package store

import (
	"context"
	"database/sql"
	"errors"
	"fmt"
	"time"
)

// CreateEnrollmentToken persists a fresh one-time token. The caller
// has already hashed the raw token; the raw form is returned to the
// operator (printed in the install snippet) and never persisted.
//
// encRepoCreds is the AEAD-encrypted blob of {repo_url, repo_username,
// repo_password} that ConsumeEnrollmentToken will promote to a
// host_credentials row. Empty string = operator chose to set creds
// later via PUT /api/hosts/{id}/repo-credentials; the agent will
// refuse backup jobs until that lands.
func (s *Store) CreateEnrollmentToken(ctx context.Context, tokenHash string, ttl time.Duration, encRepoCreds string) error {
	now := time.Now().UTC()
	var enc any = nil
	if encRepoCreds != "" {
		enc = encRepoCreds
	}
	_, err := s.db.ExecContext(ctx,
		`INSERT INTO enrollment_tokens (token_hash, created_at, expires_at, enc_repo_creds)
		 VALUES (?, ?, ?, ?)`,
		tokenHash,
		now.Format(time.RFC3339Nano),
		now.Add(ttl).Format(time.RFC3339Nano),
		enc)
	if err != nil {
		return fmt.Errorf("store: create enrollment token: %w", err)
	}
	return nil
}

// ConsumeEnrollmentToken atomically validates a token (must exist,
// not be consumed, not be expired), marks it consumed by hostID, and
// — if the token carries encrypted repo creds — promotes them to a
// host_credentials row in the same tx. The encrypted blob is
// re-encrypted by the caller with host_id as additional data; we
// don't crack it open here.
//
// Returns ErrNotFound on any failure.
func (s *Store) ConsumeEnrollmentToken(ctx context.Context, tokenHash, hostID, encRepoCredsForHost string) error {
	now := time.Now().UTC().Format(time.RFC3339Nano)
	tx, err := s.db.BeginTx(ctx, nil)
	if err != nil {
		return fmt.Errorf("store: consume enrollment token: begin: %w", err)
	}
	defer func() { _ = tx.Rollback() }()

	res, err := tx.ExecContext(ctx,
		`UPDATE enrollment_tokens
		 SET consumed_at = ?, consumed_host = ?
		 WHERE token_hash = ? AND consumed_at IS NULL AND expires_at > ?`,
		now, hostID, tokenHash, now)
	if err != nil {
		return fmt.Errorf("store: consume enrollment token: %w", err)
	}
	n, _ := res.RowsAffected()
	if n == 0 {
		return ErrNotFound
	}

	if encRepoCredsForHost != "" {
		if _, err := tx.ExecContext(ctx,
			`INSERT INTO host_credentials (host_id, enc_repo_creds, updated_at)
			 VALUES (?, ?, ?)
			 ON CONFLICT(host_id) DO UPDATE SET
				enc_repo_creds = excluded.enc_repo_creds,
				updated_at     = excluded.updated_at`,
			hostID, encRepoCredsForHost, now); err != nil {
			return fmt.Errorf("store: promote host credentials: %w", err)
		}
	}

	if err := tx.Commit(); err != nil {
		return fmt.Errorf("store: consume enrollment token: commit: %w", err)
	}
	return nil
}

// GetEnrollmentTokenCreds returns the encrypted repo-creds blob the
// operator stashed when creating the token, or ("", ErrNotFound) if
// the token is gone / consumed / expired / had no creds attached.
//
// The caller decrypts using token_hash as the AEAD additional data,
// then re-encrypts using host_id as additional data before passing
// to ConsumeEnrollmentToken.
func (s *Store) GetEnrollmentTokenCreds(ctx context.Context, tokenHash string) (string, error) {
	now := time.Now().UTC().Format(time.RFC3339Nano)
	row := s.db.QueryRowContext(ctx,
		`SELECT enc_repo_creds FROM enrollment_tokens
		 WHERE token_hash = ? AND consumed_at IS NULL AND expires_at > ?`,
		tokenHash, now)
	var enc sql.NullString
	if err := row.Scan(&enc); err != nil {
		if errors.Is(err, sql.ErrNoRows) {
			return "", ErrNotFound
		}
		return "", fmt.Errorf("store: get enrollment token creds: %w", err)
	}
	if !enc.Valid {
		return "", nil
	}
	return enc.String, nil
}

// PurgeExpiredEnrollmentTokens deletes long-expired token rows. Tokens
// retained for ~24h after expiry so audit traces still resolve them.
func (s *Store) PurgeExpiredEnrollmentTokens(ctx context.Context) (int64, error) {
	cutoff := time.Now().Add(-24 * time.Hour).UTC().Format(time.RFC3339Nano)
	res, err := s.db.ExecContext(ctx,
		`DELETE FROM enrollment_tokens WHERE expires_at <= ?`, cutoff)
	if err != nil {
		return 0, fmt.Errorf("store: purge enrollment tokens: %w", err)
	}
	n, _ := res.RowsAffected()
	return n, nil
}