package services

import (
	"database/sql"
	"errors"

	"go-sjles-pta-vote/server/db"
	"go-sjles-pta-vote/server/models"
)

var ErrQuestionAlreadyExists = errors.New("Question already exists")
var ErrQuestionDoesntExist = errors.New("Question does not exist yet")

func CreatePoll(poll *models.Poll) (*models.Poll, error) {
	new_poll := models.Poll{}

	db_conn, err := db.Connect()
	if err != nil {
		return nil, err
	}
	defer db.Close()

	get_stmt, err := db_conn.Prepare(`
		SELECT id 
			FROM polls 
			WHERE question == $1
	`)
	if err != nil {
		return nil, err
	}
	defer get_stmt.Close()

	var id int
	err = get_stmt.QueryRow(poll.Question).Scan(&id)
	if err != sql.ErrNoRows {
		if err != nil {
			return nil, err
		}
		return nil, ErrQuestionAlreadyExists
	}
	
	stmt, err := db_conn.Prepare(`
		INSERT INTO polls (
			question,
			expires_at
		) VALUES (
		 	$1,
			$2
		) RETURNING ID;
	`)

	if err != nil {
		return nil, err
	}

	defer stmt.Close()

	res, err := stmt.Exec(poll.Question, poll.ExpiresAt)
	if err != nil {
		return nil, err
	}

	new_poll.ID, err = res.LastInsertId()
	
	return &new_poll, err
}

func GetPollByQuestion(question string) (*models.Poll, error) {
	new_poll := models.Poll{}

	db_conn, err := db.Connect()
	if err != nil {
		return nil, err
	}
	defer db.Close()

	get_poll_stmt, err := db_conn.Prepare(`
		SELECT 
			id, question, 
			member_yes_votes, member_no_votes,
			non_member_yes_votes, non_member_no_votes,
			created_at, updated_at,
			expires_at
		FROM polls 
		WHERE question == $1
	`)
	if err != nil {
		return nil, err
	}
	defer get_poll_stmt.Close()

	err = get_poll_stmt.QueryRow(question).Scan(
		&new_poll.ID, &new_poll.Question,
		&new_poll.MemberYes, &new_poll.MemberNo,
		&new_poll.NonMemberYes, &new_poll.NonMemberNo,
		&new_poll.CreatedAt, &new_poll.UpdatedAt,
		&new_poll.ExpiresAt,
	)

	if err == sql.ErrNoRows {
		return nil, ErrQuestionDoesntExist
	} else if err != nil {
		return nil, err
	}

	get_voters_stmt, err := db_conn.Prepare (`
		SELECT voter_email 
		FROM voters
		WHERE poll_id == $1
	`)
	if err != nil {
		return nil, err
	}
	defer get_voters_stmt.Close()

	rows, err := get_voters_stmt.Query(new_poll.ID)

	for rows.Next() {
		var voter_email string
		err = rows.Scan(&voter_email)
		if err != nil {
			return nil, err
		}
		new_poll.WhoVoted = append(new_poll.WhoVoted, voter_email)
	}

	return &new_poll, nil
}