/*
 *  Copyright (c) 2024 Your Name / Yggmail Contributor
 *  (Original Copyright (c) 2021 Neil Alexander)
 *
 *  This Source Code Form is subject to the terms of the Mozilla Public
 *  License, v. 2.0. If a copy of the MPL was not distributed with this
 *  file, You can obtain one at http://mozilla.org/MPL/2.0/.
 */

package sqlite3

import (
	"database/sql"
	"fmt"

	"github.com/neilalexander/yggmail/internal/storage/types"
)

type TableQueue struct {
	db                              *sql.DB
	writer                          *Writer
	queueSelectDestinations         *sql.Stmt
	queueSelectIDsForDestination    *sql.Stmt
	queueInsertDestinationForID     *sql.Stmt
	queueDeleteIDForDestination     *sql.Stmt
	queueSelectIsMessagePendingSend *sql.Stmt
}

const queueSchema = `
	CREATE TABLE IF NOT EXISTS queue (
		account_pubkey TEXT NOT NULL,
		destination    TEXT NOT NULL,
		mailbox        TEXT NOT NULL DEFAULT 'Outbox',
		id             INTEGER NOT NULL,
		mail           TEXT NOT NULL, -- Это поле From в оригинале
		rcpt           TEXT NOT NULL,
		PRIMARY KEY (account_pubkey, destination, mailbox, id),
		FOREIGN KEY (account_pubkey, mailbox, id) REFERENCES mails(account_pubkey, mailbox, id) ON DELETE CASCADE ON UPDATE CASCADE
	);
`

const queueSelectDestinationsStmt = `
	SELECT DISTINCT destination FROM queue
`

const queueSelectIDsForDestinationStmt = `
	SELECT account_pubkey, id, mail, rcpt FROM queue WHERE destination = $1
	ORDER BY id DESC
`

const queueInsertDestinationForIDStmt = `
	INSERT INTO queue (account_pubkey, destination, mailbox, id, mail, rcpt) VALUES($1, $2, $3, $4, $5, $6)
`

const deleteDestinationForIDStmt = `
    DELETE FROM queue WHERE account_pubkey = $1 AND destination = $2 AND mailbox = $3 AND id = $4
`

const queueSelectIsMessagePendingSendStmt = `
	SELECT COUNT(*) FROM queue WHERE account_pubkey = $1 AND mailbox = $2 AND id = $3
`

func NewTableQueue(db *sql.DB, writer *Writer) (*TableQueue, error) {
	t := &TableQueue{
		db:     db,
		writer: writer,
	}
	_, err := db.Exec(queueSchema)
	if err != nil {
		return nil, fmt.Errorf("db.Exec: %w", err)
	}
	t.queueSelectDestinations, err = db.Prepare(queueSelectDestinationsStmt)
	if err != nil {
		return nil, fmt.Errorf("db.Prepare(queueSelectDestinationsStmt): %w", err)
	}
	t.queueSelectIDsForDestination, err = db.Prepare(queueSelectIDsForDestinationStmt)
	if err != nil {
		return nil, fmt.Errorf("db.Prepare(queueSelectIDsForDestinationStmt): %w", err)
	}
	t.queueInsertDestinationForID, err = db.Prepare(queueInsertDestinationForIDStmt)
	if err != nil {
		return nil, fmt.Errorf("db.Prepare(queueInsertDestinationForIDStmt): %w", err)
	}
	t.queueDeleteIDForDestination, err = db.Prepare(deleteDestinationForIDStmt)
	if err != nil {
		return nil, fmt.Errorf("db.Prepare(deleteDestinationForIDStmt): %w", err)
	}
	t.queueSelectIsMessagePendingSend, err = db.Prepare(queueSelectIsMessagePendingSendStmt)
	if err != nil {
		return nil, fmt.Errorf("db.Prepare(queueSelectIsMessagePendingSendStmt): %w", err)
	}
	return t, nil
}

func (t *TableQueue) QueueListDestinations() ([]string, error) {
	rows, err := t.queueSelectDestinations.Query()
	if err != nil {
		if err == sql.ErrNoRows {
			return nil, nil
		}
		return nil, fmt.Errorf("t.queueSelectDestinations.Query: %w", err)
	}
	defer rows.Close()
	var destinations []string
	for rows.Next() {
		var destination string
		if err := rows.Scan(&destination); err != nil {
			return nil, fmt.Errorf("rows.Scan: %w", err)
		}
		destinations = append(destinations, destination)
	}
	return destinations, nil
}

func (t *TableQueue) QueueMailIDsForDestination(destination string) ([]types.QueuedMail, error) {
	rows, err := t.queueSelectIDsForDestination.Query(destination)
	if err != nil {
		if err == sql.ErrNoRows {
			return nil, nil
		}
		return nil, fmt.Errorf("t.queueSelectIDsForDestination.Query: %w", err)
	}
	defer rows.Close()

	var ids []types.QueuedMail
	for rows.Next() {
		var aPk string
		var id int
		var from, rcpt string
		if err := rows.Scan(&aPk, &id, &from, &rcpt); err != nil {
			return nil, fmt.Errorf("rows.Scan: %w", err)
		}
		ids = append(ids, types.QueuedMail{
			AccountPubKey: aPk,
			ID:            id,
			From:          from,
			Rcpt:          rcpt,
		})
	}
	return ids, nil
}

func (t *TableQueue) QueueInsertDestinationForID(pk string, destination string, id int, from, rcpt string) error {
	return t.writer.Do(t.db, nil, func(txn *sql.Tx) error {
		_, err := t.queueInsertDestinationForID.Exec(pk, destination, "Outbox", id, from, rcpt)
		return err
	})
}

func (t *TableQueue) QueueDeleteDestinationForID(pk string, destination string, id int) error {
	return t.writer.Do(t.db, nil, func(txn *sql.Tx) error {
		_, err := t.queueDeleteIDForDestination.Exec(pk, destination, "Outbox", id)
		return err
	})
}

func (t *TableQueue) QueueSelectIsMessagePendingSend(pk string, mailbox string, id int) (bool, error) {
	row := t.queueSelectIsMessagePendingSend.QueryRow(pk, mailbox, id)
	var count int
	if err := row.Scan(&count); err != nil {
		if err == sql.ErrNoRows {
			return false, nil
		}
		return false, fmt.Errorf("row.Scan: %w", err)
	}
	return count > 0, nil
}