#!/usr/bin/env python
# -------------------------------------------------------------------------------------
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, version 3.
#
# This program is distributed in the hope that it will be useful, but
# WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
# General Public License for more details.
#
# The text of the license is located in the root directory of the source package.
# -------------------------------------------------------------------------------------

__author__ = "Tristan Hoellinger, Mayeul Aubin"
__version__ = "0.1"
__date__ = "2024"
__license__ = "GPLv3"

"""
Tools to deal with low-level operations e.g. redirecting C stdout.
"""

from contextlib import contextmanager
import ctypes
import io
import os, sys
import tempfile

libc = ctypes.CDLL(None)
c_stdout = ctypes.c_void_p.in_dll(libc, "stdout")


# Taken from:
# https://eli.thegreenplace.net/2015/redirecting-all-kinds-of-stdout-in-python/
@contextmanager
def stdout_redirector(stream):
    """A context manager that redirects stdout to the given stream. For instance, this
    could be used to redirect C code stdout to None (to avoid cluttering the terminal eg
    when using tqdm).

    Args:
        stream (file-like object): The stream to which stdout should be redirected.
    Example:
        >>> with stdout_redirector(stream):
        >>>     print("Hello world!") # Will be printed to stream instead of stdout.
    """
    # The original fd stdout points to. Usually 1 on POSIX systems.
    original_stdout_fd = sys.stdout.fileno()

    def _redirect_stdout(to_fd):
        """Redirect stdout to the given file descriptor."""
        # Flush the C-level buffer stdout
        libc.fflush(c_stdout)
        # Flush and close sys.stdout - also closes the file descriptor (fd)
        sys.stdout.close()
        # Make original_stdout_fd point to the same file as to_fd
        os.dup2(to_fd, original_stdout_fd)
        # Create a new sys.stdout that points to the redirected fd
        sys.stdout = io.TextIOWrapper(os.fdopen(original_stdout_fd, "wb"))

    # Save a copy of the original stdout fd in saved_stdout_fd
    saved_stdout_fd = os.dup(original_stdout_fd)
    try:
        # Create a temporary file and redirect stdout to it
        tfile = tempfile.TemporaryFile(mode="w+b")
        _redirect_stdout(tfile.fileno())
        # Yield to caller, then redirect stdout back to the saved fd
        yield
        _redirect_stdout(saved_stdout_fd)
        # Copy contents of temporary file to the given stream
        tfile.flush()
        tfile.seek(0, io.SEEK_SET)
        stream.write(tfile.read())
    finally:
        tfile.close()
        os.close(saved_stdout_fd)


# Adapted from:
# https://eli.thegreenplace.net/2015/redirecting-all-kinds-of-stdout-in-python/
c_stderr = ctypes.c_void_p.in_dll(libc, "stderr")


@contextmanager
def stderr_redirector(stream):
    """A context manager that redirects stderr to the given stream.
    For instance, this could be used to redirect C code stderr to None (to avoid
    cluttering the terminal eg when using tqdm).
    WARNING: this should be used with CAUTION as it redirects all stderr, so NONE OF THE
             ERRORS WILL BE DISPLAYED, no matter the severity.

    Args:
        stream (file-like object): The stream to which stdout should be redirected.
    """
    # The original fd stdout points to. Usually 1 on POSIX systems.
    original_stderr_fd = sys.stderr.fileno()

    def _redirect_stderr(to_fd):
        """Redirect stderr to the given file descriptor."""
        # Flush the C-level buffer stderr
        libc.fflush(c_stderr)
        # Flush and close sys.stderr - also closes the file descriptor (fd)
        sys.stderr.close()
        # Make original_stderr_fd point to the same file as to_fd
        os.dup2(to_fd, original_stderr_fd)
        # Create a new sys.stderr that points to the redirected fd
        sys.stderr = io.TextIOWrapper(os.fdopen(original_stderr_fd, "wb"))

    # Save a copy of the original stdout fd in saved_stdout_fd
    saved_stderr_fd = os.dup(original_stderr_fd)
    try:
        # Create a temporary file and redirect stdout to it
        tfile = tempfile.TemporaryFile(mode="w+b")
        _redirect_stderr(tfile.fileno())
        # Yield to caller, then redirect stdout back to the saved fd
        yield
        _redirect_stderr(saved_stderr_fd)
        # Copy contents of temporary file to the given stream
        tfile.flush()
        tfile.seek(0, io.SEEK_SET)
        stream.write(tfile.read())
    finally:
        tfile.close()
        os.close(saved_stderr_fd)


def print_level(level:int, module:str):
    """
    Generate a string with the current time, the module name and the level of the message.
    """
    from datetime import datetime

    max_len_module = 14

    date = datetime.now()
    out=""
    out+=date.strftime("%H:%M:%S")
    out+=" | "
    out+=module.upper().center(max_len_module)
    out+=" | "
    out+=">"*level
    out+=" "

    return out


def print_message(message:str, level:int, module:str, verbose:int = 1):
    """
    Print a message with a given level and module name.
    """
    if verbose >= 1:
        print(print_level(level, module)+message)


def print_header(verbose:int=1):
    """
    Print the header of the program.
    """
    if verbose >= 1:
        from datetime import datetime
        date = datetime.now()
        width=40
        program_name="SBMY CONTROL"
        print("#"*width)
        print("# "+program_name.center(width-4)+" #")
        print("# "+date.strftime("%Y-%m-%d %H:%M:%S").center(width-4)+" #")
        print("#"*width)
        print("")


def print_starting_module(module:str, verbose:int=1):
    """
    Print the starting message of a module.
    """
    if verbose >= 1:
        print(print_level(0, module)+f"Starting {module} module.")


def print_ending_module(module:str, verbose:int=1):
    """
    Print the ending message of a module.
    """
    if verbose >= 1:
        print(print_level(0, module)+f"Ending {module} module.")


def wait_until_file_exists(filename:str, verbose:int=1, limit:int=1200):
    """
    Wait until a file exists.
    """
    from time import sleep
    from os.path import isfile

    k=0
    while not isfile(filename) and k<limit:
        if k%60 == -1:
            print_message(f"Waiting for {filename} to exist. {k//60} minutes elapsed.", 3, "low level", verbose=verbose)
        sleep(1)
    if k>=limit:
        raise TimeoutError(f"File {filename} not found after {limit} seconds.")
    if k>60:
        print_message(f"File {filename} exists. {k//60} minutes elapsed.", 3, "low level", verbose=verbose)


def get_progress_from_logfile(filename):
    """
    Get the number of operations done and the total number of operations from a log file.
    """
    current_operation = 0
    total_operations = 0
    from os.path import isfile
    if not isfile(filename):
        raise FileNotFoundError(f"Log file {filename} not found.")
    with open(filename, "r") as f:
        lines = f.readlines()
    for line in lines:
        if " operation " in line:
            try:
                splitted_line = line.split(" operation ")[1]
                splitted_line = splitted_line.split(":")[0]
                current_operation = int(splitted_line.split("/")[0])
                total_operations = int(splitted_line.split("/")[1])
            except:
                pass
        elif "Fatal" in line or "Error" in line:
            return -1, -1
    return current_operation, total_operations


def progress_bar_from_logfile(filename:str, desc:str="", verbose:int=1, **kwargs):
    """
    Print a progress bar from a log file.
    """
    from tqdm import tqdm
    from time import sleep
    k=0
    limit=600
    update_interval=0.2
    sleep(2) # Wait for the process to be launched, and for the previous log file to be overwritten if necessary.
    wait_until_file_exists(filename, verbose=verbose, limit=limit)
    current_operation, total_operations = get_progress_from_logfile(filename)
    previous_operation = 0

    while total_operations == 0: # Wait for the simulation to be initialised, and to run the first operation 
        sleep(2)
        current_operation, total_operations = get_progress_from_logfile(filename)

    if current_operation == total_operations:
        # print_message("Progress bar not needed, the process is already finished.", 3, "low level", verbose=verbose)
        if current_operation == -1:
            print_message("Error appeared in log file, skipping it.",level=3,module="low level",verbose=verbose)
        return
    
    with tqdm(desc=desc, total=total_operations, disable=(verbose==0), **kwargs) as pbar:
        while current_operation < total_operations and k*update_interval < limit:
            sleep(update_interval)
            current_operation, total_operations = get_progress_from_logfile(filename)
            if current_operation > previous_operation:
                pbar.update(current_operation-previous_operation)
                previous_operation = current_operation
            if current_operation == -1:
                print_message("Error appeared in log file, skipping it.",level=3,module="low level",verbose=verbose)
                return
            k+=1
    if k*update_interval >= limit:
        print_message(f"Progress bar timed out after {limit} seconds.", 3, "low level", verbose=verbose)
    
    return