/*
 Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.
 You may obtain a copy of the License at

     https://www.apache.org/licenses/LICENSE-2.0

 Unless required by applicable law or agreed to in writing, software
 distributed under the License is distributed on an "AS IS" BASIS,
 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 See the License for the specific language governing permissions and
 limitations under the License.
*/

package statistics

import (
	"database/sql"
	"os"
	"regexp"
	"strings"
	"sync"
	"time"

	_ "github.com/mattn/go-sqlite3" // this is required for the sqlite driver
	"opendev.org/airship/airshipui/pkg/configs"
	"opendev.org/airship/airshipui/pkg/log"
)

// Transaction will record the details of the CTL transaction and record them to the DB
type Transaction struct {
	Table        configs.WsComponentType
	SubComponent configs.WsSubComponentType
	User         *string
	ActionType   *string
	Target       *string
	Started      int64
	Recordable   bool
}

var (
	doNotRecordRegex = regexp.MustCompile(`(?i)^get|^init$`) // the default gets we don't care about

	writeMutex sync.Mutex
	// DB is public so other packages can do selects on it
	DB *sql.DB
	// Tables is public so other packages can range over it
	Tables = []string{"baremetal", "cluster", "config", "document", "image", "phase", "secret"}
)

const (
	// the table structure used for the records
	tableCreate = `CREATE TABLE IF NOT EXISTS table (
		subcomponent varchar(64) null,
		user varchar(64),
		type text check(type in ('direct', 'phase')) null,
		target text null,
		success tinyint(1) default 0,
		started bigint,
		elapsed bigint,
		stopped bigint)`
	// the prepared statement used for inserts
	// TODO (aschiefe): determine if we need to batch inserts
	insert = `INSERT INTO table(subcomponent,
								user,
								type,
								target,
								success,
								started,
								elapsed,
								stopped)
								values(?,?,?,?,?,?,?,?)`
)

// Init will create the database if it doesn't exist or open the existing database
func Init() {
	intitTables := false
	// TODO (aschiefe): pull the db location out to the confing
	if _, err := os.Stat("./sqlite/statistics.db"); os.IsNotExist(err) {
		intitTables = true
	}
	// need to define error so that the program will set the global db variable
	var err error
	// TODO (aschiefe): encrypt & password protect the database
	// TODO (aschiefe): pull the db location out to the confing
	DB, err = sql.Open("sqlite3", "./sqlite/statistics.db")
	if err != nil {
		log.Fatal(err)
	}
	if intitTables {
		err = createTables()
		if err != nil {
			log.Fatal(err)
		}
	}
}

// createTables is only used when there is no database to write the correct structure for the records
func createTables() error {
	for _, table := range Tables {
		stmt, err := DB.Prepare(strings.ReplaceAll(tableCreate, "table", table))

		if err != nil {
			return err
		}

		_, err = stmt.Exec()
		if err != nil {
			return err
		}
		log.Tracef("%s table created.", table)
	}
	return nil
}

// NewTransaction establishes the transaction which will record
func NewTransaction(user *string, request configs.WsMessage) *Transaction {
	return &Transaction{
		Table:        request.Component,
		SubComponent: request.SubComponent,
		ActionType:   request.ActionType,
		Target:       request.Target,
		Started:      time.Now().UnixNano() / 1000000,
		User:         user,
		Recordable:   isRecordable(request),
	}
}

// Complete will put an entry into the statistics database for the transaction
func (transaction *Transaction) Complete(errorMessageNotPresent bool) {
	if transaction.User != nil && transaction.Recordable {
		stmt, err := DB.Prepare(strings.ReplaceAll(insert, "table", string(transaction.Table)))
		if err != nil {
			log.Error(err)
			return
		}

		started := transaction.Started
		stopped := time.Now().UnixNano() / 1000000

		success := 0
		if errorMessageNotPresent {
			success = 1
		}

		writeMutex.Lock()
		defer writeMutex.Unlock()
		result, err := stmt.Exec(transaction.SubComponent,
			transaction.User,
			transaction.ActionType,
			transaction.Target,
			success,
			started,
			(stopped - started),
			stopped)

		if err != nil {
			log.Error(err)
			return
		}

		rows, err := result.RowsAffected()
		if err != nil {
			log.Error(err)
			return
		}

		log.Tracef("%d rows inserted into %s.", rows, transaction.Table)
	}
}

// isRecordable will shuffle through the transaction and determine if we should write it to the database
func isRecordable(request configs.WsMessage) bool {
	recordable := true
	// don't record auth attempts
	if request.Component == configs.Auth {
		recordable = false
	}

	// don't record default get data events
	if doNotRecordRegex.MatchString(string(request.SubComponent)) {
		recordable = false
	}

	// don't request actions taken against multiple targets, the individual action will be recorded
	if request.Targets != nil {
		recordable = false
	}

	return recordable
}