EnvelopeGenerator/EnvelopeGenerator.API/Controllers/CacheController.cs

using Microsoft.AspNetCore.Authorization;
using Microsoft.AspNetCore.Mvc;
using Microsoft.Extensions.Caching.Distributed;
using Microsoft.Extensions.Options;
using System.Text.Json;
using EnvelopeGenerator.API.Options;
using EnvelopeGenerator.Domain.Constants;
using EnvelopeGenerator.API.Extensions;

namespace EnvelopeGenerator.API.Controllers;

/// <summary>
/// Manages cached data for receivers using distributed cache.
/// </summary>
[ApiController]
[Route("api/[controller]")]
[Authorize(Policy = AuthPolicy.Receiver)]
public class CacheController(
    IDistributedCache cache,
    IOptions<CacheOptions> cacheOptions) : ControllerBase
{
    private const string SignatureCacheKeyPrefix = "envelope-generator.receiver-ui.signature:";

    /// <summary>
    /// Stores a receiver's signature in cache for the specified envelope.
    /// </summary>
    [Authorize(Policy = AuthPolicy.Receiver)]
    [HttpPost("SignatureCapture/{envelopeKey}")]
    public async Task<IActionResult> SaveSignature(
        [FromRoute] string envelopeKey,
        [FromBody] SignatureCacheRequest request,
        CancellationToken cancel)
    {
        var cacheKey = $"{SignatureCacheKeyPrefix}{User.ReceiverSignature}";
        var json = JsonSerializer.Serialize(request);
        
        var options = cacheOptions.Value.SignatureCacheExpiration.HasValue
            ? new DistributedCacheEntryOptions { AbsoluteExpirationRelativeToNow = cacheOptions.Value.SignatureCacheExpiration.Value }
            : null;

        await cache.SetStringAsync(cacheKey, json, options ?? new DistributedCacheEntryOptions(), cancel);

        return Ok();
    }

    /// <summary>
    /// Retrieves a cached signature for the specified envelope.
    /// </summary>
    [Authorize(Policy = AuthPolicy.Receiver)]
    [HttpGet("SignatureCapture/{envelopeKey}")]
    public async Task<IActionResult> GetSignature([FromRoute] string envelopeKey, CancellationToken cancel)
    {
        var cacheKey = $"{SignatureCacheKeyPrefix}{User.ReceiverSignature}";
        var json = await cache.GetStringAsync(cacheKey, cancel);

        if (json is null)
            return NotFound();

        var signature = JsonSerializer.Deserialize<SignatureCacheRequest>(json);
        return Ok(signature);
    }

    /// <summary>
    /// Deletes a cached signature for the specified envelope.
    /// </summary>
    [Authorize(Policy = AuthPolicy.Receiver)]
    [HttpDelete("SignatureCapture/{envelopeKey}")]
    public async Task<IActionResult> DeleteSignature([FromRoute] string envelopeKey, CancellationToken cancel)
    {
        var cacheKey = $"{SignatureCacheKeyPrefix}{User.ReceiverSignature}";
        await cache.RemoveAsync(cacheKey, cancel);

        return Ok();
    }
}

/// <summary>
/// Request model for caching signature data.
/// </summary>
public sealed record SignatureCacheRequest(
    string DataUrl,
    string FullName,
    string Place,
    string? Position = null);