// 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, 2019 by via donau
//   – Österreichische Wasserstraßen-Gesellschaft mbH
// Software engineering by Intevation GmbH
//
// Author(s):
//  * Sascha L. Teichmann <sascha.teichmann@intevation.de>
//  * Tom Gottfried <tom.gottfried@intevation.de>

package imports

import (
	"context"
	"database/sql"
	"encoding/json"
	"errors"
	"fmt"
	"io"
	"time"

	"gemma.intevation.de/gemma/pkg/pgxutils"
	"gemma.intevation.de/gemma/pkg/wfs"
)

// WaterwayAxis is an import job to import
// the waterway axes in form of line string geometries
// and attribute data from a WFS service.
type WaterwayAxis struct {
	// URL the GetCapabilities URL of the WFS service.
	URL string `json:"url"`
	// FeatureType selects the feature type of the WFS service.
	FeatureType string `json:"feature-type"`
	// SortBy works around misconfigured services to
	// establish a sort order to get the features.
	SortBy string `json:"sort-by"`
	// User is an optional username for Basic Auth.
	User string `json:"user,omitempty"`
	// Password is an optional password for Basic Auth.
	Password string `json:"password,omitempty"`
}

// Description gives a short info about relevant facts of this import.
func (wx *WaterwayAxis) Description() (string, error) {
	return wx.URL + "|" + wx.FeatureType, nil
}

// WXJobKind is the import queue type identifier.
const WXJobKind JobKind = "wx"

type wxJobCreator struct{}

func init() {
	RegisterJobCreator(WXJobKind, wxJobCreator{})
}

func (wxJobCreator) Description() string { return "waterway axis" }

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

func (wxJobCreator) Create() Job { return new(WaterwayAxis) }

func (wxJobCreator) Depends() [2][]string {
	return [2][]string{
		{"waterway_axis"},
		{},
	}
}

// StageDone is a NOP for waterway axis imports.
func (wxJobCreator) StageDone(context.Context, *sql.Tx, int64) error {
	return nil
}

// CleanUp for waterway axis imports is a NOP.
func (*WaterwayAxis) CleanUp() error { return nil }

type waterwayAxisProperties struct {
	ObjNam  string  `json:"hydro_objnam"`
	NObjNnm *string `json:"hydro_nobjnm"`
}

const (
	deleteWaterwayAxisSQL = `
DELETE FROM waterway.waterway_axis
`

	insertWaterwayAxisSQL = `
WITH resp AS (
  SELECT users.current_user_area_utm() AS a
)
INSERT INTO waterway.waterway_axis (wtwaxs, objnam, nobjnam)
SELECT
    ST_Multi(ST_Node(ST_CollectionExtract(ST_Transform(new_ax, 4326), 2))),
    $3, $4
  FROM ST_GeomFromWKB($1, $2::integer) AS new_line (new_line),
    LATERAL (SELECT
      CASE WHEN pg_has_role('sys_admin', 'MEMBER')
        THEN new_line
        ELSE ST_Intersection((SELECT ST_Buffer(a, -0.0001) FROM resp),
          ST_Node(ST_Transform(new_line, (SELECT ST_SRID(a) FROM resp))))
        END) AS new_ax (new_ax)
  -- Do nothing if intersection is empty:
  WHERE NOT ST_IsEmpty(new_ax)
RETURNING id
`
)

// Do executes the actual waterway axis import.
func (wx *WaterwayAxis) Do(
	ctx context.Context,
	importID int64,
	conn *sql.Conn,
	feedback Feedback,
) (interface{}, error) {

	start := time.Now()

	feedback.Info("Import waterway axis")

	feedback.Info("Loading capabilities from %s", wx.URL)
	caps, err := wfs.GetCapabilities(wx.URL)
	if err != nil {
		feedback.Error("Loading capabilities failed: %v", err)
		return nil, err
	}

	ft := caps.FindFeatureType(wx.FeatureType)
	if ft == nil {
		return nil, fmt.Errorf("unknown feature type '%s'", wx.FeatureType)
	}

	feedback.Info("Found feature type '%s'", wx.FeatureType)

	epsg, err := wfs.CRSToEPSG(ft.DefaultCRS)
	if err != nil {
		feedback.Error("Unsupported CRS: '%s'", ft.DefaultCRS)
		return nil, err
	}

	if wx.SortBy != "" {
		feedback.Info("Features will be sorted by '%s'", wx.SortBy)
	}

	dl, err := wfs.GetFeatures(caps, wx.FeatureType, wx.SortBy)
	if err != nil {
		feedback.Error("Cannot create GetFeature URLs. %v", err)
		return nil, err
	}

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

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

	// Delete the old features.
	if _, err := tx.ExecContext(ctx, deleteWaterwayAxisSQL); err != nil {
		return nil, err
	}

	var (
		unsupported       = stringCounter{}
		missingProperties int
		badProperties     int
		outside           int
		features          int
	)

	if err := dl.Download(wx.User, wx.Password, func(url string, r io.Reader) error {
		feedback.Info("Get features from: '%s'", url)
		rfc, err := wfs.ParseRawFeatureCollection(r)
		if err != nil {
			return fmt.Errorf("parsing GetFeature document failed: %v", err)
		}
		if rfc.CRS != nil {
			crsName := rfc.CRS.Properties.Name
			if epsg, err = wfs.CRSToEPSG(crsName); err != nil {
				feedback.Error("Unsupported CRS: %d", crsName)
				return err
			}
		}

		// No features -> ignore.
		if rfc.Features == nil {
			return nil
		}

		feedback.Info("Using EPSG: %d", epsg)

		savepoint := Savepoint(ctx, tx, "feature")

		for _, feature := range rfc.Features {
			if feature.Properties == nil || feature.Geometry.Coordinates == nil {
				missingProperties++
				continue
			}

			var props waterwayAxisProperties

			if err := json.Unmarshal(*feature.Properties, &props); err != nil {
				badProperties++
				continue
			}

			var nobjnam sql.NullString
			if props.NObjNnm != nil {
				nobjnam = sql.NullString{String: *props.NObjNnm, Valid: true}
			}

			var ls multiLineSlice
			switch feature.Geometry.Type {
			case "LineString":
				var l lineSlice
				if err := json.Unmarshal(*feature.Geometry.Coordinates, &l); err != nil {
					return err
				}
				ls = append(ls, l)
			case "MultiLineString":
				if err := json.Unmarshal(*feature.Geometry.Coordinates, &ls); err != nil {
					return err
				}
			default:
				unsupported[feature.Geometry.Type]++
				continue
			}
			if err := storeLinestring(
				ctx,
				savepoint,
				feedback,
				ls,
				epsg,
				props,
				nobjnam,
				&outside,
				&features,
				insertStmt); err != nil {
				return err
			}
		}
		return nil
	}); err != nil {
		return nil, err
	}

	if badProperties > 0 {
		feedback.Warn("Bad properties: %d", badProperties)
	}

	if missingProperties > 0 {
		feedback.Warn("Missing properties: %d", missingProperties)
	}

	if len(unsupported) != 0 {
		feedback.Warn("Unsupported types found: %s", unsupported)
	}

	if outside > 0 {
		feedback.Info("Features outside responsibility area: %d", outside)
	}

	if features == 0 {
		return nil, errors.New("no features found")
	}

	if err = tx.Commit(); err == nil {
		feedback.Info("Storing %d features took %s",
			features, time.Since(start))
	}

	return nil, err
}

func storeLinestring(
	ctx context.Context,
	savepoint func(func() error) error,
	feedback Feedback,
	l multiLineSlice,
	epsg int,
	props waterwayAxisProperties,
	nobjnam sql.NullString,
	outside, features *int,
	insertStmt *sql.Stmt,
) error {
	var id int
	err := savepoint(func() error {
		err := insertStmt.QueryRowContext(
			ctx,
			l.asWKB(),
			epsg,
			props.ObjNam,
			nobjnam,
		).Scan(&id)
		return err
	})
	switch {
	case err == sql.ErrNoRows:
		*outside++
		// ignore -> filtered by responsibility_areas
		return nil
	case err != nil:
		feedback.Error(pgxutils.ReadableError{Err: err}.Error())
	default:
		*features++
	}
	return nil
}