package db

import (
	"context"
	"database/sql"
	"fmt"
	"time"

	"git.cryptic.systems/volker.raschek/flucky/pkg/types"
	"git.cryptic.systems/volker.raschek/go-logger"
)

// Postgres implementation
type Postgres struct {
	dbo     *sql.DB
	flogger logger.Logger
	queries map[string]string
}

// Close closes the database and prevents new queries from starting. Close then
// waits for all queries that have started processing on the server to finish.
func (postgres *Postgres) Close() error {
	return postgres.dbo.Close()
}

// DeleteDevices from the database
func (postgres *Postgres) DeleteDevices(ctx context.Context, deviceIDs ...string) error {
	queryFile := "deleteDevice.sql"
	query, present := postgres.queries[queryFile]
	if !present {
		return fmt.Errorf("SQLite-Backend: File %v not found", queryFile)
	}

	tx, err := postgres.dbo.BeginTx(ctx, &sql.TxOptions{ReadOnly: false})
	if err != nil {
		return fmt.Errorf("Failed to begin new transaction: %v", err)
	}

	stmt, err := tx.Prepare(query)
	if err != nil {
		return fmt.Errorf("Failed to prepare statement: %v", err)
	}
	defer stmt.Close()

	for _, deviceID := range deviceIDs {
		_, err = stmt.Exec(deviceID)
		if err != nil {
			tx.Rollback()
			return err
		}
	}

	return tx.Commit()
}

// DeleteSensors from the database
func (postgres *Postgres) DeleteSensors(ctx context.Context, sensorIDs ...string) error {
	queryFile := "deleteSensor.sql"
	query, present := postgres.queries[queryFile]
	if !present {
		return fmt.Errorf("SQLite-Backend: File %v not found", queryFile)
	}

	tx, err := postgres.dbo.BeginTx(ctx, &sql.TxOptions{ReadOnly: false})
	if err != nil {
		return fmt.Errorf("Failed to begin new transaction: %v", err)
	}

	stmt, err := tx.Prepare(query)
	if err != nil {
		return fmt.Errorf("Failed to prepare statement: %v", err)
	}
	defer stmt.Close()

	for _, sensorID := range sensorIDs {
		_, err = stmt.Exec(sensorID)
		if err != nil {
			tx.Rollback()
			return err
		}
	}

	return tx.Commit()
}

// InsertDevices into the database
func (postgres *Postgres) InsertDevices(ctx context.Context, devices ...*types.Device) error {
	queryFile := "insertDevice.sql"
	query, present := postgres.queries[queryFile]
	if !present {
		return fmt.Errorf("SQLite-Backend: File %v not found", queryFile)
	}

	tx, err := postgres.dbo.BeginTx(ctx, &sql.TxOptions{ReadOnly: false})
	if err != nil {
		return fmt.Errorf("Failed to begin new transaction: %v", err)
	}

	stmt, err := tx.Prepare(query)
	if err != nil {
		return fmt.Errorf("Failed to prepare statement: %v", err)
	}
	defer stmt.Close()

	for _, device := range devices {
		_, err = stmt.Exec(&device.ID, &device.Name, &device.Location, &device.CreationDate, &device.UpdateDate)
		if err != nil {
			tx.Rollback()
			return fmt.Errorf("Failed to execute statement: %v", err)
		}
	}

	return tx.Commit()
}

// InsertMeasuredValues into the database
func (postgres *Postgres) InsertMeasuredValues(ctx context.Context, measuredValues ...*types.MeasuredValue) error {
	splittedMeasuredValues := make(map[types.MeasuredValueType][]*types.MeasuredValue, 0)

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

	tx, err := postgres.dbo.BeginTx(ctx, &sql.TxOptions{ReadOnly: false})
	if err != nil {
		return fmt.Errorf("Failed to begin new transaction: %v", err)
	}

	// General insert function
	insert := func(tx *sql.Tx, queryFile string, measuredValues []*types.MeasuredValue) error {
		query, present := postgres.queries[queryFile]
		if !present {
			return fmt.Errorf("SQLite-Backend: File %v not found", queryFile)
		}

		stmt, err := tx.Prepare(query)
		if err != nil {
			return fmt.Errorf("Failed to prepare statement: %v", err)
		}
		defer stmt.Close()

		for _, measuredValue := range measuredValues {
			_, err := stmt.Exec(
				&measuredValue.ID,
				&measuredValue.Value,
				&measuredValue.Date,
				&measuredValue.SensorID,
				&measuredValue.CreationDate,
				&measuredValue.UpdateDate,
			)

			if err != nil {
				return fmt.Errorf("Failed to execute statement: %v", err)
			}
		}

		return nil
	}

	for measuredValueType, measuredValues := range splittedMeasuredValues {
		var queryFile string

		switch measuredValueType {
		case types.Humidity:
			queryFile = "insertHumidity.sql"
		case types.Pressure:
			queryFile = "insertPressure.sql"
		case types.Temperature:
			queryFile = "insertTemperature.sql"
		default:
			tx.Rollback()
			return fmt.Errorf("Measured value type %v not supported", measuredValueType)
		}

		err := insert(tx, queryFile, measuredValues)
		if err != nil {
			tx.Rollback()
			return err
		}
	}

	return tx.Commit()
}

// InsertSensors into the database
func (postgres *Postgres) InsertSensors(ctx context.Context, sensors ...*types.Sensor) error {
	queryFile := "insertSensor.sql"
	query, present := postgres.queries[queryFile]
	if !present {
		return fmt.Errorf("SQLite-Backend: File %v not found", queryFile)
	}

	tx, err := postgres.dbo.BeginTx(ctx, &sql.TxOptions{ReadOnly: false})
	if err != nil {
		return fmt.Errorf("Failed to begin new transaction: %v", err)
	}

	stmt, err := tx.Prepare(query)
	if err != nil {
		return fmt.Errorf("Failed to prepare statement: %v", err)
	}
	defer stmt.Close()

	for _, sensor := range sensors {
		_, err = stmt.Exec(
			&sensor.ID,
			&sensor.Name,
			&sensor.Location,
			&sensor.WireID,
			&sensor.I2CBus,
			&sensor.I2CAddress,
			&sensor.GPIONumber,
			&sensor.Model,
			&sensor.Enabled,
			&sensor.TickDuration,
			&sensor.DeviceID,
			&sensor.CreationDate,
			&sensor.UpdateDate,
		)
		if err != nil {
			tx.Rollback()
			return fmt.Errorf("Failed to execute statement: %v", err)
		}
	}

	return tx.Commit()
}

// Scheme creates all required tables if not exist
func (postgres *Postgres) Scheme(ctx context.Context) error {
	for _, query := range []string{
		postgres.queries["createTableDevices.sql"],
		postgres.queries["createTableSensors.sql"],
		postgres.queries["createTableHumidities.sql"],
		postgres.queries["createTablePressures.sql"],
		postgres.queries["createTableTemperatures.sql"],
	} {
		_, err := postgres.dbo.ExecContext(ctx, query)
		if err != nil {
			return err
		}
	}
	return nil
}

// SelectDevice from database
func (postgres *Postgres) SelectDevice(ctx context.Context, id string) (*types.Device, error) {
	queryFile := "selectDevice.sql"
	query, present := postgres.queries[queryFile]
	if !present {
		return nil, fmt.Errorf("SQLite-Backend: File %v not found", queryFile)
	}

	tx, err := postgres.dbo.BeginTx(ctx, &sql.TxOptions{ReadOnly: true})
	if err != nil {
		return nil, fmt.Errorf("Failed to begin new transaction: %v", err)
	}

	devices, err := postgres.selectDevices(tx, query, id)
	if err != nil {
		return nil, err
	}

	err = tx.Commit()
	if err != nil {
		return nil, err
	}

	if len(devices) == 0 {
		return nil, nil
	}

	return devices[0], nil
}

// SelectDevices from the database
func (postgres *Postgres) SelectDevices(ctx context.Context) ([]*types.Device, error) {
	queryFile := "selectDevices.sql"
	query, present := postgres.queries[queryFile]
	if !present {
		return nil, fmt.Errorf("SQLite-Backend: File %v not found", queryFile)
	}

	tx, err := postgres.dbo.BeginTx(ctx, &sql.TxOptions{ReadOnly: true})
	if err != nil {
		return nil, fmt.Errorf("Failed to begin new transaction: %v", err)
	}

	devices, err := postgres.selectDevices(tx, query)
	if err != nil {
		return nil, err
	}

	err = tx.Commit()
	if err != nil {
		return nil, fmt.Errorf("Failed to commit transaction: %v", err)
	}

	return devices, nil
}

func (postgres *Postgres) selectDevices(tx *sql.Tx, query string, args ...interface{}) ([]*types.Device, error) {
	stmt, err := tx.Prepare(query)
	if err != nil {
		return nil, fmt.Errorf("Failed to prepare statement: %v", err)
	}
	defer stmt.Close()

	rows, err := stmt.Query(args...)
	if err != nil {
		return nil, fmt.Errorf("Failed to query statement: %v", err)
	}

	devices := make([]*types.Device, 0)
	for rows.Next() {
		device := new(types.Device)
		err = rows.Scan(
			&device.ID,
			&device.Name,
			&device.Location,
			&device.CreationDate,
			&device.UpdateDate,
		)
		if err != nil {
			return nil, fmt.Errorf("Failed to scan row: %v", err)
		}
		devices = append(devices, device)
	}

	return devices, nil
}

// SelectHumidity returns humidity from the database
func (postgres *Postgres) SelectHumidity(ctx context.Context, id string) (*types.MeasuredValue, error) {
	queryFile := "selectHumidity.sql"
	query, present := postgres.queries[queryFile]
	if !present {
		return nil, fmt.Errorf("SQLite-Backend: File %v not found", queryFile)
	}

	tx, err := postgres.dbo.BeginTx(ctx, &sql.TxOptions{ReadOnly: true})
	if err != nil {
		return nil, err
	}

	measuredValues, err := postgres.selectMeasuredValue(tx, query, id)
	if err != nil {
		return nil, err
	}

	err = tx.Commit()
	if err != nil {
		return nil, err
	}

	if measuredValues == nil {
		return nil, nil
	}

	for _, measuredValue := range measuredValues {
		measuredValue.ValueType = types.Humidity
	}

	return measuredValues[0], nil
}

// SelectHumidities returns humidities from the database
func (postgres *Postgres) SelectHumidities(ctx context.Context) ([]*types.MeasuredValue, error) {
	queryFile := "selectHumidities.sql"
	query, present := postgres.queries[queryFile]
	if !present {
		return nil, fmt.Errorf("SQLite-Backend: File %v not found", queryFile)
	}

	tx, err := postgres.dbo.BeginTx(ctx, &sql.TxOptions{ReadOnly: true})
	if err != nil {
		return nil, err
	}

	measuredValues, err := postgres.selectMeasuredValue(tx, query, nil)
	if err != nil {
		return nil, err
	}

	err = tx.Commit()
	if err != nil {
		return nil, err
	}

	for _, measuredValue := range measuredValues {
		measuredValue.ValueType = types.Humidity
	}

	return measuredValues, nil
}

func (postgres *Postgres) selectMeasuredValue(tx *sql.Tx, query string, args ...interface{}) ([]*types.MeasuredValue, error) {
	stmt, err := tx.Prepare(query)
	if err != nil {
		tx.Rollback()
		return nil, err
	}
	defer stmt.Close()

	rows, err := stmt.Query(args...)
	if err != nil {
		tx.Rollback()
		return nil, err
	}

	measuredValues := make([]*types.MeasuredValue, 0)
	for rows.Next() {
		measuredValue := new(types.MeasuredValue)
		err := rows.Scan(
			&measuredValue.ID,
			&measuredValue.Value,
			&measuredValue.SensorID,
			&measuredValue.Date,
			&measuredValue.CreationDate,
			&measuredValue.UpdateDate,
		)

		if err != nil {
			tx.Rollback()
			return nil, err
		}

		measuredValues = append(measuredValues, measuredValue)
	}

	return measuredValues, nil
}

// SelectPressure returns pressure from the database
func (postgres *Postgres) SelectPressure(ctx context.Context, id string) (*types.MeasuredValue, error) {
	queryFile := "selectPressure.sql"
	query, present := postgres.queries[queryFile]
	if !present {
		return nil, fmt.Errorf("SQLite-Backend: File %v not found", queryFile)
	}

	tx, err := postgres.dbo.BeginTx(ctx, &sql.TxOptions{ReadOnly: true})
	if err != nil {
		return nil, err
	}

	measuredValues, err := postgres.selectMeasuredValue(tx, query, id)
	if err != nil {
		return nil, err
	}

	err = tx.Commit()
	if err != nil {
		return nil, err
	}

	if measuredValues == nil {
		return nil, nil
	}

	for _, measuredValue := range measuredValues {
		measuredValue.ValueType = types.Pressure
	}

	return measuredValues[0], nil
}

// SelectPressures returns pressure from the database
func (postgres *Postgres) SelectPressures(ctx context.Context) ([]*types.MeasuredValue, error) {
	queryFile := "selectPressures.sql"
	query, present := postgres.queries[queryFile]
	if !present {
		return nil, fmt.Errorf("SQLite-Backend: File %v not found", queryFile)
	}

	tx, err := postgres.dbo.BeginTx(ctx, &sql.TxOptions{ReadOnly: true})
	if err != nil {
		return nil, err
	}

	measuredValues, err := postgres.selectMeasuredValue(tx, query, nil)
	if err != nil {
		return nil, err
	}

	err = tx.Commit()
	if err != nil {
		return nil, err
	}

	for _, measuredValue := range measuredValues {
		measuredValue.ValueType = types.Pressure
	}

	return measuredValues, nil
}

// SelectSensor from database
func (postgres *Postgres) SelectSensor(ctx context.Context, id string) (*types.Sensor, error) {
	queryFile := "selectSensor.sql"
	query, present := postgres.queries[queryFile]
	if !present {
		return nil, fmt.Errorf("SQLite-Backend: File %v not found", queryFile)
	}

	tx, err := postgres.dbo.BeginTx(ctx, &sql.TxOptions{ReadOnly: true})
	if err != nil {
		return nil, fmt.Errorf("Failed to begin new transaction: %v", err)
	}

	sensors, err := postgres.selectSensors(tx, query, id)
	if err != nil {
		return nil, err
	}

	err = tx.Commit()
	if err != nil {
		return nil, fmt.Errorf("Failed to commit transaction: %v", err)
	}

	if len(sensors) == 0 {
		return nil, nil
	}

	return sensors[0], nil
}

// SelectSensors from the database
func (postgres *Postgres) SelectSensors(ctx context.Context) ([]*types.Sensor, error) {
	queryFile := "selectSensors.sql"
	query, present := postgres.queries[queryFile]
	if !present {
		return nil, fmt.Errorf("SQLite-Backend: File %v not found", queryFile)
	}

	tx, err := postgres.dbo.BeginTx(ctx, &sql.TxOptions{ReadOnly: true})
	if err != nil {
		return nil, fmt.Errorf("Failed to begin new transaction: %v", err)
	}

	sensors, err := postgres.selectSensors(tx, query)
	if err != nil {
		return nil, err
	}

	err = tx.Commit()
	if err != nil {
		return nil, fmt.Errorf("Failed to commit transaction: %v", err)
	}

	return sensors, nil
}

func (postgres *Postgres) selectSensors(tx *sql.Tx, query string, args ...interface{}) ([]*types.Sensor, error) {
	stmt, err := tx.Prepare(query)
	if err != nil {
		return nil, fmt.Errorf("Failed to prepare statement: %v", err)
	}
	defer stmt.Close()

	rows, err := stmt.Query(args...)
	if err != nil {
		return nil, fmt.Errorf("Failed to query statement: %v", err)
	}

	sensors := make([]*types.Sensor, 0)
	for rows.Next() {
		sensor := new(types.Sensor)
		err = rows.Scan(
			&sensor.ID,
			&sensor.Name,
			&sensor.Location,
			&sensor.WireID,
			&sensor.I2CBus,
			&sensor.I2CAddress,
			&sensor.GPIONumber,
			&sensor.Model,
			&sensor.Enabled,
			&sensor.TickDuration,
			&sensor.DeviceID,
			&sensor.CreationDate,
			&sensor.UpdateDate,
		)

		if err != nil {
			return nil, fmt.Errorf("Failed to scan row: %v", err)
		}
		sensors = append(sensors, sensor)
	}

	return sensors, nil
}

// SelectTemperature returns temperatures from the database
func (postgres *Postgres) SelectTemperature(ctx context.Context, id string) (*types.MeasuredValue, error) {
	queryFile := "selectTemperature.sql"
	query, present := postgres.queries[queryFile]
	if !present {
		return nil, fmt.Errorf("SQLite-Backend: File %v not found", queryFile)
	}

	tx, err := postgres.dbo.BeginTx(ctx, &sql.TxOptions{ReadOnly: true})
	if err != nil {
		return nil, err
	}

	measuredValues, err := postgres.selectMeasuredValue(tx, query, id)
	if err != nil {
		return nil, err
	}

	err = tx.Commit()
	if err != nil {
		return nil, err
	}

	if measuredValues == nil {
		return nil, nil
	}

	for _, measuredValue := range measuredValues {
		measuredValue.ValueType = types.Temperature
	}

	return measuredValues[0], nil
}

// SelectTemperatures returns temperatures from the database
func (postgres *Postgres) SelectTemperatures(ctx context.Context) ([]*types.MeasuredValue, error) {
	queryFile := "selectTemperatures.sql"
	query, present := postgres.queries[queryFile]
	if !present {
		return nil, fmt.Errorf("SQLite-Backend: File %v not found", queryFile)
	}

	tx, err := postgres.dbo.BeginTx(ctx, &sql.TxOptions{ReadOnly: true})
	if err != nil {
		return nil, err
	}

	measuredValues, err := postgres.selectMeasuredValue(tx, query, nil)
	if err != nil {
		return nil, err
	}

	err = tx.Commit()
	if err != nil {
		return nil, err
	}

	for _, measuredValue := range measuredValues {
		measuredValue.ValueType = types.Temperature
	}

	return measuredValues, nil
}

// UpdateDevices updates a device in the database
func (postgres *Postgres) UpdateDevices(ctx context.Context, devices ...*types.Device) error {
	queryFile := "updateDevice.sql"
	query, present := postgres.queries[queryFile]
	if !present {
		return fmt.Errorf("SQLite-Backend: File %v not found", queryFile)
	}

	tx, err := postgres.dbo.BeginTx(ctx, &sql.TxOptions{ReadOnly: false})
	if err != nil {
		return err
	}

	stmt, err := tx.Prepare(query)
	if err != nil {
		tx.Rollback()
		return err
	}
	defer stmt.Close()

	for _, device := range devices {
		now := time.Now()
		device.UpdateDate = &now

		_, err := stmt.Exec(
			&device.Name,
			&device.Location,
			&device.CreationDate,
			&device.UpdateDate,
			&device.ID,
		)
		if err != nil {
			tx.Rollback()
			return err
		}
	}

	return tx.Commit()
}

// UpdateSensors updates a sensor in the database
func (postgres *Postgres) UpdateSensors(ctx context.Context, sensors ...*types.Sensor) error {
	queryFile := "updateSensor.sql"
	query, present := postgres.queries[queryFile]
	if !present {
		return fmt.Errorf("SQLite-Backend: File %v not found", queryFile)
	}

	tx, err := postgres.dbo.BeginTx(ctx, &sql.TxOptions{ReadOnly: false})
	if err != nil {
		return err
	}

	stmt, err := tx.Prepare(query)
	if err != nil {
		tx.Rollback()
		return err
	}
	defer stmt.Close()

	for _, sensor := range sensors {
		now := time.Now()
		sensor.UpdateDate = &now
		_, err := stmt.Exec(
			&sensor.Name,
			&sensor.Location,
			&sensor.WireID,
			&sensor.I2CBus,
			&sensor.I2CAddress,
			&sensor.GPIONumber,
			&sensor.Model,
			&sensor.Enabled,
			&sensor.TickDuration,
			&sensor.DeviceID,
			&sensor.CreationDate,
			&sensor.UpdateDate,
			&sensor.ID,
		)
		if err != nil {
			tx.Rollback()
			return err
		}
	}

	return tx.Commit()
}