package main

import (
	"bufio"
	"bytes"
	"net/url"
	"path"
	"regexp"
	"strings"
)

func rewriteM3U8(raw []byte, id string) []byte {
	// Wir bauen alle URIs so um, dass sie wieder über /api/record/preview laufen.
	// Wichtig: play=1 bleibt dran, damit Folge-Requests (segments, chunklists) auch ohne Hover gehen.
	base := "/api/record/preview?id=" + url.QueryEscape(id) + "&file="

	var out bytes.Buffer
	sc := bufio.NewScanner(bytes.NewReader(raw))

	// Scanner default token limit 64K – m3u8 ist normalerweise klein, passt.
	// Wenn du riesige Playlists hast, kannst du Buffer erhöhen.

	for sc.Scan() {
		line := sc.Text()
		trim := strings.TrimSpace(line)

		if trim == "" {
			out.WriteByte('\n')
			continue
		}

		// Kommentare/Tags: ggf. URI="..." in Tags rewriten
		if strings.HasPrefix(trim, "#") {
			// EXT-X-KEY:URI="..."
			line = rewriteAttrURI(line, base)
			out.WriteString(line)
			out.WriteByte('\n')
			continue
		}

		// Nicht-Tag => URI (segment oder child-playlist)
		u := trim

		// Absolut? dann lassen
		if strings.HasPrefix(u, "http://") || strings.HasPrefix(u, "https://") {
			out.WriteString(line)
			out.WriteByte('\n')
			continue
		}

		// Wenn es schon unser API ist, lassen
		if strings.Contains(u, "/api/record/preview") {
			out.WriteString(line)
			out.WriteByte('\n')
			continue
		}

		// Nur basename nehmen (ffmpeg schreibt i.d.R. keine Subdirs)
		name := path.Base(u)

		// Hier play=1 mitschicken:
		out.WriteString(base + url.QueryEscape(name) + "&play=1")
		out.WriteByte('\n')
	}

	if err := sc.Err(); err != nil {
		// Wenn Scanner aus irgendeinem Grund scheitert: lieber raw zurück (besser als kaputt)
		return raw
	}
	return out.Bytes()
}

func rewriteAttrURI(line, base string) string {
	// Rewritet URI="xyz" in EXT-X-KEY / EXT-X-MAP / EXT-X-MEDIA / EXT-X-I-FRAME-STREAM-INF etc.
	// Nur relative URIs werden angefasst.
	const key = `URI="`
	i := strings.Index(line, key)
	if i < 0 {
		return line
	}

	j := strings.Index(line[i+len(key):], `"`)
	if j < 0 {
		return line
	}

	start := i + len(key)
	end := start + j
	val := line[start:end]
	valTrim := strings.TrimSpace(val)

	// absolut oder schon preview => nix tun
	if strings.HasPrefix(valTrim, "http://") || strings.HasPrefix(valTrim, "https://") || strings.Contains(valTrim, "/api/record/preview") {
		return line
	}

	name := path.Base(valTrim)
	repl := base + url.QueryEscape(name) + "&play=1"

	return line[:start] + repl + line[end:]
}

func rewriteQuotedURI(line, id string) string {
	re := regexp.MustCompile(`URI="([^"]+)"`)
	return re.ReplaceAllStringFunc(line, func(m string) string {
		sub := re.FindStringSubmatch(m)
		if len(sub) != 2 {
			return m
		}
		u := sub[1]
		uu := strings.TrimSpace(u)
		if uu == "" || strings.HasPrefix(uu, "http://") || strings.HasPrefix(uu, "https://") || strings.HasPrefix(uu, "/") {
			return m
		}
		repl := "/api/record/preview?id=" + url.QueryEscape(id) + "&file=" + url.QueryEscape(uu)
		return `URI="` + repl + `"`
	})
}

func rewriteM3U8ToPreviewEndpoint(m3u8 string, id string) string {
	lines := strings.Split(m3u8, "\n")
	escapedID := url.QueryEscape(id)

	for i, line := range lines {
		l := strings.TrimSpace(line)
		if l == "" || strings.HasPrefix(l, "#") {
			continue
		}
		// Segment/URI-Zeilen umschreiben
		lines[i] = "/api/record/preview?id=" + escapedID + "&file=" + url.QueryEscape(l)
	}

	return strings.Join(lines, "\n")
}