package repository

import (
	"context"
	"errors"
	"git.sch9.ru/new_gate/ms-tester/internal/models"
	"git.sch9.ru/new_gate/ms-tester/pkg/utils"
	"github.com/jackc/pgerrcode"
	"github.com/jackc/pgx/v5/pgconn"
	"github.com/jmoiron/sqlx"
	"go.uber.org/zap"
)

type ContestRepository struct {
	db     *sqlx.DB
	logger *zap.Logger
}

func NewContestRepository(db *sqlx.DB, logger *zap.Logger) *ContestRepository {
	return &ContestRepository{
		db:     db,
		logger: logger,
	}
}

const createContestQuery = "INSERT INTO contest (title) VALUES (?) RETURNING id"

func (r *ContestRepository) CreateContest(ctx context.Context, title string) (int32, error) {
	query := r.db.Rebind(createContestQuery)

	rows, err := r.db.QueryxContext(ctx, query, title)
	if err != nil {
		return 0, handlePgErr(err)
	}

	defer rows.Close()
	var id int32
	rows.Next()
	err = rows.Scan(&id)
	if err != nil {
		return 0, handlePgErr(err)
	}

	return id, nil
}

const readContestByIdQuery = "SELECT * from contest WHERE id=? LIMIT 1"

func (r *ContestRepository) ReadContestById(ctx context.Context, id int32) (*models.Contest, error) {
	var contest models.Contest
	query := r.db.Rebind(readContestByIdQuery)
	err := r.db.GetContext(ctx, &contest, query, id)
	if err != nil {
		return nil, handlePgErr(err)
	}
	return &contest, nil
}

const deleteContestQuery = "DELETE FROM contest WHERE id=?"

func (r *ContestRepository) DeleteContest(ctx context.Context, id int32) error {
	query := r.db.Rebind(deleteContestQuery)
	_, err := r.db.ExecContext(ctx, query, id)
	if err != nil {
		return handlePgErr(err)
	}

	return nil
}

const addTaskQuery = "INSERT INTO task (problem_id, contest_id, position) VALUES (?, ?,COALESCE(SELECT MAX(position) FROM task WHERE contest_id = ? ,0) + 1) RETURNING id"

func (r *ContestRepository) AddTask(ctx context.Context, contestId int32, problem_id int32) (int32, error) {
	query := r.db.Rebind(addTaskQuery)
	rows, err := r.db.QueryxContext(ctx, query, problem_id, contestId, contestId)
	if err != nil {
		return 0, handlePgErr(err)
	}
	defer rows.Close()
	var id int32
	rows.Next()
	err = rows.Scan(&id)
	if err != nil {
		return 0, handlePgErr(err)
	}
	return id, nil
}

const deleteTaskQuery = "DELETE FROM task WHERE id=?"

func (r *ContestRepository) DeleteTask(ctx context.Context, taskId int32) error {
	query := r.db.Rebind(deleteTaskQuery)
	_, err := r.db.ExecContext(ctx, query, taskId)
	if err != nil {
		return handlePgErr(err)
	}
	return nil
}

const addParticipantQuery = "INSERT INTO participant (user_id ,contest_id, name) VALUES (?, ?, ?) RETURNING id"

func (r *ContestRepository) AddParticipant(ctx context.Context, contestId int32, userId int32) (int32, error) {
	query := r.db.Rebind(addParticipantQuery)
	name := ""
	rows, err := r.db.QueryxContext(ctx, query, contestId, userId, name)
	if err != nil {
		return 0, handlePgErr(err)
	}
	defer rows.Close()
	var id int32
	rows.Next()
	err = rows.Scan(&id)
	if err != nil {
		return 0, err
	}
	return id, nil
}

const deleteParticipantQuery = "DELETE FROM participant WHERE id=?"

func (r *ContestRepository) DeleteParticipant(ctx context.Context, participantId int32) error {
	query := r.db.Rebind(deleteParticipantQuery)
	_, err := r.db.ExecContext(ctx, query, participantId)
	if err != nil {
		return handlePgErr(err)
	}
	return nil
}

func handlePgErr(err error) error {
	var pgErr *pgconn.PgError
	if !errors.As(err, &pgErr) {
		return utils.StorageError(err, utils.ErrUnknown, "unexpected error from postgres")
	}
	if pgerrcode.IsIntegrityConstraintViolation(pgErr.Code) {
		// TODO: probably should specify which constraint
		return utils.StorageError(err, utils.ErrConflict, pgErr.Message)
	}
	if pgerrcode.IsNoData(pgErr.Code) {
		return utils.StorageError(err, utils.ErrNotFound, pgErr.Message)
	}
	return utils.StorageError(err, utils.ErrUnimplemented, "unimplemented error")
}