feat(app): add internal components batch 2

internal/app/download_quality.go

@@ -0,0 +1,93 @@
+package app
+
+import (
+	"context"
+	"encoding/json"
+	"io"
+	"net/http"
+)
+
+func readDownloadRequest(writer http.ResponseWriter, request *http.Request) ([]string, *int, bool) {
+	var input struct {
+		IDs     []string `json:"ids"`
+		Quality *int     `json:"quality"`
+	}
+	decoder := json.NewDecoder(http.MaxBytesReader(writer, request.Body, 1<<20))
+	decoder.DisallowUnknownFields()
+	if err := decoder.Decode(&input); err != nil {
+		writeJSON(writer, http.StatusBadRequest, map[string]string{"error": "下载参数无效"})
+		return nil, nil, false
+	}
+	if decoder.Decode(new(any)) != io.EOF || input.Quality != nil && (*input.Quality < 0 || *input.Quality > 4320) {
+		writeJSON(writer, http.StatusBadRequest, map[string]string{"error": "下载清晰度选项无效"})
+		return nil, nil, false
+	}
+	ids, ok := cleanIDList(writer, input.IDs)
+	if !ok {
+		return nil, nil, false
+	}
+	for index, id := range ids {
+		_, sourceID, valid := splitProviderDramaID(id)
+		if !valid {
+			writeJSON(writer, http.StatusBadRequest, map[string]string{"error": "此版本仅支持红果剧集 ID"})
+			return nil, nil, false
+		}
+		ids[index] = providerDramaID(sourceHongguo, sourceID)
+	}
+	return ids, input.Quality, true
+}
+
+func preferredDownloadQuality(requested int, available []int) int {
+	best, lowest := 0, 0
+	for _, quality := range available {
+		if quality <= 0 || quality > 4320 {
+			continue
+		}
+		if lowest == 0 || quality < lowest {
+			lowest = quality
+		}
+		if (requested <= 0 || quality <= requested) && quality > best {
+			best = quality
+		}
+	}
+	if best == 0 {
+		return lowest
+	}
+	return best
+}
+
+func (downloader *Downloader) selectDownloadQuality(ctx context.Context, task Task, media providerMedia) (providerMedia, error) {
+	qualities := []int{media.Quality}
+	validVariants := make([]providerMedia, 0, len(media.Variants)+1)
+	for _, variant := range media.Variants {
+		if isProviderHTTPMediaURL(variant.URL) {
+			qualities = append(qualities, variant.Quality)
+			validVariants = append(validVariants, variant)
+		}
+	}
+	if isProviderHTTPMediaURL(media.URL) {
+		current := media
+		current.Variants = nil
+		validVariants = append(validVariants, current)
+	}
+	media.Variants = validVariants
+	if variants := playbackHLSVariants(media.Playlist); len(variants) > 0 {
+		qualities = nil
+		for _, variant := range variants {
+			qualities = append(qualities, variant.quality)
+		}
+	}
+	quality := preferredDownloadQuality(task.DownloadQuality, qualities)
+	selected, err := downloader.selectPlaybackQuality(context.WithValue(ctx, playbackQualityKey{}, quality), media)
+	if err != nil {
+		return providerMedia{}, err
+	}
+	var available []int
+	for _, option := range playbackQualityOptions(selected) {
+		available = append(available, option.Value)
+	}
+	downloader.recordDiagnostic(diagnosticEvent{Level: "info", Event: "download.media", Source: sourceFromDramaID(task.DramaID),
+		DramaID: task.DramaID, DramaTitle: task.DramaTitle, Episode: task.Index, Quality: selected.Quality, RequestedQuality: task.DownloadQuality, AvailableQualities: available,
+		Message: "下载保留源媒体的音视频编码和分辨率"})
+	return selected, nil
+}