"""
Content Viewer - Center panel for displaying lesson content
"""

from PyQt5.QtWidgets import QWidget, QVBoxLayout, QLabel
from PyQt5.QtWebEngineWidgets import QWebEngineView, QWebEnginePage
from PyQt5.QtCore import Qt, pyqtSignal, QUrl
from pathlib import Path
import markdown
from pymdownx import superfences, arithmatex

from app import config
from app.models import Lesson
from app.utils import VariableWrapper


class ContentViewer(QWidget):
    """Center panel for displaying lesson content with markdown and MathJax"""

    # Signals
    scroll_position_changed = pyqtSignal(float)  # For auto-save

    def __init__(self, parent=None):
        super().__init__(parent)
        self.current_lesson = None
        self.markdown_converter = self._init_markdown()
        self.variable_wrapper = VariableWrapper()

        self.init_ui()

    def init_ui(self):
        """Initialize the UI components"""
        layout = QVBoxLayout(self)
        layout.setContentsMargins(0, 0, 0, 0)

        # Lesson title bar
        self.title_label = QLabel("No lesson selected")
        self.title_label.setStyleSheet(f"""
            background-color: {config.COLOR_PRIMARY};
            color: white;
            font-size: 16pt;
            font-weight: bold;
            padding: 12px;
        """)
        self.title_label.setWordWrap(True)
        layout.addWidget(self.title_label)

        # Web view for content
        self.web_view = QWebEngineView()
        self.web_view.setPage(QWebEnginePage(self.web_view))
        layout.addWidget(self.web_view, 1)

        # Load welcome page
        self.show_welcome()

    def _init_markdown(self):
        """Initialize markdown converter with extensions"""
        return markdown.Markdown(
            extensions=[
                'extra',
                'codehilite',
                'tables',
                'toc',
                'pymdownx.arithmatex',
                'pymdownx.superfences',
                'pymdownx.highlight',
                'pymdownx.inlinehilite',
            ],
            extension_configs={
                'pymdownx.arithmatex': {
                    'generic': True
                },
                'codehilite': {
                    'css_class': 'highlight',
                    'linenums': False
                }
            }
        )

    def show_welcome(self):
        """Display welcome message"""
        html = self._wrap_html("""
            <div style="text-align: center; padding: 60px 20px;">
                <h1>Welcome to Tesla Coil Spark Physics Course</h1>
                <p style="font-size: 18px; color: #666;">
                    Select a lesson from the navigation panel to begin learning.
                </p>
                <p style="margin-top: 40px; color: #999;">
                    ⚡ Explore the fascinating world of Tesla coils and electromagnetic theory ⚡
                </p>
            </div>
        """, "Welcome")
        self.web_view.setHtml(html)
        self.title_label.setText("Welcome")

    def load_lesson(self, lesson: Lesson):
        """Load and display a lesson"""
        self.current_lesson = lesson
        self.title_label.setText(f"{lesson.order}. {lesson.title}")

        # Read markdown file
        lesson_path = Path(lesson.file_path)
        if not lesson_path.exists():
            self.show_error(f"Lesson file not found: {lesson.file_path}")
            return

        try:
            with open(lesson_path, 'r', encoding='utf-8') as f:
                markdown_content = f.read()

            # Convert markdown to HTML
            html_content = self.markdown_converter.convert(markdown_content)

            # Process custom tags
            html_content = self._process_custom_tags(html_content, lesson)

            # Wrap variables with tooltips
            html_content = self.variable_wrapper.wrap_in_context(html_content)

            # Wrap in full HTML document
            full_html = self._wrap_html(html_content, lesson.title)

            # Load into web view
            self.web_view.setHtml(full_html, QUrl.fromLocalFile(str(lesson_path.parent)))

        except Exception as e:
            self.show_error(f"Error loading lesson: {str(e)}")

    def _process_custom_tags(self, html: str, lesson: Lesson) -> str:
        """Process custom tags like {exercise:id} and {image:file}"""
        import re

        # Process {exercise:id} tags
        def replace_exercise(match):
            exercise_id = match.group(1)
            return f'''
                <div class="exercise-placeholder" data-exercise-id="{exercise_id}">
                    <h3>📝 Exercise: {exercise_id}</h3>
                    <p><em>Interactive exercise will be loaded here</em></p>
                </div>
            '''
        html = re.sub(r'\{exercise:([^}]+)\}', replace_exercise, html)

        # Process {image:file} tags
        def replace_image(match):
            image_file = match.group(1)
            image_path = config.IMAGES_DIR / image_file
            return f'<img src="{image_path}" alt="{image_file}" style="max-width: 100%; height: auto;" />'
        html = re.sub(r'\{image:([^}]+)\}', replace_image, html)

        return html

    def _wrap_html(self, content: str, title: str) -> str:
        """Wrap content in full HTML document with styling and MathJax"""
        return f"""
<!DOCTYPE html>
<html>
<head>
    <meta charset="UTF-8">
    <title>{title}</title>
    <style>
        body {{
            font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
            line-height: 1.6;
            color: {config.COLOR_TEXT};
            max-width: 900px;
            margin: 0 auto;
            padding: 20px 40px;
            background-color: white;
        }}

        h1, h2, h3, h4, h5, h6 {{
            color: {config.COLOR_PRIMARY};
            margin-top: 1.5em;
            margin-bottom: 0.5em;
        }}

        h1 {{ font-size: 2.2em; border-bottom: 3px solid {config.COLOR_PRIMARY}; padding-bottom: 10px; }}
        h2 {{ font-size: 1.8em; border-bottom: 2px solid {config.COLOR_SECONDARY}; padding-bottom: 8px; }}
        h3 {{ font-size: 1.4em; }}

        p {{ margin: 1em 0; }}

        code {{
            background-color: #f4f4f4;
            padding: 2px 6px;
            border-radius: 3px;
            font-family: 'Consolas', 'Monaco', monospace;
            font-size: 0.9em;
        }}

        pre {{
            background-color: #f4f4f4;
            padding: 15px;
            border-radius: 5px;
            overflow-x: auto;
            border-left: 4px solid {config.COLOR_PRIMARY};
        }}

        pre code {{
            background-color: transparent;
            padding: 0;
        }}

        blockquote {{
            border-left: 4px solid {config.COLOR_WARNING};
            padding-left: 20px;
            margin-left: 0;
            color: #666;
            font-style: italic;
        }}

        table {{
            border-collapse: collapse;
            width: 100%;
            margin: 1.5em 0;
        }}

        th, td {{
            border: 1px solid #ddd;
            padding: 10px;
            text-align: left;
        }}

        th {{
            background-color: {config.COLOR_PRIMARY};
            color: white;
            font-weight: bold;
        }}

        tr:nth-child(even) {{
            background-color: #f9f9f9;
        }}

        img {{
            max-width: 100%;
            height: auto;
            display: block;
            margin: 20px auto;
            border-radius: 5px;
            box-shadow: 0 2px 8px rgba(0,0,0,0.1);
        }}

        .exercise-placeholder {{
            background-color: #fff8dc;
            border: 2px dashed {config.COLOR_WARNING};
            padding: 20px;
            margin: 20px 0;
            border-radius: 5px;
        }}

        .math {{
            font-size: 1.1em;
        }}

        /* Syntax highlighting */
        .highlight {{
            background: #f4f4f4;
        }}

        /* Variable tooltip styles */
        .var-tooltip {{
            color: {config.COLOR_PRIMARY};
            font-weight: 600;
            cursor: help;
            border-bottom: 1px dotted {config.COLOR_PRIMARY};
            position: relative;
            display: inline-block;
            transition: all 0.2s ease;
        }}

        .var-tooltip:hover {{
            color: {config.COLOR_SECONDARY};
            border-bottom-color: {config.COLOR_SECONDARY};
        }}

        /* Tooltip popup */
        .tooltip-popup {{
            position: absolute;
            background-color: #2c3e50;
            color: white;
            padding: 12px 16px;
            border-radius: 6px;
            font-size: 13px;
            font-weight: normal;
            max-width: 350px;
            z-index: 10000;
            box-shadow: 0 4px 12px rgba(0,0,0,0.4);
            line-height: 1.6;
            white-space: pre-wrap;
            pointer-events: none;
            opacity: 0;
            transition: opacity 0.2s ease;
        }}

        .tooltip-popup.show {{
            opacity: 1;
        }}

        .tooltip-arrow {{
            position: absolute;
            width: 0;
            height: 0;
            border-left: 8px solid transparent;
            border-right: 8px solid transparent;
            border-top: 8px solid #2c3e50;
            bottom: -8px;
            left: 50%;
            transform: translateX(-50%);
        }}
    </style>

    <!-- MathJax for equation rendering -->
    <script>
        MathJax = {{
            tex: {{
                inlineMath: [['$', '$'], ['\\\\(', '\\\\)']],
                displayMath: [['$$', '$$'], ['\\\\[', '\\\\]']],
                processEscapes: true
            }},
            svg: {{
                fontCache: 'global'
            }}
        }};
    </script>
    <script src="https://cdn.jsdelivr.net/npm/mathjax@3/es5/tex-svg.js" async></script>

    <!-- Variable tooltip JavaScript -->
    <script>
        // Create tooltip element
        let tooltipPopup = null;

        function createTooltip() {{
            if (!tooltipPopup) {{
                tooltipPopup = document.createElement('div');
                tooltipPopup.className = 'tooltip-popup';

                const arrow = document.createElement('div');
                arrow.className = 'tooltip-arrow';
                tooltipPopup.appendChild(arrow);

                const content = document.createElement('div');
                content.className = 'tooltip-content';
                tooltipPopup.appendChild(content);

                document.body.appendChild(tooltipPopup);
            }}
        }}

        function showTooltip(element, text) {{
            createTooltip();

            // Set content
            const content = tooltipPopup.querySelector('.tooltip-content');
            content.textContent = text.replace(/&#10;/g, '\\n');

            // Position tooltip
            const rect = element.getBoundingClientRect();
            const tooltipRect = tooltipPopup.getBoundingClientRect();

            const left = rect.left + (rect.width / 2) - (tooltipPopup.offsetWidth / 2);
            const top = rect.top - tooltipPopup.offsetHeight - 10;

            tooltipPopup.style.left = Math.max(10, left) + 'px';
            tooltipPopup.style.top = Math.max(10, top) + window.scrollY + 'px';

            // Show tooltip
            setTimeout(() => {{
                tooltipPopup.classList.add('show');
            }}, 10);
        }}

        function hideTooltip() {{
            if (tooltipPopup) {{
                tooltipPopup.classList.remove('show');
            }}
        }}

        // Attach event listeners after DOM loads
        document.addEventListener('DOMContentLoaded', function() {{
            const varTooltips = document.querySelectorAll('.var-tooltip');

            varTooltips.forEach(element => {{
                element.addEventListener('mouseenter', function() {{
                    const tooltipText = this.getAttribute('title');
                    if (tooltipText) {{
                        showTooltip(this, tooltipText);
                        // Remove title to prevent browser default tooltip
                        this.setAttribute('data-original-title', tooltipText);
                        this.removeAttribute('title');
                    }}
                }});

                element.addEventListener('mouseleave', function() {{
                    hideTooltip();
                    // Restore title
                    const originalTitle = this.getAttribute('data-original-title');
                    if (originalTitle) {{
                        this.setAttribute('title', originalTitle);
                    }}
                }});
            }});
        }});
    </script>
</head>
<body>
    {content}
</body>
</html>
        """

    def show_error(self, message: str):
        """Display an error message"""
        html = self._wrap_html(f"""
            <div style="text-align: center; padding: 60px 20px; color: {config.COLOR_ERROR};">
                <h1>⚠ Error</h1>
                <p style="font-size: 18px;">{message}</p>
            </div>
        """, "Error")
        self.web_view.setHtml(html)

    def get_scroll_position(self) -> float:
        """Get current scroll position (0.0 to 1.0)"""
        # This would require JavaScript execution in QWebEngineView
        # For now, return 0.0 - can be implemented later
        return 0.0

    def set_scroll_position(self, position: float):
        """Set scroll position (0.0 to 1.0)"""
        # This would require JavaScript execution in QWebEngineView
        # For now, do nothing - can be implemented later
        pass