package database

import (
	"context"
	"database/sql"
	"errors"
	"sync"
	"time"

	"github.com/gravitl/netmaker/db"
	_ "github.com/mattn/go-sqlite3" // need to blank import this package
)

// SqliteDB is the db object for sqlite database connections
var SqliteDB *sql.DB

// sqliteWriteMu serializes SQLite write operations to reduce lock contention.
var sqliteWriteMu sync.Mutex

// SQLITE_FUNCTIONS - contains a map of the functions for sqlite
var SQLITE_FUNCTIONS = map[string]interface{}{
	INIT_DB:      initSqliteDB,
	CREATE_TABLE: sqliteCreateTable,
	INSERT:       sqliteInsert,
	INSERT_PEER:  sqliteInsertPeer,
	DELETE:       sqliteDeleteRecord,
	DELETE_ALL:   sqliteDeleteAllRecords,
	FETCH_ALL:    sqliteFetchRecords,
	FETCH_ONE:    sqliteFetchRecord,
	CLOSE_DB:     sqliteCloseDB,
	isConnected:  sqliteConnected,
}

func initSqliteDB() error {
	gormDB := db.FromContext(db.WithContext(context.TODO()))

	var dbOpenErr error
	SqliteDB, dbOpenErr = gormDB.DB()
	if dbOpenErr != nil {
		return dbOpenErr
	}

	return nil
}

func sqliteCreateTable(tableName string) error {
	sqliteWriteMu.Lock()
	defer sqliteWriteMu.Unlock()

	statement, err := SqliteDB.Prepare("CREATE TABLE IF NOT EXISTS " + tableName + " (key TEXT NOT NULL UNIQUE PRIMARY KEY, value TEXT)")
	if err != nil {
		return err
	}
	defer statement.Close()
	_, err = statement.Exec()
	if err != nil {
		return err
	}
	return nil
}

func sqliteInsert(key string, value string, tableName string) error {
	if key != "" && value != "" {
		sqliteWriteMu.Lock()
		defer sqliteWriteMu.Unlock()

		insertSQL := "INSERT OR REPLACE INTO " + tableName + " (key, value) VALUES (?, ?)"
		statement, err := SqliteDB.Prepare(insertSQL)
		if err != nil {
			return err
		}
		defer statement.Close()
		_, err = statement.Exec(key, value)
		if err != nil {
			return err
		}
		return nil
	}
	return errors.New("invalid insert " + key + " : " + value)
}

func sqliteInsertPeer(key string, value string) error {
	if key != "" && value != "" {
		err := sqliteInsert(key, value, PEERS_TABLE_NAME)
		if err != nil {
			return err
		}
		return nil
	}
	return errors.New("invalid peer insert " + key + " : " + value)
}

func sqliteDeleteRecord(tableName string, key string) error {
	sqliteWriteMu.Lock()
	defer sqliteWriteMu.Unlock()

	deleteSQL := "DELETE FROM " + tableName + " WHERE key = ?"
	statement, err := SqliteDB.Prepare(deleteSQL)
	if err != nil {
		return err
	}
	defer statement.Close()
	if _, err = statement.Exec(key); err != nil {
		return err
	}
	return nil
}

func sqliteDeleteAllRecords(tableName string) error {
	sqliteWriteMu.Lock()
	defer sqliteWriteMu.Unlock()

	deleteSQL := "DELETE FROM " + tableName
	statement, err := SqliteDB.Prepare(deleteSQL)
	if err != nil {
		return err
	}
	defer statement.Close()
	if _, err = statement.Exec(); err != nil {
		return err
	}
	return nil
}

func sqliteFetchRecord(tableName string, key string) (string, error) {
	var value string
	err := SqliteDB.QueryRow("SELECT value FROM "+tableName+" WHERE key = ?", key).Scan(&value)
	if err != nil {
		if err == sql.ErrNoRows {
			return "", errors.New(NO_RECORD)
		}
		return "", err
	}
	return value, nil
}

func sqliteFetchRecords(tableName string) (map[string]string, error) {
	row, err := SqliteDB.Query("SELECT * FROM " + tableName + " ORDER BY key")
	if err != nil {
		return nil, err
	}
	records := make(map[string]string)
	defer row.Close()
	for row.Next() { // Iterate and fetch the records from result cursor
		var key string
		var value string
		row.Scan(&key, &value)
		records[key] = value
	}
	if len(records) == 0 {
		return nil, errors.New(NO_RECORDS)
	}
	return records, nil
}

func sqliteCloseDB() {
	//SqliteDB.Close()
}

func sqliteConnected() bool {
	ctx, cancel := context.WithTimeout(context.Background(), 2*time.Second)
	defer cancel()
	return SqliteDB.PingContext(ctx) == nil
}