#include "simulator.h"

enum { RemoteAccessCost = 6};

Simulator::Simulator() {
    programs.reserve(FIELDS_XY * FIELDS_XY);

//    std::srand(std::time(0));
    std::srand(0);
}


Position Simulator::calcPosition(Position position, Direction direction, int32_t distance) {
    switch(direction) {
    default:
    case Right: return Position{(position.x + distance) % FIELDS_XY, position.y};
    case Down: return Position{position.x, (position.y + distance) % FIELDS_XY};
    case Left: return Position{(position.x - distance) % FIELDS_XY, position.y};
    case Up: return Position{position.x, (position.y - distance) % FIELDS_XY};
    }
}

void Simulator::decode(Program& program, Task& task, int& v, int*& var_v, int param, int& additionalCycles) {
    var_v = nullptr;

    switch(param) {
        case Local_1 : v = program.vars[0];  var_v = &program.vars[0]; break;
        case Local_2 : v = program.vars[1];  var_v = &program.vars[1]; break;
        case Local_3 : v = program.vars[2];  var_v = &program.vars[2]; break;
        case Local_4 : v = program.vars[3];  var_v = &program.vars[3]; break;
        case Local_5 : v = program.vars[4];  var_v = &program.vars[4]; break;
        case Local_6 : v = program.vars[5];  var_v = &program.vars[5]; break;
        case Local_7 : v = program.vars[6];  var_v = &program.vars[6]; break;
        case Local_8 : v = program.vars[7];  var_v = &program.vars[7]; break;
        case Local_9 : v = program.vars[8];  var_v = &program.vars[8]; break;
        case Local_10: v = program.vars[9];  var_v = &program.vars[9]; break;
        case Local_11: v = program.vars[10]; var_v = &program.vars[10]; break;
        case Local_12: v = program.vars[11]; var_v = &program.vars[11]; break;
        case Local_13: v = program.vars[12]; var_v = &program.vars[12]; break;
        case Local_14: v = program.vars[13]; var_v = &program.vars[13]; break;
        case Local_15: v = program.vars[14]; var_v = &program.vars[14]; break;
        case Local_16: v = program.vars[15]; var_v = &program.vars[15]; break;
        case Local_17: v = program.vars[16]; var_v = &program.vars[16]; break;
        case Local_18: v = program.vars[17]; var_v = &program.vars[17]; break;
        case Local_19: v = program.vars[18]; var_v = &program.vars[18]; break;
        case Local_20: v = program.vars[19]; var_v = &program.vars[19]; break;
        case LocalActive:
            v = program.active;
            var_v = &program.active;
            break;
        case LocalBanks:
            v = program.banks.size();
            break;
        case LocalInstrSet:
            v = program.instructionSet;
            break;
        case LocalMobile:
            v = program.mobile;
            break;
        case LocalAge:
            v = cycle - program.creationCycle;
            break;
        case LocalTasks:
            v = program.tasks.size();
            break;
        case LocalGeneration:
            v = program.generation;
            break;
        case LocalId:
            v = program.team->id;
            break;
        case RemoteActive: {
            additionalCycles += RemoteAccessCost;
            auto remotePosition = calcPosition(program.position, task.direction, 1);
            auto remoteProgram = findProgram(remotePosition);
            if(remoteProgram) {
                v = remoteProgram->active;
                var_v = &remoteProgram->active;
            }
            else {
                v = 0;
                var_v = nullptr;
            }
            break;
        }
        case RemoteBanks: {
            additionalCycles += RemoteAccessCost;
            auto remotePosition = calcPosition(program.position, task.direction, 1);
            auto remoteProgram = findProgram(remotePosition);
            v = remoteProgram ? remoteProgram->banks.size() : 0;
            break;
        }
        case RemoteInstrSet: {
            additionalCycles += RemoteAccessCost;
            auto remotePosition = calcPosition(program.position, task.direction, 1);
            auto remoteProgram = findProgram(remotePosition);
            v = remoteProgram ? remoteProgram->instructionSet : 0;
            break;
        }
        case RemoteMobile: {
            additionalCycles += RemoteAccessCost;
            auto remotePosition = calcPosition(program.position, task.direction, 1);
            auto remoteProgram = findProgram(remotePosition);
            v = remoteProgram ? remoteProgram->mobile: 0;
            break;
        }
        case RemoteAge: {
            additionalCycles += RemoteAccessCost;
            auto remotePosition = calcPosition(program.position, task.direction, 1);
            auto remoteProgram = findProgram(remotePosition);
            v = remoteProgram ? (cycle - remoteProgram->creationCycle) : 0;
            break;
        }
        case RemoteTasks: {
            additionalCycles += RemoteAccessCost;
            auto remotePosition = calcPosition(program.position, task.direction, 1);
            auto remoteProgram = findProgram(remotePosition);
            v = remoteProgram ? remoteProgram->tasks.size() : 0;
            break;
        }
        case RemoteGeneration: {
            additionalCycles += RemoteAccessCost;
            auto remotePosition = calcPosition(program.position, task.direction, 1);
            auto remoteProgram = findProgram(remotePosition);
            v = remoteProgram ? remoteProgram->generation : 0;
            break;
        }
        case GlobalPub:
            v = pub;
            var_v = &pub;
            break;
        case GlobalTeam:
            v = program.team->var;
            var_v = &program.team->var;
            break;
        case GlobalOwn:
            v = program.team->programCount;
            break;
        case GlobalOthers:
            v = 0;
            for(auto& team : teams) {
                if(team != program.team) {
                    v += team->programCount;
                }
            }
            break;
        case GlobalFields:
            v = FIELDS_XY * FIELDS_XY;
            break;
        case GlobalTime:
            v = cycle;
            break;
        case GlobalTimeout:
            v = CYCLE_TIMEOUT;
            break;
    }
}

void Simulator::decodeInstructionParameters(Program& program, Task& task, const Instruction& instruction, int& additionalCycles) {
    task.a = instruction.a;
    task.b = instruction.b;
    task.c = instruction.c;
    task.var_a = nullptr;
    task.var_b = nullptr;
    task.var_c = nullptr;

    switch(instruction.params) {
        case N:
            break;
        case L:
            task.a = instruction.a;
            break;
        case V:
            decode(program, task, task.a, task.var_a, instruction.a, additionalCycles);
            break;
        case LL:
            task.a = instruction.a;
            task.b = instruction.b;
            break;
        case LV:
            task.a = instruction.a;
            decode(program, task, task.b, task.var_b, instruction.b, additionalCycles);
            break;
        case VL:
            decode(program, task, task.a, task.var_a, instruction.a, additionalCycles);
            task.b = instruction.b;
            break;
        case VV:
            decode(program, task, task.a, task.var_a, instruction.a, additionalCycles);
            decode(program, task, task.b, task.var_b, instruction.b, additionalCycles);
            break;
        case LLL:
            task.a = instruction.a;
            task.b = instruction.b;
            task.c = instruction.c;
            break;
        case LLV:
            task.a = instruction.a;
            task.b = instruction.b;
            decode(program, task, task.c, task.var_c, instruction.c, additionalCycles);
            break;
        case LVL:
            task.a = instruction.a;
            decode(program, task, task.b, task.var_b, instruction.b, additionalCycles);
            task.c = instruction.c;
            break;
        case LVV:
            task.a = instruction.a;
            decode(program, task, task.b, task.var_b, instruction.b, additionalCycles);
            decode(program, task, task.c, task.var_c, instruction.c, additionalCycles);
            break;
        case VLL:
            decode(program, task, task.a, task.var_a, instruction.a, additionalCycles);
            task.b = instruction.b;
            task.c = instruction.c;
            break;
        case VLV:
            decode(program, task, task.a, task.var_a, instruction.a, additionalCycles);
            task.b = instruction.b;
            decode(program, task, task.c, task.var_c, instruction.c, additionalCycles);
            break;
        case VVL:
            decode(program, task, task.a, task.var_a, instruction.a, additionalCycles);
            decode(program, task, task.b, task.var_b, instruction.b, additionalCycles);
            task.c = instruction.c;
            break;
        case VVV:
            decode(program, task, task.a, task.var_a, instruction.a, additionalCycles);
            decode(program, task, task.b, task.var_b, instruction.b, additionalCycles);
            decode(program, task, task.c, task.var_c, instruction.c, additionalCycles);
            break;
    }
}


Program* Simulator::findProgram(Position position) {
    for(auto& program : programs) {
        if(program.position.x == position.x && program.position.y == position.y && program.error == NoError) {
            return &program;
        }
    }
    return nullptr;
}


void Simulator::removeErroneousPrograms() {
    auto it = std::remove_if(programs.begin(), programs.end(), [](const Program& program){ return program.error != NoError; });

    for(auto itr = it; itr != programs.end(); ++itr) {
        --(itr->team->programCount);
    }

    programs.erase(it, programs.end());
}

void Simulator::simulate() {
    removeErroneousPrograms();

    for (auto& program : programs) {
        auto& taskIndex = program.taskIndex;

        // do nothing if not active
        if(!program.active) {
            continue;
        }

        // error if no active task exists
        if(find_if(program.tasks.begin(), program.tasks.end(), [](const Task& task){ return !task.paused; }) == program.tasks.end()) {
            program.error = Unemployment;
            continue;
        }

        // switch to next unpasued task
        do {
            taskIndex = (taskIndex + 1) % program.tasks.size();
        } while(program.tasks[taskIndex].paused);

        // check if we are still executing an instruction
        auto& task = program.tasks[taskIndex];
        if(task.remainingCycles > 0) {
            --task.remainingCycles;
            continue;
        }
        else {
            endInstruction(program, task);
            beginInstruction(program, task);
        }
    }

    ++cycle;
}

void Simulator::beginInstruction(Program& program, Task& task) {
    // handle invalid bank number
    if(program.banks.empty() || task.bankIndex >= program.banks.size()) {
        program.error = InvalidBankNumber;
        return;
    }

    // handle autoreset to bank 0,0 if instructionIndex is out of banks bound or bank is empty
    if(!program.banks[task.bankIndex] || task.instIndex >= program.banks[task.bankIndex]->instructions.size()) {
        task.bankIndex  = 0;
        task.instIndex  = 0;
    }

    // handle data hunger
    if(task.bankIndex == 0 && !program.banks[0]) {
        program.error = DataHunger;
        return;
    }

    task.execBank = program.banks[task.bankIndex];

    auto& instruction = program.banks[task.bankIndex]->instructions[task.instIndex];

    // decode instruction parameters
    int additionalCycles = 0;
    decodeInstructionParameters(program, task, instruction, additionalCycles);

    // calculate cycle durations and check preconditions
    switch(instruction.command) {
        case CREATE:
            if(program.instructionSet < 2) {
                program.error = HigherInstructionSetRequired;
                break;
            }
            if(task.a < 0 || task.a > 2 || task.b < 1 || task.b > 50 || task.c < 0 || task.c > 1) {
                program.error = InvalidParameter;
                break;
            }
            task.remainingCycles = 100 + 50 * task.a + 25 * task.b + 120 * task.c + additionalCycles;
            break;

        case MOVE:
            if(program.mobile < 1) {
                program.error = MobilityRequired;
                break;
            }
            task.remainingCycles = 20 + additionalCycles;
            break;

        case DIE:
            task.remainingCycles = 1 + additionalCycles;
            break;

        case TRANS: {
            int ar = task.a - 1;
            //int br = task.b - 1;
            if(program.instructionSet < 1) {
                program.error = HigherInstructionSetRequired;
                break;
            }
            if(ar < 0 || ar >= static_cast<int>(program.banks.size())) {
                program.error = InvalidBankNumber;
                break;
            }
            const auto& bank = program.banks[ar];
            task.remainingCycles = 14 + (bank ? bank->instructions.size() : 0);
            break;
        }

        case RTRANS: {
            int ar = task.a - 1;
            int br = task.b - 1;
            if(program.instructionSet < 1) {
                program.error = HigherInstructionSetRequired;
                break;
            }
            if(ar < 0 || ar >= 50 || br < 0 || br >= static_cast<int>(program.banks.size())) {
                program.error = InvalidBankNumber;
                break;
            }
            auto remotePosition = calcPosition(program.position, task.direction, 1);
            auto remoteProgram = findProgram(remotePosition);
            task.remainingCycles = 14  + additionalCycles + remoteProgram ? (ar < static_cast<int>(remoteProgram->banks.size()) ? (remoteProgram->banks[ar] ? remoteProgram->banks[ar]->instructions.size() : 0): 0): 0;
            break;
        }

        case TURN:
            task.remainingCycles = 8 + additionalCycles;
            break;

        case JUMP:
            task.remainingCycles = 1 + additionalCycles;
            break;

        case AJUMP:
            task.remainingCycles = 1 + additionalCycles;
            break;

        case BJUMP:
            task.remainingCycles = 2 + additionalCycles;
            break;

        case SCAN:
            if(program.instructionSet < 1) {
                program.error = HigherInstructionSetRequired;
                break;
            }
            task.remainingCycles = 8 + additionalCycles;
            break;

        case FARSCAN:
            if(program.instructionSet < 1) {
                program.error = HigherInstructionSetRequired;
                break;
            }
            task.remainingCycles = 10 + 3 * task.c;
            break;

        case SET:
            task.remainingCycles = 2 + additionalCycles;
            break;

        case ADD:
            task.remainingCycles = 2 + additionalCycles;
            break;

        case SUB:
            task.remainingCycles = 2 + additionalCycles;
            break;

        case MUL:
            task.remainingCycles = 2 + additionalCycles;
            break;

        case DIV:
            task.remainingCycles = 2 + additionalCycles;
            break;

        case MOD:
            task.remainingCycles = 2 + additionalCycles;
            break;

        case MIN:
            task.remainingCycles = 2 + additionalCycles;
            break;

        case MAX:
            task.remainingCycles = 2 + additionalCycles;
            break;

        case RANDOM:
            if(task.b > task.c) {
                program.error = InvalidParameter;
                break;
            }
            task.remainingCycles = 1 + additionalCycles;
            break;

        case IF:
            task.remainingCycles = 2 + additionalCycles;
            break;

        case IFN:
            task.remainingCycles = 2 + additionalCycles;
            break;

        case IFG:
            task.remainingCycles = 2 + additionalCycles;
            break;

        case IFL:
            task.remainingCycles = 2 + additionalCycles;
            break;

        case IFGE:
            task.remainingCycles = 2 + additionalCycles;
            break;

        case IFLE:
            task.remainingCycles = 2 + additionalCycles;
            break;

        case INIT:
            task.remainingCycles = 2 + additionalCycles;
            break;

        case BREAK:
            task.remainingCycles = 1 + additionalCycles;
            break;

        case RESUME:
            task.remainingCycles = 1 + additionalCycles;
            break;

        case SEIZE:
            task.remainingCycles = 1 + additionalCycles;
            break;

        case SLEEP:
            if(task.a > 2000) {
                program.error = InvalidParameter;
                break;
            }
            task.remainingCycles = task.a + additionalCycles;
            break;

        case QUIT:
            task.remainingCycles = 1 + additionalCycles;
            break;
    }
}

void Simulator::endInstruction(Program& program, Task& task) {
    // we are not executing yet
    if(!task.execBank || program.error != NoError) {
        return;
    }

    // check if bank is overwritten, skip execution of current command and begin new bank at instruction 0
    if(task.execBank != program.banks[task.bankIndex]) {
        task.instIndex = 0;
        return;
    }

    // execute command
    auto& instruction = task.execBank->instructions[task.instIndex];
    switch(instruction.command) {
        case CREATE: {
            auto remotePosition = calcPosition(program.position, task.direction, 1);
            auto remoteProgram = findProgram(remotePosition);
            if(!remoteProgram) {
                programs.push_back(Program(program.team, task.direction, remotePosition, task.a, task.b, task.c));
                ++program.team->programCount;
            }
            task.instIndex += 1;
            break;
        }

        case MOVE: {
            auto remotePosition = calcPosition(program.position, task.direction, 1);
            auto remoteProgram = findProgram(remotePosition);
            if(!remoteProgram) {
                program.position = remotePosition;
            }
            task.instIndex += 1;
            break;
        }

        case DIE: {
            program.error = DieExecuted;
            task.instIndex += 1;
            break;
        }

        case TRANS: {
            int ar = task.a - 1;
            int br = task.b - 1;
            auto remotePosition = calcPosition(program.position, task.direction, 1);
            auto remoteProgram = findProgram(remotePosition);
            if(remoteProgram && br < static_cast<int>(remoteProgram->banks.size()) && ar < static_cast<int>(program.banks.size())) {
                remoteProgram->banks[br] = program.banks[ar];
            }
            task.instIndex += 1;
            break;
        }

        case RTRANS: {
            int ar = task.a - 1;
            int br = task.b - 1;
            auto remotePosition = calcPosition(program.position, task.direction, 1);
            auto remoteProgram = findProgram(remotePosition);
            if(remoteProgram && ar < static_cast<int>(remoteProgram->banks.size()) && br < static_cast<int>(program.banks.size())) {
                program.banks[br] = remoteProgram->banks[ar];
            }
            task.instIndex += 1;
            break;
        }

        case TURN: {
            task.direction = static_cast<Direction>(qMax(0, (task.direction + ((task.a >= 0) ? 1 : -1)) % 4));
            task.instIndex += 1;
            break;
        }

        case JUMP: {
            task.instIndex += task.a;
            break;
        }

        case AJUMP: {
            task.instIndex = task.a - 1;
            break;
        }

        case BJUMP: {
            task.bankIndex = task.a - 1;
            task.instIndex = task.b - 1;
            break;
        }

        case SCAN: {
            // Scans a field, result in #a
            // #a=0 ...empty.
            // #a=1 ...enemy
            // #a=2 ...friend
            auto remotePosition = calcPosition(program.position, task.direction, 1);
            auto remoteProgram = findProgram(remotePosition);
            *task.var_a = !remoteProgram ? 0 : remoteProgram->team == program.team ? 2: 1;
            task.instIndex += 1;
            break;
        }

        case FARSCAN: {
            // Scans up to c fields straight in front of the bot.
            // The nearest bot's type is stored in #a:
            // #a=0 ...empty.
            // #a=1 ...enemy
            // #a=2 ...friend
            // Its distance is stored in #b.
            *task.var_a = 0;
            *task.var_b = 0;
            for(int i = 0; i < task.c; ++i) {
                auto remotePosition = calcPosition(program.position, task.direction, i + 1);
                auto remoteProgram = findProgram(remotePosition);
                if(remoteProgram) {
                    *task.var_a = remoteProgram->team == program.team ? 2: 1;
                    *task.var_b = i;
                    break;
                }
            }
            task.instIndex += 1;
            break;
        }

        case SET:
            *task.var_a = task.b;
            task.instIndex += 1;
            break;

        case ADD:
            *task.var_a += task.b;
            task.instIndex += 1;
            break;

        case SUB:
            *task.var_a -= task.b;
            task.instIndex += 1;
            break;

        case MUL:
            *task.var_a *= task.b;
            task.instIndex += 1;
            break;

        case DIV:
            if(task.b == 0) {
                program.error = DivisionByZero;
                break;
            }
            *task.var_a /= task.b;
            task.instIndex += 1;
            break;

        case MOD:
            if(task.b == 0) {
                program.error = DivisionByZero;
                break;
            }
            *task.var_a %= task.b;
            task.instIndex += 1;
            break;

        case MIN:
            *task.var_a = qMin(task.a, task.b);
            task.instIndex += 1;
            break;

        case MAX:
            *task.var_a = qMax(task.a, task.b);
            task.instIndex += 1;
            break;

        case RANDOM:
            *task.var_a = task.b + (rand() % (task.c - task.b + 1));
            task.instIndex += 1;
            break;

        case IF:
            task.instIndex += ((task.a == task.b) ? 1 : 2);
            break;

        case IFN:
            task.instIndex += ((task.a != task.b) ? 1 : 2);
            break;

        case IFG:
            task.instIndex += ((task.a > task.b) ? 1 : 2);
            break;

        case IFL:
            task.instIndex += ((task.a < task.b) ? 1 : 2);
            break;

        case IFGE:
            task.instIndex += ((task.a >= task.b) ? 1 : 2);
            break;

        case IFLE:
            task.instIndex += ((task.a <= task.b) ? 1 : 2);
            break;

        case INIT:
            task.instIndex += 1;
            break;

        case BREAK:
            task.instIndex += 1;
            break;

        case RESUME:
            task.instIndex += 1;
            break;

        case SEIZE:
            task.instIndex += 1;
            break;

        case SLEEP:
            task.instIndex += 1;
            break;

        case QUIT:
            task.instIndex += 1;
            break;

        default:
            task.instIndex += 1;
            break;
    }
}