PayPal Configuration

"Mode": "sandbox"

"ClientId": "Ab76A0qILXO-h6926is0lH2xuGAPMB_ZglqXBhNY..."

"ClientSecret": "EM-X5J8ka4gstL8McLxh69ZRZFY_QWrNmFyIyorv..."

"BaseUrl": "https://api-m.sandbox.paypal.com"

public class PaypalService : IPaypalService
{
    private readonly HttpClient _httpClient;
    private readonly PaypalOptions _options;

    public PaypalService(HttpClient httpClient, IOptions<PaypalOptions> options)
    {
        _httpClient = httpClient;
        _options = options.Value;
    }

    // 1. Get OAuth access token
    public async Task<string> GetAccessTokenAsync()
    {
        var auth = Convert.ToBase64String(
            Encoding.UTF8.GetBytes($"{_options.ClientId}:{_options.ClientSecret}")
        );

        var request = new HttpRequestMessage(HttpMethod.Post, $"{_options.BaseUrl}/v1/oauth2/token")
        {
            Headers = { { "Authorization", $"Basic {auth}" } },
            Content = new FormUrlEncodedContent(new[] {
                new KeyValuePair<string, string>("grant_type", "client_credentials")
            })
        };

        var response = await _httpClient.SendAsync(request);
        var json = await response.Content.ReadAsStringAsync();
        var tokenResponse = JsonSerializer.Deserialize<TokenResponse>(json);
        return tokenResponse.AccessToken;
    }

    // 2. Create order
    public async Task<string> CreateOrderAsync(decimal amount, string currency = "USD")
    {
        var token = await GetAccessTokenAsync();
        
        var orderRequest = new
        {
            intent = "CAPTURE",
            purchase_units = new[]
            {
                new
                {
                    amount = new
                    {
                        currency_code = currency,
                        value = amount.ToString("F2")
                    }
                }
            }
        };

        var request = new HttpRequestMessage(HttpMethod.Post, $"{_options.BaseUrl}/v2/checkout/orders")
        {
            Headers = { { "Authorization", $"Bearer {token}" } },
            Content = new StringContent(
                JsonSerializer.Serialize(orderRequest),
                Encoding.UTF8,
                "application/json"
            )
        };

        var response = await _httpClient.SendAsync(request);
        var json = await response.Content.ReadAsStringAsync();
        var order = JsonSerializer.Deserialize<PayPalOrder>(json);
        return order.Id;
    }

    // 3. Capture payment
    public async Task<bool> CaptureOrderAsync(string orderId)
    {
        var token = await GetAccessTokenAsync();

        var request = new HttpRequestMessage(
            HttpMethod.Post,
            $"{_options.BaseUrl}/v2/checkout/orders/{orderId}/capture"
        )
        {
            Headers = { { "Authorization", $"Bearer {token}" } }
        };

        var response = await _httpClient.SendAsync(request);
        return response.IsSuccessStatusCode;
    }
}