#!/usr/bin/env python3

"""
Generate C file to handle keysym names
"""

import argparse
import itertools
import random
import sys
from pathlib import Path
from typing import Generator, Iterable, Iterator

import perfect_hash

# Root of the project
SCRIPT = Path(__file__)
ROOT = SCRIPT.parent.parent

sys.path.append(str(SCRIPT.parent))

from keysyms import Keysym, Keysyms, Semantics  # noqa: E402

# libxkbcommon Keysyms names header
KEYSYMS_NAMES_HEADER = ROOT / "src" / "keysym-names.h"
if not KEYSYMS_NAMES_HEADER.is_file():
    raise FileNotFoundError(KEYSYMS_NAMES_HEADER)


# Parse commands
parser = argparse.ArgumentParser(description="Generate C file to handle keysym names")
parser.add_argument(
    "c_header", type=Path, help="Path to the libxkbcommon keysym header"
)
parser.add_argument("gperf", type=Path, help="Path to the gperf file")
args = parser.parse_args()

# Set the seed explicitly, so we reduce diff
random.seed(b"libxkbcommon")


all_keysyms = Keysyms.parse_file(args.c_header)
entries: tuple[Keysym, ...] = tuple(
    itertools.chain.from_iterable(all_keysyms.by_value.values())
)

# Sort based on the keysym name:
#   1. Sort by the casefolded name: e.g. kana_ya < kana_YO.
#   2. If same casefolded name, then sort by cased name, i.e for
#      ASCII: upper before lower: e.g kana_YA < kana_ya.
# E.g. kana_YA < kana_ya < kana_YO < kana_yo
# WARNING: this sort must not be changed, as some functions e.g.
# xkb_keysym_from_name rely on upper case variant occuring first.
entries_isorted = sorted(entries, key=lambda e: (e.name.casefold(), e.name))
# Sort based on keysym value. Sort is stable so in case of duplicate, the first
# keysym occurence stays first.
entries_kssorted = sorted(entries, key=lambda e: e.value)

print(
    f"""
/**
 * This file comes from libxkbcommon and was generated by {SCRIPT.name}
 * You can always fetch the latest version from:
 * https://raw.github.com/xkbcommon/libxkbcommon/master/{KEYSYMS_NAMES_HEADER.relative_to(ROOT)}
 */
#pragma once
"""
)

entry_offsets: dict[str, int] = {}
UINT16_MAX = (1 << 16) - 1
UNICODE_KEYSYM = UINT16_MAX - 1
DEPRECATED_KEYSYM = UINT16_MAX
MAX_EXPLICIT_DEPRECATED_ALIAS_INDEX_LOG2 = 8
MAX_EXPLICIT_DEPRECATED_ALIAS_INDEX = 1 << MAX_EXPLICIT_DEPRECATED_ALIAS_INDEX_LOG2
MAX_EXPLICIT_DEPRECATED_ALIAS_COUNT_LOG2 = 4
MAX_EXPLICIT_DEPRECATED_ALIAS_COUNT = 1 << MAX_EXPLICIT_DEPRECATED_ALIAS_COUNT_LOG2
MAX_OFFSET = UNICODE_KEYSYM - 1
XKB_KEYSYM_UNICODE_MIN = 0x01000100
XKB_KEYSYM_UNICODE_MAX = 0x0110FFFF

print(
    """
#include "config.h"

#include <stddef.h>
#include <stdint.h>

#include "xkbcommon/xkbcommon.h"
#include "utils.h"

#ifdef __GNUC__
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Woverlength-strings"
#endif
static const char *keysym_names =
""".strip()
)
offs = 0
for keysym in entries_isorted:
    if offs >= MAX_OFFSET:
        raise ValueError(f"Offset must be kept under {MAX_OFFSET}, got: {offs}.")
    entry_offsets[keysym.name] = offs
    print(f'    "{keysym.name}\\0"')
    offs += len(keysym.name) + 1
print(
    """
;
#ifdef __GNUC__
#pragma GCC diagnostic pop
#endif
""".strip()
)

template = r"""
static const uint16_t keysym_name_G[] = {
    $G
};

static inline size_t
keysym_name_perfect_hash(const char *key)
{
    const char *T1 = "$S1";
    const char *T2 = "$S2";
    size_t h1 = 0;
    size_t h2 = 0;
    for (size_t i = 0; key[i] != '\0'; i++) {
        h1 += (size_t) (T1[i % $NS] * key[i]);
        h2 += (size_t) (T2[i % $NS] * key[i]);
    }
    return (keysym_name_G[h1 % $NG] + keysym_name_G[h2 % $NG]) % $NG;
}
"""
print(
    perfect_hash.generate_code(
        keys=[keysym.name for keysym in entries_isorted],
        template=template,
    )
)

print(
    """
struct name_keysym {
    xkb_keysym_t keysym;
    uint16_t offset;
};\n"""
)


def print_entries(entries: Iterable[Keysym]):
    for entry in entries:
        print(
            "    {{ 0x{value:08x}, {offs} }}, /* {name} */".format(
                offs=entry_offsets[entry.name], value=entry.value, name=entry.name
            )
        )


print("static const struct name_keysym name_to_keysym[] = {")
print_entries(entries_isorted)
print("};\n")

# *.sort() is stable so we always get the first keysym for duplicate
print("static const struct name_keysym keysym_to_name[] = {")
print_entries(
    next(g[1]) for g in itertools.groupby(entries_kssorted, key=lambda e: e.value)
)
print("};\n")


def make_deprecated_entry(
    value,
    keysyms: list[Keysym],
    entry_offsets: dict[str, int],
    explicit_deprecated_aliases_index: int,
) -> tuple[str | None, tuple[int, ...]]:
    assert keysyms

    if all(not k.deprecated for k in keysyms):
        # No name is deprecated
        return None, ()

    canonical = keysyms[0]
    assert canonical.is_canonical
    ref = canonical.preferred
    non_deprecated_names = tuple(k for k in keysyms if not k.deprecated)
    deprecated_names = tuple(k for k in keysyms if k.deprecated)
    deprecated_names_indices: tuple[int, ...] = ()

    if non_deprecated_names:
        # Keysym is not deprecated, but some of its names are.
        assert not ref.deprecated, ref
        ref_name = f"Reference: {ref.name}. "
        ref_index = str(entry_offsets[ref.name])
        assert deprecated_names or ref.deprecated, keysyms

        if any(k is not ref for k in non_deprecated_names):
            # Keysym has both multiple valid names and some deprecated names
            deprecated_names_indices = tuple(
                entry_offsets[k.name] for k in deprecated_names
            )
            assert (
                explicit_deprecated_aliases_index < MAX_EXPLICIT_DEPRECATED_ALIAS_INDEX
            )
            assert len(deprecated_names_indices) < MAX_EXPLICIT_DEPRECATED_ALIAS_COUNT
        else:
            # Keysym has a single valid name and some deprecated names
            assert len(non_deprecated_names) == 1, non_deprecated_names
            assert deprecated_names
            # Do *not* use an explicit list of deprecated names
            explicit_deprecated_aliases_index = 0
    else:
        # Keysym is deprecated
        assert ref.deprecated, ref
        ref_name = ""
        ref_index = (
            "DEPRECATED_KEYSYM"
            if value < XKB_KEYSYM_UNICODE_MIN or value > XKB_KEYSYM_UNICODE_MAX
            else "UNICODE_KEYSYM"
        )
        # Do *not* use an explicit list of deprecated names
        explicit_deprecated_aliases_index = 0

    if non_deprecated_aliases := tuple(k for k in non_deprecated_names if k is not ref):
        non_deprecated = (
            "Non deprecated aliases: "
            + ", ".join(k.name for k in non_deprecated_aliases)
            + ". "
        )
    else:
        non_deprecated = ""

    deprecated = ", ".join(k.name for k in deprecated_names)
    comment = f"{ref_name}{non_deprecated}Deprecated: {deprecated}"
    return (
        f"    {{ 0x{value:0>8x}, {ref_index: <17}, {explicit_deprecated_aliases_index}, {len(deprecated_names_indices)} }}, /* {comment} */",
        deprecated_names_indices,
    )


def generate_deprecated_keysyms(
    all_keysyms: Keysyms, entry_offsets: dict[str, int]
) -> Generator[tuple[int, ...], None, None]:
    explicit_deprecated_aliases_index = 0
    for value, keysyms in sorted(all_keysyms.by_value.items(), key=lambda e: e[0]):
        assert keysyms
        c_entry, explicit_deprecated_aliases = make_deprecated_entry(
            value, keysyms, entry_offsets, explicit_deprecated_aliases_index
        )
        if c_entry is not None:
            print(c_entry)
        if explicit_deprecated_aliases:
            yield explicit_deprecated_aliases
            explicit_deprecated_aliases_index += len(explicit_deprecated_aliases)


def generate_mixed_aliases(aliases: Iterable[Iterable[int]]):
    for xs in aliases:
        for x in xs:
            print(f"    {x},")


print(f"#define UNICODE_KEYSYM    0x{UNICODE_KEYSYM:x}")
print(f"#define DEPRECATED_KEYSYM 0x{DEPRECATED_KEYSYM:x}")
# NOTE: Alternative implementation, useful the day the indices do not fit uint16_t.
# print(f"""
# struct deprecated_keysym {{
#     xkb_keysym_t keysym;
#     union {{
#         uint32_t offset;
#         struct {{
#             uint32_t offset:{MAX_OFFSET_LOG2};
#             /* Explicit deprecated aliases start index & count */
#             uint8_t explicit_index:{MAX_EXPLICIT_DEPRECATED_ALIAS_INDEX_LOG2};
#             uint8_t explicit_count:{MAX_EXPLICIT_DEPRECATED_ALIAS_COUNT_LOG2};
#         }} details;
#     }};
# }};
# """)
print("""
struct deprecated_keysym {
    xkb_keysym_t keysym;
    uint16_t offset;
    /* Explicit deprecated aliases start index & count */
    uint8_t explicit_index;
    uint8_t explicit_count;
};
""")
print("static const struct deprecated_keysym deprecated_keysyms[] = {")
explicit_deprecated_aliases = tuple(
    generate_deprecated_keysyms(all_keysyms, entry_offsets)
)
print("};\n")
print("static const uint32_t explicit_deprecated_aliases[] = {")
generate_mixed_aliases(explicit_deprecated_aliases)
print("};")
print("""
static_assert(ARRAY_SIZE(explicit_deprecated_aliases) < UINT8_MAX,
              "Cannot encode index and count in deprecated_keysym::explicit_*");\
""")

print(f"max name offset: {max(entry_offsets.values())}", file=sys.stderr)


# Check that the keywords of our XKB parser that clash with keysyms are handled properly
def parse_gperf_keywords(path: Path) -> Iterator[str]:
    with path.open("rt", encoding="utf-8") as fd:
        in_keyword_section = False
        for line in fd:
            if line.startswith(r"%%"):
                # This is a boundary of the keywords section
                if in_keyword_section:
                    break
                in_keyword_section = True
            elif in_keyword_section:
                # Parse the keywords
                keyword, *_ = line.split(",")
                yield keyword.strip().casefold()
            # Skip any line until we reach the keywords
        else:
            raise ValueError("Parse error: keywords section boundary not found")


SUPPORTED_KEYWORDS_CLASHES = {"section"}
UNSUPPORTED_KEYWORDS_CLASHES = frozenset(parse_gperf_keywords(args.gperf)).difference(
    SUPPORTED_KEYWORDS_CLASHES
)
expected_clashes: set[str] = set()
errors = 0
for entry in entries:
    if entry.name.casefold() in UNSUPPORTED_KEYWORDS_CLASHES:
        print(
            f"ERROR: keysym “{entry.name}” (0x{entry.value:0>4x}) clashes with keywords",
            "and cannot be parsed properly.",
            file=sys.stderr,
        )
        errors += 1
    elif (lower := entry.name.lower()) in SUPPORTED_KEYWORDS_CLASHES:
        if not entry.name.islower():
            # Keywords’s atoms are registered in *lower* case, so the keysym will be
            # replaced by the keysym with the corresponding name, but they may not match.
            entry2: Keysym = Keysym(
                name="NoSymbol",
                value=0,
                char=None,
                char_aliases=[],
                char_semantics=Semantics.Default,
                deprecation=None,
                _canonical=None,
                _preferred=None,
                aliases=[],
                comment="",
            )
            if any(
                e.name == lower
                for e in all_keysyms.by_value[entry.value]
                if e.name != entry.value
            ):
                # There is a keysym in lower case that is an alias
                print(
                    f"WARNING: keysym “{entry.name}”",
                    f"will be parsed as “{lower}” (expected)",
                    file=sys.stderr,
                )
            else:
                # Lookup the keysym mismatch
                for e in entries:
                    if e.name == lower:
                        entry2 = e
                        break
                print(
                    f"ERROR: keysym “{entry.name}” (0x{entry.value:0>4x})",
                    r"clashes with keywords and will be replaced by",
                    f"“{entry2.name}” (0x{entry2.value:0>4x}).",
                    file=sys.stderr,
                )
                errors += 1
        else:
            print(
                f"WARNING: keysym “{entry.name}” clashing with keywords (expected)",
                file=sys.stderr,
            )
            expected_clashes.add(entry.name)
if diff := SUPPORTED_KEYWORDS_CLASHES.difference(expected_clashes):
    print(f"ERROR: Unexpected missing clashing keysyms: {diff}", file=sys.stderr)
    errors += 1
if errors:
    print(
        f" {errors} ERRORS ".center(80, "-"),
        "Please update the parser file `parser.y` to handle keysyms causing clashes.",
        "The relevant entries are:",
        "- Keysym",
        "- Element (for modmap, parsed via: Expr -> Term -> Lhs -> FieldSpec -> Element)",
        file=sys.stderr,
        sep="\n",
    )
    exit(1)