package routing

import (
	"context"
	"database/sql"
	"encoding/json"
	"errors"
	"fmt"
	"time"

	dbx "github.com/wangjia/pangolin/server/internal/db"
)

// Store wraps a *sql.DB and exposes the routing_profiles CRUD the routing
// package needs.
type Store struct {
	db      *sql.DB
	dialect dbx.Dialect
}

// NewStore creates a Store backed by the given connection pool (MySQL or SQLite).
func NewStore(db *sql.DB) *Store { return &Store{db: db, dialect: dbx.DialectForDB(db)} }

// Get returns the user's routing profile, or (nil, nil) if none is set yet
// (caller should fall back to Default()).
func (s *Store) Get(ctx context.Context, userID int64) (*Profile, error) {
	var raw string
	err := s.db.QueryRowContext(ctx,
		`SELECT profile_json FROM routing_profiles WHERE user_id = ?`, userID).Scan(&raw)
	if errors.Is(err, sql.ErrNoRows) {
		return nil, nil
	}
	if err != nil {
		return nil, fmt.Errorf("store.Get: %w", err)
	}
	var p Profile
	if err := json.Unmarshal([]byte(raw), &p); err != nil {
		return nil, fmt.Errorf("store.Get: unmarshal: %w", err)
	}
	return &p, nil
}

// Upsert creates or overwrites the user's routing profile.
func (s *Store) Upsert(ctx context.Context, userID int64, p *Profile) error {
	raw, err := json.Marshal(p)
	if err != nil {
		return fmt.Errorf("store.Upsert: marshal: %w", err)
	}
	now := time.Now().UTC()
	q := `INSERT INTO routing_profiles (user_id, profile_json, updated_at) VALUES (?,?,?) ` +
		s.dialect.Upsert([]string{"user_id"},
			"profile_json = EXCLUDED.profile_json", "updated_at = EXCLUDED.updated_at")
	if _, err := s.db.ExecContext(ctx, q, userID, string(raw), now); err != nil {
		return fmt.Errorf("store.Upsert: %w", err)
	}
	return nil
}