package sqlite

import (
	"database/sql"
	"encoding/json"
	"fmt"
	"path/filepath"
	"time"

	_ "github.com/mattn/go-sqlite3"
	log "github.com/sirupsen/logrus"

	"github.com/netbirdio/netbird/management/server/activity"
)

const (
	// eventSinkDB is the default name of the events database
	eventSinkDB      = "events.db"
	createTableQuery = "CREATE TABLE IF NOT EXISTS events " +
		"(id INTEGER PRIMARY KEY AUTOINCREMENT, " +
		"activity INTEGER, " +
		"timestamp DATETIME, " +
		"initiator_id TEXT," +
		"account_id TEXT," +
		"meta TEXT," +
		" target_id TEXT);"

	creatTableDeletedUsersQuery = `CREATE TABLE IF NOT EXISTS deleted_users (id TEXT NOT NULL, email TEXT NOT NULL, name TEXT);`

	selectDescQuery = `SELECT events.id, activity, timestamp, initiator_id, i.name as "initiator_name", i.email as "initiator_email", target_id, t.name as "target_name", t.email as "target_email", account_id, meta
		FROM events 
		LEFT JOIN (
		    SELECT id, MAX(name) as name, MAX(email) as email 
		    FROM deleted_users
		    GROUP BY id
		) i ON events.initiator_id = i.id 
		LEFT JOIN (
		    SELECT id, MAX(name) as name, MAX(email) as email 
		    FROM deleted_users
		    GROUP BY id
		) t ON events.target_id = t.id
		WHERE account_id = ? 
		ORDER BY timestamp DESC LIMIT ? OFFSET ?;`

	selectAscQuery = `SELECT events.id, activity, timestamp, initiator_id, i.name as "initiator_name", i.email as "initiator_email", target_id, t.name as "target_name", t.email as "target_email", account_id, meta
		FROM events 
		LEFT JOIN (
		    SELECT id, MAX(name) as name, MAX(email) as email 
		    FROM deleted_users
		    GROUP BY id
		) i ON events.initiator_id = i.id 
		LEFT JOIN (
		    SELECT id, MAX(name) as name, MAX(email) as email 
		    FROM deleted_users
		    GROUP BY id
		) t ON events.target_id = t.id
		WHERE account_id = ? 
		ORDER BY timestamp ASC LIMIT ? OFFSET ?;`

	insertQuery = "INSERT INTO events(activity, timestamp, initiator_id, target_id, account_id, meta) " +
		"VALUES(?, ?, ?, ?, ?, ?)"

	insertDeleteUserQuery = `INSERT INTO deleted_users(id, email, name) VALUES(?, ?, ?)`

	fallbackName  = "unknown"
	fallbackEmail = "unknown@unknown.com"
)

// Store is the implementation of the activity.Store interface backed by SQLite
type Store struct {
	db           *sql.DB
	fieldEncrypt *FieldEncrypt

	insertStatement     *sql.Stmt
	selectAscStatement  *sql.Stmt
	selectDescStatement *sql.Stmt
	deleteUserStmt      *sql.Stmt
}

// NewSQLiteStore creates a new Store with an event table if not exists.
func NewSQLiteStore(dataDir string, encryptionKey string) (*Store, error) {
	dbFile := filepath.Join(dataDir, eventSinkDB)
	db, err := sql.Open("sqlite3", dbFile)
	if err != nil {
		return nil, err
	}

	crypt, err := NewFieldEncrypt(encryptionKey)
	if err != nil {
		_ = db.Close()
		return nil, err
	}

	_, err = db.Exec(createTableQuery)
	if err != nil {
		_ = db.Close()
		return nil, err
	}

	_, err = db.Exec(creatTableDeletedUsersQuery)
	if err != nil {
		_ = db.Close()
		return nil, err
	}

	err = updateDeletedUsersTable(db)
	if err != nil {
		_ = db.Close()
		return nil, err
	}

	insertStmt, err := db.Prepare(insertQuery)
	if err != nil {
		_ = db.Close()
		return nil, err
	}

	selectDescStmt, err := db.Prepare(selectDescQuery)
	if err != nil {
		_ = db.Close()
		return nil, err
	}

	selectAscStmt, err := db.Prepare(selectAscQuery)
	if err != nil {
		_ = db.Close()
		return nil, err
	}

	deleteUserStmt, err := db.Prepare(insertDeleteUserQuery)
	if err != nil {
		_ = db.Close()
		return nil, err
	}

	s := &Store{
		db:                  db,
		fieldEncrypt:        crypt,
		insertStatement:     insertStmt,
		selectDescStatement: selectDescStmt,
		selectAscStatement:  selectAscStmt,
		deleteUserStmt:      deleteUserStmt,
	}

	return s, nil
}

func (store *Store) processResult(result *sql.Rows) ([]*activity.Event, error) {
	events := make([]*activity.Event, 0)
	var cryptErr error
	for result.Next() {
		var id int64
		var operation activity.Activity
		var timestamp time.Time
		var initiator string
		var initiatorName *string
		var initiatorEmail *string
		var target string
		var targetUserName *string
		var targetEmail *string
		var account string
		var jsonMeta string
		err := result.Scan(&id, &operation, &timestamp, &initiator, &initiatorName, &initiatorEmail, &target, &targetUserName, &targetEmail, &account, &jsonMeta)
		if err != nil {
			return nil, err
		}

		meta := make(map[string]any)
		if jsonMeta != "" {
			err = json.Unmarshal([]byte(jsonMeta), &meta)
			if err != nil {
				return nil, err
			}
		}

		if targetUserName != nil {
			name, err := store.fieldEncrypt.Decrypt(*targetUserName)
			if err != nil {
				cryptErr = fmt.Errorf("failed to decrypt username for target id: %s", target)
				meta["username"] = fallbackName
			} else {
				meta["username"] = name
			}
		}

		if targetEmail != nil {
			email, err := store.fieldEncrypt.Decrypt(*targetEmail)
			if err != nil {
				cryptErr = fmt.Errorf("failed to decrypt email address for target id: %s", target)
				meta["email"] = fallbackEmail
			} else {
				meta["email"] = email
			}
		}

		event := &activity.Event{
			Timestamp:   timestamp,
			Activity:    operation,
			ID:          uint64(id),
			InitiatorID: initiator,
			TargetID:    target,
			AccountID:   account,
			Meta:        meta,
		}

		if initiatorName != nil {
			name, err := store.fieldEncrypt.Decrypt(*initiatorName)
			if err != nil {
				cryptErr = fmt.Errorf("failed to decrypt username of initiator: %s", initiator)
				event.InitiatorName = fallbackName
			} else {
				event.InitiatorName = name
			}
		}

		if initiatorEmail != nil {
			email, err := store.fieldEncrypt.Decrypt(*initiatorEmail)
			if err != nil {
				cryptErr = fmt.Errorf("failed to decrypt email address of initiator: %s", initiator)
				event.InitiatorEmail = fallbackEmail
			} else {
				event.InitiatorEmail = email
			}
		}

		events = append(events, event)
	}

	if cryptErr != nil {
		log.Warnf("%s", cryptErr)
	}

	return events, nil
}

// Get returns "limit" number of events from index ordered descending or ascending by a timestamp
func (store *Store) Get(accountID string, offset, limit int, descending bool) ([]*activity.Event, error) {
	stmt := store.selectDescStatement
	if !descending {
		stmt = store.selectAscStatement
	}

	result, err := stmt.Query(accountID, limit, offset)
	if err != nil {
		return nil, err
	}

	defer result.Close() //nolint
	return store.processResult(result)
}

// Save an event in the SQLite events table end encrypt the "email" element in meta map
func (store *Store) Save(event *activity.Event) (*activity.Event, error) {
	var jsonMeta string
	meta, err := store.saveDeletedUserEmailAndNameInEncrypted(event)
	if err != nil {
		return nil, err
	}

	if meta != nil {
		metaBytes, err := json.Marshal(event.Meta)
		if err != nil {
			return nil, err
		}
		jsonMeta = string(metaBytes)
	}

	result, err := store.insertStatement.Exec(event.Activity, event.Timestamp, event.InitiatorID, event.TargetID, event.AccountID, jsonMeta)
	if err != nil {
		return nil, err
	}

	id, err := result.LastInsertId()
	if err != nil {
		return nil, err
	}

	eventCopy := event.Copy()
	eventCopy.ID = uint64(id)
	return eventCopy, nil
}

// saveDeletedUserEmailAndNameInEncrypted if the meta contains email and name then store it in encrypted way and delete
// this item from meta map
func (store *Store) saveDeletedUserEmailAndNameInEncrypted(event *activity.Event) (map[string]any, error) {
	email, ok := event.Meta["email"]
	if !ok {
		return event.Meta, nil
	}

	name, ok := event.Meta["name"]
	if !ok {
		return event.Meta, nil
	}

	encryptedEmail := store.fieldEncrypt.Encrypt(fmt.Sprintf("%s", email))
	encryptedName := store.fieldEncrypt.Encrypt(fmt.Sprintf("%s", name))
	_, err := store.deleteUserStmt.Exec(event.TargetID, encryptedEmail, encryptedName)
	if err != nil {
		return nil, err
	}

	if len(event.Meta) == 2 {
		return nil, nil // nolint
	}
	delete(event.Meta, "email")
	delete(event.Meta, "name")
	return event.Meta, nil
}

// Close the Store
func (store *Store) Close() error {
	if store.db != nil {
		return store.db.Close()
	}
	return nil
}

func updateDeletedUsersTable(db *sql.DB) error {
	log.Debugf("check deleted_users table version")
	rows, err := db.Query(`PRAGMA table_info(deleted_users);`)
	if err != nil {
		return err
	}
	defer rows.Close()
	found := false
	for rows.Next() {
		var (
			cid      int
			name     string
			dataType string
			notNull  int
			dfltVal  sql.NullString
			pk       int
		)
		err := rows.Scan(&cid, &name, &dataType, &notNull, &dfltVal, &pk)
		if err != nil {
			return err
		}
		if name == "name" {
			found = true
			break
		}
	}

	err = rows.Err()
	if err != nil {
		return err
	}

	if found {
		return nil
	}

	log.Debugf("update delted_users table")
	_, err = db.Exec(`ALTER TABLE deleted_users ADD COLUMN name TEXT;`)
	return err
}