feat: Implement vim-style input handling

Add complete vim-style keyboard navigation:
- Normal mode: hjkl movement, gg/G jump, numeric prefixes
- Command mode: :q, :o URL, :r, :h, :[number]
- Search mode: / for search, n/N for next/previous match
- Link navigation: Tab/Shift-Tab, Enter to follow
- Scroll commands: Ctrl-D/U, Space, b for page up/down
- History navigation: h for back, l for forward

Input handler manages mode transitions and command parsing
with full vim compatibility.

src/input_handler.cpp

@@ -0,0 +1,253 @@
+#include "input_handler.h"
+#include <curses.h>
+#include <cctype>
+#include <sstream>
+
+class InputHandler::Impl {
+public:
+    InputMode mode = InputMode::NORMAL;
+    std::string buffer;
+    std::string count_buffer;
+    std::function<void(const std::string&)> status_callback;
+
+    void set_status(const std::string& msg) {
+        if (status_callback) {
+            status_callback(msg);
+        }
+    }
+
+    InputResult process_normal_mode(int ch) {
+        InputResult result;
+        result.action = Action::NONE;
+        result.number = 0;
+        result.has_count = false;
+        result.count = 1;
+
+        // 处理数字前缀
+        if (std::isdigit(ch) && (ch != '0' || !count_buffer.empty())) {
+            count_buffer += static_cast<char>(ch);
+            return result;
+        }
+
+        // 解析count
+        if (!count_buffer.empty()) {
+            result.has_count = true;
+            result.count = std::stoi(count_buffer);
+            count_buffer.clear();
+        }
+
+        // 处理vim风格的命令
+        switch (ch) {
+            // 移动
+            case 'j':
+            case KEY_DOWN:
+                result.action = Action::SCROLL_DOWN;
+                break;
+            case 'k':
+            case KEY_UP:
+                result.action = Action::SCROLL_UP;
+                break;
+            case 'h':
+            case KEY_LEFT:
+                result.action = Action::GO_BACK;
+                break;
+            case 'l':
+            case KEY_RIGHT:
+                result.action = Action::GO_FORWARD;
+                break;
+
+            // 翻页
+            case 4: // Ctrl-D
+            case ' ':
+                result.action = Action::SCROLL_PAGE_DOWN;
+                break;
+            case 21: // Ctrl-U
+            case 'b':
+                result.action = Action::SCROLL_PAGE_UP;
+                break;
+
+            // 跳转
+            case 'g':
+                buffer += 'g';
+                if (buffer == "gg") {
+                    result.action = Action::GOTO_TOP;
+                    buffer.clear();
+                }
+                break;
+            case 'G':
+                if (result.has_count) {
+                    result.action = Action::GOTO_LINE;
+                    result.number = result.count;
+                } else {
+                    result.action = Action::GOTO_BOTTOM;
+                }
+                break;
+
+            // 搜索
+            case '/':
+                mode = InputMode::SEARCH;
+                buffer = "/";
+                break;
+            case 'n':
+                result.action = Action::SEARCH_NEXT;
+                break;
+            case 'N':
+                result.action = Action::SEARCH_PREV;
+                break;
+
+            // 链接导航
+            case '\t': // Tab
+                result.action = Action::NEXT_LINK;
+                break;
+            case KEY_BTAB: // Shift-Tab (可能不是所有终端都支持)
+            case 'T':
+                result.action = Action::PREV_LINK;
+                break;
+            case '\n': // Enter
+            case '\r':
+                result.action = Action::FOLLOW_LINK;
+                break;
+
+            // 命令模式
+            case ':':
+                mode = InputMode::COMMAND;
+                buffer = ":";
+                break;
+
+            // 其他操作
+            case 'r':
+                result.action = Action::REFRESH;
+                break;
+            case 'q':
+                result.action = Action::QUIT;
+                break;
+            case '?':
+                result.action = Action::HELP;
+                break;
+
+            default:
+                buffer.clear();
+                break;
+        }
+
+        return result;
+    }
+
+    InputResult process_command_mode(int ch) {
+        InputResult result;
+        result.action = Action::NONE;
+
+        if (ch == '\n' || ch == '\r') {
+            // 执行命令
+            std::string command = buffer.substr(1); // 去掉':'
+
+            if (command == "q" || command == "quit") {
+                result.action = Action::QUIT;
+            } else if (command == "h" || command == "help") {
+                result.action = Action::HELP;
+            } else if (command == "r" || command == "refresh") {
+                result.action = Action::REFRESH;
+            } else if (command.rfind("o ", 0) == 0 || command.rfind("open ", 0) == 0) {
+                // :o URL 或 :open URL
+                size_t space_pos = command.find(' ');
+                if (space_pos != std::string::npos) {
+                    result.action = Action::OPEN_URL;
+                    result.text = command.substr(space_pos + 1);
+                }
+            } else if (!command.empty() && std::isdigit(command[0])) {
+                // 跳转到行号
+                try {
+                    result.action = Action::GOTO_LINE;
+                    result.number = std::stoi(command);
+                } catch (...) {
+                    set_status("Invalid line number");
+                }
+            }
+
+            mode = InputMode::NORMAL;
+            buffer.clear();
+        } else if (ch == 27) { // ESC
+            mode = InputMode::NORMAL;
+            buffer.clear();
+        } else if (ch == KEY_BACKSPACE || ch == 127 || ch == 8) {
+            if (buffer.length() > 1) {
+                buffer.pop_back();
+            } else {
+                mode = InputMode::NORMAL;
+                buffer.clear();
+            }
+        } else if (std::isprint(ch)) {
+            buffer += static_cast<char>(ch);
+        }
+
+        return result;
+    }
+
+    InputResult process_search_mode(int ch) {
+        InputResult result;
+        result.action = Action::NONE;
+
+        if (ch == '\n' || ch == '\r') {
+            // 执行搜索
+            if (buffer.length() > 1) {
+                result.action = Action::SEARCH_FORWARD;
+                result.text = buffer.substr(1); // 去掉'/'
+            }
+            mode = InputMode::NORMAL;
+            buffer.clear();
+        } else if (ch == 27) { // ESC
+            mode = InputMode::NORMAL;
+            buffer.clear();
+        } else if (ch == KEY_BACKSPACE || ch == 127 || ch == 8) {
+            if (buffer.length() > 1) {
+                buffer.pop_back();
+            } else {
+                mode = InputMode::NORMAL;
+                buffer.clear();
+            }
+        } else if (std::isprint(ch)) {
+            buffer += static_cast<char>(ch);
+        }
+
+        return result;
+    }
+};
+
+InputHandler::InputHandler() : pImpl(std::make_unique<Impl>()) {}
+
+InputHandler::~InputHandler() = default;
+
+InputResult InputHandler::handle_key(int ch) {
+    switch (pImpl->mode) {
+        case InputMode::NORMAL:
+            return pImpl->process_normal_mode(ch);
+        case InputMode::COMMAND:
+            return pImpl->process_command_mode(ch);
+        case InputMode::SEARCH:
+            return pImpl->process_search_mode(ch);
+        default:
+            break;
+    }
+
+    InputResult result;
+    result.action = Action::NONE;
+    return result;
+}
+
+InputMode InputHandler::get_mode() const {
+    return pImpl->mode;
+}
+
+std::string InputHandler::get_buffer() const {
+    return pImpl->buffer;
+}
+
+void InputHandler::reset() {
+    pImpl->mode = InputMode::NORMAL;
+    pImpl->buffer.clear();
+    pImpl->count_buffer.clear();
+}
+
+void InputHandler::set_status_callback(std::function<void(const std::string&)> callback) {
+    pImpl->status_callback = callback;
+}

src/input_handler.h

@@ -0,0 +1,67 @@
+#pragma once
+
+#include <string>
+#include <functional>
+
+enum class InputMode {
+    NORMAL,    // 正常浏览模式
+    COMMAND,   // 命令模式 (:)
+    SEARCH,    // 搜索模式 (/)
+    LINK       // 链接选择模式
+};
+
+enum class Action {
+    NONE,
+    SCROLL_UP,
+    SCROLL_DOWN,
+    SCROLL_PAGE_UP,
+    SCROLL_PAGE_DOWN,
+    GOTO_TOP,
+    GOTO_BOTTOM,
+    GOTO_LINE,
+    SEARCH_FORWARD,
+    SEARCH_NEXT,
+    SEARCH_PREV,
+    NEXT_LINK,
+    PREV_LINK,
+    FOLLOW_LINK,
+    GO_BACK,
+    GO_FORWARD,
+    OPEN_URL,
+    REFRESH,
+    QUIT,
+    HELP
+};
+
+struct InputResult {
+    Action action;
+    std::string text;  // 用于命令、搜索、URL输入
+    int number;        // 用于跳转行号、链接编号等
+    bool has_count;    // 是否有数字前缀（如 5j）
+    int count;         // 数字前缀
+};
+
+class InputHandler {
+public:
+    InputHandler();
+    ~InputHandler();
+
+    // 处理单个按键
+    InputResult handle_key(int ch);
+
+    // 获取当前模式
+    InputMode get_mode() const;
+
+    // 获取当前输入缓冲（用于显示命令行）
+    std::string get_buffer() const;
+
+    // 重置状态
+    void reset();
+
+    // 设置状态栏消息回调
+    void set_status_callback(std::function<void(const std::string&)> callback);
+
+private:
+    class Impl;
+    std::unique_ptr<Impl> pImpl;
+};