package secrets

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

	"github.com/google/uuid"
	"github.com/jmoiron/sqlx"
)

type sqliteStore struct {
	db     *sqlx.DB // writer
	ro     *sqlx.DB // reader
	crypto *MasterKeyProvider
	ownsDB bool
}

var _ SecretStore = (*sqliteStore)(nil)

// Provide creates the SQLite secret store using separate writer and reader pools.
func Provide(writer, reader *sqlx.DB, crypto *MasterKeyProvider) (*sqliteStore, func() error, error) {
	store := &sqliteStore{db: writer, ro: reader, crypto: crypto}
	if err := store.initSchema(); err != nil {
		return nil, nil, fmt.Errorf("secrets schema init: %w", err)
	}
	return store, store.Close, nil
}

func (s *sqliteStore) initSchema() error {
	schema := `
	CREATE TABLE IF NOT EXISTS secrets (
		id              TEXT PRIMARY KEY,
		name            TEXT NOT NULL,
		encrypted_value BLOB NOT NULL,
		nonce           BLOB NOT NULL,
		created_at      TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
		updated_at      TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP
	);
	`
	_, err := s.db.Exec(schema)
	return err
}

func (s *sqliteStore) Close() error {
	if !s.ownsDB {
		return nil
	}
	return s.db.Close()
}

func (s *sqliteStore) Create(ctx context.Context, secret *SecretWithValue) error {
	if secret.ID == "" {
		secret.ID = uuid.New().String()
	}
	now := time.Now().UTC()
	secret.CreatedAt = now
	secret.UpdatedAt = now

	ciphertext, nonce, err := Encrypt([]byte(secret.Value), s.crypto.Key())
	if err != nil {
		return fmt.Errorf("encrypt secret: %w", err)
	}

	_, err = s.db.ExecContext(ctx, `
		INSERT INTO secrets (id, name, encrypted_value, nonce, created_at, updated_at)
		VALUES (?, ?, ?, ?, ?, ?)`,
		secret.ID, secret.Name, ciphertext, nonce, now, now,
	)
	if err != nil {
		return fmt.Errorf("insert secret: %w", err)
	}
	return nil
}

func (s *sqliteStore) Get(ctx context.Context, id string) (*Secret, error) {
	var row secretRow
	err := s.ro.GetContext(ctx, &row, `
		SELECT id, name, created_at, updated_at
		FROM secrets WHERE id = ?`, id)
	if err != nil {
		if err == sql.ErrNoRows {
			return nil, fmt.Errorf("secret not found: %s", id)
		}
		return nil, fmt.Errorf("get secret: %w", err)
	}
	return row.toSecret(), nil
}

func (s *sqliteStore) Reveal(ctx context.Context, id string) (string, error) {
	var ciphertext, nonce []byte
	err := s.ro.QueryRowContext(ctx, `
		SELECT encrypted_value, nonce FROM secrets WHERE id = ?`, id).
		Scan(&ciphertext, &nonce)
	if err != nil {
		if err == sql.ErrNoRows {
			return "", fmt.Errorf("secret not found: %s", id)
		}
		return "", fmt.Errorf("reveal secret: %w", err)
	}

	plaintext, err := Decrypt(ciphertext, nonce, s.crypto.Key())
	if err != nil {
		return "", fmt.Errorf("decrypt secret: %w", err)
	}
	return string(plaintext), nil
}

func (s *sqliteStore) Update(ctx context.Context, id string, req *UpdateSecretRequest) error {
	existing, err := s.Get(ctx, id)
	if err != nil {
		return err
	}

	now := time.Now().UTC()

	if req.Name != nil {
		existing.Name = *req.Name
	}

	if req.Value != nil {
		ciphertext, nonce, err := Encrypt([]byte(*req.Value), s.crypto.Key())
		if err != nil {
			return fmt.Errorf("encrypt secret: %w", err)
		}
		_, err = s.db.ExecContext(ctx, `
			UPDATE secrets SET name = ?, encrypted_value = ?, nonce = ?, updated_at = ?
			WHERE id = ?`,
			existing.Name, ciphertext, nonce, now, id,
		)
		if err != nil {
			return fmt.Errorf("update secret: %w", err)
		}
	} else {
		_, err = s.db.ExecContext(ctx, `
			UPDATE secrets SET name = ?, updated_at = ?
			WHERE id = ?`,
			existing.Name, now, id,
		)
		if err != nil {
			return fmt.Errorf("update secret: %w", err)
		}
	}
	return nil
}

func (s *sqliteStore) Delete(ctx context.Context, id string) error {
	result, err := s.db.ExecContext(ctx, `DELETE FROM secrets WHERE id = ?`, id)
	if err != nil {
		return fmt.Errorf("delete secret: %w", err)
	}
	rows, _ := result.RowsAffected()
	if rows == 0 {
		return fmt.Errorf("secret not found: %s", id)
	}
	return nil
}

func (s *sqliteStore) List(ctx context.Context) ([]*SecretListItem, error) {
	var rows []secretListRow
	err := s.ro.SelectContext(ctx, &rows, `
		SELECT id, name, 1 as has_value, created_at, updated_at
		FROM secrets ORDER BY created_at DESC`)
	if err != nil {
		return nil, fmt.Errorf("list secrets: %w", err)
	}
	return toSecretListItems(rows), nil
}

// secretRow is the DB scan target for secret metadata queries.
type secretRow struct {
	ID        string    `db:"id"`
	Name      string    `db:"name"`
	CreatedAt time.Time `db:"created_at"`
	UpdatedAt time.Time `db:"updated_at"`
}

func (r *secretRow) toSecret() *Secret {
	return &Secret{
		ID:        r.ID,
		Name:      r.Name,
		CreatedAt: r.CreatedAt,
		UpdatedAt: r.UpdatedAt,
	}
}

// secretListRow is the DB scan target for list queries.
type secretListRow struct {
	ID        string    `db:"id"`
	Name      string    `db:"name"`
	HasValue  bool      `db:"has_value"`
	CreatedAt time.Time `db:"created_at"`
	UpdatedAt time.Time `db:"updated_at"`
}

func toSecretListItems(rows []secretListRow) []*SecretListItem {
	items := make([]*SecretListItem, len(rows))
	for i, r := range rows {
		items[i] = &SecretListItem{
			ID:        r.ID,
			Name:      r.Name,
			HasValue:  r.HasValue,
			CreatedAt: r.CreatedAt,
			UpdatedAt: r.UpdatedAt,
		}
	}
	return items
}