package storage

import (
	"context"
	"errors"
	"time"

	"github.com/google/uuid"
	"github.com/jackc/pgx/v5"
	"github.com/jackc/pgx/v5/pgconn"
	"github.com/jackc/pgx/v5/pgxpool"

	"github.com/alchemistkay/guestguard/internal/domain"
)

type TokenRepo struct {
	pool *pgxpool.Pool
}

func NewTokenRepo(db *DB) *TokenRepo {
	return &TokenRepo{pool: db.Pool}
}

type CreateTokenParams struct {
	GuestID   uuid.UUID
	TokenHash string
	ExpiresAt time.Time
}

func (r *TokenRepo) Create(ctx context.Context, p CreateTokenParams) (*domain.Token, error) {
	const q = `
        INSERT INTO tokens (guest_id, token_hash, expires_at, status)
        VALUES ($1, $2, $3, 'active')
        RETURNING id, guest_id, token_hash, expires_at, status, used_at, created_at
    `
	row := r.pool.QueryRow(ctx, q, p.GuestID, p.TokenHash, p.ExpiresAt)
	tk, err := scanToken(row)
	if err != nil {
		var pgErr *pgconn.PgError
		if errors.As(err, &pgErr) && pgErr.Code == "23505" {
			return nil, errors.New("guest already has a token")
		}
		return nil, err
	}
	return tk, nil
}

func (r *TokenRepo) GetByHash(ctx context.Context, hash string) (*domain.Token, error) {
	const q = `
        SELECT id, guest_id, token_hash, expires_at, status, used_at, created_at
        FROM tokens WHERE token_hash = $1
    `
	tk, err := scanToken(r.pool.QueryRow(ctx, q, hash))
	if err != nil {
		if errors.Is(err, pgx.ErrNoRows) {
			return nil, domain.ErrTokenNotFound
		}
		return nil, err
	}
	return tk, nil
}

// RotateForGuest replaces the guest's existing token with a freshly-minted
// one in a single transaction. The old token row is hard-deleted (the
// guests.id UNIQUE constraint requires it, and "the old link must stop
// working" is the point). Cascade-deletes the old access_logs rows that
// reference it via the token_id FK with ON DELETE SET NULL — those rows
// stay, with token_id nulled.
func (r *TokenRepo) RotateForGuest(ctx context.Context, p CreateTokenParams) (*domain.Token, error) {
	tx, err := r.pool.Begin(ctx)
	if err != nil {
		return nil, err
	}
	defer tx.Rollback(ctx)

	if _, err := tx.Exec(ctx, `DELETE FROM tokens WHERE guest_id = $1`, p.GuestID); err != nil {
		return nil, err
	}
	const q = `
        INSERT INTO tokens (guest_id, token_hash, expires_at, status)
        VALUES ($1, $2, $3, 'active')
        RETURNING id, guest_id, token_hash, expires_at, status, used_at, created_at
    `
	row := tx.QueryRow(ctx, q, p.GuestID, p.TokenHash, p.ExpiresAt)
	tk, err := scanToken(row)
	if err != nil {
		return nil, err
	}
	if err := tx.Commit(ctx); err != nil {
		return nil, err
	}
	return tk, nil
}

func (r *TokenRepo) MarkUsed(ctx context.Context, id uuid.UUID) error {
	tag, err := r.pool.Exec(ctx, `
        UPDATE tokens SET status = 'used', used_at = now()
        WHERE id = $1 AND status = 'active'
    `, id)
	if err != nil {
		return err
	}
	if tag.RowsAffected() == 0 {
		return domain.ErrTokenNotFound
	}
	return nil
}

func scanToken(s rowScanner) (*domain.Token, error) {
	var tk domain.Token
	err := s.Scan(
		&tk.ID, &tk.GuestID, &tk.TokenHash, &tk.ExpiresAt,
		&tk.Status, &tk.UsedAt, &tk.CreatedAt,
	)
	if err != nil {
		return nil, err
	}
	return &tk, nil
}