246 lines
8.5 KiB
C#
246 lines
8.5 KiB
C#
using DramaLing.Api.Data;
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using DramaLing.Api.Models.DTOs.SpacedRepetition;
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using DramaLing.Api.Models.Entities;
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using Microsoft.EntityFrameworkCore;
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namespace DramaLing.Api.Services;
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/// <summary>
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/// 題目生成服務介面
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/// </summary>
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public interface IQuestionGeneratorService
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{
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Task<QuestionData> GenerateQuestionAsync(Guid flashcardId, string questionType);
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}
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/// <summary>
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/// 題目生成服務實現
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/// </summary>
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public class QuestionGeneratorService : IQuestionGeneratorService
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{
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private readonly DramaLingDbContext _context;
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private readonly ILogger<QuestionGeneratorService> _logger;
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public QuestionGeneratorService(
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DramaLingDbContext context,
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ILogger<QuestionGeneratorService> logger)
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{
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_context = context;
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_logger = logger;
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}
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/// <summary>
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/// 根據題型生成對應的題目數據
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/// </summary>
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public async Task<QuestionData> GenerateQuestionAsync(Guid flashcardId, string questionType)
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{
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var flashcard = await _context.Flashcards.FindAsync(flashcardId);
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if (flashcard == null)
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throw new ArgumentException($"Flashcard {flashcardId} not found");
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_logger.LogInformation("Generating {QuestionType} question for flashcard {FlashcardId}, word: {Word}",
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questionType, flashcardId, flashcard.Word);
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return questionType switch
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{
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"vocab-choice" => await GenerateVocabChoiceAsync(flashcard),
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"sentence-fill" => GenerateFillBlankQuestion(flashcard),
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"sentence-reorder" => GenerateReorderQuestion(flashcard),
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"sentence-listening" => await GenerateSentenceListeningAsync(flashcard),
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_ => new QuestionData
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{
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QuestionType = questionType,
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CorrectAnswer = flashcard.Word
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}
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};
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}
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/// <summary>
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/// 生成詞彙選擇題選項
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/// </summary>
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private async Task<QuestionData> GenerateVocabChoiceAsync(Flashcard flashcard)
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{
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// 從相同用戶的其他詞卡中選擇3個干擾選項
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var distractors = await _context.Flashcards
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.Where(f => f.UserId == flashcard.UserId &&
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f.Id != flashcard.Id &&
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!f.IsArchived)
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.OrderBy(x => Guid.NewGuid()) // 隨機排序
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.Take(3)
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.Select(f => f.Word)
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.ToListAsync();
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// 如果沒有足夠的詞卡，添加一些預設選項
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while (distractors.Count < 3)
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{
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var defaultOptions = new[] { "example", "sample", "test", "word", "basic", "simple", "common", "usual" };
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var availableDefaults = defaultOptions.Where(opt => opt != flashcard.Word && !distractors.Contains(opt));
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distractors.AddRange(availableDefaults.Take(3 - distractors.Count));
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}
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var options = new List<string> { flashcard.Word };
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options.AddRange(distractors.Take(3));
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// 隨機打亂選項順序
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var shuffledOptions = options.OrderBy(x => Guid.NewGuid()).ToArray();
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return new QuestionData
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{
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QuestionType = "vocab-choice",
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Options = shuffledOptions,
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CorrectAnswer = flashcard.Word
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};
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}
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/// <summary>
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/// 生成填空題
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/// </summary>
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private QuestionData GenerateFillBlankQuestion(Flashcard flashcard)
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{
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if (string.IsNullOrEmpty(flashcard.Example))
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{
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throw new ArgumentException($"Flashcard {flashcard.Id} has no example sentence for fill-blank question");
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}
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// 在例句中將目標詞彙替換為空白
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var blankedSentence = flashcard.Example.Replace(flashcard.Word, "______", StringComparison.OrdinalIgnoreCase);
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// 如果沒有替換成功，嘗試其他變化形式
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if (blankedSentence == flashcard.Example)
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{
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// TODO: 未來可以實現更智能的詞形變化識別
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blankedSentence = flashcard.Example + " (請填入: " + flashcard.Word + ")";
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}
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return new QuestionData
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{
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QuestionType = "sentence-fill",
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BlankedSentence = blankedSentence,
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CorrectAnswer = flashcard.Word,
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Sentence = flashcard.Example
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};
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}
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/// <summary>
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/// 生成例句重組題
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/// </summary>
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private QuestionData GenerateReorderQuestion(Flashcard flashcard)
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{
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if (string.IsNullOrEmpty(flashcard.Example))
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{
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throw new ArgumentException($"Flashcard {flashcard.Id} has no example sentence for reorder question");
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}
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// 將例句拆分為單字並打亂順序
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var words = flashcard.Example
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.Split(new[] { ' ', '\t', '\n', '\r' }, StringSplitOptions.RemoveEmptyEntries)
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.Select(word => word.Trim('.',',','!','?',';',':')) // 移除標點符號
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.Where(word => !string.IsNullOrEmpty(word))
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.ToArray();
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// 隨機打亂順序
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var scrambledWords = words.OrderBy(x => Guid.NewGuid()).ToArray();
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return new QuestionData
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{
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QuestionType = "sentence-reorder",
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ScrambledWords = scrambledWords,
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CorrectAnswer = flashcard.Example,
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Sentence = flashcard.Example
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};
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}
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/// <summary>
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/// 生成例句聽力題選項
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/// </summary>
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private async Task<QuestionData> GenerateSentenceListeningAsync(Flashcard flashcard)
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{
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if (string.IsNullOrEmpty(flashcard.Example))
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{
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throw new ArgumentException($"Flashcard {flashcard.Id} has no example sentence for listening question");
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}
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// 從其他詞卡中選擇3個例句作為干擾選項
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var distractorSentences = await _context.Flashcards
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.Where(f => f.UserId == flashcard.UserId &&
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f.Id != flashcard.Id &&
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!f.IsArchived &&
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!string.IsNullOrEmpty(f.Example))
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.OrderBy(x => Guid.NewGuid())
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.Take(3)
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.Select(f => f.Example!)
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.ToListAsync();
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// 如果沒有足夠的例句，添加預設選項
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while (distractorSentences.Count < 3)
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{
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var defaultSentences = new[]
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{
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"This is a simple example sentence.",
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"I think this is a good opportunity.",
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"She decided to take a different approach.",
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"They managed to solve the problem quickly."
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};
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var availableDefaults = defaultSentences
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.Where(sent => sent != flashcard.Example && !distractorSentences.Contains(sent));
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distractorSentences.AddRange(availableDefaults.Take(3 - distractorSentences.Count));
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}
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var options = new List<string> { flashcard.Example };
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options.AddRange(distractorSentences.Take(3));
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// 隨機打亂選項順序
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var shuffledOptions = options.OrderBy(x => Guid.NewGuid()).ToArray();
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return new QuestionData
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{
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QuestionType = "sentence-listening",
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Options = shuffledOptions,
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CorrectAnswer = flashcard.Example,
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Sentence = flashcard.Example,
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AudioUrl = $"/audio/sentences/{flashcard.Id}.mp3" // 未來音頻服務用
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};
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}
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/// <summary>
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/// 判斷是否為A1學習者
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/// </summary>
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public bool IsA1Learner(int userLevel) => userLevel <= 20; // 固定A1門檻
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/// <summary>
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/// 獲取適配情境描述
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/// </summary>
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public string GetAdaptationContext(int userLevel, int wordLevel)
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{
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var difficulty = wordLevel - userLevel;
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if (userLevel <= 20) // 固定A1門檻
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return "A1學習者";
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if (difficulty < -10)
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return "簡單詞彙";
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if (difficulty >= -10 && difficulty <= 10)
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return "適中詞彙";
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return "困難詞彙";
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}
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/// <summary>
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/// 獲取選擇原因說明
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/// </summary>
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private string GetSelectionReason(string selectedMode, int userLevel, int wordLevel)
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{
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var context = GetAdaptationContext(userLevel, wordLevel);
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return context switch
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{
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"A1學習者" => "A1學習者使用基礎題型建立信心",
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"簡單詞彙" => "簡單詞彙重點練習應用和拼寫",
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"適中詞彙" => "適中詞彙進行全方位練習，包括口說",
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"困難詞彙" => "困難詞彙回歸基礎重建記憶",
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_ => "系統智能選擇最適合的複習方式"
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};
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}
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} |