#include "string.h"
#include "SomaSolve.h"
#include "math.h"

/*
void get_dims_input(int dims[3]) {
    print("Enter dimensions separated by newlines. (x*y*z must not exceed 64)\n");
    bool success = false;
    while (!success) {
        std::cout << "x: ";
        std::cin >> dims[0];
        std::cout << "y: ";
        std::cin >> dims[1];
        std::cout << "z: ";
        std::cin >> dims[2];

        int size = dims[0]*dims[1]*dims[2];
        if (size <= 64) {
            success = true;
        } else {
            print("That resulted in %zu units. Try again", size);
        }
        std::cin.ignore();
    }
}
*/

/*
std::vector<uint64> get_reprs_input(int units_required) {
    print("Enter bit-representations (big endian, max 64 bits, total 1s must add up to %zu). press ENTER twice to finish input.\n", units_required );
    std::vector<uint64> reprs = std::vector<uint64>();
    int total_units = 0;
    while (true) {
        std::string input = std::string();
        std::getline(std::cin, input);
        if (input.size() == 0) {
            if (total_units == units_required) {
                break;
            } else {
                std::cout << "Bad number of units. You entered: " << total_units << ", but exactly " << units_required << " were required.\n";
                total_units = 0;
                continue;
            }
        }
        uint64 bit_repr = 0;
        int i = 0;
        bool good_repr = true;
        for (auto it = input.rbegin(); it < input.rend(); it++, i++) {
            if (*it == '1') {
                bit_repr |= 1ull << i;
                total_units++;
            } else if (*it != '0' || i >= 64) {
                std::cout << "Input invalid. Enter a binary string only with max 64 bits." << '\n';
                good_repr = false;
                break;
            }
        }
        if (good_repr) {
            reprs.push_back(bit_repr);
        }
    }
    return reprs;
}
*/

DefineList(size_t, Offset);

typedef struct Solver Solver;
struct Solver {
    VoxelSpaceReprList *input;
    OffsetList *offsets;
    SomaSolutionList *solutions;
};

/*
void backtrack_solve_iter(std::vector<uint64> *polycube_input, std::vector<int> *offsets) {
    size_t num_inputs = offsets->size() - 1;

    std::vector<int> solns = std::vector<int>();

    std::vector<int> iter_stack = std::vector<int>();
    std::vector<int> curr_soln_stack = std::vector<int>();
    std::vector<uint64> soln_spaces_stack = std::vector<uint64>();
    soln_spaces_stack.push_back(0ul);

    int depth = 0;

    while (depth >= 0) {
        if (depth >= iter_stack.size()) {
            iter_stack.push_back(offsets->at(depth));
        }
        int end = offsets->at(depth + 1);
        bool broke = false;
        for (; iter_stack[depth] < end; iter_stack[depth]++) {
            uint64 next_space = polycube_input->at(iter_stack[depth]);
            uint64 soln_space = soln_spaces_stack[depth];
            std::cout << next_space << " " << soln_space << std::endl;
            bool successful_fuse = (soln_space | next_space) == (soln_space ^ next_space);
            if (successful_fuse) {
                soln_spaces_stack.push_back(soln_space |= next_space);
                curr_soln_stack.push_back(iter_stack[depth]);
                depth++;
                if (curr_soln_stack.size() == num_inputs) {
                    solns.push_back(1);
                    curr_soln_stack.pop_back();
                    soln_spaces_stack.pop_back();
                    depth--;
                } else {
                    depth++;
                    broke = true;
                    break;
                }
            }
        }
        if (!broke) {
            curr_soln_stack.pop_back();
            soln_spaces_stack.pop_back();
            depth--;
        }
    }
    std::cout << "Done. Found " << solns.size() << " solutions." << std::endl;
}
*/

void backtrackSolve(Arena *arena, Solver *solver, uint64 working_solution, size_t curr_piece) {
    VoxelSpaceReprList *input = solver->input;
    OffsetList *offsets = solver->offsets;
    SomaSolutionList *solutions = solver->solutions;
    size_t start = offsets->data[curr_piece];
    size_t end = offsets->data[curr_piece + 1];
    size_t num_pieces = offsets->length - 1;
    for (size_t i = start; i < end; i++) {
        bool successful_fuse = !collides(working_solution, input->data[i]);
        if (successful_fuse) {
            uint64 new_working_solution = working_solution | input->data[i];
            solutions->data[solutions->length - 1].data[curr_piece] = input->data[i];
            if (curr_piece == num_pieces - 1) {
                VoxelSpaceReprList last_soln = solutions->data[solutions->length - 1];
                VoxelSpaceReprList last_soln_copy = PushList(arena, VoxelSpaceReprList, last_soln.length);
                last_soln_copy.length = last_soln.length;
                memcpy(last_soln_copy.data, last_soln.data, last_soln.length * ListElementSize(VoxelSpaceReprList));
                AppendList(solutions, last_soln_copy);
                return;
            } else {
                backtrackSolve(arena, solver, new_working_solution, curr_piece + 1);
            }
        }
    }
    if (curr_piece == 0) {
        solutions->length -= 1;
    }
}

SomaSolutionList getSolutionRotations(Arena *arena, SomaSolution *solution, int dims[3]) {
    SomaSolutionList result = PushFullList(arena, SomaSolutionList, NUM_ROTS_3D);
    for (EachIn(result, i)) {
        result.data[i] = PushList(arena, SomaSolution, solution->length);
    }
    for (int piece_i = 0; piece_i < solution->length; piece_i++) {
        VoxelSpace space = {
            solution->data[piece_i],
            dims[0],
            dims[1],
            dims[2],
        };
        VoxelSpaceList pieceRotations = getAllRotations(arena, &space);
        for (EachIn(pieceRotations, rot_i)) {
            AppendList(&result.data[rot_i], pieceRotations.data[rot_i].space);
        }
    }
    return result;
}

SomaSolutionList filterUnique(Arena *arena, SomaSolutionList *solutions, int dims[3]) {
    if (solutions->length == 0) {
        return (SomaSolutionList)EmptyList();
    }
    SomaSolutionList uniqueSolns = PushList(arena, SomaSolutionList, solutions->length);
    for (EachEl(*solutions, SomaSolution, solution)) {
        bool foundMatch = false;
        Scratch temp = scratchStart(&arena, 1);
        SomaSolutionList rots = getSolutionRotations(temp.arena, solution, dims);
        for (EachEl(rots, SomaSolution, rotation)) {
            for (EachEl(uniqueSolns, SomaSolution, unique_soln)) {
                bool isMatch = true;
                for (EachIn(*unique_soln, piece_i)) {
                    if (rotation->data[piece_i] != unique_soln->data[piece_i]) {
                        isMatch = false;
                        break;
                    }
                }
                if (isMatch) {
                    foundMatch = true;
                    break;
                }
            }
            if (foundMatch) {
                break;
            }
        }
        scratchEnd(temp);
        if (!foundMatch) {
            SomaSolution solutionCopy = PushList(arena, SomaSolution, solution->length);
            solutionCopy.capacity = solution->length;
            solutionCopy.length = solution->length;
            memcpy(solutionCopy.data, solution->data, ListElementSize(SomaSolutionList) * solution->length);
            AppendList(&uniqueSolns, solutionCopy);
        }
    }
    return uniqueSolns;
}

uint64 factorial(int n) {
    uint64 result = 1;
    for (int i = 1; i <= n; i++) {
        result *= i;
    }
    return result;
}

SomaSolutionList solveSoma(Arena *solutionsArena, VoxelSpaceReprList reprsInput, int dims[3]) {
    Arena *generalArena = arenaAlloc(Megabytes(64));
    Arena *permsArena = arenaAlloc(Megabytes(128));

    OffsetList offsets = PushList(generalArena, OffsetList, reprsInput.length + 1);

    VoxelSpaceReprList polycubes = PushList(generalArena, VoxelSpaceReprList, 0);

    VoxelSpace emptyVoxelSpace = {
        0,
        dims[0],
        dims[1],
        dims[2],
    };

    AppendList(&offsets, 0);

    uint64 possibleCombos = 0;

    {
        VoxelSpace voxelSpace = emptyVoxelSpace;
        voxelSpace.space = reprsInput.data[0];
        cullEmptySpace(&voxelSpace);
        VoxelSpaceReprList positions = getAllPositionsInPrism(permsArena, &voxelSpace, dims);
        possibleCombos += positions.length;
        VoxelSpaceReprList_underlying *insertion = PushArray(generalArena, uint64, positions.capacity);
        polycubes.capacity += positions.capacity;
        polycubes.length += positions.length;
        memcpy(insertion, positions.data, positions.capacity * ListElementSize(VoxelSpaceReprList));
    };

    for (size_t i = 1; i < reprsInput.length; i++) {
        AppendList(&offsets, polycubes.capacity);
        VoxelSpace space = emptyVoxelSpace;
        space.space = reprsInput.data[i];
        cullEmptySpace(&space);
        VoxelSpaceReprList perms = getAllPermutationsInPrism(permsArena, &space, dims);
        possibleCombos *= perms.length;
        VoxelSpaceReprList_underlying *insertion = PushArray(generalArena, VoxelSpaceReprList_underlying, perms.capacity);
        polycubes.capacity += perms.capacity;
        polycubes.length += perms.length;
        memcpy(insertion, perms.data, perms.capacity * ListElementSize(VoxelSpaceReprList));
    }

    AppendList(&offsets, polycubes.length);

    SomaSolutionList solutions = PushList(permsArena, SomaSolutionList, (size_t)floor(sqrt(possibleCombos)));
    AppendList(&solutions, PushFullList(permsArena, SomaSolution, reprsInput.length));

    Solver solver = {
        &polycubes,
        &offsets,
        &solutions,
    };

    backtrackSolve(permsArena, &solver, 0, 0);

    SomaSolutionList uniqueSolns = filterUnique(solutionsArena, solver.solutions, dims);

    arenaFree(permsArena);
    arenaFree(generalArena);

    return uniqueSolns;
}

void interactiveCmdLineSolveSoma() {
    //get_dims_input(dims);
    //std::cout << '\n';
    //std::vector<uint64> reprs = get_reprs_input(dims[0]*dims[1]*dims[2]);
    //print("Great. Calculating solutions...\n");
    //SomaSolutionList solutions = solveSoma(AsList(VoxelSpaceReprList, STD_SOMA), (int[]){ 3, 3, 3 });
    //print("%zu solutions found.\n", solutions.length);
}