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.cpp

@@ -1,6 +1,7 @@
 #include "translationservice.h"
 
 #include "apikeystore.h"
+#include "mediainfo.h"
 #include "qtpotatosettings.h"
 #include "translationpresets.h"
 #include "translationstore.h"
@@ -69,6 +70,10 @@ struct TranslationService::Job {
     std::atomic_bool cancelled = false;
     std::unique_ptr<LlmClient> client;
     QString mediaTitle;
+    bool playlist = false;
+    // In a playlist: the episode being translated (from 0) and how many there are.
+    int episode = 0;
+    int episodes = 0;
 };
 
 struct TranslationService::Batches {
@@ -160,6 +165,25 @@ QString TranslationService::glossaryError() const
     return m_glossaryError;
 }
 
+QUrl TranslationService::currentVideo() const
+{
+    return m_currentVideo;
+}
+
+void TranslationService::setCurrentVideo(const QUrl &url)
+{
+    if (url == m_currentVideo) {
+        return;
+    }
+    m_currentVideo = url;
+    forgetTranslation();
+    // A playlist translation is meant to go on while the episodes play.
+    if (m_job && !m_job->playlist) {
+        cancel();
+    }
+    Q_EMIT currentVideoChanged();
+}
+
 void TranslationService::loadGlossary(const QUrl &videoUrl)
 {
     const QString directory = videoUrl.isLocalFile() ? QFileInfo(videoUrl.toLocalFile()).absolutePath() : QString();
@@ -323,7 +347,25 @@ void TranslationService::translate(const QUrl &videoUrl, const QVariantMap &trac
     cancel();
     m_job = std::make_shared<Job>();
     m_job->mediaTitle = mediaTitle;
-    run(videoUrl, track);
+    run(m_job, videoUrl, track);
+}
+
+void TranslationService::translatePlaylist(const QList<QUrl> &urls, const QVariantMap &currentTrack, const QString &currentTitle)
+{
+    cancel();
+    // Start with the episode playing, then the ones after it, which are watched next.
+    QList<QUrl> ordered;
+    const qsizetype current = std::max<qsizetype>(0, urls.indexOf(m_currentVideo));
+    for (qsizetype i = 0; i < urls.size(); ++i) {
+        const QUrl &url = urls.at((current + i) % urls.size());
+        if (!ordered.contains(url)) {
+            ordered.append(url);
+        }
+    }
+    m_job = std::make_shared<Job>();
+    m_job->playlist = true;
+    m_job->episodes = ordered.size();
+    runPlaylist(m_job, ordered, currentTrack, currentTitle);
 }
 
 void TranslationService::cancel()
@@ -408,10 +450,8 @@ QCoro::Task<Subtitles::ExtractResult> TranslationService::loadCues(std::shared_p
     });
 }
 
-QCoro::Task<> TranslationService::run(QUrl videoUrl, QVariantMap track)
+QCoro::Task<std::optional<LlmClient::Config>> TranslationService::startJob(std::shared_ptr<Job> job)
 {
-    const std::shared_ptr<Job> job = m_job;
-
     setErrorText({});
     setProgress(0);
     setBusy(true);
@@ -419,29 +459,123 @@ QCoro::Task<> TranslationService::run(QUrl videoUrl, QVariantMap track)
 
     auto [config, configError] = co_await loadConfig();
     if (job->cancelled) {
-        co_return;
+        co_return std::nullopt;
+    }
+    if (configError.isEmpty() && config.model.isEmpty()) {
+        configError = i18n("Choose a model in Settings first.");
     }
     if (!configError.isEmpty()) {
         fail(job, configError);
-        co_return;
-    }
-    if (config.model.isEmpty()) {
-        fail(job, i18n("Choose a model in Settings first."));
-        co_return;
+        co_return std::nullopt;
     }
+    co_return config;
+}
 
-    Subtitles::ExtractResult source = co_await loadCues(job, videoUrl, track);
+QCoro::Task<> TranslationService::run(std::shared_ptr<Job> job, QUrl videoUrl, QVariantMap track)
+{
+    const std::optional<LlmClient::Config> config = co_await startJob(job);
+    if (!config) {
+        co_return;
+    }
+    const Outcome outcome = co_await translateVideo(job, *config, videoUrl, track);
     if (job->cancelled) {
         co_return;
     }
-    if (!source.error.isEmpty()) {
-        fail(job, source.error);
+    const QString error = outcome.error.isEmpty() ? publish(job, videoUrl, outcome) : outcome.error;
+    if (!error.isEmpty()) {
+        fail(job, error);
         co_return;
     }
+    endJob(job);
+}
+
+QCoro::Task<> TranslationService::runPlaylist(std::shared_ptr<Job> job, QList<QUrl> urls, QVariantMap currentTrack, QString currentTitle)
+{
+    const std::optional<LlmClient::Config> config = co_await startJob(job);
+    if (!config) {
+        co_return;
+    }
+
+    int translatedCount = 0;
+    int alreadyTranslatedCount = 0;
+    QStringList problems;
+    for (qsizetype i = 0; i < urls.size(); ++i) {
+        const QUrl videoUrl = urls.at(i);
+        const QString name = videoUrl.fileName();
+        job->episode = int(i);
+        setJobProgress(*job, 0);
+        setJobStatus(*job, i18n("Reading subtitles…"));
+        if (!savedTranslation(videoUrl).isEmpty()) {
+            ++alreadyTranslatedCount;
+            continue;
+        }
+
+        QVariantMap track = currentTrack;
+        job->mediaTitle = currentTitle;
+        if (videoUrl != m_currentVideo || currentTrack.isEmpty()) {
+            if (!videoUrl.isLocalFile()) {
+                problems.append(i18nc("@info %1 is a file name", "%1: only subtitles of local files can be translated", name));
+                continue;
+            }
+            const QString path = videoUrl.toLocalFile();
+            const Subtitles::SourceResult source = co_await QtConcurrent::run([path] {
+                return Subtitles::findTranslationSource(path);
+            });
+            if (job->cancelled) {
+                co_return;
+            }
+            if (!source.error.isEmpty() || source.streamIndex < 0) {
+                problems.append(source.error.isEmpty() ? i18nc("@info %1 is a file name", "%1: no text subtitle", name)
+                                                       : i18nc("@info %1 is a file name, %2 an error", "%1: %2", name, source.error));
+                continue;
+            }
+            track = QVariantMap{{u"ffIndex"_s, source.streamIndex}};
+            job->mediaTitle = MediaInfo::cleanTitle(name);
+        }
+
+        const Outcome outcome = co_await translateVideo(job, *config, videoUrl, track);
+        if (job->cancelled) {
+            co_return;
+        }
+        if (!outcome.error.isEmpty() && !outcome.skippable) {
+            // Errors from the API or the disk would repeat for every episode.
+            fail(job, i18nc("@info %1 is a file name, %2 an error", "Stopped translating the playlist at %1: %2", name, outcome.error));
+            co_return;
+        }
+        const QString error = outcome.error.isEmpty() ? publish(job, videoUrl, outcome) : outcome.error;
+        if (error.isEmpty()) {
+            ++translatedCount;
+        } else {
+            problems.append(i18nc("@info %1 is a file name, %2 an error", "%1: %2", name, error));
+        }
+    }
+
+    endJob(job);
+    if (!problems.isEmpty()) {
+        setErrorText(i18np("Translated %2 of %3 episodes. Skipped one:\n%4",
+                           "Translated %2 of %3 episodes. Skipped %1:\n%4",
+                           problems.size(),
+                           translatedCount + alreadyTranslatedCount,
+                           urls.size(),
+                           problems.join(u'\n')));
+    }
+    Q_EMIT playlistTranslated(translatedCount, alreadyTranslatedCount, int(problems.size()));
+}
+
+QCoro::Task<TranslationService::Outcome> TranslationService::translateVideo(std::shared_ptr<Job> job, LlmClient::Config config, QUrl videoUrl, QVariantMap track)
+{
+    setJobProgress(*job, 0);
+    setJobStatus(*job, i18n("Reading subtitles…"));
+    Subtitles::ExtractResult source = co_await loadCues(job, videoUrl, track);
+    if (job->cancelled) {
+        co_return Outcome{};
+    }
+    if (!source.error.isEmpty()) {
+        co_return Outcome::failed(source.error, true);
+    }
     const QList<SubtitleCue> cues = Subtitles::mergeRepeated(source.cues);
     if (cues.isEmpty()) {
-        fail(job, i18n("This subtitle track has no text to translate."));
-        co_return;
+        co_return Outcome::failed(i18n("This subtitle track has no text to translate."), true);
     }
 
     // Episodes in one folder share a glossary. Streams have no folder, so they get none.
@@ -449,24 +583,30 @@ QCoro::Task<> TranslationService::run(QUrl videoUrl, QVariantMap track)
     const bool useGlossary = !seriesDirectory.isEmpty();
     GlossaryStore::Glossary glossary = useGlossary ? GlossaryStore::load(seriesDirectory) : GlossaryStore::Glossary{};
     const QString episode = videoUrl.isLocalFile() ? QFileInfo(videoUrl.toLocalFile()).completeBaseName() : job->mediaTitle;
-    const auto saveGlossaryGroups = [&]() {
+    // Returns an error message.
+    const auto saveGlossaryGroups = [&]() -> QString {
         QString error;
         if (!GlossaryStore::save(glossary, &error)) {
-            fail(job, i18n("Could not save the translation glossary: %1", error));
-            return false;
+            return i18n("Could not save the translation glossary: %1", error);
         }
-        m_glossary = glossary;
-        m_glossaryEpisode = episode;
-        Q_EMIT glossaryChanged();
-        return true;
+        // Another episode of the playlist only updates the terms of the open series.
+        if (!job->playlist || videoUrl == m_currentVideo) {
+            m_glossary = glossary;
+            m_glossaryEpisode = episode;
+            Q_EMIT glossaryChanged();
+        } else if (m_glossary.directory == glossary.directory) {
+            m_glossary = glossary;
+            Q_EMIT glossaryChanged();
+        }
+        return {};
     };
     if (useGlossary) {
         // New terms belong to the episode being translated. Migrate legacy or
         // imported entries without provenance to this first episode too. This
         // happens before the cache shortcut and never changes translation text.
         glossary = GlossaryStore::assignUnassigned(glossary, episode);
-        if (!saveGlossaryGroups()) {
-            co_return;
+        if (const QString error = saveGlossaryGroups(); !error.isEmpty()) {
+            co_return Outcome::failed(error);
         }
     }
     const QString sourceSrt = Subtitles::toSrt(cues);
@@ -488,12 +628,11 @@ QCoro::Task<> TranslationService::run(QUrl videoUrl, QVariantMap track)
     QString outputPath = TranslationStore::cachePath(cacheDir(), videoUrl, configKey, suffix);
 
     if (QFileInfo::exists(outputPath)) {
-        finish(job, videoUrl, suffix, configKey, outputPath, true);
-        co_return;
+        co_return Outcome::ready(outputPath, suffix, configKey, true);
     }
 
     if (useGlossary && QtPotatoSettings::self()->autoBuildGlossary()) {
-        setStatusText(i18n("Building glossary…"));
+        setJobStatus(*job, i18n("Building glossary…"));
         QStringList extractionLines;
         QHash<QString, bool> seen;
         for (const SubtitleCue &cue : cues) {
@@ -518,7 +657,7 @@ QCoro::Task<> TranslationService::run(QUrl videoUrl, QVariantMap track)
         job->client = std::make_unique<LlmClient>(m_network, config);
         const LlmClient::BatchResult extracted = co_await job->client->extractGlossary(sampled, job->mediaTitle);
         if (job->cancelled) {
-            co_return;
+            co_return Outcome{};
         }
         if (extracted.error.isEmpty()) {
             QList<GlossaryStore::Entry> additions;
@@ -529,17 +668,16 @@ QCoro::Task<> TranslationService::run(QUrl videoUrl, QVariantMap track)
             // Suggestions extracted while translating this episode belong to
             // this episode. Existing terms keep their original ownership.
             glossary = GlossaryStore::merge(glossary, additions, episode);
-            if (!saveGlossaryGroups()) {
-                co_return;
+            if (const QString error = saveGlossaryGroups(); !error.isEmpty()) {
+                co_return Outcome::failed(error);
             }
         } else {
-            setStatusText(i18n("Glossary unavailable; translating without it."));
+            setJobStatus(*job, i18n("Glossary unavailable; translating without it."));
         }
         configKey = configKeyFor(glossary);
         outputPath = TranslationStore::cachePath(cacheDir(), videoUrl, configKey, suffix);
         if (QFileInfo::exists(outputPath)) {
-            finish(job, videoUrl, suffix, configKey, outputPath, true);
-            co_return;
+            co_return Outcome::ready(outputPath, suffix, configKey, true);
         }
     }
 
@@ -567,7 +705,7 @@ QCoro::Task<> TranslationService::run(QUrl videoUrl, QVariantMap track)
     batches->lines = uniqueLines;
     batches->translations.resize(uniqueLines.size());
     batches->batchSize = QtPotatoSettings::self()->batchSize();
-    setStatusText(i18n("Translating… %1 of %2 lines", 0, uniqueLines.size()));
+    setLinesStatus(*job, 0, uniqueLines.size());
 
     // Tasks start running as soon as they are created; awaiting them just waits for the end.
     std::vector<QCoro::Task<>> workers;
@@ -578,11 +716,10 @@ QCoro::Task<> TranslationService::run(QUrl videoUrl, QVariantMap track)
         co_await std::move(worker);
     }
     if (job->cancelled) {
-        co_return;
+        co_return Outcome{};
     }
     if (!batches->error.isEmpty()) {
-        fail(job, batches->error);
-        co_return;
+        co_return Outcome::failed(batches->error);
     }
 
     QList<SubtitleCue> output = cues;
@@ -593,36 +730,64 @@ QCoro::Task<> TranslationService::run(QUrl videoUrl, QVariantMap track)
     QDir().mkpath(QFileInfo(outputPath).absolutePath());
     QSaveFile file(outputPath);
     if (!file.open(QIODevice::WriteOnly) || file.write(Subtitles::toSrt(output).toUtf8()) < 0 || !file.commit()) {
-        fail(job, i18n("Could not save the translation to %1: %2", outputPath, file.errorString()));
-        co_return;
+        co_return Outcome::failed(i18n("Could not save the translation to %1: %2", outputPath, file.errorString()));
     }
-
-    finish(job, videoUrl, suffix, configKey, outputPath, false);
+    co_return Outcome::ready(outputPath, suffix, configKey, false);
 }
 
-void TranslationService::finish(const std::shared_ptr<Job> &job,
-                                const QUrl &videoUrl,
-                                const QString &suffix,
-                                const QString &configKey,
-                                const QString &cacheFile,
-                                bool fromCache)
+QString TranslationService::publish(const std::shared_ptr<Job> &job, const QUrl &videoUrl, const Outcome &outcome)
 {
-    QFile file(cacheFile);
+    QFile file(outcome.cacheFile);
     if (!file.open(QIODevice::ReadOnly)) {
-        fail(job, i18n("Could not read the translation from %1: %2", cacheFile, file.errorString()));
-        return;
+        return i18n("Could not read the translation from %1: %2", outcome.cacheFile, file.errorString());
     }
     // The cache keeps every version; the published copy is the one players load.
     const QString registryFile = TranslationStore::registryFile();
     TranslationStore::Registry registry = TranslationStore::load(registryFile);
-    const TranslationStore::PublishResult published = TranslationStore::publish(registry, videoUrl, suffix, configKey, file.readAll(), cacheFile);
+    const TranslationStore::PublishResult published =
+        TranslationStore::publish(registry, videoUrl, outcome.suffix, outcome.configKey, file.readAll(), outcome.cacheFile);
     TranslationStore::save(registryFile, registry);
 
+    // Other episodes of a playlist load their translation when they are opened.
+    if (!job->playlist || videoUrl == m_currentVideo) {
+        m_lastTranslationPath = published.path;
+        Q_EMIT translated(QUrl::fromLocalFile(published.path), outcome.fromCache);
+    }
+    return {};
+}
+
+void TranslationService::endJob(const std::shared_ptr<Job> &job)
+{
+    if (m_job != job) {
+        return;
+    }
     m_job.reset();
-    m_lastTranslationPath = published.path;
     setBusy(false);
     setStatusText({});
-    Q_EMIT translated(QUrl::fromLocalFile(published.path), fromCache);
+}
+
+void TranslationService::setJobStatus(const Job &job, const QString &text)
+{
+    if (!job.playlist) {
+        setStatusText(text);
+        return;
+    }
+    setStatusText(i18nc("@info:status %1 and %2 are numbers, %3 is what is being done",
+                        "Episode %1 of %2: %3",
+                        job.episode + 1,
+                        job.episodes,
+                        text));
+}
+
+void TranslationService::setLinesStatus(const Job &job, qsizetype done, qsizetype total)
+{
+    // The line count would not fit after the episode number; the progress bar shows it.
+    setJobStatus(job, job.playlist ? i18n("Translating…") : i18n("Translating… %1 of %2 lines", done, total));
+}
+
+void TranslationService::setJobProgress(const Job &job, double episodeProgress)
+{
+    setProgress(job.playlist ? (job.episode + episodeProgress) / job.episodes : episodeProgress);
 }
 
 QString TranslationService::savedTranslation(const QUrl &videoUrl) const
@@ -716,8 +881,8 @@ QCoro::Task<> TranslationService::translateBatches(std::shared_ptr<Job> job, std
             batches->translations[start + i] = result.translations.at(i);
         }
         batches->doneLines += result.translations.size();
-        setProgress(double(batches->doneLines) / batches->lines.size());
-        setStatusText(i18n("Translating… %1 of %2 lines", batches->doneLines, batches->lines.size()));
+        setJobProgress(*job, double(batches->doneLines) / batches->lines.size());
+        setLinesStatus(*job, batches->doneLines, batches->lines.size());
     }
 }