feat(translate): translate a whole playlist so the next episodes are ready (#16)

Co-authored-by: Tri Vo Khac <git@trivk.dev>

src/translate/translationservice.h

@@ -15,6 +15,7 @@
 
 #include <atomic>
 #include <memory>
+#include <optional>
 
 class QNetworkAccessManager;
 
@@ -37,6 +38,9 @@ class TranslationService : public QObject
     Q_PROPERTY(QString glossaryEpisode READ glossaryEpisode NOTIFY glossaryChanged)
     Q_PROPERTY(QStringList glossaryEpisodes READ glossaryEpisodes NOTIFY glossaryChanged)
     Q_PROPERTY(QString glossaryError READ glossaryError NOTIFY glossaryErrorChanged)
+    // The video playing. Its translations are shown when ready; others are only saved.
+    // Opening another video stops a single translation but not a playlist one.
+    Q_PROPERTY(QUrl currentVideo READ currentVideo WRITE setCurrentVideo NOTIFY currentVideoChanged)
 
 public:
     explicit TranslationService(QObject *parent = nullptr);
@@ -54,9 +58,15 @@ public:
     QString glossaryEpisode() const;
     QStringList glossaryEpisodes() const;
     QString glossaryError() const;
+    QUrl currentVideo() const;
+    void setCurrentVideo(const QUrl &url);
 
     // \a track is an entry of MpvItem::subtitleTracks.
     Q_INVOKABLE void translate(const QUrl &videoUrl, const QVariantMap &track, const QString &mediaTitle);
+    // Translates every video in \a urls that has no saved translation yet, one after
+    // another, starting at the current video. The current one uses \a currentTrack when
+    // set; the others use the embedded subtitle findTranslationSource() picks.
+    Q_INVOKABLE void translatePlaylist(const QList<QUrl> &urls, const QVariantMap &currentTrack, const QString &currentTitle);
     Q_INVOKABLE void cancel();
     // Asks the API configured in the settings for its models.
     Q_INVOKABLE void fetchModels();
@@ -83,12 +93,46 @@ Q_SIGNALS:
     void glossaryChanged();
     void glossaryErrorChanged();
     void translated(const QUrl &subtitleUrl, bool fromCache);
+    void currentVideoChanged();
+    // A playlist translation ended without being cancelled. Problems are in errorText.
+    void playlistTranslated(int translatedCount, int alreadyTranslatedCount, int problemCount);
 
 private:
     struct Job;
     struct Batches;
+    // Where translateVideo() left a translation, or why it could not make one.
+    struct Outcome {
+        QString cacheFile;
+        QString suffix;
+        QString configKey;
+        bool fromCache = false;
+        QString error;
+        // The error is about this video's subtitles; other videos may still work.
+        bool skippable = false;
 
-    QCoro::Task<> run(QUrl videoUrl, QVariantMap track);
+        static Outcome ready(const QString &cacheFile, const QString &suffix, const QString &configKey, bool fromCache)
+        {
+            Outcome outcome;
+            outcome.cacheFile = cacheFile;
+            outcome.suffix = suffix;
+            outcome.configKey = configKey;
+            outcome.fromCache = fromCache;
+            return outcome;
+        }
+        static Outcome failed(const QString &error, bool skippable = false)
+        {
+            Outcome outcome;
+            outcome.error = error;
+            outcome.skippable = skippable;
+            return outcome;
+        }
+    };
+
+    QCoro::Task<> run(std::shared_ptr<Job> job, QUrl videoUrl, QVariantMap track);
+    QCoro::Task<> runPlaylist(std::shared_ptr<Job> job, QList<QUrl> urls, QVariantMap currentTrack, QString currentTitle);
+    // Reads the settings and the API key for \a job; nothing (after failing it) when they are not usable.
+    QCoro::Task<std::optional<LlmClient::Config>> startJob(std::shared_ptr<Job> job);
+    QCoro::Task<Outcome> translateVideo(std::shared_ptr<Job> job, LlmClient::Config config, QUrl videoUrl, QVariantMap track);
     QCoro::Task<> runFetchModels();
     // Translates \a lines, retrying failures and asking again for lines the model skipped.
     QCoro::Task<LlmClient::BatchResult> translateLines(std::shared_ptr<Job> job, QStringList lines, QStringList context);
@@ -100,8 +144,14 @@ private:
     // something is missing.
     QCoro::Task<std::pair<LlmClient::Config, QString>> loadConfig();
     void fail(const std::shared_ptr<Job> &job, const QString &error);
-    // Saves the translation in \a cacheFile where players find it and announces it.
-    void finish(const std::shared_ptr<Job> &job, const QUrl &videoUrl, const QString &suffix, const QString &configKey, const QString &cacheFile, bool fromCache);
+    // Saves the translation where players find it and, for the current video, shows it.
+    // Returns an error message on failure.
+    QString publish(const std::shared_ptr<Job> &job, const QUrl &videoUrl, const Outcome &outcome);
+    void endJob(const std::shared_ptr<Job> &job);
+    // In a playlist, prefixes the episode number and counts finished episodes in the progress.
+    void setJobStatus(const Job &job, const QString &text);
+    void setJobProgress(const Job &job, double episodeProgress);
+    void setLinesStatus(const Job &job, qsizetype done, qsizetype total);
 
     void setBusy(bool busy);
     void setProgress(double progress);
@@ -122,4 +172,5 @@ private:
     GlossaryStore::Glossary m_glossary;
     QString m_glossaryEpisode;
     QString m_lastTranslationPath;
+    QUrl m_currentVideo;
 };