// 将正则表达式转换为非确定性有限自动机
#include "nfa.h"



// 处理正则表达式，描述终态
NFA RexToNFA() {
    //由于里面存在||,所以不同正则间使用空格分隔代表| l代表letter，_代表下划线，0代表数字(也可以是d，但是为了使用已经有的函数)，
    //[lu]代表l|u
    std::string rex = "+ - * / % = > < == <= >= != && || ( ) { } , ; [l_][l_0]* -?00*";
    
    //正则对应的输出(终态)
    vector<WordType> finalState = {
        WordType::OP_ADD, 
        WordType::OP_SUB,
        WordType::OP_MUL,
        WordType::OP_DIV,
        WordType::OP_MOD,
        WordType::OP_ASSIGN,
        WordType::OP_GT,
        WordType::OP_LT,
        WordType::OP_EQ,
        WordType::OP_LE,
        WordType::OP_GE,
        WordType::OP_NE,
        WordType::OP_AND,
        WordType::OP_OR,
        WordType::SE_LBRAC, 
        WordType::SE_RBRAC,
        WordType::SE_LCBRAC,
        WordType::SE_RCBRAC,
        WordType::SE_COMMA,
        WordType::SE_SEMI,
        WordType::IDN,
        WordType::INT_VAL
    };

    stringstream ss(rex);
    string target;

    // 创建初始状态
    int stateIndex = 0;
    int finalIndex = 0;
    State* startState = new State(stateIndex++);
    set<State*, StatePtrCompare> endStates;
    set<State*, StatePtrCompare> allStates = { startState };
    
    // 按空格分割
    while (getline(ss, target,' ')) {
        //如获得[l_][l_0]*
        State* currentState = startState;

        for (size_t i = 0; i < target.length();i++) {
            //创建一个新状态，startState通过输入InputCharType到达该状态
            State* newState = new State(stateIndex++);
            allStates.insert(newState);
            //需要往后看一个符号
            if (target[i] == '[') {
                //[...]构成一种输入，查看]后面是否有？或者*，来判断当前状态的构成
                for (i=i+1; i < target.length() && target[i] != ']'; i++) {
                    InputCharType input = getInputCharType(target[i]);
                    if (input != InputCharType::EPSILON) {
                        // 添加转移函数，从当前状态向新状态转移
                        currentState->addTransition(input, newState);
                    }
                }
            }
            else {
                InputCharType input = getInputCharType(target[i]);
                currentState->addTransition(input, newState);
            }
            //往后查看一个输入
            if (i + 1 < target.length() && target[i + 1] == '?') {
                //创建EPSILON转移状态
                State* epsState = new State(stateIndex++);
                allStates.insert(epsState);
                currentState->addTransition(InputCharType::EPSILON, epsState);
                newState->addTransition(InputCharType::EPSILON, epsState);
                currentState = epsState;
                // 跳过'?'字符
                i++;
            }
            else if (i + 1 < target.length() && target[i + 1] == '*') {
                State* epsState = new State(stateIndex++);
                allStates.insert(epsState);
                currentState->addTransition(InputCharType::EPSILON, epsState);
                newState->addTransition(InputCharType::EPSILON, epsState);
                epsState->addTransition(InputCharType::EPSILON, currentState);
                currentState = epsState;
                // 跳过'*'字符
                i++;
            }
            else {
                currentState = newState;
            }
            //判断是否是终止状态
            if (i == (target.length() - 1)) {
                // 到达最后一个字符，将当前状态设置为终止状态
                currentState->setFinalState(true, finalState[endStates.size()]);
                endStates.insert(currentState);
            }
        }//for
    }
    // 返回字符集合对应的NFA
    return NFA(startState, endStates, allStates);
}

void printNFA(const NFA& nfa) {
    cout << "Start state: " << nfa.startState->id << endl;
    cout << "End states: "<<endl;
    for (auto state : nfa.endStates) {
        cout << state->id << " " << getWordTypeName(state->wordType) << " " << (state->isFinalState == true) << endl;
    }
    cout << endl;

    cout << "States and transitions:" << endl;
    for (auto state : nfa.states) {
        cout << "State " << state->id << ":" << endl;
        for (auto transition : state->transitions) {
            cout << "\tInput " << getInputChartypeName(transition.first) << ": ";
            for (auto targetState : transition.second) {
                cout << targetState->id << " ";
            }
            cout << endl;
        }
    }
}

set<State*, StatePtrCompare> move(const set<State*, StatePtrCompare>& states, InputCharType input) {
    set<State*, StatePtrCompare> targetStates;
    for (State* state : states) {
        auto it = state->transitions.find(input);
        if (it != state->transitions.end()) {
            for (State* targetState : it->second) {
                if (targetStates.find(targetState) == targetStates.end()) {
                    targetStates.insert(targetState);
                }
            }
        }
    }
    return targetStates;
}


set<State*, StatePtrCompare> epsilonClosure(const set<State*, StatePtrCompare>& states) {
    set<State*, StatePtrCompare> closure = states;
    stack<State*> stateStack;
    for (State* state : states) {
        stateStack.push(state);
    }
    while (!stateStack.empty()) {
        State* currentState = stateStack.top();
        stateStack.pop();
        auto it = currentState->transitions.find(InputCharType::EPSILON);
        if (it != currentState->transitions.end()) {
            for (State* nextState : it->second) {
                if (closure.find(nextState) == closure.end()) {//防止同一状态多次进栈，set自带去重
                    closure.insert(nextState);
                    stateStack.push(nextState);
                }
            }
        }
    }
    return closure;
}

DFA nfaToDFA(const NFA& nfa) {
    map<set<State*, StatePtrCompare>, State*, SetComparator> dfaStatesMap; // 用于映射NFA状态集合到DFA状态的映射表
    queue<set<State*, StatePtrCompare>> nfaStatesQueue; // 用于BFS遍历的集合队列
    set<State*, StatePtrCompare> dfaStates;
    set<State*, StatePtrCompare> dfaEndStates;

    set<State*, StatePtrCompare> nfaStartClosure = epsilonClosure({ nfa.startState });
    State* dfaStartState = new State(0);
    dfaStatesMap[nfaStartClosure] = dfaStartState;
    dfaStates.insert(dfaStartState);
    nfaStatesQueue.push(nfaStartClosure);

    int nextStateId = 1;
    //set<State*, StatePtrCompare> nfaStartClosure
    while (!nfaStatesQueue.empty()) {
        set<State*, StatePtrCompare> currentNFAStates = nfaStatesQueue.front();
        nfaStatesQueue.pop();
        State* currentDFAState = dfaStatesMap[currentNFAStates];

        // 检查是否有终止状态，如果有，设置DFA状态为终止状态
        for (State* nfaState : currentNFAStates) {
            if (nfaState->isFinalState) {
               // cout << nfaState->id << "is FinalState" << endl;
                currentDFAState->setFinalState(true, nfaState->wordType);
                dfaEndStates.insert(currentDFAState);
                break;
            }
        }

        // 遍历所有输入字符类型
        for (int i = 0; i < static_cast<int>(InputCharType::EPSILON); i++) {
            InputCharType inputCharType = static_cast<InputCharType>(i);
            set<State*, StatePtrCompare> nextNFAStates = epsilonClosure(move(currentNFAStates, inputCharType));
            if (nextNFAStates.empty()) {
                continue;
            }

            // 如果NFA状态集合不存在于映射表中，则创建新的DFA状态
            if (dfaStatesMap.find(nextNFAStates) == dfaStatesMap.end()) {
                State* newDFAState = new State(nextStateId++);
                dfaStatesMap[nextNFAStates] = newDFAState;
                dfaStates.insert(newDFAState);
                nfaStatesQueue.push(nextNFAStates);
            }
            currentDFAState->addTransition(inputCharType, dfaStatesMap[nextNFAStates]);
        }
    }

    return DFA(dfaStartState, dfaEndStates, dfaStates);
}

void printDFA(const DFA& dfa) {
    cout << "Start state: " << dfa.startState->id << endl;
    cout << "End states: "<<endl;
    for (auto state : dfa.endStates) {
        cout << state->id << " " << getWordTypeName(state->wordType) << endl;
    }
    cout << endl;
    cout << "States and transitions:" << endl;
    for (auto state : dfa.states) {
        cout << "State " << state->id << ":" << endl;
        for (auto transition : state->transitions) {
            cout << "\tInput " << getInputChartypeName(transition.first) << ": ";
            for (auto targetState : transition.second) {
                cout << targetState->id << " ";
            }
            cout << endl;
        }
    }
}