feat: Add edit file tool (#249)

* feat: Add edit file tool
* feat: Add icons for action buttons

context/ChangesManager.h

@@ -22,8 +22,10 @@
 #include <texteditor/textdocument.h>
 #include <QDateTime>
 #include <QHash>
+#include <QMutex>
 #include <QQueue>
 #include <QTimer>
+#include <QUndoStack>
 
 namespace QodeAssist::Context {
 
@@ -39,21 +41,117 @@ public:
         QString lineContent;
     };
 
+    enum FileEditStatus { Pending, Applied, Rejected, Archived };
+
+    struct DiffHunk
+    {
+        int oldStartLine;       // Starting line in old file (1-based)
+        int oldLineCount;       // Number of lines in old file
+        int newStartLine;       // Starting line in new file (1-based)
+        int newLineCount;       // Number of lines in new file
+        QStringList contextBefore;  // Lines of context before the change (for anchoring)
+        QStringList removedLines;   // Lines to remove (prefixed with -)
+        QStringList addedLines;     // Lines to add (prefixed with +)
+        QStringList contextAfter;   // Lines of context after the change (for anchoring)
+    };
+
+    struct DiffInfo
+    {
+        QList<DiffHunk> hunks;       // List of diff hunks
+        QString originalContent;     // Full original file content (for fallback)
+        QString modifiedContent;     // Full modified file content (for fallback)
+        int contextLines = 3;        // Number of context lines to keep
+        bool useFallback = false;    // If true, use original content-based approach
+    };
+
+    struct FileEdit
+    {
+        QString editId;
+        QString filePath;
+        QString oldContent;      // Kept for backward compatibility and fallback
+        QString newContent;      // Kept for backward compatibility and fallback
+        DiffInfo diffInfo;       // Initial diff (created once, may become stale after formatting)
+        FileEditStatus status;
+        QDateTime timestamp;
+        bool wasAutoApplied = false;  // Track if edit was already auto-applied once
+        bool isFromHistory = false;   // Track if edit was loaded from chat history
+        QString statusMessage;
+    };
+
     static ChangesManager &instance();
 
     void addChange(
         TextEditor::TextDocument *document, int position, int charsRemoved, int charsAdded);
     QString getRecentChangesContext(const TextEditor::TextDocument *currentDocument) const;
 
+    void addFileEdit(
+        const QString &editId,
+        const QString &filePath,
+        const QString &oldContent,
+        const QString &newContent,
+        bool autoApply = true,
+        bool isFromHistory = false,
+        const QString &requestId = QString());
+    bool applyFileEdit(const QString &editId);
+    bool rejectFileEdit(const QString &editId);
+    bool undoFileEdit(const QString &editId);
+    FileEdit getFileEdit(const QString &editId) const;
+    QList<FileEdit> getPendingEdits() const;
+    
+    bool applyPendingEditsForRequest(const QString &requestId, QString *errorMsg = nullptr);
+    
+    QList<FileEdit> getEditsForRequest(const QString &requestId) const;
+    
+    bool undoAllEditsForRequest(const QString &requestId, QString *errorMsg = nullptr);
+    
+    bool reapplyAllEditsForRequest(const QString &requestId, QString *errorMsg = nullptr);
+    
+    void archiveAllNonArchivedEdits();
+
+signals:
+    void fileEditAdded(const QString &editId);
+    void fileEditApplied(const QString &editId);
+    void fileEditRejected(const QString &editId);
+    void fileEditUndone(const QString &editId);
+    void fileEditArchived(const QString &editId);
+
 private:
     ChangesManager();
     ~ChangesManager();
     ChangesManager(const ChangesManager &) = delete;
     ChangesManager &operator=(const ChangesManager &) = delete;
 
-    void cleanupOldChanges();
+    bool performFileEdit(const QString &filePath, const QString &oldContent, const QString &newContent, QString *errorMsg = nullptr);
+    bool performFileEditWithDiff(const QString &filePath, const DiffInfo &diffInfo, bool reverse, QString *errorMsg = nullptr);
+    QString readFileContent(const QString &filePath) const;
+    
+    DiffInfo createDiffInfo(const QString &originalContent, const QString &modifiedContent, const QString &filePath);
+    bool applyDiffToContent(QString &content, const DiffInfo &diffInfo, bool reverse, QString *errorMsg = nullptr);
+    bool findHunkLocation(const QStringList &fileLines, const DiffHunk &hunk, int &actualStartLine, QString *debugInfo = nullptr) const;
+    
+    // Helper method for fragment-based apply/undo operations
+    bool performFragmentReplacement(
+        const QString &filePath,
+        const QString &searchContent,
+        const QString &replaceContent,
+        bool isAppendOperation,
+        QString *errorMsg = nullptr);
+    
+    int levenshteinDistance(const QString &s1, const QString &s2) const;
+    QString findBestMatch(const QString &fileContent, const QString &searchContent, double threshold = 0.8, double *outSimilarity = nullptr) const;
+    QString findBestMatchWithNormalization(const QString &fileContent, const QString &searchContent, double *outSimilarity = nullptr, QString *outMatchType = nullptr) const;
+
+    struct RequestEdits
+    {
+        QStringList editIds;
+        bool autoApplyPending = false;
+    };
 
     QHash<TextEditor::TextDocument *, QQueue<ChangeInfo>> m_documentChanges;
+    QHash<QString, FileEdit> m_fileEdits;
+    QHash<QString, RequestEdits> m_requestEdits;  // requestId → ordered edits
+    QUndoStack *m_undoStack;
+    mutable QMutex m_mutex;
 };
 
 } // namespace QodeAssist::Context

context/ProjectUtils.cpp

@@ -51,4 +51,23 @@ bool ProjectUtils::isFileInProject(const QString &filePath)
     return false;
 }
 
+QString ProjectUtils::findFileInProject(const QString &filename)
+{
+    QList<ProjectExplorer::Project *> projects = ProjectExplorer::ProjectManager::projects();
+
+    for (auto project : projects) {
+        if (!project)
+            continue;
+
+        Utils::FilePaths projectFiles = project->files(ProjectExplorer::Project::SourceFiles);
+        for (const auto &projectFile : std::as_const(projectFiles)) {
+            if (projectFile.fileName() == filename) {
+                return projectFile.toFSPathString();
+            }
+        }
+    }
+
+    return QString();
+}
+
 } // namespace QodeAssist::Context

context/ProjectUtils.hpp

@@ -41,6 +41,17 @@ public:
      * @return true if file is part of any open project, false otherwise
      */
     static bool isFileInProject(const QString &filePath);
+
+    /**
+     * @brief Find a file in open projects by filename
+     * 
+     * Searches all open projects for a file matching the given filename.
+     * If multiple files with the same name exist, returns the first match.
+     * 
+     * @param filename File name to search for (e.g., "main.cpp")
+     * @return Absolute file path if found, empty string otherwise
+     */
+    static QString findFileInProject(const QString &filename);
 };
 
 } // namespace QodeAssist::Context