// 23_task_manager.cpp
// vector 实战演练：用 std::vector 写一个任务管理器（增删查、remove-erase、容量观察）

#include <algorithm>
#include <iostream>
#include <string>
#include <vector>

struct Task {
    std::string description;
    bool done;
    Task(std::string desc) : description(std::move(desc)), done(false) {}
};

class TaskManager {
  public:
    void add_task(const std::string& desc) {
        tasks_.emplace_back(desc);
        std::cout << "  Added: \"" << desc << "\"\n";
    }

    void complete_task(int index) {
        if (index < 0 || index >= static_cast<int>(tasks_.size())) {
            std::cout << "  Invalid index: " << index << "\n";
            return;
        }
        tasks_[index].done = true;
        std::cout << "  Completed: \"" << tasks_[index].description << "\"\n";
    }

    void remove_completed() {
        // remove-erase 惯用法：删除所有 done == true 的任务
        auto it =
            std::remove_if(tasks_.begin(), tasks_.end(), [](const Task& t) { return t.done; });
        int removed = static_cast<int>(tasks_.end() - it);
        tasks_.erase(it, tasks_.end());
        std::cout << "  Removed " << removed << " completed task(s)\n";
    }

    void list_all() const {
        if (tasks_.empty()) {
            std::cout << "  (no tasks)\n";
            return;
        }
        for (std::size_t i = 0; i < tasks_.size(); ++i) {
            std::cout << "  [" << i << "] " << (tasks_[i].done ? "[x]" : "[ ]") << " "
                      << tasks_[i].description << "\n";
        }
    }

    void show_status() const {
        std::cout << "  size: " << tasks_.size() << ", capacity: " << tasks_.capacity() << "\n";
    }

  private:
    std::vector<Task> tasks_;
};

int main() {
    TaskManager mgr;

    std::cout << "=== Adding tasks ===\n";
    mgr.add_task("Write vector tutorial");
    mgr.add_task("Review pull requests");
    mgr.add_task("Fix build warnings");
    mgr.add_task("Update documentation");

    std::cout << "\n=== All tasks ===\n";
    mgr.list_all();
    mgr.show_status();

    std::cout << "\n=== Completing tasks ===\n";
    mgr.complete_task(0);
    mgr.complete_task(2);

    std::cout << "\n=== Removing completed ===\n";
    mgr.remove_completed();

    std::cout << "\n=== Remaining tasks ===\n";
    mgr.list_all();
    mgr.show_status();

    return 0;
}