using DramaLing.Api.Models.DTOs;
using DramaLing.Api.Models.Entities;

namespace DramaLing.Api.Services.AI.Gemini;

/// <summary>
/// 圖片描述生成服務實作
/// </summary>
public class ImageDescriptionGenerator : IImageDescriptionGenerator
{
    private readonly IGeminiClient _geminiClient;
    private readonly ILogger<ImageDescriptionGenerator> _logger;

    public ImageDescriptionGenerator(
        IGeminiClient geminiClient,
        ILogger<ImageDescriptionGenerator> logger)
    {
        _geminiClient = geminiClient ?? throw new ArgumentNullException(nameof(geminiClient));
        _logger = logger ?? throw new ArgumentNullException(nameof(logger));
    }

    public async Task<string> GenerateImageDescriptionAsync(Flashcard flashcard, GenerationOptionsDto options)
    {
        try
        {
            _logger.LogInformation("Starting image description generation for flashcard {FlashcardId}", flashcard.Id);

            var prompt = BuildImageDescriptionPrompt(flashcard, options);
            var response = await _geminiClient.CallGeminiAPIAsync(prompt);

            if (string.IsNullOrWhiteSpace(response))
            {
                throw new InvalidOperationException("Gemini API returned empty response");
            }

            var description = ExtractImageDescription(response);
            var optimizedPrompt = OptimizeForReplicate(description, options);

            _logger.LogInformation("Image description generated successfully for flashcard {FlashcardId}", flashcard.Id);

            return optimizedPrompt;
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "Image description generation failed for flashcard {FlashcardId}", flashcard.Id);
            throw;
        }
    }

    private string BuildImageDescriptionPrompt(Flashcard flashcard, GenerationOptionsDto options)
    {
        return $@"# 總覽
你是一位專業插畫設計師兼職英文老師，專門為英語學習教材製作插畫圖卡，用來幫助學生理解英文例句的意思。

# 例句資訊
例句：{flashcard.Example}

# SOP
1. 根據上述英文例句，請撰寫一段圖像描述提示詞，用於提供圖片生成AI作為生成圖片的提示詞
2. 請將下方「風格指南」的所有要求加入提示詞中
3. 並於圖片提示詞最後加上：「Absolutely no visible text, characters, letters, numbers, symbols, handwriting, labels, or any form of writing anywhere in the image — including on signs, books, clothing, screens, or backgrounds.」

# 圖片提示詞規範

## 情境清楚
1. 角色描述具體清楚
2. 動作明確具象
3. 場景明確具體
4. 物品明確具體
5. 語意需與原句一致
6. 避免過於抽象或象徵性符號

## 風格指南
- 風格類型：扁平插畫（Flat Illustration）
- 線條特徵：無描邊線條（outline-less）
- 色調：暖色調、柔和、低飽和
- 人物樣式：簡化卡通人物，表情自然，不誇張
- 背景構成：圖形簡化，使用色塊區分層次
- 整體氛圍：溫馨、平靜、適合教育情境
- 技術風格：無紋理、無漸層、無光影寫實感

請根據以上規範，為這個英文例句生成圖片描述提示詞，並確保完全符合風格指南要求。";
    }

    private string ExtractImageDescription(string geminiResponse)
    {
        // 從 Gemini 回應中提取圖片描述
        var description = geminiResponse.Trim();

        // 移除可能的 markdown 標記
        if (description.StartsWith("```"))
        {
            var lines = description.Split('\n');
            description = string.Join('\n', lines.Skip(1).SkipLast(1));
        }

        return description.Trim();
    }

    private string OptimizeForReplicate(string description, GenerationOptionsDto options)
    {
        var optimizedPrompt = description;

        // 確保包含扁平插畫風格要求
        if (!optimizedPrompt.Contains("flat illustration"))
        {
            optimizedPrompt += ". Style guide: flat illustration style, outline-less shapes, warm and soft color tones, low saturation, cartoon-style characters with natural expressions, simplified background with color blocks, cozy and educational atmosphere, no texture, no gradients, no photorealism, no fantasy elements.";
        }

        // 強制加入禁止文字的規則
        if (!optimizedPrompt.Contains("Absolutely no visible text"))
        {
            optimizedPrompt += " Absolutely no visible text, characters, letters, numbers, symbols, handwriting, labels, or any form of writing anywhere in the image — including on signs, books, clothing, screens, or backgrounds.";
        }

        return optimizedPrompt;
    }
}