<?php
require_once 'Todo.php';

class TodoController {
    private $dataFile = 'todos.json';
    
    public function __construct() {
        // Create data file if it doesn't exist
        if (!file_exists($this->dataFile)) {
            file_put_contents($this->dataFile, json_encode([]));
        }
    }
    
    private function loadTodos() {
        $data = file_get_contents($this->dataFile);
        $todosData = json_decode($data, true) ?: [];
        
        $todos = [];
        foreach ($todosData as $todoData) {
            $todos[] = new Todo(
                $todoData['id'],
                $todoData['title'],
                $todoData['description'] ?? '',
                $todoData['completed'] ?? false
            );
        }
        
        return $todos;
    }
    
    private function saveTodos($todos) {
        $todosData = [];
        foreach ($todos as $todo) {
            $todosData[] = $todo->toArray();
        }
        
        file_put_contents($this->dataFile, json_encode($todosData, JSON_PRETTY_PRINT));
    }
    
    private function getNextId() {
        $todos = $this->loadTodos();
        if (empty($todos)) {
            return 1;
        }
        
        $maxId = 0;
        foreach ($todos as $todo) {
            if ($todo->getId() > $maxId) {
                $maxId = $todo->getId();
            }
        }
        
        return $maxId + 1;
    }
    
    public function getAllTodos() {
        try {
            $todos = $this->loadTodos();
            $todosArray = [];
            
            foreach ($todos as $todo) {
                $todosArray[] = $todo->toArray();
            }
            
            echo json_encode($todosArray);
        } catch (Exception $e) {
            http_response_code(500);
            echo json_encode(['error' => 'Failed to fetch todos: ' . $e->getMessage()]);
        }
    }
    
    public function createTodo() {
        try {
            $input = json_decode(file_get_contents('php://input'), true);
            
            if (!$input || !isset($input['title']) || empty(trim($input['title']))) {
                http_response_code(400);
                echo json_encode(['error' => 'Title is required']);
                return;
            }
            
            $id = $this->getNextId();
            $title = trim($input['title']);
            $description = isset($input['description']) ? trim($input['description']) : '';
            $completed = isset($input['completed']) ? (bool)$input['completed'] : false;
            
            $todo = new Todo($id, $title, $description, $completed);
            
            $todos = $this->loadTodos();
            $todos[] = $todo;
            $this->saveTodos($todos);
            
            http_response_code(201);
            echo json_encode($todo->toArray());
        } catch (Exception $e) {
            http_response_code(500);
            echo json_encode(['error' => 'Failed to create todo: ' . $e->getMessage()]);
        }
    }
    
    public function updateTodo($id) {
        try {
            $input = json_decode(file_get_contents('php://input'), true);
            
            if (!$input) {
                http_response_code(400);
                echo json_encode(['error' => 'Invalid JSON input']);
                return;
            }
            
            $todos = $this->loadTodos();
            $todoIndex = -1;
            
            for ($i = 0; $i < count($todos); $i++) {
                if ($todos[$i]->getId() === $id) {
                    $todoIndex = $i;
                    break;
                }
            }
            
            if ($todoIndex === -1) {
                http_response_code(404);
                echo json_encode(['error' => 'Todo not found']);
                return;
            }
            
            $todo = $todos[$todoIndex];
            
            // Update fields if provided
            if (isset($input['title'])) {
                if (empty(trim($input['title']))) {
                    http_response_code(400);
                    echo json_encode(['error' => 'Title cannot be empty']);
                    return;
                }
                $todo->setTitle(trim($input['title']));
            }
            
            if (isset($input['description'])) {
                $todo->setDescription(trim($input['description']));
            }
            
            if (isset($input['completed'])) {
                $todo->setCompleted((bool)$input['completed']);
            }
            
            $this->saveTodos($todos);
            
            echo json_encode($todo->toArray());
        } catch (Exception $e) {
            http_response_code(500);
            echo json_encode(['error' => 'Failed to update todo: ' . $e->getMessage()]);
        }
    }
    
    public function deleteTodo($id) {
        try {
            $todos = $this->loadTodos();
            $todoIndex = -1;
            
            for ($i = 0; $i < count($todos); $i++) {
                if ($todos[$i]->getId() === $id) {
                    $todoIndex = $i;
                    break;
                }
            }
            
            if ($todoIndex === -1) {
                http_response_code(404);
                echo json_encode(['error' => 'Todo not found']);
                return;
            }
            
            $deletedTodo = $todos[$todoIndex];
            array_splice($todos, $todoIndex, 1);
            $this->saveTodos($todos);
            
            echo json_encode([
                'message' => 'Todo deleted successfully',
                'deleted_todo' => $deletedTodo->toArray()
            ]);
        } catch (Exception $e) {
            http_response_code(500);
            echo json_encode(['error' => 'Failed to delete todo: ' . $e->getMessage()]);
        }
    }
}
?>