/**
    Lab 6C - Maze Drawer, a program to parse a .maze text file and display it using SFML.

    @author Tyler Beckman (tyler_beckman@myriation.xyz)
    @date 12/4/24
 */
#include <SFML/Graphics.hpp>
#include <SFML/Window/Keyboard.hpp>
#include <queue>
#include <stack>
#include <utility>
#include <variant>
using namespace sf;

#include <iostream>
#include <fstream>
using namespace std;

enum class State {
    Unexplored,
    Added,
    Explored,
    UsedInPath
};

struct Node {
    char character;
    State state;
    Node* prevNode;
};

int main(int argc, char** argv) {
    string filename;
    if (argc >= 2) {
        filename = argv[1];
    } else {
        cout << "Please enter a maze filename to load: ";
        cin >> filename;
    }
    cout << "Loading maze file " << filename << endl;

    ifstream mazeFile(filename);
    if (mazeFile.fail()) {
        std::cout << "Failed to open specified file path " << filename
                << ", does it exist?" << std::endl;
        return 1;
    }

    int rows, cols;
    mazeFile >> rows >> cols;
    mazeFile.get(); // move cursor past newline to actual grid characters

    Node** grid = new Node*[rows];
    pair<int, int> startNode(-1, -1);
    for (int row = 0; row < rows; row++) {
        grid[row] = new Node[cols];
        for (int col = 0; col < cols; col++) {
            grid[row][col].character = mazeFile.get();
            grid[row][col].state = State::Unexplored;
            grid[row][col].prevNode = nullptr;
            // Save start as starting node and mark as visited
            if (grid[row][col].character == 'S') {
                startNode = make_pair(row, col);
                grid[row][col].state = State::Explored;
            };
        }
        mazeFile.get(); // advance past newline
    }

    char searchType = '\0';
    cout << "Would you like to use a [b]readth-first search or a [d]epth-first search? ";
    cin >> searchType;
    if (searchType != 'b' && searchType != 'B' && searchType != 'd' && searchType != 'D') {
        cout << "Search type '" << searchType << "' is unrecognized. Please enter a valid search type." << endl;
        return 1;
    }

    variant<queue<pair<int, int>>, stack<pair<int, int>>> nodeList;
    // Create stack or queue with start node
    if (searchType == 'b' || searchType == 'B') {
        nodeList = queue<pair<int, int>>({startNode});
    } else {
        nodeList = stack<pair<int, int>>({startNode});
    }

    bool searching = true;

    // create a window
    RenderWindow window( VideoMode(15*cols, 15*rows), "Maze Runner" );
    window.setVerticalSyncEnabled(true);

    // create an event object once to store future events
    Event event;

    // while the window is open
    while( window.isOpen() ) {
        // clear any existing contents
        window.clear();

        /////////////////////////////////////
        // BEGIN DRAWING HERE

        // Draw unsolved maze from grid by iterating over each column in each row
        for (int row = 0; row < rows; row++) {
            for (int col = 0; col < cols; col++) {
                sf::RectangleShape rectangle;
                rectangle.setSize(Vector2f(15, 15));
                rectangle.setPosition(col * 15, row * 15);
                switch (grid[row][col].character) {
                    case 'S':
                        rectangle.setFillColor(Color::Green);
                        break;
                    case 'E':
                        rectangle.setFillColor(Color::Red);
                        break;
                    case '#':
                        rectangle.setFillColor(Color::Black);
                        break;
                    case '.':
                        rectangle.setFillColor(Color::White);
                        break;
                }

                if (grid[row][col].character != 'S' && grid[row][col].character != 'E') {
                    switch (grid[row][col].state) {
                        case State::Added:
                            rectangle.setFillColor(Color::Blue);
                            break;
                        case State::Explored:
                            rectangle.setFillColor(Color::Magenta);
                            break;
                        case State::UsedInPath:
                            rectangle.setFillColor(Color::Yellow);
                            break;
                        default:
                            break;
                    }
                }

                window.draw(rectangle);
            }
        }

        // Solve maze
        if (searching) {
            // Take a node off the stack or queue
            pair<int, int> dequeuedNode;
            if (searchType == 'B' || searchType == 'b') {
                queue<pair<int, int>>& nodeQueue = get<queue<pair<int, int>>>(nodeList);
                if (nodeQueue.size() == 0) {
                    // Handle unsolvable mazes
                    searching = false;
                    cout << "Maze is unsolvable :c" << endl;
                    continue;
                }
                dequeuedNode = nodeQueue.front();
                nodeQueue.pop();
            } else {
                stack<pair<int, int>>& nodeStack = get<stack<pair<int, int>>>(nodeList);
                if (nodeStack.size() == 0) {
                    // Handle unsolvable mazes
                    searching = false;
                    cout << "Maze is unsolvable :c" << endl;
                    continue;
                }
                dequeuedNode = nodeStack.top();
                nodeStack.pop();
            }
            grid[dequeuedNode.first][dequeuedNode.second].state = State::Explored;

            // If end, print end and empty structure, then calculate true path
            if (grid[dequeuedNode.first][dequeuedNode.second].character == 'E') {
                cout << "End reached!" << endl;
                searching = false;

                // Empty stack/queue
                if (searchType == 'B' || searchType == 'b') {
                    queue<pair<int, int>>& nodeQueue = get<queue<pair<int, int>>>(nodeList);
                    for (size_t i = 0; i < nodeQueue.size(); i++) {
                        nodeQueue.pop();
                    }
                } else {
                    stack<pair<int, int>>& nodeStack = get<stack<pair<int, int>>>(nodeList);
                    for (size_t i = 0; i < nodeStack.size(); i++) {
                        nodeStack.pop();
                    }
                }

                // Mark all path-nodes as State::UsedInPath
                for (Node* node = &grid[dequeuedNode.first][dequeuedNode.second]; node != nullptr; node = node->prevNode) {
                    node->state = State::UsedInPath;
                }
            } else {
                // Take dequeued node and process it
                pair<int, int> nodesToAdd[4];
                int nodesAdded = 0;

                // Add all adjacent nodes in South->East->North->West order, if not added already

                // South
                if (
                    dequeuedNode.first != (rows - 1) 
                    && grid[dequeuedNode.first + 1][dequeuedNode.second].state == State::Unexplored
                    && grid[dequeuedNode.first + 1][dequeuedNode.second].character != '#'
                ) {
                    nodesToAdd[nodesAdded] = make_pair(dequeuedNode.first + 1, dequeuedNode.second);
                    nodesAdded++;
                }
                // East
                if (
                    dequeuedNode.second != (cols - 1) 
                    && grid[dequeuedNode.first][dequeuedNode.second + 1].state == State::Unexplored
                    && grid[dequeuedNode.first][dequeuedNode.second + 1].character != '#'
                ) {
                    nodesToAdd[nodesAdded] = make_pair(dequeuedNode.first, dequeuedNode.second + 1);
                    nodesAdded++;
                }
                // North
                if (
                    dequeuedNode.first != 0 
                    && grid[dequeuedNode.first - 1][dequeuedNode.second].state == State::Unexplored
                    && grid[dequeuedNode.first - 1][dequeuedNode.second].character != '#'
                ) {
                    nodesToAdd[nodesAdded] = make_pair(dequeuedNode.first - 1, dequeuedNode.second);
                    nodesAdded++;
                }
                // West
                if (
                    dequeuedNode.second != 0 
                    &&grid[dequeuedNode.first][dequeuedNode.second - 1].state == State::Unexplored
                    && grid[dequeuedNode.first][dequeuedNode.second - 1].character != '#'
                ) {
                    nodesToAdd[nodesAdded] = make_pair(dequeuedNode.first, dequeuedNode.second - 1);
                    nodesAdded++;
                }

                // Mark all added notes as State::Added, and link to current node to later display path
                for (int i = 0; i < nodesAdded; i++) {
                    grid[nodesToAdd[i].first][nodesToAdd[i].second].state = State::Added;
                    grid[nodesToAdd[i].first][nodesToAdd[i].second].prevNode = &grid[dequeuedNode.first][dequeuedNode.second];
                    if (searchType == 'B' || searchType == 'b') {
                        queue<pair<int, int>>& nodeQueue = get<queue<pair<int, int>>>(nodeList);
                        nodeQueue.push(nodesToAdd[i]);
                    } else {
                        stack<pair<int, int>>& nodeStack = get<stack<pair<int, int>>>(nodeList);
                        nodeStack.push(nodesToAdd[i]);
                    }
                }
                
                // Sleep to avoid solving instantly
                sleep(milliseconds(50));
            }
        }

        //  END  DRAWING HERE
        /////////////////////////////////////


        // display the current contents of the window
        window.display();

        /////////////////////////////////////
        // BEGIN EVENT HANDLING HERE
        // check if any events happened since the last time checked
        while( window.pollEvent(event) ) {
            // if event type corresponds to pressing window X
            if (event.type == Event::Closed) {
                // tell the window to close
                window.close();
            }
            // If event type corresponds to pressing Q or Esc
            if (event.type == Event::KeyPressed) {
                switch (event.key.code) {
                    case Keyboard::Key::Q:
                    case Keyboard::Key::Escape:
                        // Tell the window to close
                        window.close();
                        break;
                    default:
                        break;
                }
            }
            // check addition event types to handle additional events
        }
        //  END  EVENT HANDLING HERE
        /////////////////////////////////////
    }

    return 0;
}