dramaling-vocab-learning/backend/DramaLing.Api/Controllers/AIController.cs

using Microsoft.AspNetCore.Mvc;
using Microsoft.EntityFrameworkCore;
using DramaLing.Api.Data;
using DramaLing.Api.Models.Entities;
using DramaLing.Api.Services;
using Microsoft.AspNetCore.Authorization;

namespace DramaLing.Api.Controllers;

[ApiController]
[Route("api/[controller]")]
[Authorize]
public class AIController : ControllerBase
{
    private readonly DramaLingDbContext _context;
    private readonly IAuthService _authService;
    private readonly IGeminiService _geminiService;
    private readonly ILogger<AIController> _logger;

    public AIController(
        DramaLingDbContext context,
        IAuthService authService,
        IGeminiService geminiService,
        ILogger<AIController> logger)
    {
        _context = context;
        _authService = authService;
        _geminiService = geminiService;
        _logger = logger;
    }

    /// <summary>
    /// AI 生成詞卡 (支援 /frontend/app/generate/page.tsx)
    /// </summary>
    [HttpPost("generate")]
    public async Task<ActionResult> GenerateCards([FromBody] GenerateCardsRequest request)
    {
        try
        {
            var userId = await _authService.GetUserIdFromTokenAsync(Request.Headers.Authorization);
            if (userId == null)
                return Unauthorized(new { Success = false, Error = "Invalid token" });

            // 基本驗證
            if (string.IsNullOrWhiteSpace(request.InputText))
            {
                return BadRequest(new { Success = false, Error = "Input text is required" });
            }

            if (request.InputText.Length > 5000)
            {
                return BadRequest(new { Success = false, Error = "Input text must be less than 5000 characters" });
            }

            if (!new[] { "vocabulary", "smart" }.Contains(request.ExtractionType))
            {
                return BadRequest(new { Success = false, Error = "Invalid extraction type" });
            }

            if (request.CardCount < 5 || request.CardCount > 20)
            {
                return BadRequest(new { Success = false, Error = "Card count must be between 5 and 20" });
            }

            // 檢查每日配額 (簡化版，未來可以基於用戶訂閱狀態)
            var today = DateOnly.FromDateTime(DateTime.Today);
            var todayStats = await _context.DailyStats
                .FirstOrDefaultAsync(ds => ds.UserId == userId && ds.Date == today);

            var todayApiCalls = todayStats?.AiApiCalls ?? 0;
            var maxApiCalls = 10; // 免費用戶每日限制

            if (todayApiCalls >= maxApiCalls)
            {
                return StatusCode(429, new
                {
                    Success = false,
                    Error = "Daily AI generation limit exceeded"
                });
            }

            // 建立生成任務 (簡化版，直接處理而不是非同步)
            try
            {
                var generatedCards = await _geminiService.GenerateCardsAsync(
                    request.InputText,
                    request.ExtractionType,
                    request.CardCount);

                if (generatedCards.Count == 0)
                {
                    return StatusCode(500, new
                    {
                        Success = false,
                        Error = "AI generated no valid cards"
                    });
                }

                // 更新每日統計
                if (todayStats == null)
                {
                    todayStats = new DailyStats
                    {
                        Id = Guid.NewGuid(),
                        UserId = userId.Value,
                        Date = today
                    };
                    _context.DailyStats.Add(todayStats);
                }

                todayStats.AiApiCalls++;
                todayStats.CardsGenerated += generatedCards.Count;
                await _context.SaveChangesAsync();

                return Ok(new
                {
                    Success = true,
                    Data = new
                    {
                        TaskId = Guid.NewGuid(), // 模擬任務 ID
                        Status = "completed",
                        GeneratedCards = generatedCards
                    },
                    Message = $"Successfully generated {generatedCards.Count} cards"
                });
            }
            catch (InvalidOperationException ex) when (ex.Message.Contains("API key"))
            {
                _logger.LogWarning("Gemini API key not configured, using mock data");

                // 返回模擬資料（開發階段）
                var mockCards = GenerateMockCards(request.CardCount);
                return Ok(new
                {
                    Success = true,
                    Data = new
                    {
                        TaskId = Guid.NewGuid(),
                        Status = "completed",
                        GeneratedCards = mockCards
                    },
                    Message = $"Generated {mockCards.Count} mock cards (Gemini API not configured)"
                });
            }
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "Error in AI card generation");
            return StatusCode(500, new
            {
                Success = false,
                Error = "Failed to generate cards",
                Timestamp = DateTime.UtcNow
            });
        }
    }

    /// <summary>
    /// 保存生成的詞卡
    /// </summary>
    [HttpPost("generate/{taskId}/save")]
    public async Task<ActionResult> SaveGeneratedCards(
        Guid taskId,
        [FromBody] SaveCardsRequest request)
    {
        try
        {
            var userId = await _authService.GetUserIdFromTokenAsync(Request.Headers.Authorization);
            if (userId == null)
                return Unauthorized(new { Success = false, Error = "Invalid token" });

            // 基本驗證
            if (request.CardSetId == Guid.Empty)
            {
                return BadRequest(new { Success = false, Error = "Card set ID is required" });
            }

            if (request.SelectedCards == null || request.SelectedCards.Count == 0)
            {
                return BadRequest(new { Success = false, Error = "Selected cards are required" });
            }

            // 驗證卡組是否屬於用戶
            var cardSet = await _context.CardSets
                .FirstOrDefaultAsync(cs => cs.Id == request.CardSetId && cs.UserId == userId);

            if (cardSet == null)
            {
                return NotFound(new { Success = false, Error = "Card set not found" });
            }

            // 將生成的詞卡轉換為資料庫實體
            var flashcardsToSave = request.SelectedCards.Select(card => new Flashcard
            {
                Id = Guid.NewGuid(),
                UserId = userId.Value,
                CardSetId = request.CardSetId,
                Word = card.Word,
                Translation = card.Translation,
                Definition = card.Definition,
                PartOfSpeech = card.PartOfSpeech,
                Pronunciation = card.Pronunciation,
                Example = card.Example,
                ExampleTranslation = card.ExampleTranslation,
                DifficultyLevel = card.DifficultyLevel
            }).ToList();

            _context.Flashcards.AddRange(flashcardsToSave);
            await _context.SaveChangesAsync();

            return Ok(new
            {
                Success = true,
                Data = new
                {
                    SavedCount = flashcardsToSave.Count,
                    Cards = flashcardsToSave.Select(f => new
                    {
                        f.Id,
                        f.Word,
                        f.Translation,
                        f.Definition
                    })
                },
                Message = $"Successfully saved {flashcardsToSave.Count} cards to your deck"
            });
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "Error saving generated cards");
            return StatusCode(500, new
            {
                Success = false,
                Error = "Failed to save cards",
                Timestamp = DateTime.UtcNow
            });
        }
    }

    /// <summary>
    /// 智能檢測詞卡內容
    /// </summary>
    [HttpPost("validate-card")]
    public async Task<ActionResult> ValidateCard([FromBody] ValidateCardRequest request)
    {
        try
        {
            var userId = await _authService.GetUserIdFromTokenAsync(Request.Headers.Authorization);
            if (userId == null)
                return Unauthorized(new { Success = false, Error = "Invalid token" });

            var flashcard = await _context.Flashcards
                .FirstOrDefaultAsync(f => f.Id == request.FlashcardId && f.UserId == userId);

            if (flashcard == null)
            {
                return NotFound(new { Success = false, Error = "Flashcard not found" });
            }

            try
            {
                var validationResult = await _geminiService.ValidateCardAsync(flashcard);

                return Ok(new
                {
                    Success = true,
                    Data = new
                    {
                        FlashcardId = request.FlashcardId,
                        ValidationResult = validationResult,
                        CheckedAt = DateTime.UtcNow
                    },
                    Message = "Card validation completed"
                });
            }
            catch (InvalidOperationException ex) when (ex.Message.Contains("API key"))
            {
                // 模擬檢測結果
                var mockResult = new ValidationResult
                {
                    Issues = new List<ValidationIssue>(),
                    Suggestions = new List<string> { "詞卡內容看起來正確", "建議添加更多例句" },
                    OverallScore = 85,
                    Confidence = 0.7
                };

                return Ok(new
                {
                    Success = true,
                    Data = new
                    {
                        FlashcardId = request.FlashcardId,
                        ValidationResult = mockResult,
                        CheckedAt = DateTime.UtcNow,
                        Note = "Mock validation (Gemini API not configured)"
                    },
                    Message = "Card validation completed (mock mode)"
                });
            }
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "Error validating card");
            return StatusCode(500, new
            {
                Success = false,
                Error = "Failed to validate card",
                Timestamp = DateTime.UtcNow
            });
        }
    }

    /// <summary>
    /// 生成模擬資料 (開發階段使用)
    /// </summary>
    private List<GeneratedCard> GenerateMockCards(int count)
    {
        var mockCards = new List<GeneratedCard>
        {
            new() {
                Word = "accomplish",
                PartOfSpeech = "verb",
                Pronunciation = "/əˈkʌmplɪʃ/",
                Translation = "完成、達成",
                Definition = "To finish something successfully or to achieve something",
                Synonyms = new() { "achieve", "complete" },
                Example = "She accomplished her goal of learning English.",
                ExampleTranslation = "她達成了學習英語的目標。",
                DifficultyLevel = "B1"
            },
            new() {
                Word = "negotiate",
                PartOfSpeech = "verb",
                Pronunciation = "/nɪˈɡəʊʃieɪt/",
                Translation = "協商、談判",
                Definition = "To discuss something with someone in order to reach an agreement",
                Synonyms = new() { "bargain", "discuss" },
                Example = "We need to negotiate a better deal.",
                ExampleTranslation = "我們需要協商一個更好的交易。",
                DifficultyLevel = "B2"
            },
            new() {
                Word = "perspective",
                PartOfSpeech = "noun",
                Pronunciation = "/pərˈspektɪv/",
                Translation = "觀點、看法",
                Definition = "A particular way of considering something",
                Synonyms = new() { "viewpoint", "opinion" },
                Example = "From my perspective, this is the best solution.",
                ExampleTranslation = "從我的觀點來看，這是最好的解決方案。",
                DifficultyLevel = "B2"
            }
        };

        return mockCards.Take(Math.Min(count, mockCards.Count)).ToList();
    }
}

// Request DTOs
public class GenerateCardsRequest
{
    public string InputText { get; set; } = string.Empty;
    public string ExtractionType { get; set; } = "vocabulary"; // vocabulary, smart
    public int CardCount { get; set; } = 10;
}

public class SaveCardsRequest
{
    public Guid CardSetId { get; set; }
    public List<GeneratedCard> SelectedCards { get; set; } = new();
}

public class ValidateCardRequest
{
    public Guid FlashcardId { get; set; }
    public Guid? ErrorReportId { get; set; }
}