#!/usr/bin/env python3
"""Write emoji.dict to stdout from result-first UTF-8 TSV files."""

import sys
import unicodedata
from pathlib import Path


SOURCES = [Path(__file__).with_name(name)
           for name in ("symbol.src", "emoji.src")]
MAXRUNES = 64
MAXCANDIDATES = 128


def fold(s):
    s = "".join(chr(ord(c) + 32) if "A" <= c <= "Z" else c for c in s)
    return unicodedata.normalize("NFC", s)


def hascontrol(s):
    return any(unicodedata.category(c) == "Cc" for c in s)


def read(path):
    entries = []
    with path.open(encoding="utf-8") as src:
        for lineno, raw in enumerate(src, 1):
            line = raw.rstrip("\r\n")
            if not line.strip():
                continue
            if "\t" not in line and line.lstrip().startswith("#"):
                continue
            fields = line.split("\t")
            if len(fields) < 2:
                raise ValueError(f"{path}:{lineno}: need a result and an alias")
            result = unicodedata.normalize("NFC", fields[0])
            if (not result or len(result) > MAXRUNES or hascontrol(result)
                    or any(c.isspace() for c in result)):
                raise ValueError(f"{path}:{lineno}: bad result")
            for field in fields[1:]:
                alias = fold(field)
                if (not alias or len(alias) > MAXRUNES or hascontrol(alias)
                        or alias != alias.strip() or alias.startswith(";")):
                    raise ValueError(f"{path}:{lineno}: bad alias")
                entries.append((result, alias))
    return entries


def build(entries):
    """One row per alias, in order of first appearance; the engine searches
    the dictionary by prefix, so no prefix rows are needed."""
    table = {}
    for result, alias in entries:
        values = table.setdefault(alias, [])
        if result not in values:
            values.append(result)
    for alias, values in table.items():
        yield f"{alias}\t{' '.join(values[:MAXCANDIDATES])}"


def main():
    paths = [Path(arg) for arg in sys.argv[1:]] or SOURCES
    try:
        entries = [entry for path in paths for entry in read(path)]
        for line in build(entries):
            print(line)
    except (OSError, UnicodeError, ValueError) as error:
        print(error, file=sys.stderr)
        return 1
    return 0


if __name__ == "__main__":
    sys.exit(main())