package protocol

import (
	"context"
	"database/sql"
	"fmt"
	"strings"

	"github.com/pkg/errors"
)

var (
	errRecordNotFound = errors.New("record not found")
)

func (db sqlitePersistence) tableUserMessagesLegacyAllFields() string {
	return `id,
    		whisper_timestamp,
    		source,
    		destination,
    		content,
    		content_type,
    		username,
    		timestamp,
    		chat_id,
    		retry_count,
    		message_type,
    		message_status,
    		clock_value,
    		show,
    		seen,
    		outgoing_status,
		reply_to`
}

func (db sqlitePersistence) tableUserMessagesLegacyAllFieldsJoin() string {
	return `m1.id,
    		m1.whisper_timestamp,
    		m1.source,
    		m1.destination,
    		m1.content,
    		m1.content_type,
    		m1.username,
    		m1.timestamp,
    		m1.chat_id,
    		m1.retry_count,
    		m1.message_type,
    		m1.message_status,
    		m1.clock_value,
    		m1.show,
    		m1.seen,
    		m1.outgoing_status,
		m1.reply_to,
		m2.source,
		m2.content,
		c.alias,
		c.identicon`
}

func (db sqlitePersistence) tableUserMessagesLegacyAllFieldsCount() int {
	return strings.Count(db.tableUserMessagesLegacyAllFields(), ",") + 1
}

type scanner interface {
	Scan(dest ...interface{}) error
}

func (db sqlitePersistence) tableUserMessagesLegacyScanAllFields(row scanner, message *Message, others ...interface{}) error {
	var quotedContent sql.NullString
	var quotedFrom sql.NullString
	var alias sql.NullString
	var identicon sql.NullString
	args := []interface{}{
		&message.ID,
		&message.WhisperTimestamp,
		&message.From, // source in table
		&message.To,   // destination in table
		&message.Content,
		&message.ContentType,
		&message.Alias,
		&message.Timestamp,
		&message.ChatID,
		&message.RetryCount,
		&message.MessageType,
		&message.MessageStatus,
		&message.ClockValue,
		&message.Show,
		&message.Seen,
		&message.OutgoingStatus,
		&message.ReplyTo,
		&quotedFrom,
		&quotedContent,
		&alias,
		&identicon,
	}
	err := row.Scan(append(args, others...)...)
	if err != nil {
		return err
	}

	if quotedContent.Valid {
		message.QuotedMessage = &QuotedMessage{
			From:    quotedFrom.String,
			Content: quotedContent.String,
		}
	}
	message.Alias = alias.String
	message.Identicon = identicon.String

	return nil
}

func (db sqlitePersistence) tableUserMessagesLegacyAllValues(message *Message) []interface{} {
	return []interface{}{
		message.ID,
		message.WhisperTimestamp,
		message.From, // source in table
		message.To,   // destination in table
		message.Content,
		message.ContentType,
		message.Alias,
		message.Timestamp,
		message.ChatID,
		message.RetryCount,
		message.MessageType,
		message.MessageStatus,
		message.ClockValue,
		message.Show,
		message.Seen,
		message.OutgoingStatus,
		message.ReplyTo,
	}
}

func (db sqlitePersistence) MessageByID(id string) (*Message, error) {
	var message Message

	allFields := db.tableUserMessagesLegacyAllFieldsJoin()
	row := db.db.QueryRow(
		fmt.Sprintf(`
			SELECT
				%s
			FROM
				user_messages_legacy m1
			LEFT JOIN
				user_messages_legacy m2
			ON
			m1.reply_to = m2.id

			LEFT JOIN
			        contacts c
		        ON
			m1.source = c.id
			WHERE
				m1.id = ?
		`, allFields),
		id,
	)
	err := db.tableUserMessagesLegacyScanAllFields(row, &message)
	switch err {
	case sql.ErrNoRows:
		return nil, errRecordNotFound
	case nil:
		return &message, nil
	default:
		return nil, err
	}
}

func (db sqlitePersistence) MessagesExist(ids []string) (map[string]bool, error) {
	result := make(map[string]bool)
	if len(ids) == 0 {
		return result, nil
	}

	idsArgs := make([]interface{}, 0, len(ids))
	for _, id := range ids {
		idsArgs = append(idsArgs, id)
	}

	inVector := strings.Repeat("?, ", len(ids)-1) + "?"
	query := fmt.Sprintf(`SELECT id FROM user_messages_legacy WHERE id IN (%s)`, inVector)
	rows, err := db.db.Query(query, idsArgs...)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	for rows.Next() {
		var id string
		err := rows.Scan(&id)
		if err != nil {
			return nil, err
		}
		result[id] = true
	}

	return result, nil
}

// MessageByChatID returns all messages for a given chatID in descending order.
// Ordering is accomplished using two concatenated values: ClockValue and ID.
// These two values are also used to compose a cursor which is returned to the result.
func (db sqlitePersistence) MessageByChatID(chatID string, currCursor string, limit int) ([]*Message, string, error) {
	cursorWhere := ""
	if currCursor != "" {
		cursorWhere = "AND cursor <= ?"
	}
	allFields := db.tableUserMessagesLegacyAllFieldsJoin()
	args := []interface{}{chatID}
	if currCursor != "" {
		args = append(args, currCursor)
	}
	// Build a new column `cursor` at the query time by having a fixed-sized clock value at the beginning
	// concatenated with message ID. Results are sorted using this new column.
	// This new column values can also be returned as a cursor for subsequent requests.
	rows, err := db.db.Query(
		fmt.Sprintf(`
			SELECT
				%s,
				substr('0000000000000000000000000000000000000000000000000000000000000000' || m1.clock_value, -64, 64) || m1.id as cursor
			FROM
				user_messages_legacy m1
			LEFT JOIN
				user_messages_legacy m2
			ON
			m1.reply_to = m2.id

			LEFT JOIN
			      contacts c
			ON

			m1.source = c.id
			WHERE
				m1.chat_id = ? %s
			ORDER BY cursor DESC
			LIMIT ?
		`, allFields, cursorWhere),
		append(args, limit+1)..., // take one more to figure our whether a cursor should be returned
	)
	if err != nil {
		return nil, "", err
	}
	defer rows.Close()

	var (
		result  []*Message
		cursors []string
	)
	for rows.Next() {
		var (
			message Message
			cursor  string
		)
		if err := db.tableUserMessagesLegacyScanAllFields(rows, &message, &cursor); err != nil {
			return nil, "", err
		}
		result = append(result, &message)
		cursors = append(cursors, cursor)
	}

	var newCursor string
	if len(result) > limit {
		newCursor = cursors[limit]
		result = result[:limit]
	}
	return result, newCursor, nil
}

func (db sqlitePersistence) SaveMessagesLegacy(messages []*Message) (err error) {
	tx, err := db.db.BeginTx(context.Background(), &sql.TxOptions{})
	if err != nil {
		return
	}
	defer func() {
		if err == nil {
			err = tx.Commit()
			return
		}
		// don't shadow original error
		_ = tx.Rollback()
	}()

	allFields := db.tableUserMessagesLegacyAllFields()
	valuesVector := strings.Repeat("?, ", db.tableUserMessagesLegacyAllFieldsCount()-1) + "?"
	query := fmt.Sprintf(`INSERT INTO user_messages_legacy(%s) VALUES (%s)`, allFields, valuesVector)
	stmt, err := tx.Prepare(query)
	if err != nil {
		return
	}

	for _, msg := range messages {
		_, err = stmt.Exec(db.tableUserMessagesLegacyAllValues(msg)...)
		if err != nil {
			return
		}
	}
	return
}

func (db sqlitePersistence) DeleteMessage(id string) error {
	_, err := db.db.Exec(`DELETE FROM user_messages_legacy WHERE id = ?`, id)
	return err
}

func (db sqlitePersistence) DeleteMessagesByChatID(id string) error {
	_, err := db.db.Exec(`DELETE FROM user_messages_legacy WHERE chat_id = ?`, id)
	return err
}

func (db sqlitePersistence) MarkMessagesSeen(ids ...string) error {
	idsArgs := make([]interface{}, 0, len(ids))
	for _, id := range ids {
		idsArgs = append(idsArgs, id)
	}

	inVector := strings.Repeat("?, ", len(ids)-1) + "?"
	_, err := db.db.Exec(
		fmt.Sprintf(`
			UPDATE user_messages_legacy
			SET seen = 1
			WHERE id IN (%s)
		`, inVector),
		idsArgs...)
	return err
}

func (db sqlitePersistence) UpdateMessageOutgoingStatus(id string, newOutgoingStatus string) error {
	_, err := db.db.Exec(`
		UPDATE user_messages_legacy
		SET outgoing_status = ?
		WHERE id = ?
	`, newOutgoingStatus, id)
	return err
}

// BlockContact updates a contact, deletes all the messages and 1-to-1 chat, updates the unread messages count and returns a map with the new count
func (db sqlitePersistence) BlockContact(contact Contact) (chats []*Chat, err error) {
	tx, err := db.db.BeginTx(context.Background(), &sql.TxOptions{})
	if err != nil {
		return
	}
	defer func() {
		if err == nil {
			err = tx.Commit()
			return
		}
		// don't shadow original error
		_ = tx.Rollback()
	}()

	// Delete messages
	_, err = tx.Exec(
		`DELETE
		 FROM user_messages_legacy
		 WHERE source = ?`,
		contact.ID,
	)
	if err != nil {
		return
	}

	// Update contact
	err = db.SaveContact(contact, tx)
	if err != nil {
		return
	}

	// Delete one-to-one chat
	_, err = tx.Exec("DELETE FROM chats WHERE id = ?", contact.ID)
	if err != nil {
		return
	}

	// Recalculate denormalized fields
	_, err = tx.Exec(`
		UPDATE chats
		SET
			unviewed_message_count = (SELECT COUNT(1) FROM user_messages_legacy WHERE seen = 0 AND chat_id = chats.id),
			last_message_content = (SELECT content from user_messages_legacy WHERE chat_id = chats.id ORDER BY clock_value DESC LIMIT 1),
			last_message_timestamp = (SELECT timestamp from user_messages_legacy WHERE chat_id = chats.id ORDER BY clock_value DESC LIMIT 1),
			last_message_clock_value = (SELECT clock_value from user_messages_legacy WHERE chat_id = chats.id ORDER BY clock_value DESC LIMIT 1),
			last_message_content_type = (SELECT content_type from user_messages_legacy WHERE chat_id = chats.id ORDER BY clock_value DESC LIMIT 1)
	`)
	if err != nil {
		return
	}

	// return the updated chats
	chats, err = db.chats(tx)
	return
}