# Replaces instances of %m3u, %pls, %srv in a command string
# ‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾
#  · Also understands short aliases %l, %f, %d.
#  · And can embed %title or %genre placeholders.
#  · Replace .pls URL with local .m3u file depending on map.
#
def interpol(cmd, source="pls", row={}, add_default=True):
    row = copy.copy(row)

    # Inject other meta fields (%title, %genre, %playing, %format, etc.)

    rx_keys = "[\$\%](" + "|".join(row.keys()) + ")\\b"
    cmd = re.sub(rx_keys, lambda m: "%r" % str(row.get(m.group(1))), cmd)

    # Add default %pls if cmd has no %url placeholder
    if not add_default and cmd.find("%") < 0:
        cmd = cmd + " %pls"
        # "pls" as default requires no conversion for most channels, and seems broadly supported by players

    # Playlist type placeholders (%pls, %m3u, %xspf, etc.)
    for dest, rx in placeholder_map.items():
        if re.search(rx, cmd, re.X):
            # no conversion
            if conf.playlist_asis:
                url = row["url"]
            # e.g. from .m3u to .pls
            else:
                url = convert_playlist(row["url"], listfmt(source), listfmt(dest), local_file=True, row=row)
            # insert quoted URL/filepath
            return re.sub(rx, quote(url), cmd, 2, re.X)

    if not add_default:
        return cmd
    else:
         return "/bin/false"


# Substitute streaming address with desired playlist format
# ‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾
# Converts input rows/urls, probes for playlist format, fetches them
# and possibly converts remote .pls to local .m3u/.xpsf filename or
# just returns direct "srv" urls.