#!/usr/bin/env python

# This Source Code Form is subject to the terms of the Mozilla Public
# License, v. 2.0. If a copy of the MPL was not distributed with this
# file, You can obtain one at https://mozilla.org/MPL/2.0/.

import re
import os
import sys

from io import BytesIO
from pseudo_elements import PseudoElementData

import build


# Matches lines like `GK_ATOM(foo, "foo")`.
PATTERN = re.compile(
    r'^GK_ATOM\(([^,]*),[^"]*"([^"]*)"\)',
    re.MULTILINE,
)
FILE = "include/nsGkAtomList.h"


def map_atom(ident):
    if ident in {
        "box",
        "loop",
        "match",
        "mod",
        "ref",
        "self",
        "type",
        "use",
        "where",
        "in",
    }:
        return ident + "_"
    return ident


class Atom:
    def __init__(self, ident, value):
        self.ident = "nsGkAtoms_{}".format(ident)
        self.original_ident = ident
        self.value = value


def collect_atoms(objdir):
    atoms = []
    path = os.path.abspath(os.path.join(objdir, FILE))
    print("cargo:rerun-if-changed={}".format(path))
    with open(path) as f:
        content = f.read()
        for result in PATTERN.finditer(content):
            atoms.append(
                Atom(result.group(1), result.group(2))
            )
    return atoms


class FileAvoidWrite(BytesIO):
    """File-like object that buffers output and only writes if content changed."""

    def __init__(self, filename):
        BytesIO.__init__(self)
        self.name = filename

    def write(self, buf):
        if isinstance(buf, str):
            buf = buf.encode("utf-8")
        BytesIO.write(self, buf)

    def close(self):
        buf = self.getvalue()
        BytesIO.close(self)
        try:
            with open(self.name, "rb") as f:
                old_content = f.read()
                if old_content == buf:
                    print("{} is not changed, skip".format(self.name))
                    return
        except IOError:
            pass
        with open(self.name, "wb") as f:
            f.write(buf)

    def __enter__(self):
        return self

    def __exit__(self, type, value, traceback):
        if not self.closed:
            self.close()


PRELUDE = """
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at https://mozilla.org/MPL/2.0/. */

// Autogenerated file created by components/style/gecko/regen_atoms.py.
// DO NOT EDIT DIRECTLY
"""[
    1:
]

RULE_TEMPLATE = """
    ("{atom}") => {{{{
        #[allow(unsafe_code)] #[allow(unused_unsafe)]
        unsafe {{ $crate::string_cache::Atom::from_index_unchecked({index}) }}
    }}}};
"""[
    1:
]

MACRO_TEMPLATE = """
/// Returns a static atom by passing the literal string it represents.
#[macro_export]
macro_rules! atom {{
{body}\
}}
"""


def write_atom_macro(atoms, file_name):
    with FileAvoidWrite(file_name) as f:
        f.write(PRELUDE)
        macro_rules = [
            RULE_TEMPLATE.format(atom=atom.value, name=atom.ident, index=i)
            for (i, atom) in enumerate(atoms)
        ]
        f.write(MACRO_TEMPLATE.format(body="".join(macro_rules)))


def generate_atoms(dist, out):
    atoms = collect_atoms(dist)
    write_atom_macro(atoms, os.path.join(out, "atom_macro.rs"))


def generate_pseudo_elements(dist, out):
    data = PseudoElementData()
    pseudo_definition_template = os.path.join(
        os.path.dirname(__file__), "pseudo_element_definition.mako.rs"
    )

    print(f"cargo:rerun-if-changed={pseudo_definition_template}")
    for f in data.path_dependencies:
        print(f"cargo:rerun-if-changed={f}")

    target = os.path.join(out, "pseudo_element_definition.rs")
    with FileAvoidWrite(target) as f:
        f.write(build.render(pseudo_definition_template, PSEUDOS=data.all_pseudos()))


if __name__ == "__main__":
    if len(sys.argv) != 3:
        print("Usage: {} dist out".format(sys.argv[0]))
        exit(2)
    dist = sys.argv[1]
    out = sys.argv[2]
    generate_atoms(dist, out)
    generate_pseudo_elements(dist, out)