// 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):
//  * Sascha L. Teichmann <sascha.teichmann@intevation.de>
//  * Tom Gottfried <tom.gottfried@intevation.de>

package models

import (
	"context"
	"database/sql"
	"log"
	"net/http"
	"sync"

	"gemma.intevation.de/gemma/pkg/auth"
	"gemma.intevation.de/gemma/pkg/config"
)

const DatabaseScheme = "waterway"

type IntEntry struct {
	Schema string  `json:"schema"`
	Name   string  `json:"name"`
	SQL    *string `json:"sql"`
	SRS    *string `json:"srs"`
	Style  bool    `json:"style"`
	WMS    bool    `json:"wms"`
	WFS    bool    `json:"wfs"`
}

type IntServices struct {
	entries []IntEntry
	mu      sync.Mutex
}

const (
	selectServicesSQL = `
SELECT schema, name,
  view_def, auth_name || ':' || auth_srid,
  style IS NOT NULL, as_wms, as_wfs
FROM sys_admin.published_services
  LEFT JOIN spatial_ref_sys USING (srid)
WHERE schema = $1
ORDER by name`

	selectStyleSQL = `
SELECT XMLSERIALIZE(DOCUMENT style AS text)
FROM sys_admin.published_services
WHERE name = $1 AND schema = $2`

	updateStyleSQL = `
UPDATE sys_admin.published_services
SET style = XMLPARSE(DOCUMENT $1)
WHERE name = $2 AND schema = $3`
)

var InternalServices = &IntServices{}

func (e *IntEntry) LoadStyle() (string, error) {
	var style string
	ctx := context.Background()
	err := auth.RunAs(ctx, "sys_admin",
		func(conn *sql.Conn) error {
			return conn.QueryRowContext(
				ctx,
				selectStyleSQL,
				e.Name, e.Schema).Scan(&style)
		})
	return style, err
}

func UpdateInternalStyle(req *http.Request, name, style string) error {
	return auth.RunAsSessionUser(req, func(conn *sql.Conn) error {
		_, err := conn.ExecContext(
			req.Context(), updateStyleSQL,
			style, name, DatabaseScheme)
		if err == nil {
			InternalServices.Invalidate()
		}
		return err
	})
}

func (ps *IntServices) Find(name string) (string, bool) {
	ps.mu.Lock()
	defer ps.mu.Unlock()

	if ps.entries == nil {
		if err := ps.load(); err != nil {
			log.Printf("error: %v\n", err)
			return "", false
		}
	}

	if ps.has(name) {
		return config.GeoServerURL() + "/" + name, true
	}
	return "", false
}

func (ps *IntServices) has(service string) bool {
	var check func(*IntEntry) bool
	switch service {
	case "wms":
		check = func(e *IntEntry) bool { return e.WMS }
	case "wfs":
		check = func(e *IntEntry) bool { return e.WFS }
	default:
		return false
	}
	for i := range ps.entries {
		if check(&ps.entries[i]) {
			return true
		}
	}
	return false
}

func (ps *IntServices) load() error {
	// make empty slice to prevent retry if slice is empty.
	ps.entries = []IntEntry{}
	ctx := context.Background()
	return auth.RunAs(ctx, "sys_admin",
		func(conn *sql.Conn) error {
			rows, err := conn.QueryContext(
				ctx, selectServicesSQL, DatabaseScheme)
			if err != nil {
				return err
			}
			defer rows.Close()
			for rows.Next() {
				var entry IntEntry
				if err := rows.Scan(
					&entry.Schema, &entry.Name,
					&entry.SQL, &entry.SRS, &entry.Style,
					&entry.WMS, &entry.WFS,
				); err != nil {
					return err
				}
				ps.entries = append(ps.entries, entry)
			}
			return rows.Err()
		})
}

func (ps *IntServices) Invalidate() {
	ps.mu.Lock()
	ps.entries = nil
	ps.mu.Unlock()
}

func InternalAll(IntEntry) bool        { return true }
func IntWMS(entry IntEntry) bool       { return entry.WMS }
func IntWFS(entry IntEntry) bool       { return entry.WFS }
func IntSQLView(entry IntEntry) bool   { return entry.SQL != nil }
func IntWithStyle(entry IntEntry) bool { return entry.Style }

func IntByName(name string) func(IntEntry) bool {
	return func(entry IntEntry) bool { return entry.Name == name }
}

func IntAnd(accept ...func(IntEntry) bool) func(IntEntry) bool {
	return func(entry IntEntry) bool {
		for _, a := range accept {
			if !a(entry) {
				return false
			}
		}
		return true
	}
}

func (ps *IntServices) Filter(accept func(IntEntry) bool) []IntEntry {
	ps.mu.Lock()
	defer ps.mu.Unlock()
	if ps.entries == nil {
		if err := ps.load(); err != nil {
			log.Printf("error: %v\n", err)
			return nil
		}
	}
	pe := make([]IntEntry, 0, len(ps.entries))
	for _, e := range ps.entries {
		if accept(e) {
			pe = append(pe, e)
		}
	}

	return pe
}