#include <os/ArgumentParser.h>
#include <stdio.h>
#include <stdlib.h>

Result<void> ArgumentParser::add_positional_argument(StringView& out, StringView name, bool required)
{
    PositionalArgument arg { &out, name, required, {} };

    return m_positional_args.try_append(move(arg));
}

Result<void> ArgumentParser::add_positional_argument(StringView& out, StringView name, bool required,
                                                     StringView fallback)
{
    PositionalArgument arg { &out, name, required, fallback };

    return m_positional_args.try_append(move(arg));
}

void ArgumentParser::parse(int argc, char* const* argv)
{
    StringView program_name = argv[0];

    for (int i = 1; i < argc; i++)
    {
        StringView arg = argv[i];
        Option<PositionalArgument> current = m_positional_args.try_dequeue();
        if (!current.has_value())
        {
            fprintf(stderr, "%s: unused argument '%s'\n", program_name.chars(), arg.chars());
            continue;
        }

        *current->out = arg;
    }

    // Loop through all remaining positional arguments.
    for (const auto& arg : m_positional_args)
    {
        if (arg.required)
        {
            fprintf(stderr, "%s: required argument '%s' not provided\n", program_name.chars(), arg.name.chars());
            exit(1);
        }
        else { *arg.out = arg.fallback; }
    }
}