public static string FetchLyrics(string trackTitle, string artist, string album)
{
var client = new WebClientEx()
{
Encoding = Encoding
};
trackTitle = HttpUtility.UrlEncode(trackTitle);
artist = HttpUtility.UrlEncode(artist);
album = HttpUtility.UrlEncode(album ?? "");
// 検索結果ページ
string lyricId;
{
string searchPage = client.DownloadString($"https://petitlyrics.com/search_lyrics?title={trackTitle}&artist={artist}&album={album}");
int startIndex = searchPage.IndexOf("id=\"lyrics_list\"");
int length = searchPage.Substring(startIndex).IndexOf("id=\"lyrics_list_pager\"");
var ms = Regex.Matches(searchPage.Substring(startIndex, length), @"href=""/lyrics/(?<lyricId>\d+)");
if (ms.Count == 0)
{
return(null);
}
lyricId = ms.Cast <Match>().First().Groups["lyricId"].Value.Trim();
}
// 歌詞ページ（別に歌詞取得には必要ないが、向こうのサーバーを欺く為）
string lyricPage = $"https://petitlyrics.com/lyrics/{lyricId}";
client.DownloadData(lyricPage);
// X-CSRF-Token
string token;
{
string tokenScript = client.DownloadString("https://petitlyrics.com/lib/pl-lib.js");
var m = Regex.Match(tokenScript, @"'X-CSRF-Token', '(?<token>[^']+)");
if (m.Success)
{
token = m.Groups["token"].Value;
}
else
{
return(null);
}
}
client.Headers.Clear();
client.Headers[HttpRequestHeader.Accept] = "*/*";
client.Headers[HttpRequestHeader.AcceptLanguage] = "ja";
client.Headers[HttpRequestHeader.Referer] = lyricPage;
client.Headers[HttpRequestHeader.UserAgent] = "Mozilla/5.0 (Windows NT 6.3; Win64; x64; Trident/7.0; rv:11.0) like Gecko";
client.Headers[HttpRequestHeader.Pragma] = "no-cache";
client.Headers[HttpRequestHeader.ContentType] = "application/x-www-form-urlencoded; charset=UTF-8";
client.Headers.Add("X-Requested-With", "XMLHttpRequest");
client.Headers.Add("X-CSRF-Token", token);
// 歌詞取得API
string json = client.UploadString("https://petitlyrics.com/com/get_lyrics.ajax", $"lyrics_id={lyricId}");
// パース
string[] lines = Regex.Matches(json, @"{""lyrics"":""(?<base64>[^""]*)""}")
.Cast <Match>()
.Select(x => x.Groups["base64"].Value.Replace(@"\/", "/"))
.Select(Convert.FromBase64String)
.Select(line => Encoding.GetString(line).TrimEnd(new[] { '\r', '\n' }))
.ToArray();
return(string.Join("\r\n", lines));
}