//

// immer: immutable data structures for C++

// Copyright (C) 2016, 2017, 2018 Juan Pedro Bolivar Puente

//

// This software is distributed under the Boost Software License, Version 1.0.

// See accompanying file LICENSE or copy at http://boost.org/LICENSE_1_0.txt

//

#include "fuzzer_input.hpp"

#include <immer/box.hpp>

#include <immer/flex_vector.hpp>

#include <array>

using st_memory = immer::memory_policy<immer::heap_policy<immer::cpp_heap>,

                                       immer::unsafe_refcount_policy,

                                       immer::no_lock_policy,

                                       immer::no_transience_policy,

                                       false>;

extern "C" int LLVMFuzzerTestOneInput(const std::uint8_t* data,

                                      std::size_t size)

{

    constexpr auto var_count = 8;

    constexpr auto bits      = 3;

    using vector_t = immer::flex_vector<int, st_memory, bits, bits>;

    using size_t   = std::uint8_t;

    auto vars = std::array<vector_t, var_count>{};

    auto is_valid_var = [&](auto idx) { return idx >= 0 && idx < var_count; };

    auto is_valid_var_neq = [](auto other) {

        return [=](auto idx) {

            return idx >= 0 && idx < var_count && idx != other;

        };

    };

    auto is_valid_index = [](auto& v) {

        return [&](auto idx) { return idx >= 0 && idx < v.size(); };

    };

    auto is_valid_size = [](auto& v) {

        return [&](auto idx) { return idx >= 0 && idx <= v.size(); };

    };

    auto can_concat = [](const auto& v1, const auto& v2) {

        // First, check max_size

        if (v1.size() + v2.size() > vector_t::max_size()) {

            return false;

        }

        // But just checking max_size is not sufficient, because there are other

        // conditions for the validity of the tree, like shift constraints, for

        // example.

        try {

            // Try to concat and catch an exception if it fails

            const auto v3 = v1 + v2;

            if (v3.size()) {

                return true;

            }

        } catch (const immer::detail::rbts::invalid_tree&) {

            return false;

        }

        return true;

    };

    auto can_compare = [](auto&& v) {

        // avoid comparing vectors that are too big, and hence, slow to compare

        return v.size() < (1 << 15);

    };

    return fuzzer_input{data, size}.run([&](auto& in) {

        enum ops

        {

            op_push_back,

            op_update,

            op_take,

            op_drop,

            op_concat,

            op_push_back_move,

            op_update_move,

            op_take_move,

            op_drop_move,

            op_concat_move_l,

            op_concat_move_r,

            op_concat_move_lr,

            op_insert,

            op_erase,

            op_compare,

        };

        auto src = read<char>(in, is_valid_var);

        auto dst = read<char>(in, is_valid_var);

        switch (read<char>(in)) {

        case op_push_back: {

            vars[dst] = vars[src].push_back(42);

            break;

        }

        case op_update: {

            auto idx  = read<size_t>(in, is_valid_index(vars[src]));

            vars[dst] = vars[src].update(idx, [](auto x) { return x + 1; });

            break;

        }

        case op_take: {

            auto idx  = read<size_t>(in, is_valid_size(vars[src]));

            vars[dst] = vars[src].take(idx);

            break;

        }

        case op_drop: {

            auto idx  = read<size_t>(in, is_valid_size(vars[src]));

            vars[dst] = vars[src].drop(idx);

            break;

        }

        case op_concat: {

            auto src2 = read<char>(in, is_valid_var);

            if (can_concat(vars[src], vars[src2]))

                vars[dst] = vars[src] + vars[src2];

            break;

        }

        case op_push_back_move: {

            vars[dst] = std::move(vars[src]).push_back(21);

            break;

        }

        case op_update_move: {

            auto idx = read<size_t>(in, is_valid_index(vars[src]));

            vars[dst] =

                std::move(vars[src]).update(idx, [](auto x) { return x + 1; });

            break;

        }

        case op_take_move: {

            auto idx  = read<size_t>(in, is_valid_size(vars[src]));

            vars[dst] = std::move(vars[src]).take(idx);

            break;

        }

        case op_drop_move: {

            auto idx  = read<size_t>(in, is_valid_size(vars[src]));

            vars[dst] = std::move(vars[src]).drop(idx);

            break;

        }

        case op_concat_move_l: {

            auto src2 = read<char>(in, is_valid_var_neq(src));

            if (can_concat(vars[src], vars[src2]))

                vars[dst] = std::move(vars[src]) + vars[src2];

            break;

        }

        case op_concat_move_r: {

            auto src2 = read<char>(in, is_valid_var_neq(src));

            if (can_concat(vars[src], vars[src2]))

                vars[dst] = vars[src] + std::move(vars[src2]);

            break;

        }

        case op_concat_move_lr: {

            auto src2 = read<char>(in, is_valid_var_neq(src));

            if (can_concat(vars[src], vars[src2]))

                vars[dst] = std::move(vars[src]) + std::move(vars[src2]);

            break;

        }

        case op_compare: {

            using std::swap;

            if (can_compare(vars[src]) && vars[src] == vars[dst])

                swap(vars[src], vars[dst]);

            break;

        }

        case op_erase: {

            auto idx  = read<size_t>(in, is_valid_index(vars[src]));

            vars[dst] = vars[src].erase(idx);

            break;

        }

        case op_insert: {

            auto idx  = read<size_t>(in, is_valid_size(vars[src]));

            vars[dst] = vars[src].insert(idx, immer::box<int>{42});

            break;

        }

        default:

            break;

        };

        return true;

    });

}