Initial import into Gitea
This commit is contained in:
Grae Jones
414
Creative/Services/ImageGeneratorService.cs
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414
Creative/Services/ImageGeneratorService.cs
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using System.Text;
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using System.Text.Json;
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using Creative.Configuration;
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using Creative.Models;
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using Microsoft.Extensions.Options;
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namespace Creative.Services;
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/// <summary>
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/// Sources images for campaign drafts.
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/// Three providers:
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/// - emulated: placeholder images (no network calls)
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/// - unsplash: free stock photos via Unsplash API
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/// - dalle: AI-generated images via OpenAI DALL-E (requires OpenAI key)
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///
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/// Google Ads Responsive Display Ad image specs:
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/// Landscape (1.91:1): 1200×628 recommended
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/// Square (1:1): 1200×1200 recommended
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/// Portrait (4:5): 960×1200 recommended (optional)
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/// </summary>
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public class ImageGeneratorService
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{
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private readonly CreativeConfig _config;
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private readonly IHttpClientFactory _httpFactory;
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private readonly ILogger<ImageGeneratorService> _logger;
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public ImageGeneratorService(
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IOptions<CreativeConfig> config,
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IHttpClientFactory httpFactory,
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ILogger<ImageGeneratorService> logger)
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{
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_config = config.Value;
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_httpFactory = httpFactory;
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_logger = logger;
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}
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/// <summary>
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/// Get images matching the analyzed content.
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/// Returns a list of ImageAssets and the provider name used.
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/// </summary>
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public async Task<(List<ImageAsset> Images, string Source)>
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GenerateAsync(UrlAnalysis analysis, CancellationToken ct)
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{
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var provider = (_config.ImageProvider ?? "emulated").ToLowerInvariant();
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_logger.LogInformation("[ImageGen] Provider={Provider} for {Url}", provider, analysis.Url);
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return provider switch
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{
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"unsplash" => await GenerateUnsplashAsync(analysis, ct),
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"dalle" => await GenerateDalleAsync(analysis, ct),
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_ => EmulateGeneration(analysis)
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};
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}
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// ============================================================
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// Emulated Provider
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// ============================================================
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private (List<ImageAsset>, string) EmulateGeneration(UrlAnalysis analysis)
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{
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_logger.LogInformation("[ImageGen] Emulated images for {Url}", analysis.Url);
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var keyword = ExtractSearchKeyword(analysis);
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var images = new List<ImageAsset>
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{
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new()
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{
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ImageId = $"emu-landscape-{Guid.NewGuid():N}"[..20],
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Url = $"https://placehold.co/1200x628/0066cc/ffffff?text={Uri.EscapeDataString(keyword)}",
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Source = "emulated",
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Orientation = "landscape",
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Width = 1200,
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Height = 628,
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AltText = $"{keyword} - landscape",
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Attribution = "Placeholder image"
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},
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new()
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{
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ImageId = $"emu-square-{Guid.NewGuid():N}"[..20],
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Url = $"https://placehold.co/1200x1200/0066cc/ffffff?text={Uri.EscapeDataString(keyword)}",
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Source = "emulated",
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Orientation = "square",
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Width = 1200,
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Height = 1200,
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AltText = $"{keyword} - square",
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Attribution = "Placeholder image"
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},
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new()
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{
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ImageId = $"emu-portrait-{Guid.NewGuid():N}"[..20],
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Url = $"https://placehold.co/960x1200/0066cc/ffffff?text={Uri.EscapeDataString(keyword)}",
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Source = "emulated",
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Orientation = "portrait",
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Width = 960,
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Height = 1200,
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AltText = $"{keyword} - portrait",
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Attribution = "Placeholder image"
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}
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};
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return (images.Take(_config.ImageCount).ToList(), "emulated");
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}
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// ============================================================
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// Unsplash Provider
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// ============================================================
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private async Task<(List<ImageAsset>, string)> GenerateUnsplashAsync(
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UrlAnalysis analysis, CancellationToken ct)
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{
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var keyword = ExtractSearchKeyword(analysis);
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_logger.LogInformation("[ImageGen] Unsplash search: '{Keyword}'", keyword);
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var client = _httpFactory.CreateClient();
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client.Timeout = TimeSpan.FromSeconds(15);
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// Unsplash supports unauthenticated requests at lower rate limits.
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// With an access key you get 50 req/hour (free tier).
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var hasKey = !string.IsNullOrWhiteSpace(_config.UnsplashAccessKey);
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if (hasKey)
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client.DefaultRequestHeaders.Add("Authorization", $"Client-ID {_config.UnsplashAccessKey}");
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var images = new List<ImageAsset>();
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var orientations = new[] { "landscape", "squarish", "portrait" };
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foreach (var orientation in orientations.Take(_config.ImageCount))
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{
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try
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{
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var queryUrl = hasKey
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? $"https://api.unsplash.com/search/photos?query={Uri.EscapeDataString(keyword)}&orientation={orientation}&per_page=1"
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: $"https://api.unsplash.com/search/photos?query={Uri.EscapeDataString(keyword)}&orientation={orientation}&per_page=1";
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var response = await client.GetAsync(queryUrl, ct);
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if (!response.IsSuccessStatusCode)
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{
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_logger.LogWarning("[ImageGen] Unsplash returned {Status} for orientation={Orientation}",
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response.StatusCode, orientation);
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// If unauthenticated and rate-limited, fall back to source.unsplash.com
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images.Add(BuildUnsplashFallback(keyword, orientation));
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continue;
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}
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var json = await response.Content.ReadAsStringAsync(ct);
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var parsed = JsonDocument.Parse(json);
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var results = parsed.RootElement.GetProperty("results");
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if (results.GetArrayLength() == 0)
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{
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_logger.LogInformation("[ImageGen] No Unsplash results for '{Keyword}' {Orientation}",
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keyword, orientation);
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images.Add(BuildUnsplashFallback(keyword, orientation));
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continue;
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}
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var photo = results[0];
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var mappedOrientation = orientation == "squarish" ? "square" : orientation;
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images.Add(new ImageAsset
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{
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ImageId = photo.GetProperty("id").GetString() ?? $"unsplash-{Guid.NewGuid():N}"[..16],
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Url = photo.GetProperty("urls").GetProperty("regular").GetString() ?? "",
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DownloadUrl = photo.GetProperty("urls").GetProperty("full").GetString(),
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Source = "unsplash",
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Orientation = mappedOrientation,
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Width = photo.GetProperty("width").GetInt32(),
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Height = photo.GetProperty("height").GetInt32(),
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AltText = photo.GetProperty("alt_description").ValueKind == JsonValueKind.Null
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? keyword
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: photo.GetProperty("alt_description").GetString(),
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Attribution = BuildUnsplashAttribution(photo)
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});
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}
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catch (Exception ex)
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{
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_logger.LogWarning(ex, "[ImageGen] Unsplash error for {Orientation}, using fallback", orientation);
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images.Add(BuildUnsplashFallback(keyword, orientation));
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}
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}
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_logger.LogInformation("[ImageGen] Unsplash returned {Count} images", images.Count);
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return (images, "unsplash");
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}
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/// <summary>
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/// Fallback using source.unsplash.com redirect (no API key needed, no rate limit).
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/// Returns a random photo matching the keyword at the requested dimensions.
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/// </summary>
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private static ImageAsset BuildUnsplashFallback(string keyword, string orientation)
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{
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var (w, h, mapped) = orientation switch
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{
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"landscape" => (1200, 628, "landscape"),
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"squarish" => (1200, 1200, "square"),
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"portrait" => (960, 1200, "portrait"),
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_ => (1200, 628, "landscape")
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};
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return new ImageAsset
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{
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ImageId = $"unsplash-fallback-{Guid.NewGuid():N}"[..24],
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Url = $"https://source.unsplash.com/{w}x{h}/?{Uri.EscapeDataString(keyword)}",
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Source = "unsplash",
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Orientation = mapped,
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Width = w,
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Height = h,
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AltText = keyword,
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Attribution = "Photo from Unsplash"
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};
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}
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private static string BuildUnsplashAttribution(JsonElement photo)
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{
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var userName = "Unknown";
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var userLink = "";
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if (photo.TryGetProperty("user", out var user))
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{
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userName = user.TryGetProperty("name", out var name)
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? name.GetString() ?? "Unknown"
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: "Unknown";
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if (user.TryGetProperty("links", out var links) &&
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links.TryGetProperty("html", out var html))
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{
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userLink = html.GetString() ?? "";
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}
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}
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// Unsplash TOS requires photographer attribution
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return string.IsNullOrEmpty(userLink)
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? $"Photo by {userName} on Unsplash"
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: $"Photo by {userName} on Unsplash ({userLink})";
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}
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// ============================================================
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// DALL-E Provider (stubbed — ready for OpenAI key)
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// ============================================================
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private async Task<(List<ImageAsset>, string)> GenerateDalleAsync(
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UrlAnalysis analysis, CancellationToken ct)
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{
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// Guard: DALL-E requires the OpenAI key
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if (string.IsNullOrWhiteSpace(_config.OpenAiApiKey))
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{
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_logger.LogWarning("[ImageGen] DALL-E requested but no OpenAI key configured, falling back to emulated");
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return EmulateGeneration(analysis);
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}
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var keyword = ExtractSearchKeyword(analysis);
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var prompt = BuildDallePrompt(analysis, keyword);
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_logger.LogInformation("[ImageGen] DALL-E generation: '{Prompt}'", prompt[..Math.Min(80, prompt.Length)]);
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var client = _httpFactory.CreateClient();
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client.Timeout = TimeSpan.FromSeconds(_config.OpenAiTimeoutSeconds);
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client.DefaultRequestHeaders.Add("Authorization", $"Bearer {_config.OpenAiApiKey}");
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var images = new List<ImageAsset>();
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// DALL-E 3 supports: 1024x1024, 1792x1024 (landscape), 1024x1792 (portrait)
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var dalleVariants = new[]
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{
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(size: "1792x1024", orientation: "landscape", w: 1792, h: 1024),
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(size: "1024x1024", orientation: "square", w: 1024, h: 1024),
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(size: "1024x1792", orientation: "portrait", w: 1024, h: 1792)
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};
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foreach (var variant in dalleVariants.Take(_config.ImageCount))
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{
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try
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{
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var requestBody = new
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{
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model = _config.DalleModel,
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prompt = prompt,
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n = 1,
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size = variant.size,
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quality = "standard",
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response_format = "url"
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};
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var json = JsonSerializer.Serialize(requestBody);
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using var content = new StringContent(json, Encoding.UTF8, "application/json");
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using var response = await client.PostAsync(
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"https://api.openai.com/v1/images/generations", content, ct);
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if (!response.IsSuccessStatusCode)
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{
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var errorBody = await response.Content.ReadAsStringAsync(ct);
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_logger.LogError("[ImageGen] DALL-E returned {Status}: {Body}",
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response.StatusCode, errorBody);
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// Fall back to emulated for this orientation
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images.Add(BuildEmulatedFallback(keyword, variant.orientation,
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variant.w, variant.h));
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continue;
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}
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var responseJson = await response.Content.ReadAsStringAsync(ct);
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var parsed = JsonDocument.Parse(responseJson);
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var data = parsed.RootElement.GetProperty("data")[0];
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var imageUrl = data.GetProperty("url").GetString() ?? "";
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var revisedPrompt = data.TryGetProperty("revised_prompt", out var rp)
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? rp.GetString() : null;
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images.Add(new ImageAsset
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{
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ImageId = $"dalle-{variant.orientation}-{Guid.NewGuid():N}"[..24],
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Url = imageUrl,
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Source = "dalle",
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Orientation = variant.orientation,
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Width = variant.w,
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Height = variant.h,
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AltText = revisedPrompt ?? keyword,
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Attribution = $"AI-generated image via {_config.DalleModel}"
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});
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_logger.LogInformation("[ImageGen] DALL-E generated {Orientation} image", variant.orientation);
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}
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catch (Exception ex)
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{
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_logger.LogWarning(ex, "[ImageGen] DALL-E error for {Orientation}, using fallback",
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variant.orientation);
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images.Add(BuildEmulatedFallback(keyword, variant.orientation,
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variant.w, variant.h));
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}
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}
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_logger.LogInformation("[ImageGen] DALL-E returned {Count} images", images.Count);
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return (images, "dalle");
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}
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/// <summary>
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/// Build a DALL-E prompt from the analysis. Aims for clean,
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/// professional ad imagery — not artistic or abstract.
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/// </summary>
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private static string BuildDallePrompt(UrlAnalysis analysis, string keyword)
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{
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var sb = new StringBuilder();
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sb.Append("Professional advertising photograph for a ");
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sb.Append(analysis.InferredCategory ?? "business");
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sb.Append(" business. ");
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if (!string.IsNullOrWhiteSpace(analysis.Title))
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{
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var businessName = analysis.Title.Split('-', '|', '–')[0].Trim();
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sb.Append($"Business: {businessName}. ");
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}
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sb.Append($"Theme: {keyword}. ");
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sb.Append("Clean, well-lit, commercial style. ");
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sb.Append("No text or watermarks. Suitable for Google Ads display.");
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return sb.ToString();
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}
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private static ImageAsset BuildEmulatedFallback(string keyword, string orientation, int w, int h)
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{
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return new ImageAsset
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{
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ImageId = $"fallback-{orientation}-{Guid.NewGuid():N}"[..24],
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Url = $"https://placehold.co/{w}x{h}/0066cc/ffffff?text={Uri.EscapeDataString(keyword)}",
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Source = "emulated",
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Orientation = orientation,
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Width = w,
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Height = h,
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AltText = $"{keyword} - {orientation}",
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Attribution = "Placeholder image (provider fallback)"
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};
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}
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// ============================================================
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// Shared Helpers
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// ============================================================
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/// <summary>
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/// Extract a concise search keyword from the analysis.
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/// Uses category first, then title, then domain.
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/// </summary>
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private static string ExtractSearchKeyword(UrlAnalysis analysis)
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{
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// Prefer inferred category (e.g., "Pizza", "Soccer")
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if (!string.IsNullOrWhiteSpace(analysis.InferredCategory))
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return analysis.InferredCategory;
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// Fall back to first meaningful heading
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var heading = analysis.Headings?.FirstOrDefault(h => h.Length > 3 && h.Length < 40);
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if (!string.IsNullOrWhiteSpace(heading))
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return heading;
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// Fall back to title (cleaned)
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if (!string.IsNullOrWhiteSpace(analysis.Title))
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{
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var title = analysis.Title.Split('-', '|', '–')[0].Trim();
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return title.Length > 30 ? title[..30] : title;
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}
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// Last resort: domain name
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try
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{
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var uri = new Uri(analysis.Url.StartsWith("http") ? analysis.Url : $"https://{analysis.Url}");
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return uri.Host.Replace("www.", "").Split('.')[0];
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}
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catch
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{
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return "business";
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}
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}
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}
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Block a user