// This is Free Software under GNU Affero General Public License v >= 3.0
// without warranty, see README.md and license for details.
//
// SPDX-License-Identifier: AGPL-3.0-or-later
// License-Filename: LICENSES/AGPL-3.0.txt
//
// Copyright (C) 2018 by via donau
//   – Österreichische Wasserstraßen-Gesellschaft mbH
// Software engineering by Intevation GmbH
//
// Author(s):
//  * Raimund Renkert <raimund.renkert@intevation.de>
//  * Sascha L. Teichmann <sascha.teichmann@intevation.de>

package imports

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

	"gemma.intevation.de/gemma/pkg/models"
	"gemma.intevation.de/gemma/pkg/soap/nts"
)

// GaugeMeasurement is an import job to import
// gauges measurement data from a NtS SOAP service.
type GaugeMeasurement struct {
	// URL is the URL of the SOAP service.
	URL string `json:"url"`
	// Insecure indicates if HTTPS traffic
	// should validate certificates or not.
	Insecure bool `json:"insecure"`
}

// GMJobKind is the import queue type identifier.
const GMJobKind JobKind = "gm"

const (
	listGaugesSQL = `
SELECT
  (location).country_code,
  (location).locode,
  (location).fairway_section,
  (location).orc,
  (location).hectometre
FROM waterway.gauges
WHERE (location).country_code = users.current_user_country()`

	// Note: we do not expect corrections of data through this service.  So
	// any constraint conflicts are triggered by actual redundat data which
	// can be dropped.
	insertGMSQL = `
INSERT INTO waterway.gauge_measurements (
  fk_gauge_id,
  measure_date,
  sender,
  language_code,
  country_code,
  date_issue,
  reference_code,
  water_level,
  predicted,
  is_waterlevel,
  value_min,
  value_max,
  date_info,
  source_organization,
  staging_done
) VALUES(
  ($1, $2, $3, $4, $5),
  $6,
  $7,
  $8,
  $9,
  $10,
  $11,
  $12,
  $13,
  $14,
  $15,
  $16,
  $17,
  $18,
  $19
)
ON CONFLICT DO NOTHING
RETURNING id
`
)

type gmJobCreator struct{}

func init() {
	RegisterJobCreator(GMJobKind, gmJobCreator{})
}

func (gmJobCreator) Description() string { return "gauge measurements" }

func (gmJobCreator) Create() Job { return new(GaugeMeasurement) }

func (gmJobCreator) Depends() []string {
	return []string{
		"gauges",
		"gauge_measurements",
	}
}

func (gmJobCreator) AutoAccept() bool { return true }

// StageDone moves the imported gauge measurement out of the staging area.
// Currently doing nothing.
func (gmJobCreator) StageDone(context.Context, *sql.Tx, int64) error {
	return nil
}

// CleanUp of a gauge measurement import is a NOP.
func (*GaugeMeasurement) CleanUp() error { return nil }

// Do executes the actual bottleneck import.
func (gm *GaugeMeasurement) Do(
	ctx context.Context,
	importID int64,
	conn *sql.Conn,
	feedback Feedback,
) (interface{}, error) {

	fetch := func() ([]*nts.RIS_Message_Type, error) {
		client := nts.NewINtSMessageService(gm.URL, gm.Insecure, nil)

		mt := nts.Message_type_typeWRM

		req := &nts.Get_messages_query{
			Message_type: &mt,
		}

		resp, err := client.Get_messages(req)
		if err != nil {
			return nil, err
		}

		result := resp.Result_message
		if result == nil {
			for _, e := range resp.Result_error {
				if e != nil {
					feedback.Error("Error code: %s", *e)
				} else {
					feedback.Error("Unknown error")
				}
			}
		}
		return result, nil
	}

	return storeGaugeMeasurements(
		ctx,
		importID,
		fetch,
		conn,
		feedback,
	)
}

func loadGauges(ctx context.Context, tx *sql.Tx) ([]string, error) {

	rows, err := tx.QueryContext(ctx, listGaugesSQL)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var gauges []string

	for rows.Next() {
		var g models.Isrs
		if err = rows.Scan(
			&g.CountryCode,
			&g.LoCode,
			&g.FairwaySection,
			&g.Orc,
			&g.Hectometre,
		); err != nil {
			return nil, err
		}
		gauges = append(gauges, g.String())
	}

	if err = rows.Err(); err != nil {
		return nil, err
	}

	sort.Strings(gauges)

	return gauges, nil
}

func storeGaugeMeasurements(
	ctx context.Context,
	importID int64,
	fetch func() ([]*nts.RIS_Message_Type, error),
	conn *sql.Conn,
	feedback Feedback,
) (interface{}, error) {

	start := time.Now()

	tx, err := conn.BeginTx(ctx, nil)
	if err != nil {
		return nil, err
	}
	defer tx.Rollback()

	// Get available gauges from database for use as filter in SOAP request
	gauges, err := loadGauges(ctx, tx)
	if err != nil {
		return nil, err
	}

	// TODO get date_issue for selected gauges
	gids, err := doForGM(ctx, gauges, fetch, tx, feedback)
	if err != nil {
		feedback.Error("Error processing %d gauges: %v", len(gauges), err)
		return nil, err
	}

	if len(gids) == 0 {
		feedback.Info("No new gauge measurements found")
		return nil, UnchangedError("No new gauge measurements found")
	}

	if err = tx.Commit(); err != nil {
		feedback.Info(
			"Importing gauge measurements failed after %s", time.Since(start))
		return nil, err
	}
	feedback.Info(
		"Importing gauge measurements successfully took %s", time.Since(start))

	// TODO: needs to be filled more useful.
	summary := struct {
		GaugeMeasuremets []string `json:"gaugeMeasurements"`
	}{
		GaugeMeasuremets: gids,
	}
	return &summary, err
}

// rescale returns a scaling function to bring the unit all to cm.
func rescale(unit string) (func(float32) float32, error) {

	var scale float32

	switch strings.ToLower(unit) {
	case "mm":
		scale = 0.1
	case "cm":
		scale = 1.0
	case "dm":
		scale = 10.0
	case "m":
		scale = 100.0
	case "hm":
		scale = 10000.0
	case "km":
		scale = 100000.0
	default:
		return nil, fmt.Errorf("unknown unit '%s'", unit)
	}

	fn := func(x float32) float32 { return scale * x }
	return fn, nil
}

func doForGM(
	ctx context.Context,
	gauges []string,
	fetch func() ([]*nts.RIS_Message_Type, error),
	tx *sql.Tx,
	feedback Feedback,
) ([]string, error) {

	insertStmt, err := tx.PrepareContext(ctx, insertGMSQL)
	if err != nil {
		return nil, err
	}
	defer insertStmt.Close()

	// lookup to see if we have gauges in the database.
	isKnown := func(s string) bool {
		idx := sort.SearchStrings(gauges, s)
		return idx < len(gauges) && gauges[idx] == s
	}

	result, err := fetch()
	if err != nil {
		return nil, err
	}

	var gids []string
	for _, msg := range result {
		var gid int64
		for _, wrm := range msg.Wrm {
			curr := string(*wrm.Geo_object.Id)
			currIsrs, err := models.IsrsFromString(curr)
			if err != nil {
				feedback.Warn("Invalid ISRS code %v", err)
				continue
			}
			feedback.Info("Found measurements for %s", curr)
			if !isKnown(curr) {
				feedback.Warn("Gauge '%s' is not in database.", curr)
				continue
			}

			var referenceCode string
			if wrm.Reference_code == nil {
				feedback.Info("'Reference_code' not specified. Assuming 'ZPG'")
				referenceCode = "ZPG"
			} else {
				referenceCode = string(*wrm.Reference_code)
			}

			var newCnt int = 0
			for _, measure := range wrm.Measure {
				var unit string
				if measure.Unit == nil {
					feedback.Info("'Unit' not specified. Assuming 'cm'")
					unit = "cm"
				} else {
					unit = string(*measure.Unit)
				}
				convert, err := rescale(unit)
				if err != nil {
					return nil, err
				}
				isWaterlevel := *measure.Measure_code == nts.Measure_code_enumWAL
				err = insertStmt.QueryRowContext(
					ctx,
					currIsrs.CountryCode,
					currIsrs.LoCode,
					currIsrs.FairwaySection,
					currIsrs.Orc,
					currIsrs.Hectometre,
					measure.Measuredate,
					msg.Identification.From,
					msg.Identification.Language_code,
					msg.Identification.Country_code,
					msg.Identification.Date_issue,
					referenceCode,
					convert(measure.Value),
					measure.Predicted,
					isWaterlevel,
					convert(measure.Value_min),
					convert(measure.Value_max),
					msg.Identification.Date_issue,
					msg.Identification.Originator,
					true, // staging_done
				).Scan(&gid)
				switch {
				case err == sql.ErrNoRows:
					// thats expected, nothing to do
				case err != nil:
					return nil, err
				default:
					newCnt++
				}
			}
			feedback.Info("Inserted %d measurements for %s",
				newCnt, curr)
			gids = append(gids, curr)
		}
	}
	return gids, nil
}