Production-Grade Passport OCR API for C#

using System;
using System.IO;
using System.Net.Http;
using System.Net.Http.Json;
using System.Text.Json;
using System.Text.Json.Serialization;
using System.Threading.Tasks;

public class PassportOcrExample
{
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    private const string ApiKey = "YOUR_API_KEY_HERE";
    private const string ApiEndpoint = "https://api.structocr.com/v1/passport";

    private static readonly HttpClient client = new HttpClient();

    public static async Task Main(string[] args)
    {
        // Note: Supports JPG, PNG, WebP (Max 4.5MB)
        string imagePath = "passport.jpg";

        if (!File.Exists(imagePath))
        {
            Console.WriteLine($"Error: File not found at {imagePath}");
            return;
        }

        try
        {
            // 1. Prepare Payload
            byte[] imageBytes = await File.ReadAllBytesAsync(imagePath);
            string base64Image = Convert.ToBase64String(imageBytes);
            var payload = new { img = base64Image };

            // 2. Setup Request
            client.DefaultRequestHeaders.Clear();
            client.DefaultRequestHeaders.Add("x-api-key", ApiKey); // Required Header

            // 3. Send POST Request
            Console.WriteLine($"Scanning passport at {ApiEndpoint}...");
            HttpResponseMessage response = await client.PostAsJsonAsync(ApiEndpoint, payload);

            // 4. Handle Response
            string responseBody = await response.Content.ReadAsStringAsync();

            if (!response.IsSuccessStatusCode)
            {
                Console.WriteLine($"API Error ({response.StatusCode}): {responseBody}");
                return;
            }

            // 5. Deserialize to Object
            var options = new JsonSerializerOptions { PropertyNameCaseInsensitive = true };
            var result = JsonSerializer.Deserialize<ApiResponse>(responseBody, options);

            if (result?.Success == true && result.Data != null)
            {
                var data = result.Data;
                Console.WriteLine("✅ Extraction Successful!");
                
                // Identity Data
                Console.WriteLine($"Passport #: {data.PassportNumber}");
                Console.WriteLine($"Name:       {data.GivenNames} {data.Surname}");
                Console.WriteLine($"Nation:     {data.Nationality} ({data.CountryCode})");

                // Visual Zone Data (Unique to StructOCR)
                Console.WriteLine($"Birth Place:{data.PlaceOfBirth}");
                Console.WriteLine($"Issued At:  {data.PlaceOfIssue}");
                
                // Dates
                Console.WriteLine($"DOB:        {data.DateOfBirth} ({data.Sex})");
                Console.WriteLine($"Expiry:     {data.DateOfExpiry}");
            }
            else
            {
                Console.WriteLine($"Extraction Failed: {result?.Error}");
            }
        }
        catch (Exception e)
        {
            Console.WriteLine($"Unexpected Error: {e.Message}");
        }
    }
}

// --- Data Models matching the Schema ---
public class ApiResponse
{
    public bool Success { get; set; }
    public PassportData Data { get; set; }
    public string Error { get; set; }
}

public class PassportData
{
    [JsonPropertyName("passport_number")]
    public string PassportNumber { get; set; }
    
    public string Surname { get; set; }
    
    [JsonPropertyName("given_names")]
    public string GivenNames { get; set; }
    
    public string Nationality { get; set; }
    
    [JsonPropertyName("country_code")]
    public string CountryCode { get; set; }
    
    [JsonPropertyName("date_of_birth")]
    public string DateOfBirth { get; set; }
    
    public string Sex { get; set; }
    
    [JsonPropertyName("date_of_expiry")]
    public string DateOfExpiry { get; set; }

    // VIZ Fields (Visual Inspection Zone)
    [JsonPropertyName("place_of_birth")]
    public string PlaceOfBirth { get; set; }
    
    [JsonPropertyName("place_of_issue")]
    public string PlaceOfIssue { get; set; }
}