# Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
# See https://llvm.org/LICENSE.txt for license information.
# SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception

import os
import shutil
import subprocess
import tempfile
from ipykernel.kernelbase import Kernel

__version__ = "0.0.1"


class TableGenKernel(Kernel):
    """Kernel using llvm-tblgen inside jupyter.

    All input is treated as TableGen unless the first non whitespace character
    is "%" in which case it is a "magic" line.

    The supported magic is:
    * %args - to set the arguments passed to llvm-tblgen.
    * %reset - to reset the cached code and magic state.

    These are "cell magic" meaning it applies to the whole cell. Therefore
    it must be the first line, or part of a run of magic lines starting
    from the first line.

    ```tablgen
    %args
    %reset
    %args --print-records --print-detailed-records
    class Stuff {
      string Name;
    }

    def a_thing : Stuff {}
    ```

    """

    implementation = "tablegen"
    implementation_version = __version__

    language_version = __version__
    language = "tablegen"
    language_info = {
        "name": "tablegen",
        "mimetype": "text/x-tablegen",
        "file_extension": ".td",
        "pygments_lexer": "text",
    }

    def __init__(self, **kwargs):
        Kernel.__init__(self, **kwargs)
        self._executable = None
        # A list of (code, magic) tuples.
        # All the previous cell's code we have run since the last reset.
        # This emulates a persistent state like a Python interpreter would have.
        self._previous_code = ""
        # The most recent set of magic since the last reset.
        self._previous_magic = {}

    @property
    def banner(self):
        return "llvm-tblgen kernel %s" % __version__

    def get_executable(self):
        """If this is the first run, search for llvm-tblgen.
        Otherwise return the cached path to it."""
        if self._executable is None:
            path = os.environ.get("LLVM_TBLGEN_EXECUTABLE")
            if path is not None and os.path.isfile(path) and os.access(path, os.X_OK):
                self._executable = path
            else:
                path = shutil.which("llvm-tblgen")
                if path is None:
                    raise OSError(
                        "llvm-tblgen not found. Put it on your PATH or set the"
                        " environment variable LLVM_TBLGEN_EXECUTABLE to point to it."
                    )
                self._executable = path

        return self._executable

    def get_magic(self, code):
        """Given a block of code remove the magic lines from it.
        Returns a tuple of newline joined code lines and a dictionary of magic.
        Where the key is the magic name (minus the %) and the values are lists
        of the arguments to the magic.

        Currently we only look for "cell magic" which must be at the start of
        the cell. Meaning the first line, or a set of lines beginning with %
        that come before the first non-magic line.

        >>> k.get_magic("")
        ('', {})
        >>> k.get_magic("Hello World.\\nHello again.")
        ('Hello World.\\nHello again.', {})
        >>> k.get_magic("   %foo a b c")
        ('', {'foo': ['a', 'b', 'c']})
        >>> k.get_magic("%foo\\n   %foo a b c\\nFoo")
        ('Foo', {'foo': ['a', 'b', 'c']})
        >>> k.get_magic("%foo\\n%bar\\nFoo")
        ('Foo', {'foo': [], 'bar': []})
        >>> k.get_magic("Foo\\n%foo\\nFoo")
        ('Foo\\n%foo\\nFoo', {})
        >>> k.get_magic("%bar\\n\\n%foo")
        ('\\n%foo', {'bar': []})
        >>> k.get_magic("%foo a b\\n   Foo\\n%foo c d")
        ('   Foo\\n%foo c d', {'foo': ['a', 'b']})
        >>> k.get_magic("%foo a b\\n \\n%foo c d")
        (' \\n%foo c d', {'foo': ['a', 'b']})
        """
        magic = {}
        code_lines = []

        lines = code.splitlines()
        while lines:
            line = lines.pop(0)
            possible_magic = line.lstrip()
            if possible_magic.startswith("%"):
                magic_parts = possible_magic.split()
                # Key has the % removed
                magic[magic_parts[0][1:]] = magic_parts[1:]
            else:
                code_lines = [line, *lines]
                break

        return "\n".join(code_lines), magic

    def get_code_and_args(self, new_code):
        """Get the code that do_execute should use, taking into account
        the code from any cached cells.

        Returns the code to compile and the arguments to use to do so.

        >>> k._previous_code = ""
        >>> k._previous_magic = {}
        >>> k.get_code_and_args("")
        ('', [])
        >>> k.get_code_and_args("%args 1\\nSome code")
        ('Some code', ['1'])
        >>> k.get_code_and_args("%args 2\\nSome more code")
        ('Some code\\nSome more code', ['2'])
        >>> k.get_code_and_args("%reset\\n%args 3 4\\nSome new code")
        ('Some new code', ['3', '4'])
        >>> k.get_code_and_args("%reset\\nSome new code")
        ('Some new code', [])
        """
        new_code, new_magic = self.get_magic(new_code)

        # Only a reset in the newest cell actually does a reset.
        if new_magic.get("reset") is not None:
            self._previous_code = new_code
            self._previous_magic = new_magic
        else:
            self._previous_code += ("\n" if self._previous_code else "") + new_code
            self._previous_magic.update(new_magic)

        return self._previous_code, self._previous_magic.get("args", [])

    def make_status(self):
        return {
            "status": "ok",
            "execution_count": self.execution_count,
            "payload": [],
            "user_expressions": {},
        }

    def send_stream(self, name, content):
        self.send_response(self.iopub_socket, "stream", {"name": name, "text": content})

        return self.make_status()

    def send_stderr(self, stderr):
        return self.send_stream("stderr", stderr)

    def send_stdout(self, stdout):
        return self.send_stream("stdout", stdout)

    def do_execute(
        self, code, silent, store_history=True, user_expressions=None, allow_stdin=False
    ):
        """Execute user code using llvm-tblgen binary."""
        all_code, args = self.get_code_and_args(code)

        # If we cannot find llvm-tblgen, propogate the error to the notebook.
        # (in case the user is not able to see the output from the Jupyter server)
        try:
            executable = self.get_executable()
        except Exception as e:
            return self.send_stderr(str(e))

        with tempfile.TemporaryFile("w+") as f:
            f.write(all_code)
            f.seek(0)
            got = subprocess.run(
                [executable, *args],
                stdin=f,
                stderr=subprocess.PIPE,
                stdout=subprocess.PIPE,
                universal_newlines=True,
            )

        if not silent:
            if got.stderr:
                return self.send_stderr(got.stderr)
            else:
                return self.send_stdout(got.stdout)
        else:
            return self.make_status()


if __name__ == "__main__":
    import doctest

    doctest.testmod(extraglobs={"k": TableGenKernel()})