package supervisor

import (
	"strings"

	"drmdecryption/app"
	"drmdecryption/apps/streamd/internal/db"
)

// streamSettings are the downloader knobs for one stream. They come from the
// stream's app module when it declares them, so the supervisor never has to
// guess from an app name or a stream name.
type streamSettings struct {
	VideoSelect  string
	AudioSelect  string
	Rewriter     string
	LiveWait     int
	TSReadyBytes int64
	// IsHLS drives packaging choices that depend on the manifest format.
	IsHLS bool
}

const (
	defaultLiveWait     = 2
	defaultTSReadyBytes = 256 * 1024
	// hlsTSReadyBytes buffers more before probing: an HLS pipe-mux often starts
	// with incomplete audio config.
	hlsTSReadyBytes = 2 * 1024 * 1024
	hlsLiveWait     = 6
)

// settingsFor resolves a stream's downloader settings: the app module's
// declarations first, then the stream row, then neutral defaults.
func settingsFor(st db.Stream) streamSettings {
	s := streamSettings{
		VideoSelect:  strings.TrimSpace(st.VideoSelect),
		AudioSelect:  strings.TrimSpace(st.AudioSelect),
		Rewriter:     strings.TrimSpace(st.Rewriter),
		LiveWait:     defaultLiveWait,
		TSReadyBytes: defaultTSReadyBytes,
		IsHLS:        isHLS(st),
	}
	if a, err := app.Get(st.App); err == nil {
		if sd, ok := a.(app.StreamDefaults); ok {
			if s.VideoSelect == "" {
				s.VideoSelect = sd.VideoSelect()
			}
			if s.AudioSelect == "" {
				s.AudioSelect = sd.AudioSelect()
			}
			if s.Rewriter == "" {
				s.Rewriter = sd.RewriterName()
			}
			if n := sd.LiveWaitSeconds(); n > 0 {
				s.LiveWait = n
			}
			if n := sd.TSReadyBytes(); n > 0 {
				s.TSReadyBytes = n
			}
		}
	}
	if s.IsHLS {
		if s.LiveWait == defaultLiveWait {
			s.LiveWait = hlsLiveWait
		}
		if s.TSReadyBytes == defaultTSReadyBytes {
			s.TSReadyBytes = hlsTSReadyBytes
		}
	}
	if s.VideoSelect == "" {
		s.VideoSelect = "for=best"
	}
	if s.AudioSelect == "" {
		s.AudioSelect = "for=best"
	}
	if s.Rewriter == "" {
		s.Rewriter = "none"
	}
	return s
}

// isHLS reports whether a stream's manifest is an HLS playlist, by URL shape.
// No provider host is consulted: a module declares its own needs through
// app.StreamDefaults.
func isHLS(st db.Stream) bool {
	return strings.Contains(strings.ToLower(strings.TrimSpace(st.MPD)), ".m3u8")
}