class JapanMapData {
  // 0: Empty/Ocean
  // 1-47: Prefecture IDs (JIS Code)
  
  // High-Resolution 8-bit Map (26 cols x 32 rows)
  // Designed to show Hokkaido size, Honshu curve, and close Kyushu/Shikoku
  static final List<List<int>> gridLayout = [
    // Hokkaido (Top) - Huge & Diamond shape approx
    // Hokkaido (Top) - Refined Diamond Shape
    [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0], // Tip
    [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0], // Widen
    [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 0, 0, 0, 0], // Widest top
    [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0], // Mid
    [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0], // Narrowing
    [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0], // Oshinima Peninsula
    [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0], // Tsugaru Strait
    
    // Tohoku (The vertical stick)
    [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 2, 2, 0, 0, 0, 0, 0, 0, 0], // Aomori
    [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 5, 5, 3, 3, 0, 0, 0, 0, 0, 0, 0], // Akita, Iwate
    [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 5, 3, 3, 3, 0, 0, 0, 0, 0, 0, 0],
    [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 6, 6, 4, 4, 0, 0, 0, 0, 0, 0, 0], // Yamagata, Miyagi
    [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 15, 15, 7, 7, 7, 0, 0, 0, 0, 0, 0, 0], // Niigata, Fukushima
    
    // Kanto & Chubu (The bulging turn)
    [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 15, 15, 10, 9, 9, 8, 8, 0, 0, 0, 0, 0, 0], // Niigata, Gunma, Tochigi, Ibaraki
    [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 17, 16, 20, 20, 11, 11, 12, 12, 0, 0, 0, 0, 0, 0], // Ishikawa, Toyama, Nagano, Saitama, Chiba
    [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 18, 21, 20, 19, 13, 13, 12, 0, 0, 0, 0, 0, 0, 0], // Fukui, Gifu, Nagano, Yamanashi, Tokyo, Chiba
    [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 18, 25, 21, 23, 22, 14, 14, 0, 0, 0, 0, 0, 0, 0], // Fukui, Shiga, Gifu, Aichi, Shizuoka, Kanagawa
    
    // Kansai & Chugoku (Stretching West)
    [0, 0, 0, 0, 0, 0, 0, 32, 31, 28, 26, 25, 24, 23, 22, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0], // Shimane, Tottori, Hyogo, Kyoto, Shiga, Mie, Aichi, Shizuoka
    [0, 0, 0, 0, 0, 35, 34, 33, 28, 27, 29, 24, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0], // Yamaguchi, Hiroshima, Okayama, Hyogo, Osaka, Nara, Mie
    
    // Shikoku (Nestled under) & Wakayama
    [0, 0, 0, 0, 0, 0, 0, 37, 36, 0, 30, 30, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0], // Kagawa, Tokushima, Wakayama
    [0, 0, 0, 0, 0, 0, 38, 38, 39, 39, 30, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0], // Ehime, Kochi
    
    // Kyushu (Connecting West)
    [0, 0, 0, 41, 40, 44, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0], // Saga, Fukuoka, Oita
    [0, 42, 42, 43, 44, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0], // Nagasaki, Kumamoto, Oita
    [0, 42, 43, 43, 45, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0], // Nagasaki, Kumamoto, Miyazaki
    [0, 0, 46, 46, 45, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0], // Kagoshima, Miyazaki
    [0, 0, 46, 46, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0], // Kagoshima
    
    // Gap
    [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
    [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
    [47, 47, 47, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0], // Okinawa
    [0, 47, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0], // Okinawa
  ];

  static const Map<int, String> prefectureNames = {
    1: '北海道',
    2: '青森県',
    3: '岩手県',
    4: '宮城県',
    5: '秋田県',
    6: '山形県',
    7: '福島県',
    8: '茨城県',
    9: '栃木県',
    10: '群馬県',
    11: '埼玉県',
    12: '千葉県',
    13: '東京都',
    14: '神奈川県',
    15: '新潟県',
    16: '富山県',
    17: '石川県',
    18: '福井県',
    19: '山梨県',
    20: '長野県',
    21: '岐阜県',
    22: '静岡県',
    23: '愛知県',
    24: '三重県',
    25: '滋賀県',
    26: '京都府',
    27: '大阪府',
    28: '兵庫県',
    29: '奈良県',
    30: '和歌山県',
    31: '鳥取県',
    32: '島根県',
    33: '岡山県',
    34: '広島県',
    35: '山口県',
    36: '徳島県',
    37: '香川県',
    38: '愛媛県',
    39: '高知県',
    40: '福岡県',
    41: '佐賀県',
    42: '長崎県',
    43: '熊本県',
    44: '大分県',
    45: '宮崎県',
    46: '鹿児島県',
    47: '沖縄県',
  };

  // Region grouping for visual rhythm (coloring)
  // 1: Hokkaido, 2: Tohoku, 3: Kanto, 4: Chubu, 5: Kansai, 6: Chugoku, 7: Shikoku, 8: Kyushu/Okinawa
  static const Map<int, String> regionNames = {
    1: '北海道',
    2: '東北',
    3: '関東',
    4: '中部',
    5: '近畿',
    6: '中国',
    7: '四国',
    8: '九州・沖縄',
  };

  static int getRegionId(int prefId) {
    if (prefId == 1) return 1;
    if (prefId >= 2 && prefId <= 7) return 2;
    if (prefId >= 8 && prefId <= 14) return 3;
    if (prefId >= 15 && prefId <= 23) return 4;
    if (prefId >= 24 && prefId <= 30) return 5;
    if (prefId >= 31 && prefId <= 35) return 6;
    if (prefId >= 36 && prefId <= 39) return 7;
    if (prefId >= 40 && prefId <= 47) return 8;
    return 0;
  }
}