package server

import (
	"PD1/internal/protocol"
	"crypto/x509"
	"database/sql"
	"fmt"
	"log"
	"time"

	_ "github.com/mattn/go-sqlite3"
)

type DataStore struct {
	db *sql.DB
}

func OpenDB() DataStore {
	db, err := sql.Open("sqlite3", "server.db")
	if err != nil {
		log.Fatalln("Error opening db file")
	}
	ds := DataStore{db: db}
	ds.CreateTables()
	return ds
}

func (ds DataStore) CreateTables() error {
	// Create users table
	_, err := ds.db.Exec(`CREATE TABLE IF NOT EXISTS users (
        UID TEXT PRIMARY KEY,
        userCert BLOB
    )`)
	if err != nil {
		fmt.Println("Error creating users table", err)
		return err
	}

	// Create messages table
	_, err = ds.db.Exec(`CREATE TABLE IF NOT EXISTS messages (
        fromUID TEXT,
        toUID TEXT,
        timestamp TIMESTAMP,
        subject BLOB,
        body BLOB,
        status INT CHECK (status IN (0,1)),
        PRIMARY KEY (toUID, fromUID, timestamp),
        FOREIGN KEY(fromUID) REFERENCES users(UID),
        FOREIGN KEY(toUID) REFERENCES users(UID)
    )`)
	if err != nil {
		fmt.Println("Error creating messages table", err)
		return err
	}

	return nil
}

func (ds DataStore) GetMessage(toUID string, position int) protocol.Packet {

	var serverMessage protocol.ServerMessagePacket
	query := `
        SELECT fromUID, toUID, subject, body, timestamp
        FROM messages
        WHERE toUID = ?
        AND status = 0
        ORDER BY timestamp
        LIMIT 1 OFFSET ?
    `
	// Execute the query
	row := ds.db.QueryRow(query, toUID, position)
	err := row.Scan(&serverMessage.FromUID, &serverMessage.ToUID, &serverMessage.Subject, &serverMessage.Body, &serverMessage.Timestamp)
	if err != nil {
		log.Printf("Error getting the message in position %v from UID %v: %v", position, toUID, err)
	}

	return protocol.NewServerMessagePacket(serverMessage.FromUID, serverMessage.ToUID, serverMessage.Subject, serverMessage.Body, serverMessage.Timestamp, true)

}

func (ds DataStore) MarkMessageInQueueAsRead(toUID string, position int) {
	query := `
        UPDATE messages
        SET status = 1
        WHERE toUID = ? AND status = 0
        ORDER BY timestamp
        LIMIT 1 OFFSET ?
    `

	// Execute the SQL statement
	_, err := ds.db.Exec(query, toUID, position)
	if err != nil {
		log.Printf("Error marking the message in position %v from UID %v as read: %v", position, toUID, err)
	}
}

func (ds DataStore) GetUnreadMessagesInfoQueue(toUID string) []protocol.Packet {
	var messageInfoPackets []protocol.Packet

	// Query to retrieve all messages from the user's queue
	query := `
        SELECT 
            fromUID,
            toUID,
            timestamp,
            queue_position,
            subject,
            status
        FROM (
            SELECT 
                fromUID,
                toUID,
                timestamp,
                ROW_NUMBER() OVER (PARTITION BY toUID ORDER BY timestamp) - 1 AS queue_position,
                subject,
                status
            FROM 
                messages
            WHERE 
                toUID = ? 
        ) AS ranked_messages
        WHERE 
            status = 0
        ORDER BY 
            timestamp;
    `

	// Execute the query
	rows, err := ds.db.Query(query, toUID)
	if err != nil {
		log.Printf("Error getting all messages for UID %v: %v", toUID, err)
	}
	defer rows.Close()

	// Iterate through the result set and scan each row into a ServerMessage struct
	//First row
	if !rows.Next() {
		return []protocol.Packet{}
	}
	for {
		var fromUID string
		var subject []byte
		var timestamp time.Time
		var queuePosition, status int
		if err := rows.Scan(&fromUID, &toUID, &timestamp, &queuePosition, &subject, &status); err != nil {
			panic(err)
		}
		var message protocol.Packet
		hasNext := rows.Next()
		if !hasNext {
			message = protocol.NewServerMessageInfoPacket(queuePosition, fromUID, subject, timestamp, true)
			messageInfoPackets = append(messageInfoPackets, message)
			break
		} else {
			message = protocol.NewServerMessageInfoPacket(queuePosition, fromUID, subject, timestamp, false)
			messageInfoPackets = append(messageInfoPackets, message)
		}
	}
	if err := rows.Err(); err != nil {
		log.Printf("Error when getting messages for UID %v: %v", toUID, err)
	}

	return messageInfoPackets
}

func (ds DataStore) AddMessageToQueue(fromUID string, message protocol.SubmitMessagePacket) {
	query := `
        INSERT INTO messages (fromUID, toUID, subject, body, timestamp, status)
        VALUES (?, ?, ?, ?, ?, 0)
    `

	// Execute the SQL statement
	currentTime := time.Now()
	_, err := ds.db.Exec(query, fromUID, message.ToUID, message.Subject, message.Body, currentTime)
	if err != nil {
		log.Printf("Error adding message to UID %v: %v", fromUID, err)
	}
}

func (ds DataStore) GetUserCertificate(uid string) protocol.Packet {
	query := `
        SELECT userCert
        FROM users
        WHERE UID = ?
    `

	// Execute the SQL query
	var userCertBytes []byte
	err := ds.db.QueryRow(query, uid).Scan(&userCertBytes)
	if err == sql.ErrNoRows {
		log.Panicf("No certificate for UID %v found in the database", uid)
	}
	//userCert,err := x509.ParseCertificate(userCertBytes)
	//if err!=nil {
	//    log.Panicf("Error parsing certificate for UID %v",uid)
	//}
	return protocol.NewSendUserCertPacket(uid, userCertBytes)
}

func (ds DataStore) userExists(uid string) bool {
	// Prepare the SQL statement for checking if a user exists
	query := `
        SELECT COUNT(*)
        FROM users
        WHERE UID = ?
    `

	var count int
	// Execute the SQL query
	err := ds.db.QueryRow(query, uid).Scan(&count)
	if err == sql.ErrNoRows {
		log.Printf("User with UID %v does not exist", uid)
		return false
	} else {
		return true
	}
}

func (ds DataStore) storeUserCertIfNotExists(uid string, cert x509.Certificate) {
	// Check if the user already exists
	if ds.userExists(uid) {
		log.Printf("User certificate for UID %s already exists.\n", uid)
		return
	}

	// Insert the user certificate
	insertQuery := `
        INSERT INTO users (UID, userCert)
        VALUES (?, ?)
    `
	_, err := ds.db.Exec(insertQuery, uid, cert.Raw)
	if err != nil {
		log.Printf("Error storing user certificate for UID %s: %v\n", uid, err)
		return
	}
	log.Printf("User certificate for UID %s stored successfully.\n", uid)
}