import sys


# Log messages sent from a plugin instance are transmitted via stderr and are
# encoded with a prefix consisting of special character SOH, then the log
# level (one of t, d, i, w, e, or p - corresponding to trace, debug, info,
# warning, error and progress levels respectively), then special character
# STX.
#
# The LogTrace, LogDebug, LogInfo, LogWarning, and LogError methods, and their equivalent
# formatted methods are intended for use by plugin instances to transmit log
# messages. The LogProgress method is also intended for sending progress data.
#


def __prefix(level_char):
    start_level_char = b"\x01"
    end_level_char = b"\x02"

    ret = start_level_char + level_char + end_level_char
    return ret.decode()


def __log(level_char, s):
    if level_char == "":
        return

    print(__prefix(level_char) + s + "\n", file=sys.stderr, flush=True)


def LogTrace(s):
    __log(b"t", s)


def LogDebug(s):
    __log(b"d", s)


def LogInfo(s):
    __log(b"i", s)


def LogWarning(s):
    __log(b"w", s)


def LogError(s):
    __log(b"e", s)


def LogProgress(p):
    progress = min(max(0, p), 1)
    __log(b"p", str(progress))