#!/usr/bin/env python3
# -*- coding: utf-8 -*-
#
# Copyright 2020 SkyWater PDK Authors
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     https://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#
# SPDX-License-Identifier: Apache-2.0

"""
A module containing various functions related to `magic` tool
"""

import os
import re
import subprocess
from typing import Tuple

FATAL_ERROR = re.compile('((Error parsing)|(No such file or directory)|(couldn\'t be read))')  # noqa: E501


class MagicError(Exception):
    """
    Raised when there are errors in magic tool execution.
    """
    def __init__(self, message, errorcode):
        self.errorcode = errorcode
        super().__init__(message)


def add_magic_tcl_header(ofile, gdsfile):
    """
    Adds a header to a TCL file.

    Parameters
    ----------
    ofile : TextIOWrapper
        output file stream
    gdsfile : str
        path to GDS file
    """
    ofile.write('#!/bin/env wish\n')
    ofile.write('drc off\n')
    ofile.write('scalegrid 1 2\n')
    ofile.write('cif istyle vendorimport\n')
    ofile.write('gds readonly true\n')
    ofile.write('gds rescale false\n')
    ofile.write('tech unlock *\n')
    ofile.write('cif warning default\n')
    ofile.write('set VDD VPWR\n')
    ofile.write('set GND VGND\n')
    ofile.write('set SUB SUBS\n')
    ofile.write(f'gds read {gdsfile}\n')


def create_tcl_plot_script_for_gds(
        input_gds,
        output_tcl=None,
        output_svg=None) -> Tuple[str, str]:
    """
    Creates TCL script for creating cell layout image from GDS file.

    Parameters
    ----------
    input_gds : str
        Path to GDS file
    output_tcl : str
        Path to created TCL file
    output_svg : str
        Path where the SVG file created by output_tcl script should be located

    Returns
    -------
    Tuple(str, str) : paths to TCL and SVG files (can be used if autogenerated)
    """
    input_gds = os.path.abspath(input_gds)

    destdir, gdsfile = os.path.split(input_gds)
    basename, ext = os.path.splitext(gdsfile)

    if not output_tcl:
        output_tcl = os.path.join(destdir, f'{basename}.gds2svg.tcl')

    if not output_svg:
        output_svg = os.path.join(destdir, f'{basename}.tmp.svg')

    with open(output_tcl, 'w') as ofile:
        add_magic_tcl_header(ofile, input_gds)
        ofile.write(f"load {basename}\n")
        ofile.write("box 0 0 0 0\n")
        ofile.write("select top cell\n")
        ofile.write("expand\n")
        ofile.write("view\n")
        ofile.write("select clear\n")
        ofile.write("box position -1000 -1000\n")
        ofile.write(f"plot svg {output_svg}\n")
        ofile.write("quit -noprompt\n")

    return output_tcl, output_svg


def run_magic(
        tcl_file,
        technology_file,
        workdir=None,
        display_workstation='NULL',
        debug=False,
        magic_executable='magic') -> int:
    """
    Generates layout files for a given TCL file and technology file.

    Uses `magic` tool for generating the layout.

    Parameters
    ----------
    tcl_file : str
        path to input TCL file
    technology_file : str
        path to the technology file
    workdir : str
        path to the working directory for `magic`
    display_workstation : str
        graphics interface, can be NULL, X11 or OpenGL
    debug : bool
        True if all output from `magic` tool should be displayed
    magic_executable : str
        Path to `magic` executable

    Returns
    -------
        int: return code for `magic` tool

    Raises
    ------
    AssertionError
        Raised when display_workstation is not NULL, X11 or OpenGL
    MagicError
        Raised when `magic` tool failed to run for given files
    """
    assert display_workstation in ['NULL', 'X11', 'OpenGL', 'XR']
    cmd = [
        magic_executable,
        '-nowrapper',
        '-noconsole',
        f'-d{display_workstation}',
        f'-T{os.path.abspath(technology_file)}',
        '-D' if debug else '',
        os.path.abspath(tcl_file)
    ]
    result = subprocess.run(
        cmd,
        stdin=subprocess.DEVNULL,
        stdout=subprocess.PIPE,
        stderr=subprocess.STDOUT,
        cwd=workdir,
        universal_newlines=True
    )

    errors_present = False
    for line in result.stdout.splitlines():
        m = FATAL_ERROR.match(line)
        if m:
            errors_present = True
            break

    if result.returncode != 0 or errors_present:
        msg = ['ERROR: There were fatal errors in magic.']
        msg += result.stdout.splitlines()
        msg += [f'ERROR: Magic exited with status {result.returncode}']
        msg.append("")
        msg.append(" ".join(cmd))
        msg.append('='*75)
        msg.append(result.stdout)
        msg.append('='*75)
        msg.append(tcl_file)
        msg.append('-'*75)
        msg.append(msg[0])
        raise MagicError('\n'.join(msg), result.returncode)

    if debug:
        print(result.stdout)