetPath, err)
		}

		postgreSQLVersionChanges := make(map[*semver.Version]string, 0)
		postgreSQLVersions := make([]*semver.Version, len(sqlAssetFiles))

		for i, sqlAssetFile := range sqlAssetFiles {
			fileSemVersion, err := semver.NewVersion(strings.ReplaceAll(sqlAssetFile, ".sql", ""))
			if err != nil {
				return fmt.Errorf("Can not create semantic version from file asset %v: %v", sqlAssetFile, err)
			}
			postgreSQLVersionChanges[fileSemVersion] = sqlAssetFile
			postgreSQLVersions[i] = fileSemVersion
		}
		sort.Sort(semver.Collection(postgreSQLVersions))

		for i, postgreSQLVersion := range postgreSQLVersions {
			if fromVersion != nil {
				if postgreSQLVersion.LessThan(fromVersion) || postgreSQLVersion.Equal(fromVersion) {
					flogger.Debug("SKIP: PostgreSQL schema version '%v' is less or eqal then the local version changes '%v'", postgreSQLVersion.String(), fromVersion.String())
					continue
				}
			}

			asset := postgreSQLVersionChanges[postgreSQLVersion]
			queryBytes, err := Asset(filepath.Join(assetPath, asset))
			if err != nil {
				return fmt.Errorf("Can not restore asset %v, %v", asset, err)
			}
			query := string(queryBytes)

			if _, err := p.dbo.ExecContext(ctx, query); err != nil {
				return fmt.Errorf("%v: %v", errorStatementExecute, err)
			}

			if i == 0 {
				if err := p.InsertInfo(ctx, "version", postgreSQLVersion.String()); err != nil {
					return fmt.Errorf("Can not insert version %v into info table: %v", postgreSQLVersion.String(), err)
				}
			} else {
				if err := p.UpdateInfo(ctx, "version", postgreSQLVersion.String()); err != nil {
					return fmt.Errorf("Can not update version %v into info table: %v", postgreSQLVersion.String(), err)
				}
			}
		}
		return nil
	}

	dbVersion, err := p.SelectInfo(ctx, "version")
	if err != nil {
		// can not select version from database, maybe the schema is not initialize
		// create db schema for the current flucky version
		return schemaFunc(ctx, nil, version)
	} else {
		fromVersion, err := semver.NewVersion(dbVersion)
		if err != nil {
			return fmt.Errorf("Can not create semantic version from database entry %v: %v", dbVersion, err)
		}
		return schemaFunc(ctx, fromVersion, version)
	}
}

// DeleteDevices delete recursively all spicified devices, including sensors and
// all measured values
func (p *Postgres) DeleteDevices(ctx context.Context, devices []*types.Device) error {
	asset := fmt.Sprintf("%v/deleteDevice.sql", postgresAssetPath)
	queryBytes, err := Asset(asset)
	if err != nil {
		return fmt.Errorf("%v: %v", errorGetAsset, err)
	}
	query := string(queryBytes)

	stmt, err := p.dbo.PrepareContext(ctx, query)
	if err != nil {
		return fmt.Errorf("%v: %v", errorPrepareStatement, err)
	}
	defer stmt.Close()

	for _, device := range devices {
		_, err := stmt.ExecContext(ctx, &device.ID)
		if err != nil {
			return fmt.Errorf("%v: %v", errorStatementExecute, err)
		}
	}

	return nil
}

// DeleteSensors delete recusively all spicified sensors, including all measured
// values
func (p *Postgres) DeleteSensors(ctx context.Context, sensors []*types.Sensor) error {
	asset := fmt.Sprintf("%v/deleteSensor.sql", postgresAssetPath)
	queryBytes, err := Asset(asset)
	if err != nil {
		return fmt.Errorf("%v: %v", errorGetAsset, err)
	}
	query := string(queryBytes)

	stmt, err := p.dbo.PrepareContext(ctx, query)
	if err != nil {
		return fmt.Errorf("%v: %v", errorPrepareStatement, err)
	}
	defer stmt.Close()

	for _, sensor := range sensors {
		_, err := stmt.ExecContext(ctx, &sensor.ID)
		if err != nil {
			return fmt.Errorf("%v: %v", errorStatementExecute, err)
		}
	}

	return nil
}

// DeleteMeasuredValues delete all spicified measured values
func (p *Postgres) DeleteMeasuredValues(ctx context.Context, measuredValues []*types.MeasuredValue) error {

	deleteMeasuredValue := func(ctx context.Context, query string, measuredValues []*types.MeasuredValue) error {
		stmt, err := p.dbo.PrepareContext(ctx, query)
		if err != nil {
			return fmt.Errorf("%v: %v", errorPrepareStatement, err)
		}
		defer stmt.Close()

		for _, measuredValue := range measuredValues {
			_, err := stmt.ExecContext(ctx, &measuredValue.ID)
			if err != nil {
				return fmt.Errorf("%v: %v", errorStatementExecute, err)
			}
		}
		return nil
	}

	sortedMeasuredValueTypes := make(map[types.MeasuredValueType][]*types.MeasuredValue)
	for _, measuredValue := range measuredValues {
		if _, ok := sortedMeasuredValueTypes[measuredValue.ValueType]; !ok {
			sortedMeasuredValueTypes[measuredValue.ValueType] = make([]*types.MeasuredValue, 0)
		}
		sortedMeasuredValueTypes[measuredValue.ValueType] = append(sortedMeasuredValueTypes[measuredValue.ValueType], measuredValue)
	}

	assetFunc := func(queryFile string) (string, error) {
		queryBytes, err := Asset(queryFile)
		if err != nil {
			return "", fmt.Errorf("%v: %v", errorGetAsset, err)
		}
		return string(queryBytes), nil
	}

	for measuredValueType, sortedMeasuredValues := range sortedMeasuredValueTypes {
		switch measuredValueType {
		case types.MeasuredValueTypeHumidity:
			query, err := assetFunc(fmt.Sprintf("%v/deleteHumidity.sql", postgresAssetPath))
			if err != nil {
				return err
			}

			if err := deleteMeasuredValue(ctx, query, sortedMeasuredValues); err != nil {
				return err
			}
		case types.MeasuredValueTypePressure:
			query, err := assetFunc(fmt.Sprintf("%v/deletePressure.sql", postgresAssetPath))
			if err != nil {
				return err
			}

			if err := deleteMeasuredValue(ctx, query, sortedMeasuredValues); err != nil {
				return err
			}
		case types.MeasuredValueTypeTemperature:
			query, err := assetFunc(fmt.Sprintf("%v/deleteTemperature.sql", postgresAssetPath))
			if err != nil {
				return err
			}

			if err := deleteMeasuredValue(ctx, query, sortedMeasuredValues); err != nil {
				return err
			}
		}
	}

	return nil
}

// InsertDevices insert all specified devices into the database
func (p *Postgres) InsertDevices(ctx context.Context, devices []*types.Device) error {
	asset := fmt.Sprintf("%v/insertDevice.sql", postgresAssetPath)
	queryBytes, err := Asset(asset)
	if err != nil {
		return fmt.Errorf("%v: %v", errorGetAsset, err)
	}
	query := string(queryBytes)

	stmt, err := p.dbo.PrepareContext(ctx, query)
	if err != nil {
		return fmt.Errorf("%v: %v", errorPrepareStatement, err)
	}
	defer stmt.Close()

	for _, device := range devices {
		_, err := stmt.ExecContext(ctx, &device.ID, &device.Name, &device.Location, &device.CreationDate)
		if err != nil {
			return fmt.Errorf("%v: %v", errorStatementExecute, err)
		}
	}

	return nil
}

// InsertInfo insert into the database additional informations, based on a key value syntax
func (p *Postgres) InsertInfo(ctx context.Context, key string, value string) error {
	asset := fmt.Sprintf("%v/insertInfo.sql", postgresAssetPath)
	queryBytes, err := Asset(asset)
	if err != nil {
		return fmt.Errorf("%v: %v", errorGetAsset, err)
	}
	query := string(queryBytes)

	stmt, err := p.dbo.PrepareContext(ctx, query)
	if err != nil {
		return fmt.Errorf("%v: %v", errorPrepareStatement, err)
	}
	defer stmt.Close()

	_, err = stmt.ExecContext(ctx, key, value)
	if err != nil {
		return fmt.Errorf("%v: %v", errorStatementExecute, err)
	}

	return nil
}

// InsertMeasuredValues insert all specified measured values into the database
func (p *Postgres) InsertMeasuredValues(ctx context.Context, measuredValues []*types.MeasuredValue) error {

	sortedMeasuredValueTypes := make(map[types.MeasuredValueType][]*types.MeasuredValue)

	for _, measuredValue := range measuredValues {
		if _, ok := sortedMeasuredValueTypes[measuredValue.ValueType]; !ok {
			sortedMeasuredValueTypes[measuredValue.ValueType] = make([]*types.MeasuredValue, 0)
		}
		sortedMeasuredValueTypes[measuredValue.ValueType] = append(sortedMeasuredValueTypes[measuredValue.ValueType], measuredValue)
	}

	for measuredValueType, sortedMeasuredValues := range sortedMeasuredValueTypes {
		switch measuredValueType {
		case types.MeasuredValueTypeHumidity:
			if err := p.insertHumidity(ctx, sortedMeasuredValues); err != nil {
				return err
			}
		case types.MeasuredValueTypePressure:
			if err := p.insertPressure(ctx, sortedMeasuredValues); err != nil {
				return err
			}
		case types.MeasuredValueTypeTemperature:
			if err := p.insertTemperature(ctx, sortedMeasuredValues); err != nil {
				return err
			}
		}
	}

	return nil
}

func (p *Postgres) insertHumidity(ctx context.Context, measuredValues []*types.MeasuredValue) error {

	asset := fmt.Sprintf("%v/insertHumidity.sql", postgresAssetPath)
	queryBytes, err := Asset(asset)
	if err != nil {
		return fmt.Errorf("%v: %v", errorGetAsset, err)
	}
	query := string(queryBytes)

	stmt, err := p.dbo.PrepareContext(ctx, query)
	if err != nil {
		return fmt.Errorf("%v: %v", errorPrepareStatement, err)
	}
	defer stmt.Close()

	for _, measuredValue := range measuredValues {

		if measuredValue.ValueType != types.MeasuredValueTypeHumidity {
			continue
		}

		_, err := stmt.ExecContext(ctx, &measuredValue.ID, &measuredValue.Value, &measuredValue.FromDate, &measuredValue.TillDate, &measuredValue.SensorID, &measuredValue.CreationDate, &measuredValue.UpdateDate)
		if err != nil {
			return fmt.Errorf("%v: %v", errorStatementExecute, err)
		}
	}
	return nil
}

func (p *Postgres) insertPressure(ctx context.Context, measuredValues []*types.MeasuredValue) error {

	asset := fmt.Sprintf("%v/insertPressure.sql", postgresAssetPath)
	queryBytes, err := Asset(asset)
	if err != nil {
		return fmt.Errorf("%v: %v", errorGetAsset, err)
	}
	query := string(queryBytes)

	stmt, err := p.dbo.PrepareContext(ctx, query)
	if err != nil {
		return fmt.Errorf("%v: %v", errorPrepareStatement, err)
	}
	defer stmt.Close()

	for _, measuredValue := range measuredValues {

		if measuredValue.ValueType != types.MeasuredValueTypePressure {
			continue
		}

		_, err := stmt.ExecContext(ctx, &measuredValue.ID, &measuredValue.Value, &measuredValue.FromDate, &measuredValue.TillDate, &measuredValue.SensorID, &measuredValue.CreationDate, &measuredValue.UpdateDate)
		if err != nil {
			return fmt.Errorf("%v: Measured value id %v: %v", errorStatementExecute, measuredValue.ID, err)
		}
	}
	return nil
}

func (p *Postgres) insertTemperature(ctx context.Context, measuredValues []*types.MeasuredValue) error {

	asset := fmt.Sprintf("%v/insertTemperature.sql", postgresAssetPath)
	queryBytes, err := Asset(asset)
	if err != nil {
		return fmt.Errorf("%v: %v", errorGetAsset, err)
	}
	query := string(queryBytes)

	stmt, err := p.dbo.PrepareContext(ctx, query)
	if err != nil {
		return fmt.Errorf("%v: %v", errorPrepareStatement, err)
	}
	defer stmt.Close()

	for _, measuredValue := range measuredValues {

		if measuredValue.ValueType != types.MeasuredValueTypeTemperature {
			continue
		}

		_, err := stmt.ExecContext(ctx, &measuredValue.ID, &measuredValue.Value, &measuredValue.FromDate, &measuredValue.TillDate, &measuredValue.SensorID, &measuredValue.CreationDate, &measuredValue.UpdateDate)
		if err != nil {
			return fmt.Errorf("%v: Measured value id %v: %v", errorStatementExecute, measuredValue.ID, err)
		}
	}
	return nil
}

// InsertSensors insert all specified sensors into the database
func (p *Postgres) InsertSensors(ctx context.Context, sensors []*types.Sensor) error {

	asset := fmt.Sprintf("%v/insertSensor.sql", postgresAssetPath)
	queryBytes, err := Asset(asset)
	if err != nil {
		return fmt.Errorf("%v: %v", errorGetAsset, err)
	}
	query := string(queryBytes)

	stmt, err := p.dbo.PrepareContext(ctx, query)
	if err != nil {
		return fmt.Errorf("%v: %v", errorPrepareStatement, err)
	}
	defer stmt.Close()

	for _, sensor := range sensors {

		_, err := stmt.ExecContext(ctx, &sensor.ID, &sensor.Name, &sensor.Location, &sensor.WireID, &sensor.I2CBus, &sensor.I2CAddress, &sensor.GPIONumber, &sensor.Model, &sensor.Enabled, &sensor.DeviceID, &sensor.CreationDate)
		if err != nil {
			return fmt.Errorf("%v: %v", errorStatementExecute, err)
		}
	}
	return nil
}

// SelectDeviceByID returns a device by his ID
func (p *Postgres) SelectDeviceByID(ctx context.Context, id string) (*types.Device, error) {
	asset := fmt.Sprintf("%v/selectDeviceByID.sql", postgresAssetPath)
	queryBytes, err := Asset(asset)
	if err != nil {
		return nil, fmt.Errorf("%v: %v", errorGetAsset, err)
	}
	query := string(queryBytes)

	stmt, err := p.dbo.PrepareContext(ctx, query)
	if err != nil {
		return nil, fmt.Errorf("%v: %v", errorPrepareStatement, err)
	}

	row := stmt.QueryRowContext(ctx, id)
	if row == nil {
		return nil, errorRowNotFound
	}

	device := new(types.Device)
	err = row.Scan(&device.ID, &device.Name, &device.Location, &device.CreationDate)
	if err != nil {
		return nil, fmt.Errorf("%v: %v", errorScanRow, err)
	}

	return device, nil
}

// SelectInfo returns the value of a key stored in the database
func (p *Postgres) SelectInfo(ctx context.Context, key string) (string, error) {
	asset := fmt.Sprintf("%v/selectInfo.sql", postgresAssetPath)
	queryBytes, err := Asset(asset)
	if err != nil {
		return "", fmt.Errorf("%v: %v", errorGetAsset, err)
	}
	query := string(queryBytes)

	stmt, err := p.dbo.PrepareContext(ctx, query)
	if err != nil {
		return "", fmt.Errorf("%v: %v", errorPrepareStatement, err)
	}

	row := stmt.QueryRowContext(ctx, key)
	if row == nil {
		return "", errorRowNotFound
	}

	value := ""
	err = row.Scan(&value)
	if err != nil {
		return "", fmt.Errorf("%v: %v", errorScanRow, err)
	}

	return value, nil
}

// SelectHumidities returns humidity values
func (p *Postgres) SelectHumidities(ctx context.Context) ([]*types.MeasuredValue, error) {
	queryFile := fmt.Sprintf("%v/selectHumidities.sql", postgresAssetPath)
	measuredValues, err := p.selectMeasuredValues(ctx, types.MeasuredValueTypeHumidity, queryFile, nil)
	if err != nil {
		return nil, err
	}
	return measuredValues, nil
}

// SelectHumidityByID returns a humidity value by his ID
func (p *Postgres) SelectHumidityByID(ctx context.Context, id string) (*types.MeasuredValue, error) {
	queryFile := fmt.Sprintf("%v/selectHumidityByID.sql", postgresAssetPath)
	args := []interface{}{id}
	measuredValues, err := p.selectMeasuredValues(ctx, types.MeasuredValueTypeHumidity, queryFile, args)
	if err != nil {
		return nil, err
	}

	if len(measuredValues) == 0 {
		return nil, fmt.Errorf("%v: %v", errorRowNotFound, id)
	}

	return measuredValues[0], nil
}

// SelectMeasuredValues returns all measured values about all diffferent value
// types
func (p *Postgres) SelectMeasuredValues(ctx context.Context) ([]*types.MeasuredValue, error) {
	measuredValues := make([]*types.MeasuredValue, 0)

	// MeasuredValue query functions
	queryFunctions := []func(ctx context.Context) ([]*types.MeasuredValue, error){
		p.SelectHumidities,
		p.SelectPressures,
		p.SelectTemperatures,
	}

	// Execute query functions
	for _, queryFunction := range queryFunctions {
		queriedMeasuredValues, err := queryFunction(ctx)
		if err != nil {
			return nil, err
		}
		measuredValues = append(measuredValues, queriedMeasuredValues...)
	}
	return measuredValues, nil
}

// SelectMeasuredValuesByIDAndType returns a measured value by his ID and type
func (p *Postgres) SelectMeasuredValuesByIDAndType(ctx context.Context, id string, valueType types.MeasuredValueType) (*types.MeasuredValue, error) {
	switch valueType {
	case types.MeasuredValueTypeHumidity:
		return p.SelectHumidityByID(ctx, id)
	case types.MeasuredValueTypePressure:
		return p.SelectPressureByID(ctx, id)
	case types.MeasuredValueTypeTemperature:
		return p.SelectTemperatureByID(ctx, id)
	default:
		return nil, fmt.Errorf("%v: %v", errorUnknownMeasuredValueType, valueType)
	}
}

// SelectPressures returns pressure values
func (p *Postgres) SelectPressures(ctx context.Context) ([]*types.MeasuredValue, error) {
	queryFile := fmt.Sprintf("%v/selectPressures.sql", postgresAssetPath)
	measuredValues, err := p.selectMeasuredValues(ctx, types.MeasuredValueTypePressure, queryFile, nil)
	if err != nil {
		return nil, err
	}
	return measuredValues, nil
}

// SelectPressureByID returns a pressure value by his ID
func (p *Postgres) SelectPressureByID(ctx context.Context, id string) (*types.MeasuredValue, error) {
	queryFile := fmt.Sprintf("%v/selectPressureByID.sql", postgresAssetPath)
	args := []interface{}{id}
	measuredValues, err := p.selectMeasuredValues(ctx, types.MeasuredValueTypePressure, queryFile, args)
	if err != nil {
		return nil, err
	}

	if len(measuredValues) == 0 {
		return nil, fmt.Errorf("%v: %v", errorRowNotFound, id)
	}

	return measuredValues[0], nil
}

// SelectSensorByID returns a sensor by his ID
func (p *Postgres) SelectSensorByID(ctx context.Context, id string) (*types.Sensor, error) {
	asset := fmt.Sprintf("%v/selectSensorByID.sql", postgresAssetPath)
	queryBytes, err := Asset(asset)
	if err != nil {
		return nil, fmt.Errorf("%v: %v", errorGetAsset, err)
	}
	query := string(queryBytes)

	stmt, err := p.dbo.PrepareContext(ctx, query)
	if err != nil {
		return nil, fmt.Errorf("%v: %v", errorPrepareStatement, err)
	}

	row := stmt.QueryRowContext(ctx, id)
	if row == nil {
		return nil, errorRowNotFound
	}

	sensor := new(types.Sensor)
	err = row.Scan(&sensor.ID, &sensor.Name, &sensor.Location, &sensor.WireID, &sensor.I2CBus, &sensor.I2CAddress, &sensor.GPIONumber, &sensor.Model, &sensor.Enabled, &sensor.DeviceID, &sensor.CreationDate)
	if err != nil {
		return nil, fmt.Errorf("%v: %v", errorScanRow, err)
	}

	return sensor, nil
}

// SelectTemperatures returns temperature values
func (p *Postgres) SelectTemperatures(ctx context.Context) ([]*types.MeasuredValue, error) {
	queryFile := fmt.Sprintf("%v/selectTemperatures.sql", postgresAssetPath)
	measuredValues, err := p.selectMeasuredValues(ctx, types.MeasuredValueTypeTemperature, queryFile, nil)
	if err != nil {
		return nil, err
	}
	return measuredValues, nil
}

// SelectTemperatureByID returns a temperature value by his ID
func (p *Postgres) SelectTemperatureByID(ctx context.Context, id string) (*types.MeasuredValue, error) {
	queryFile := fmt.Sprintf("%v/selectTemperatureByID.sql", postgresAssetPath)
	args := []interface{}{id}
	measuredValues, err := p.selectMeasuredValues(ctx, types.MeasuredValueTypeTemperature, queryFile, args)
	if err != nil {
		return nil, err
	}

	if len(measuredValues) == 0 {
		return nil, fmt.Errorf("%v: %v", errorRowNotFound, id)
	}

	return measuredValues[0], nil
}

func (p *Postgres) selectMeasuredValues(ctx context.Context, measuredValueType types.MeasuredValueType, queryFile string, queryArgs []interface{}) ([]*types.MeasuredValue, error) {
	queryBytes, err := Asset(queryFile)
	if err != nil {
		return nil, fmt.Errorf("%v: %v", errorGetAsset, err)
	}
	query := string(queryBytes)

	stmt, err := p.dbo.PrepareContext(ctx, query)
	if err != nil {
		return nil, fmt.Errorf("%v: %v", errorPrepareStatement, err)
	}

	rows, err := stmt.QueryContext(ctx, queryArgs...)
	if err != nil {
		return nil, fmt.Errorf("%v: %v", errorStatementQuery, err)
	}

	measuredValues := make([]*types.MeasuredValue, 0)
	for rows.Next() {
		measuredValue := new(types.MeasuredValue)
		measuredValue.ValueType = measuredValueType
		rows.Scan(&measuredValue.ID, &measuredValue.Value, &measuredValue.FromDate, &measuredValue.TillDate, &measuredValue.SensorID, &measuredValue.CreationDate, &measuredValue.UpdateDate)
		measuredValues = append(measuredValues, measuredValue)
	}

	return measuredValues, nil
}

// UpdateDevices updates all specified devices into the database
func (p *Postgres) UpdateDevices(ctx context.Context, devices []*types.Device) error {
	return nil
}

// UpdateInfo updates the value which is stored to a key in the database
func (p *Postgres) UpdateInfo(ctx context.Context, key string, value string) error {
	asset := fmt.Sprintf("%v/updateInfo.sql", postgresAssetPath)
	queryBytes, err := Asset(asset)
	if err != nil {
		return fmt.Errorf("%v: %v", errorGetAsset, err)
	}
	query := string(queryBytes)

	stmt, err := p.dbo.PrepareContext(ctx, query)
	if err != nil {
		return fmt.Errorf("%v: %v", errorPrepareStatement, err)
	}
	defer stmt.Close()

	_, err = stmt.ExecContext(ctx, key, value)
	if err != nil {
		return fmt.Errorf("%v: %v", errorStatementExecute, err)
	}

	return nil
}

// UpdateMeasuredValues updates the measured values which are stored in the database
func (p *Postgres) UpdateMeasuredValues(ctx context.Context, measuredValues []*types.MeasuredValue) error {
	return nil
}

// UpdateSensors updates the sensors which are stored in the database
func (p *Postgres) UpdateSensors(ctx context.Context, sensots []*types.Sensor) error {
	return nil
}