package postgres

import (
	"context"
	"crypto/rand"
	"errors"

	"github.com/jackc/pgx/v5"
	"github.com/jackc/pgx/v5/pgxpool"

	"github.com/snip/backend/internal/domain"
)

type UserRepo struct{ pool *pgxpool.Pool }

func NewUserRepo(pool *pgxpool.Pool) *UserRepo { return &UserRepo{pool: pool} }

func (r *UserRepo) Upsert(ctx context.Context, u *domain.User) (*domain.User, error) {
	id := newUserID()
	var out domain.User
	err := r.pool.QueryRow(ctx,
		`INSERT INTO users (id, email, name, provider, subject)
		 VALUES ($1,$2,$3,$4,$5)
		 ON CONFLICT (provider, subject)
		 DO UPDATE SET email = EXCLUDED.email, name = EXCLUDED.name
		 RETURNING id, email, name, provider, subject`,
		id, u.Email, u.Name, u.Provider, u.Subject).
		Scan(&out.ID, &out.Email, &out.Name, &out.Provider, &out.Subject)
	if err != nil {
		return nil, err
	}
	return &out, nil
}

func (r *UserRepo) GetByID(ctx context.Context, id string) (*domain.User, error) {
	var u domain.User
	err := r.pool.QueryRow(ctx,
		`SELECT id, email, name, provider, subject FROM users WHERE id=$1`, id).
		Scan(&u.ID, &u.Email, &u.Name, &u.Provider, &u.Subject)
	if errors.Is(err, pgx.ErrNoRows) {
		return nil, domain.ErrNotFound
	}
	if err != nil {
		return nil, err
	}
	return &u, nil
}

func newUserID() string {
	const hex = "0123456789abcdef"
	b := make([]byte, 16)
	_, _ = rand.Read(b)
	out := make([]byte, 16)
	for i := range out {
		out[i] = hex[int(b[i])%16]
	}
	return "u_" + string(out)
}