// 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 Wilde <sascha.wilde@intevation.de>

package controllers

import (
	"bytes"
	"context"
	"database/sql"
	"fmt"
	"net/http"
	"os"
	"regexp"
	"strings"
	"sync"
	"time"

	"github.com/gorilla/mux"

	"gemma.intevation.de/gemma/pkg/auth"
	"gemma.intevation.de/gemma/pkg/common"
	"gemma.intevation.de/gemma/pkg/config"
	"gemma.intevation.de/gemma/pkg/geoserver"
	"gemma.intevation.de/gemma/pkg/imports"
	"gemma.intevation.de/gemma/pkg/log"
	"gemma.intevation.de/gemma/pkg/models"

	mw "gemma.intevation.de/gemma/pkg/middleware"
)

const (
	getSettingsSQL = `
SELECT config_key, config_val
FROM sys_admin.system_config`

	getConfigSQL = `
SELECT config_val
FROM sys_admin.system_config
WHERE config_key = $1`

	updateSettingSQL = `
INSERT INTO sys_admin.system_config (config_key, config_val)
VALUES ($1, $2)
ON CONFLICT (config_key) DO UPDATE SET config_val = $2`

	deleteSoundingDiffsSQL = `
DELETE FROM caching.sounding_differences`
)

// System status end points

func showSystemLog(req *http.Request) (jr mw.JSONResult, err error) {

	serviceName := mux.Vars(req)["service"]
	fileName := mux.Vars(req)["file"]

	// The following check is currently most likely unnecessary as I wasn't
	// able to inject a verbatim '/' via the middleware, but better be on
	// the safe site...
	if strings.Contains(fileName, "/") {
		err = mw.JSONError{
			Code:    http.StatusBadRequest,
			Message: "error: no slashes allowed in file name",
		}
		return
	}

	var path string

	switch serviceName {
	case "apache2", "postgresql":
		path = "/var/log/" + serviceName + "/" + fileName
	default:
		err = mw.JSONError{
			Code:    http.StatusBadRequest,
			Message: "error: invalid service: " + serviceName,
		}
		return
	}

	var txt []byte

	if txt, err = os.ReadFile(path); err != nil {
		return
	}

	jr = mw.JSONResult{
		Result: struct {
			Path    string `json:"path"`
			Content string `json:"content"`
		}{path, string(txt)},
	}
	return
}

func getSystemConfig(*http.Request) (jr mw.JSONResult, err error) {

	cfg := config.PublishedConfig()
	if cfg == "" {
		jr = mw.JSONResult{Result: strings.NewReader("{}")}
		return
	}

	var data []byte
	if data, err = os.ReadFile(cfg); err != nil {
		return
	}

	jr = mw.JSONResult{Result: bytes.NewReader(data)}
	return
}

func getSystemSettings(req *http.Request) (jr mw.JSONResult, err error) {

	var rows *sql.Rows
	if rows, err = mw.JSONConn(req).QueryContext(req.Context(), getSettingsSQL); err != nil {
		return
	}
	defer rows.Close()

	settings := map[string]string{}

	for rows.Next() {
		var key, val string
		if err = rows.Scan(&key, &val); err != nil {
			return
		}
		settings[key] = val
	}
	if err = rows.Err(); err != nil {
		return
	}

	jr = mw.JSONResult{Result: settings}
	return
}

type reconfFunc func(sql.NullString, string) (func(*http.Request), error)

var (
	reconfigureFuncsMu sync.Mutex
	reconfigureFuncs   = map[string]reconfFunc{}
)

func registerReconfigureFunc(key string, fn reconfFunc) {
	reconfigureFuncsMu.Lock()
	defer reconfigureFuncsMu.Unlock()
	reconfigureFuncs[key] = fn
}

func reconfigureFunc(key string) reconfFunc {
	reconfigureFuncsMu.Lock()
	defer reconfigureFuncsMu.Unlock()
	return reconfigureFuncs[key]
}

var validColorRe = regexp.MustCompile(`#[[:xdigit:]]{6}`)

func reconfigureWMSLayer(
	old sql.NullString, curr,
	which string,
) (func(*http.Request), error) {

	if !validColorRe.MatchString(curr) {
		return nil, fmt.Errorf("'%v' is not a valid color", curr)
	}

	if !old.Valid || old.String != strings.ToLower(curr) {
		return func(*http.Request) { geoserver.ReconfigureStyle(which) }, nil
	}

	return nil, nil
}

func reconfigureClassBreaks(
	old sql.NullString, curr,
	which string,
	recalc func(*http.Request),
) (func(*http.Request), error) {

	// If new values are broken, don't proceed.
	currCVs, err := models.ParseColorValues(curr)
	if err != nil {
		return nil, err
	}

	styles := strings.Split(which, ",")

	doBoth := func(req *http.Request) {
		log.Infof("trigger re-calculation of %s.", which)
		for _, style := range styles {
			geoserver.ReconfigureStyle(style)
		}
		recalc(req)
	}

	if !old.Valid {
		return doBoth, nil
	}

	oldCVs, err := models.ParseColorValues(old.String)
	if err != nil {
		log.Warnf("old config value is broken: %v\n", err)
		return doBoth, nil
	}

	if len(currCVs) != len(oldCVs) {
		return doBoth, nil
	}

	colorChanged := false

	for i := range currCVs {
		if currCVs[i].Value != oldCVs[i].Value {
			return doBoth, nil
		}
		if currCVs[i].Color != oldCVs[i].Color {
			colorChanged = true
		}
	}

	// Only the color changed -> no expensive recalc needed.
	if colorChanged {
		log.Infof("only colors changed.")
		return func(*http.Request) {
			for _, style := range styles {
				geoserver.ReconfigureStyle(style)
			}
		}, nil
	}

	return nil, nil
}

func init() {
	registerReconfigureFunc("morphology_classbreaks",
		func(old sql.NullString, curr string) (func(*http.Request), error) {
			return reconfigureClassBreaks(
				old, curr,
				"sounding_results_areas_geoserver,sounding_results_marking_points_geoserver",
				func(req *http.Request) {
					if s, ok := auth.GetSession(req); ok {
						triggerSoundingResultsContoursRecalc(s.User, curr)
					}
				})
		})
	registerReconfigureFunc("morphology_classbreaks_compare",
		func(old sql.NullString, curr string) (func(*http.Request), error) {
			return reconfigureClassBreaks(
				old, curr,
				"sounding_differences",
				func(*http.Request) { go deleteSoundingDiffs() })
		})

	reconf := func(which string) func(sql.NullString, string) (func(*http.Request), error) {
		return func(old sql.NullString, curr string) (func(*http.Request), error) {
			return reconfigureWMSLayer(old, curr, which)
		}
	}

	dm := reconf("distance_marks_geoserver")
	registerReconfigureFunc("distance_marks_fill", dm)
	registerReconfigureFunc("distance_marks_stroke", dm)

	dma := reconf("distance_marks_ashore_geoserver")
	registerReconfigureFunc("distance_marks_ashore_fill", dma)
	registerReconfigureFunc("distance_marks_ashore_stroke", dma)

	registerReconfigureFunc("waterway_area_stroke", reconf("waterway_area"))
	registerReconfigureFunc("waterway_axis_stroke", reconf("waterway_axis"))

	// TODO: Add more layers.
}

func triggerSoundingResultsContoursRecalc(who, breaks string) {
	var serialized string
	job := &imports.IsoRefresh{ClassBreaks: breaks}
	serialized, err := common.ToJSONString(job)
	if err != nil {
		log.Errorf("%v\n", err)
		return
	}
	var jobID int64
	if jobID, err = imports.AddJob(
		imports.ISRJobKind,
		time.Time{},
		nil,
		nil,
		who,
		false,
		serialized,
	); err != nil {
		log.Errorf("%v\n", err)
		return
	}
	log.Infof(
		"recalculate sounding results contours in job %d.\n",
		jobID)

}

func deleteSoundingDiffs() {
	// TODO: Better do that in import queue?
	ctx := context.Background()

	if err := auth.RunAs(ctx, "sys_admin",
		func(conn *sql.Conn) error {
			_, err := conn.ExecContext(ctx, deleteSoundingDiffsSQL)
			return err
		},
	); err != nil {
		log.Errorf("cleaning sounding diffs cache failed: %v\n", err)
	}
}

func setSystemSettings(req *http.Request) (jr mw.JSONResult, err error) {

	settings := mw.JSONInput(req).(*map[string]string)

	ctx := req.Context()
	var tx *sql.Tx
	if tx, err = mw.JSONConn(req).BeginTx(ctx, nil); err != nil {
		return
	}
	defer tx.Rollback()

	var setStmt *sql.Stmt
	if setStmt, err = tx.PrepareContext(ctx, updateSettingSQL); err != nil {
		return
	}
	defer setStmt.Close()
	var getStmt *sql.Stmt
	if getStmt, err = tx.PrepareContext(ctx, getConfigSQL); err != nil {
		return
	}
	defer getStmt.Close()

	reconfigure := map[string]func(*http.Request){}

	for key, value := range *settings {
		var old sql.NullString
		err = getStmt.QueryRowContext(ctx, key).Scan(&old)
		switch {
		case err == sql.ErrNoRows:
			old.Valid, err = false, nil
		case err != nil:
			return
		}

		if cmp := reconfigureFunc(key); cmp != nil {
			var fn func(*http.Request)
			if fn, err = cmp(old, value); err != nil {
				return
			}
			if fn != nil {
				reconfigure[key] = fn
			}
		}

		if _, err = setStmt.ExecContext(ctx, key, value); err != nil {
			return
		}
	}

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

	for _, fn := range reconfigure {
		fn(req)
	}

	jr = mw.JSONResult{
		Code: http.StatusCreated,
		Result: struct {
			Result string `json:"result"`
		}{"success"},
	}
	return
}