#!/usr/bin/python3.6

from pathlib import Path

EXPR_TYPES = {
    'Binary': ('left: Expr', 'operator: Token', 'right: Expr'),
    'Grouping': ('expression: Expr',),
    'Unary': ('operator: Token', 'right: Expr'),

    # NOTE: when adding new Literals, add new Literal types, instead of just
    # doing Literal with an 'Object value'. it won't work.
}

def _gen_expr_decls():
    res = []

    for expr_type, expr_params in EXPR_TYPES.items():
        res.append(f'pub const {expr_type} = struct {{')

        for param in expr_params:
            res.append(f'    {param},')

        res.append('};\n')

    return '\n'.join(res)


def do_base_union(union_name: str):
    res = [
        'const Token = @import("token.zig").Token;\n'
    ]

    res.append(_gen_expr_decls())

    res.append(f'pub const {union_name}Type = enum {{')
    for expr_type in EXPR_TYPES:
        res.append(f'    {expr_type},')
    res.append('};\n')


    res.append(f'pub const {union_name} = union({union_name}Type) {{')

    for expr_type in EXPR_TYPES:
        res.append(f'    {expr_type}: {expr_type},')

    res.append('};\n')

    return '\n'.join(res)


def main():
    expr_file = Path('./src') / 'expr.zig'
    expr_file.touch()
    expr_file.unlink()
    expr_file.write_text(do_base_union('Expr'))


if __name__ == '__main__':
    main()