// 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/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"`
}

// 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() []string {
	return []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 = `
WITH resp AS (
  SELECT best_utm(area::geometry) AS t,
         ST_Transform(area::geometry, best_utm(area::geometry)) AS a
  FROM users.responsibility_areas
  WHERE country = users.current_user_country()
)
DELETE FROM waterway.waterway_axis
WHERE pg_has_role('sys_admin', 'MEMBER')
  OR ST_Covers((SELECT a FROM resp),
    ST_Transform(wtwaxs::geometry, (SELECT t FROM resp)))
`

	checkCrossingAxisSQL = `
SELECT ST_AsText(ST_Intersection(new_line.wtwaxs, axis.wtwaxs))
  FROM waterway.waterway_axis AS axis, waterway.waterway_axis AS new_line
  WHERE new_line.id = $1 AND axis.id <> $1
    AND ST_Crosses(new_line.wtwaxs::geometry, axis.wtwaxs::geometry)
`

	insertWaterwayAxisSQL = `
WITH resp AS (
  SELECT best_utm(area::geometry) AS t,
         ST_Transform(area::geometry, best_utm(area::geometry)) AS a
  FROM users.responsibility_areas
  WHERE country = users.current_user_country()
)
INSERT INTO waterway.waterway_axis (wtwaxs, objnam, nobjnam)
SELECT ST_Transform(clipped.geom, 4326)::geography, $3, $4
  FROM resp,
    ST_Node(ST_Transform(
      ST_GeomFromWKB($1, $2::integer), t)) AS new_line (new_line),
    LATERAL (SELECT (ST_Dump(
      CASE WHEN pg_has_role('sys_admin', 'MEMBER')
        THEN new_line
        ELSE ST_Intersection(a, new_line)
        END
      )).geom AS geom
    ) AS clipped
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 name '%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()

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

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

	var (
		unsupported       = stringCounter{}
		missingProperties int
		badProperties     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}
			}

			switch feature.Geometry.Type {
			case "LineString":
				var l lineSlice
				if err := json.Unmarshal(*feature.Geometry.Coordinates, &l); err != nil {
					return err
				}
				if err := storeLinestring(
					ctx,
					savepoint,
					feedback,
					l,
					epsg,
					props,
					nobjnam,
					checkCrossingStmt,
					insertStmt); err != nil {
					return err
				}
				features++
			case "MultiLineString":
				var ls []lineSlice
				if err := json.Unmarshal(*feature.Geometry.Coordinates, &ls); err != nil {
					return err
				}
				for _, l := range ls {
					if err := storeLinestring(
						ctx,
						savepoint,
						feedback,
						l,
						epsg,
						props,
						nobjnam,
						checkCrossingStmt,
						insertStmt); err != nil {
						return err
					}
					features++
				}
			default:
				unsupported[feature.Geometry.Type]++
			}
		}
		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 features == 0 {
		err := errors.New("No features found")
		feedback.Error("%v", err)
		return nil, err
	}

	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 lineSlice,
	epsg int,
	props waterwayAxisProperties,
	nobjnam sql.NullString,
	checkCrossingStmt, insertStmt *sql.Stmt,
) error {
	var id int
	if err := savepoint(func() error {
		err := insertStmt.QueryRowContext(
			ctx,
			l.asWKB(),
			epsg,
			props.ObjNam,
			nobjnam,
		).Scan(&id)
		return err
	}); err != nil {
		feedback.Warn(handleError(err).Error())
	}

	var crossing string
	switch err := checkCrossingStmt.QueryRowContext(
		ctx,
		id,
	).Scan(&crossing); {
	case err != nil && err != sql.ErrNoRows:
		return err
	case err == nil:
		feedback.Warn(
			"Linestring %d crosses previously imported linestring near %s. "+
				"Finding a contiguous axis may not work here",
			id, crossing)
	}
	return nil
}