// Copyright (C) 2025-2026 Petr Mironychev
// SPDX-License-Identifier: GPL-3.0-or-later
// Additional attribution terms under GPLv3 §7(b) apply — see LICENSE

#include "QuickRefactorHandler.hpp"

#include <memory>

#include <LLMQore/BaseClient.hpp>
#include <LLMQore/ContentBlocks.hpp>
#include <LLMQore/ToolsManager.hpp>
#include <QJsonArray>
#include <QJsonDocument>
#include <QUuid>

#include <projectexplorer/project.h>
#include <projectexplorer/projectmanager.h>
#include <utils/filepath.h>

#include <context/DocumentContextReader.hpp>
#include <context/DocumentReaderQtCreator.hpp>
#include <context/Utils.hpp>
#include <logger/Logger.hpp>
#include <sources/common/ResponseCleaner.hpp>
#include <settings/QuickRefactorSettings.hpp>
#include <settings/ToolsSettings.hpp>

#include "sources/common/ContextData.hpp"

#include <AgentFactory.hpp>
#include <AgentRouter.hpp>
#include <Session.hpp>
#include <SessionManager.hpp>
#include <SystemPromptBuilder.hpp>

#include "sources/settings/PipelinesConfig.hpp"
#include "tools/ToolsRegistration.hpp"

namespace QodeAssist {

QuickRefactorHandler::QuickRefactorHandler(QObject *parent)
    : QObject(parent)
    , m_currentEditor(nullptr)
    , m_isRefactoringInProgress(false)
    , m_contextManager(this)
{
}

QuickRefactorHandler::~QuickRefactorHandler() {}

void QuickRefactorHandler::setSessionManager(SessionManager *sessionManager)
{
    m_sessionManager = sessionManager;
}

void QuickRefactorHandler::setAgentFactory(AgentFactory *agentFactory)
{
    m_agentFactory = agentFactory;
}

void QuickRefactorHandler::sendRefactorRequest(
    TextEditor::TextEditorWidget *editor, const QString &instructions)
{
    if (m_isRefactoringInProgress) {
        cancelRequest();
    }

    m_currentEditor = editor;

    Utils::Text::Range range;
    if (editor->textCursor().hasSelection()) {
        QTextCursor cursor = editor->textCursor();
        int startPos = cursor.selectionStart();
        int endPos = cursor.selectionEnd();

        QTextBlock startBlock = editor->document()->findBlock(startPos);
        int startLine = startBlock.blockNumber() + 1;
        int startColumn = startPos - startBlock.position();

        QTextBlock endBlock = editor->document()->findBlock(endPos);
        int endLine = endBlock.blockNumber() + 1;
        int endColumn = endPos - endBlock.position();

        Utils::Text::Position startPosition;
        startPosition.line = startLine;
        startPosition.column = startColumn;

        Utils::Text::Position endPosition;
        endPosition.line = endLine;
        endPosition.column = endColumn;

        range = Utils::Text::Range();
        range.begin = startPosition;
        range.end = endPosition;
    } else {
        QTextCursor cursor = editor->textCursor();
        int cursorPos = cursor.position();

        QTextBlock block = editor->document()->findBlock(cursorPos);
        int line = block.blockNumber() + 1;
        int column = cursorPos - block.position();

        Utils::Text::Position cursorPosition;
        cursorPosition.line = line;
        cursorPosition.column = column;
        range = Utils::Text::Range();
        range.begin = cursorPosition;
        range.end = cursorPosition;
    }

    m_currentRange = range;
    prepareAndSendRequest(editor, instructions, range);
}

QString QuickRefactorHandler::pickRefactorAgent(const QString &filePath) const
{
    const QStringList roster = Settings::PipelinesConfig::load().rosters.quickRefactor;
    if (roster.isEmpty() || !m_agentFactory)
        return {};

    AgentRouter::Context ctx;
    ctx.filePath = filePath;
    if (auto *project = ProjectExplorer::ProjectManager::projectForFile(
            Utils::FilePath::fromString(filePath)))
        ctx.projectName = project->displayName();

    return AgentRouter::pickAgent(roster, ctx, *m_agentFactory);
}

void QuickRefactorHandler::prepareAndSendRequest(
    TextEditor::TextEditorWidget *editor,
    const QString &instructions,
    const Utils::Text::Range &range)
{
    const auto emitError = [this, editor](const QString &error) {
        LOG_MESSAGE(error);
        RefactorResult result;
        result.success = false;
        result.errorMessage = error;
        result.editor = editor;
        emit refactoringCompleted(result);
    };

    if (!m_sessionManager) {
        emitError(QStringLiteral("Quick refactor session manager is not available"));
        return;
    }

    const QString filePath = editor->textDocument()->filePath().toUrlishString();
    const QString agentName = pickRefactorAgent(filePath);
    if (agentName.isEmpty()) {
        emitError(QStringLiteral("No quick refactor agent matches: %1").arg(filePath));
        return;
    }

    QString sessionError;
    Session *session = m_sessionManager->createSession(agentName, &sessionError);
    if (!session) {
        emitError(sessionError.isEmpty() ? QStringLiteral("No quick refactor agent selected")
                                         : sessionError);
        return;
    }

    auto *client = session->client();
    if (!client) {
        m_sessionManager->removeSession(session);
        emitError(QStringLiteral("Quick refactor agent has no live client"));
        return;
    }

    const bool enableTools = Settings::quickRefactorSettings().useTools();
    if (enableTools) {
        Tools::registerQodeAssistTools(client->tools());
        client->setMaxToolContinuations(Settings::toolsSettings().maxToolContinuations());
    }

    session->systemPrompt()->setLayer(
        QStringLiteral("refactor"), buildSystemPrompt(editor, range));

    provider->client()->setTransferTimeout(
        static_cast<int>(Settings::generalSettings().requestTimeout() * 1000));

    m_isRefactoringInProgress = true;

    connect(
        client, &::LLMQore::BaseClient::requestCompleted,
        this, &QuickRefactorHandler::handleFullResponse, Qt::UniqueConnection);
    connect(
        client, &::LLMQore::BaseClient::requestFinalized,
        this, &QuickRefactorHandler::handleRequestFinalized, Qt::UniqueConnection);
    connect(
        client, &::LLMQore::BaseClient::requestFailed,
        this, &QuickRefactorHandler::handleRequestFailed, Qt::UniqueConnection);

    std::vector<std::unique_ptr<LLMQore::ContentBlock>> blocks;
    const QString userMessage = instructions.isEmpty()
        ? QStringLiteral("Refactor the code to improve its quality and maintainability.")
        : instructions;
    blocks.push_back(std::make_unique<LLMQore::TextContent>(userMessage));

    const LLMQore::RequestID requestId = session->send(std::move(blocks), enableTools);
    if (requestId.isEmpty()) {
        m_isRefactoringInProgress = false;
        m_sessionManager->removeSession(session);
        emitError(QStringLiteral("Failed to start quick refactor request for agent: %1")
                      .arg(agentName));
        return;
    }

    m_lastRequestId = requestId;
    m_activeRequests[requestId] = {QJsonObject{{"id", requestId}}, session};
}

QString QuickRefactorHandler::buildSystemPrompt(
    TextEditor::TextEditorWidget *editor, const Utils::Text::Range &range)
{
    Q_UNUSED(range)

    auto textDocument = editor->textDocument();
    Context::DocumentReaderQtCreator documentReader;
    auto documentInfo = documentReader.readDocument(textDocument->filePath().toUrlishString());

    if (!documentInfo.document) {
        LOG_MESSAGE("Error: Document is not available");
        return Settings::quickRefactorSettings().systemPrompt();
    }

    QTextCursor cursor = editor->textCursor();
    int cursorPos = cursor.position();

    Context::DocumentContextReader
        reader(documentInfo.document, documentInfo.mimeType, documentInfo.filePath);

    QString taggedContent;
    bool readFullFile = Settings::quickRefactorSettings().readFullFile();

    if (cursor.hasSelection()) {
        int selStart = cursor.selectionStart();
        int selEnd = cursor.selectionEnd();

        QTextBlock startBlock = documentInfo.document->findBlock(selStart);
        int startLine = startBlock.blockNumber();
        int startColumn = selStart - startBlock.position();

        QTextBlock endBlock = documentInfo.document->findBlock(selEnd);
        int endLine = endBlock.blockNumber();
        int endColumn = selEnd - endBlock.position();

        QString contextBefore;
        if (readFullFile) {
            contextBefore = reader.readWholeFileBefore(startLine, startColumn);
        } else {
            contextBefore = reader.getContextBefore(
                startLine, startColumn, Settings::quickRefactorSettings().readStringsBeforeCursor() + 1);
        }

        QString selectedText = cursor.selectedText();
        selectedText.replace(QChar(0x2029), "\n");

        QString contextAfter;
        if (readFullFile) {
            contextAfter = reader.readWholeFileAfter(endLine, endColumn);
        } else {
            contextAfter = reader.getContextAfter(
                endLine, endColumn, Settings::quickRefactorSettings().readStringsAfterCursor() + 1);
        }

        taggedContent = contextBefore;
        if (selStart == cursorPos) {
            taggedContent += "<cursor><selection_start>" + selectedText + "<selection_end>";
        } else {
            taggedContent += "<selection_start>" + selectedText + "<selection_end><cursor>";
        }
        taggedContent += contextAfter;
    } else {
        QTextBlock block = documentInfo.document->findBlock(cursorPos);
        int line = block.blockNumber();
        int column = cursorPos - block.position();

        QString contextBefore;
        if (readFullFile) {
            contextBefore = reader.readWholeFileBefore(line, column);
        } else {
            contextBefore = reader.getContextBefore(
                line, column, Settings::quickRefactorSettings().readStringsBeforeCursor() + 1);
        }

        QString contextAfter;
        if (readFullFile) {
            contextAfter = reader.readWholeFileAfter(line, column);
        } else {
            contextAfter = reader.getContextAfter(
                line, column, Settings::quickRefactorSettings().readStringsAfterCursor() + 1);
        }

        taggedContent = contextBefore + "<cursor>" + contextAfter;
    }

    QString systemPrompt = Settings::quickRefactorSettings().systemPrompt();

    systemPrompt += "\n\nFile information:";
    systemPrompt += "\nLanguage: " + documentInfo.mimeType;
    systemPrompt += "\nFile path: " + documentInfo.filePath;

    systemPrompt += "\n\n# Code Context with Position Markers\n" + taggedContent;

    systemPrompt += "\n\n# Output Requirements\n## What to Generate:";
    systemPrompt += cursor.hasSelection()
        ? "\n- Generate ONLY the code that should REPLACE the selected text between "
          "<selection_start> and <selection_end> markers"
          "\n- Your output will completely replace the selected code"
        : "\n- Generate ONLY the code that should be INSERTED at the <cursor> position"
          "\n- Your output will be inserted at the cursor location";

    systemPrompt += "\n\n## Formatting Rules:"
                    "\n- Output ONLY the code itself, without ANY explanations or descriptions"
                    "\n- Do NOT include markdown code blocks (no ```, no language tags)"
                    "\n- Do NOT add comments explaining what you changed"
                    "\n- Do NOT repeat existing code, be precise with context"
                    "\n- Do NOT send in answer <cursor> or </cursor> and other tags"
                    "\n- The output must be ready to insert directly into the editor as-is";

    systemPrompt += "\n\n## Indentation and Whitespace:";

    if (cursor.hasSelection()) {
        QTextBlock startBlock = documentInfo.document->findBlock(cursor.selectionStart());
        int leadingSpaces = 0;
        for (QChar c : startBlock.text()) {
            if (c == ' ') leadingSpaces++;
            else if (c == '\t') leadingSpaces += 4;
            else break;
        }
        if (leadingSpaces > 0) {
            systemPrompt += QString("\n- CRITICAL: The code to replace starts with %1 spaces of indentation"
                                   "\n- Your output MUST start with exactly %1 spaces (or equivalent tabs)"
                                   "\n- Each line in your output must maintain this base indentation")
                               .arg(leadingSpaces);
        }
        systemPrompt += "\n- PRESERVE all indentation from the original code";
    } else {
        QTextBlock block = documentInfo.document->findBlock(cursorPos);
        QString lineText = block.text();
        int leadingSpaces = 0;
        for (QChar c : lineText) {
            if (c == ' ') leadingSpaces++;
            else if (c == '\t') leadingSpaces += 4;
            else break;
        }
        if (leadingSpaces > 0) {
            systemPrompt += QString("\n- CRITICAL: Current line has %1 spaces of indentation"
                                   "\n- If generating multiline code, EVERY line must start with at least %1 spaces"
                                   "\n- If generating single-line code, it will be inserted inline (no indentation needed)")
                               .arg(leadingSpaces);
        }
    }

    systemPrompt += "\n- Use the same indentation style (spaces or tabs) as the surrounding code"
                    "\n- Maintain consistent indentation for nested blocks"
                    "\n- Do NOT remove or reduce the base indentation level"
                    "\n\n## Code Style:"
                    "\n- Match the coding style of the surrounding code (naming, spacing, braces, etc.)"
                    "\n- Preserve the original code structure when possible"
                    "\n- Only change what is necessary to fulfill the user's request";

    if (Settings::quickRefactorSettings().useOpenFilesInQuickRefactor()) {
        systemPrompt += "\n\n" + m_contextManager.openedFilesContext({documentInfo.filePath});
    }

    return systemPrompt;
}

void QuickRefactorHandler::handleLLMResponse(
    const QString &response, const QJsonObject &request, bool isComplete)
{
    if (request["id"].toString() != m_lastRequestId) {
        return;
    }

    if (isComplete) {
        m_isRefactoringInProgress = false;
        QString cleanedResponse = ResponseCleaner::clean(response);

        RefactorResult result;
        result.newText = cleanedResponse;
        result.insertRange = m_currentRange;
        result.success = true;
        result.editor = m_currentEditor;

        LOG_MESSAGE("Refactoring completed successfully. New code to insert: ");
        LOG_MESSAGE("---------- BEGIN REFACTORED CODE ----------");
        LOG_MESSAGE(cleanedResponse);
        LOG_MESSAGE("----------- END REFACTORED CODE -----------");

        emit refactoringCompleted(result);
    }
}

void QuickRefactorHandler::cancelRequest()
{
    if (!m_isRefactoringInProgress)
        return;

    const auto id = m_lastRequestId;
    m_isRefactoringInProgress = false;
    m_lastRequestId.clear();

    auto it = m_activeRequests.find(id);
    if (it != m_activeRequests.end()) {
        Session *session = it.value().session;
        m_activeRequests.erase(it);
        if (session) {
            if (auto *client = session->client())
                disconnect(client, nullptr, this, nullptr);
            if (m_sessionManager)
                m_sessionManager->removeSession(session);
        }
    }

    RefactorResult result;
    result.success = false;
    result.errorMessage = "Refactoring request was cancelled";
    emit refactoringCompleted(result);
}

void QuickRefactorHandler::handleFullResponse(const QString &requestId, const QString &fullText)
{
    if (requestId != m_lastRequestId)
        return;

    auto it = m_activeRequests.find(requestId);
    Session *session = (it != m_activeRequests.end()) ? it.value().session.data() : nullptr;
    if (it != m_activeRequests.end())
        m_activeRequests.erase(it);

    QJsonObject request{{"id", requestId}};
    handleLLMResponse(fullText, request, true);

    if (session && m_sessionManager)
        m_sessionManager->removeSession(session);
}

void QuickRefactorHandler::handleRequestFinalized(
    const ::LLMQore::RequestID &requestId, const ::LLMQore::CompletionInfo &info)
{
    if (requestId != m_lastRequestId || !info.usage)
        return;

    const auto &u = *info.usage;
    LOG_MESSAGE(
        QString("Quick refactor usage [%1]: prompt=%2 completion=%3 cached=%4 reasoning=%5")
            .arg(requestId)
            .arg(u.promptTokens)
            .arg(u.completionTokens)
            .arg(u.cachedPromptTokens)
            .arg(u.reasoningTokens));
}

void QuickRefactorHandler::handleRequestFailed(const QString &requestId, const QString &error)
{
    if (requestId != m_lastRequestId)
        return;

    auto it = m_activeRequests.find(requestId);
    Session *session = (it != m_activeRequests.end()) ? it.value().session.data() : nullptr;
    if (it != m_activeRequests.end())
        m_activeRequests.erase(it);

    m_isRefactoringInProgress = false;
    RefactorResult result;
    result.success = false;
    result.errorMessage = error;
    result.editor = m_currentEditor;
    emit refactoringCompleted(result);

    if (session && m_sessionManager)
        m_sessionManager->removeSession(session);
}

} // namespace QodeAssist