"""
Message API Routes
===================

Send, edit, delete, forward messages within conversations.
"""

import re
import logging
from datetime import datetime, timedelta
from collections import defaultdict

from flask import jsonify, request, url_for
from flask_login import login_required, current_user
from sqlalchemy import and_

from . import bp
from database import (
    SessionLocal, User, Conversation, ConversationMember,
    ConvMessage, MessageAttachment, MessageReaction, UserBlock,
)
from utils.decorators import member_required
from utils.helpers import sanitize_html
from redis_service import publish_event

logger = logging.getLogger(__name__)


# ============================================================
# HELPERS
# ============================================================

def strip_html(text):
    """Strip HTML tags for plain-text previews."""
    return re.sub(r'<[^>]+>', '', text or '').strip()


def _verify_membership(db, conversation_id, user_id):
    """Return ConversationMember or None."""
    return db.query(ConversationMember).filter_by(
        conversation_id=conversation_id,
        user_id=user_id,
    ).first()


def _publish_to_conv(db, conversation_id, event_type, data, exclude_user_id=None):
    """Publish SSE event to all conversation members (except excluded)."""
    members = db.query(ConversationMember).filter_by(
        conversation_id=conversation_id,
    ).all()
    for m in members:
        if exclude_user_id is not None and m.user_id == exclude_user_id:
            continue
        publish_event(m.user_id, event_type, data)


def _message_to_json(msg, db):
    """Serialize a ConvMessage to JSON dict."""
    # Sender info
    sender = None
    if msg.sender:
        sender = {
            'id': msg.sender_id,
            'name': msg.sender.name or msg.sender.email.split('@')[0],
        }

    # Reply-to info
    reply_to = None
    if msg.reply_to_id and msg.reply_to:
        reply_sender_name = None
        if msg.reply_to.sender:
            reply_sender_name = msg.reply_to.sender.name or msg.reply_to.sender.email.split('@')[0]
        reply_to = {
            'id': msg.reply_to_id,
            'sender_name': reply_sender_name,
            'content_preview': strip_html(msg.reply_to.content)[:100] if not msg.reply_to.is_deleted else '',
        }

    # If deleted, clear sensitive fields
    if msg.is_deleted:
        return {
            'id': msg.id,
            'conversation_id': msg.conversation_id,
            'sender': sender,
            'content': '',
            'reply_to': None,
            'reactions': [],
            'attachments': [],
            'link_preview': None,
            'edited_at': None,
            'is_deleted': True,
            'created_at': msg.created_at.isoformat() if msg.created_at else None,
        }

    # Reactions — group by emoji
    reactions_by_emoji = defaultdict(list)
    for r in msg.reactions:
        user_info = {'id': r.user_id}
        if r.user:
            user_info['name'] = r.user.name or r.user.email.split('@')[0]
        reactions_by_emoji[r.emoji].append(user_info)

    reactions = [
        {'emoji': emoji, 'count': len(users), 'users': users}
        for emoji, users in reactions_by_emoji.items()
    ]

    # Attachments
    attachments = [
        {
            'id': a.id,
            'filename': a.filename,
            'mime_type': a.mime_type,
            'file_size': a.file_size,
            'stored_filename': a.stored_filename,
        }
        for a in msg.attachments
    ]

    return {
        'id': msg.id,
        'conversation_id': msg.conversation_id,
        'sender': sender,
        'content': msg.content,
        'reply_to': reply_to,
        'reactions': reactions,
        'attachments': attachments,
        'link_preview': msg.link_preview,
        'edited_at': msg.edited_at.isoformat() if msg.edited_at else None,
        'is_deleted': False,
        'created_at': msg.created_at.isoformat() if msg.created_at else None,
    }


# ============================================================
# 1. GET MESSAGES
# ============================================================

@bp.route('/api/conversations/<int:conv_id>/messages', methods=['GET'])
@login_required
@member_required
def get_messages(conv_id):
    """Get messages for a conversation with cursor-based pagination."""
    db = SessionLocal()
    try:
        # Verify membership
        membership = _verify_membership(db, conv_id, current_user.id)
        if not membership:
            return jsonify({'error': 'Brak dostępu do konwersacji'}), 403

        # Cursor-based pagination
        before_id = request.args.get('before_id', type=int)
        limit = 50

        query = db.query(ConvMessage).filter_by(conversation_id=conv_id)
        if before_id:
            query = query.filter(ConvMessage.id < before_id)

        query = query.order_by(ConvMessage.created_at.desc()).limit(limit + 1)
        messages = query.all()

        has_more = len(messages) > limit
        if has_more:
            messages = messages[:limit]

        result = [_message_to_json(msg, db) for msg in messages]

        return jsonify({'messages': result, 'has_more': has_more})

    except Exception as e:
        logger.error(f"get_messages error: {e}")
        return jsonify({'error': 'Błąd serwera'}), 500
    finally:
        db.close()


# ============================================================
# 2. SEND MESSAGE
# ============================================================

@bp.route('/api/conversations/<int:conv_id>/messages', methods=['POST'])
@login_required
@member_required
def send_message(conv_id):
    """Send a message to a conversation."""
    db = SessionLocal()
    try:
        # Verify membership
        membership = _verify_membership(db, conv_id, current_user.id)
        if not membership:
            return jsonify({'error': 'Brak dostępu do konwersacji'}), 403

        # Parse content from JSON or form data
        if request.is_json:
            data = request.get_json()
            content = data.get('content', '').strip()
            reply_to_id = data.get('reply_to_id')
        else:
            content = request.form.get('content', '').strip()
            reply_to_id = request.form.get('reply_to_id', type=int)

        # Check for files
        files = request.files.getlist('files')

        if not content and not files:
            return jsonify({'error': 'Treść wiadomości jest wymagana'}), 400

        # Sanitize content
        content = sanitize_html(content) if content else ''

        # Create message
        message = ConvMessage(
            conversation_id=conv_id,
            sender_id=current_user.id,
            content=content,
            reply_to_id=reply_to_id,
        )
        db.add(message)
        db.flush()  # get message.id

        # Handle file attachments
        if files:
            try:
                from message_upload_service import MessageUploadService
                from flask import current_app
                upload_service = MessageUploadService(current_app.root_path)
                for f in files:
                    result = upload_service.save_file(f)
                    if result['success']:
                        attachment = MessageAttachment(
                            conv_message_id=message.id,
                            filename=result['filename'],
                            stored_filename=result['stored_filename'],
                            file_size=result['file_size'],
                            mime_type=result['mime_type'],
                        )
                        db.add(attachment)
            except ImportError:
                logger.warning("MessageUploadService not available, skipping file attachments")

        # Fetch link preview
        try:
            from blueprints.messages.link_preview import fetch_link_preview
            preview = fetch_link_preview(content)
            if preview:
                message.link_preview = preview
        except ImportError:
            pass  # link_preview module not yet created

        # Update conversation
        conversation = db.query(Conversation).get(conv_id)
        conversation.updated_at = datetime.now()
        conversation.last_message_id = message.id

        db.commit()
        db.refresh(message)

        # Build response JSON
        msg_json = _message_to_json(message, db)

        # Publish SSE event to all members except sender
        _publish_to_conv(db, conv_id, 'new_message', msg_json, exclude_user_id=current_user.id)

        # Send email notifications
        _send_message_email_notifications(db, conv_id, conversation, message, content)

        # Send Web Push notifications
        _send_message_push_notifications(db, conv_id, conversation, message, content)

        return jsonify(msg_json), 201

    except Exception as e:
        db.rollback()
        logger.error(f"send_message error: {e}")
        return jsonify({'error': 'Błąd wysyłania wiadomości'}), 500
    finally:
        db.close()


def _send_message_email_notifications(db, conv_id, conversation, message, content):
    """Send email notifications to eligible conversation members."""
    try:
        from email_service import send_email, build_message_notification_email

        members = db.query(ConversationMember).filter(
            ConversationMember.conversation_id == conv_id,
            ConversationMember.user_id != current_user.id,
            ConversationMember.is_muted == False,  # noqa: E712
        ).all()

        sender_name = current_user.name or current_user.email.split('@')[0]
        preview = strip_html(content)[:200]
        conv_name = conversation.name or sender_name
        message_url = url_for('messages.conversations_page', _external=True) + f'?conv={conv_id}'
        settings_url = url_for('auth.konto_prywatnosc', _external=True)
        subject_line = f'Nowa wiadomość od {sender_name} — Norda Biznes'

        for m in members:
            user = db.query(User).get(m.user_id)
            if not user or not user.email:
                continue
            if user.notify_email_messages is False:
                continue

            email_html, email_text = build_message_notification_email(
                sender_name, conv_name, preview, message_url, settings_url,
            )
            send_email(
                to=[user.email],
                subject=subject_line,
                body_text=email_text,
                body_html=email_html,
                email_type='message_notification',
                user_id=user.id,
                recipient_name=user.name,
            )

    except ImportError:
        logger.warning("email_service not available, skipping email notifications")
    except Exception as e:
        logger.error(f"Email notification error: {e}")


def _send_message_push_notifications(db, conv_id, conversation, message, content):
    """Send Web Push notifications to eligible conversation members.

    Gate whitelist (PUSH_USER_WHITELIST) siedzi w send_push() — tu filtrujemy
    tylko członków konwersacji + muted + notify_push_messages.
    """
    try:
        from blueprints.push.push_service import send_push

        members = db.query(ConversationMember).filter(
            ConversationMember.conversation_id == conv_id,
            ConversationMember.user_id != current_user.id,
            ConversationMember.is_muted == False,  # noqa: E712
        ).all()

        sender_name = current_user.name or current_user.email.split('@')[0]
        title = f'Nowa wiadomość od {sender_name}'
        plain = strip_html(content or '')
        preview = (plain[:80] + '…') if len(plain) > 80 else plain

        for m in members:
            user = db.query(User).get(m.user_id)
            if not user or user.notify_push_messages is False:
                continue
            send_push(
                user_id=user.id,
                title=title,
                body=preview or '(załącznik)',
                url=f'/wiadomosci?conv={conv_id}',
                tag=f'conv-{conv_id}',
                icon='/static/img/favicon-192.png',
            )
    except ImportError:
        logger.warning("push_service not available, skipping push notifications")
    except Exception as e:
        logger.error(f"Push notification error: {e}")


# ============================================================
# 3. EDIT MESSAGE
# ============================================================

@bp.route('/api/messages/<int:message_id>', methods=['PATCH'])
@login_required
@member_required
def edit_message(message_id):
    """Edit a message (within 24h, sender only)."""
    db = SessionLocal()
    try:
        message = db.query(ConvMessage).get(message_id)
        if not message:
            return jsonify({'error': 'Wiadomość nie znaleziona'}), 404

        if message.sender_id != current_user.id:
            return jsonify({'error': 'Nie możesz edytować cudzej wiadomości'}), 403

        # Check 24h limit
        if message.created_at < datetime.now() - timedelta(hours=24):
            return jsonify({'error': 'Wiadomość jest zbyt stara do edycji (limit 24h)'}), 403

        data = request.get_json()
        new_content = data.get('content', '').strip()
        if not new_content:
            return jsonify({'error': 'Treść wiadomości jest wymagana'}), 400

        message.content = sanitize_html(new_content)
        message.edited_at = datetime.now()
        db.commit()
        db.refresh(message)

        msg_json = _message_to_json(message, db)

        # Publish SSE event
        _publish_to_conv(db, message.conversation_id, 'message_edited', msg_json)

        return jsonify(msg_json)

    except Exception as e:
        db.rollback()
        logger.error(f"edit_message error: {e}")
        return jsonify({'error': 'Błąd edycji wiadomości'}), 500
    finally:
        db.close()


# ============================================================
# 4. DELETE MESSAGE (soft)
# ============================================================

@bp.route('/api/messages/<int:message_id>', methods=['DELETE'])
@login_required
@member_required
def delete_message(message_id):
    """Soft-delete a message (sender only)."""
    db = SessionLocal()
    try:
        message = db.query(ConvMessage).get(message_id)
        if not message:
            return jsonify({'error': 'Wiadomość nie znaleziona'}), 404

        if message.sender_id != current_user.id:
            return jsonify({'error': 'Nie możesz usunąć cudzej wiadomości'}), 403

        message.is_deleted = True
        db.commit()

        # Publish SSE event
        _publish_to_conv(db, message.conversation_id, 'message_deleted', {
            'id': message.id,
            'conversation_id': message.conversation_id,
        })

        return jsonify({'ok': True})

    except Exception as e:
        db.rollback()
        logger.error(f"delete_message error: {e}")
        return jsonify({'error': 'Błąd usuwania wiadomości'}), 500
    finally:
        db.close()


# ============================================================
# 5. FORWARD MESSAGE
# ============================================================

@bp.route('/api/messages/<int:message_id>/forward', methods=['POST'])
@login_required
@member_required
def forward_message(message_id):
    """Forward a message to another conversation."""
    db = SessionLocal()
    try:
        # Find source message
        message = db.query(ConvMessage).get(message_id)
        if not message:
            return jsonify({'error': 'Wiadomość nie znaleziona'}), 404

        # Verify user is member of source conversation
        source_membership = _verify_membership(db, message.conversation_id, current_user.id)
        if not source_membership:
            return jsonify({'error': 'Brak dostępu do źródłowej konwersacji'}), 403

        data = request.get_json()
        target_conv_id = data.get('conversation_id')
        if not target_conv_id:
            return jsonify({'error': 'Wymagany identyfikator konwersacji docelowej'}), 400

        # Verify user is member of target conversation
        target_membership = _verify_membership(db, target_conv_id, current_user.id)
        if not target_membership:
            return jsonify({'error': 'Brak dostępu do konwersacji docelowej'}), 403

        # Create new message in target conversation
        new_message = ConvMessage(
            conversation_id=target_conv_id,
            sender_id=current_user.id,
            content=message.content,
        )
        db.add(new_message)
        db.flush()

        # Update target conversation
        target_conv = db.query(Conversation).get(target_conv_id)
        target_conv.updated_at = datetime.now()
        target_conv.last_message_id = new_message.id

        db.commit()
        db.refresh(new_message)

        msg_json = _message_to_json(new_message, db)

        # Publish SSE to target conversation members
        _publish_to_conv(db, target_conv_id, 'new_message', msg_json, exclude_user_id=current_user.id)

        return jsonify(msg_json), 201

    except Exception as e:
        db.rollback()
        logger.error(f"forward_message error: {e}")
        return jsonify({'error': 'Błąd przekazywania wiadomości'}), 500
    finally:
        db.close()


# ============================================================
# 6. GET /api/messages/search — Search message content
# ============================================================

@bp.route('/api/messages/search', methods=['GET'])
@login_required
@member_required
def search_messages():
    """Search messages across all user's conversations."""
    query = request.args.get('q', '').strip()
    if len(query) < 3:
        return jsonify({'results': []})

    db = SessionLocal()
    try:
        from sqlalchemy import func

        # Get user's conversation IDs
        user_conv_ids = [m.conversation_id for m in
                         db.query(ConversationMember.conversation_id).filter_by(
                             user_id=current_user.id
                         ).all()]

        if not user_conv_ids:
            return jsonify({'results': []})

        # Search in message content (strip HTML via regexp_replace)
        search_term = f'%{query}%'
        messages = db.query(ConvMessage).filter(
            ConvMessage.conversation_id.in_(user_conv_ids),
            ConvMessage.is_deleted == False,  # noqa: E712
            func.regexp_replace(ConvMessage.content, '<[^>]+>', '', 'g').ilike(search_term),
        ).order_by(ConvMessage.created_at.desc()).limit(20).all()

        results = []
        for msg in messages:
            # Get conversation display name
            conv = msg.conversation
            conv_name = conv.name
            if not conv.is_group:
                other = [m for m in conv.members if m.user_id != current_user.id]
                if other and other[0].user:
                    conv_name = other[0].user.name or other[0].user.email.split('@')[0]

            # Build preview with context around match
            plain = strip_html(msg.content)
            lower_plain = plain.lower()
            idx = lower_plain.find(query.lower())
            if idx >= 0:
                start = max(0, idx - 30)
                end = min(len(plain), idx + len(query) + 50)
                preview = ('...' if start > 0 else '') + plain[start:end] + ('...' if end < len(plain) else '')
            else:
                preview = plain[:80]

            results.append({
                'message_id': msg.id,
                'conversation_id': msg.conversation_id,
                'conversation_name': conv_name,
                'sender_name': msg.sender.name if msg.sender else '',
                'preview': preview,
                'created_at': msg.created_at.isoformat() if msg.created_at else None,
            })

        return jsonify({'results': results})

    except Exception as e:
        logger.error(f"search_messages error: {e}")
        return jsonify({'results': []})
    finally:
        db.close()