"""
Alert Notes Router
API endpoints for contextual customer/contact alert system
"""

from fastapi import APIRouter, HTTPException, Depends, Query
from typing import List, Optional, Dict
import logging
from datetime import datetime

from app.core.database import execute_query, execute_update
from app.core.auth_dependencies import require_permission, get_current_user
from app.alert_notes.backend.schemas import (
    AlertNoteCreate, AlertNoteUpdate, AlertNoteFull, AlertNoteCheck,
    AlertNoteRestriction, AlertNoteAcknowledgement, EntityType, Severity
)

logger = logging.getLogger(__name__)

router = APIRouter()


def _check_user_can_handle(alert_id: int, current_user: dict) -> bool:
    """
    Check if current user is allowed to handle the entity based on restrictions.
    Returns True if no restrictions exist OR user matches a restriction.
    """
    # Superadmins bypass restrictions
    if current_user.get("is_superadmin"):
        return True
    
    # Get restrictions for this alert
    restrictions = execute_query(
        """
        SELECT restriction_type, restriction_id
        FROM alert_note_restrictions
        WHERE alert_note_id = %s
        """,
        (alert_id,)
    )
    
    # No restrictions = everyone can handle
    if not restrictions:
        return True
    
    user_id = current_user["id"]
    
    # Get user's group IDs
    user_groups = execute_query(
        "SELECT group_id FROM user_groups WHERE user_id = %s",
        (user_id,)
    )
    user_group_ids = [g["group_id"] for g in user_groups]
    
    # Check if user matches any restriction
    for restriction in restrictions:
        if restriction["restriction_type"] == "user" and restriction["restriction_id"] == user_id:
            return True
        if restriction["restriction_type"] == "group" and restriction["restriction_id"] in user_group_ids:
            return True
    
    return False


def _get_entity_name(entity_type: str, entity_id: int) -> Optional[str]:
    """Get the name of the entity (customer or contact)"""
    if entity_type == "customer":
        result = execute_query(
            "SELECT name FROM customers WHERE id = %s",
            (entity_id,)
        )
        return result[0]["name"] if result else None
    elif entity_type == "contact":
        result = execute_query(
            "SELECT first_name, last_name FROM contacts WHERE id = %s",
            (entity_id,)
        )
        if result:
            return f"{result[0]['first_name']} {result[0]['last_name']}"
    return None


def _get_alert_with_relations(alert_id: int, current_user: dict) -> Optional[Dict]:
    """Get alert note with all its relations"""
    # Get main alert
    alerts = execute_query(
        """
        SELECT an.*, u.full_name as created_by_user_name
        FROM alert_notes an
        LEFT JOIN users u ON an.created_by_user_id = u.user_id
        WHERE an.id = %s
        """,
        (alert_id,)
    )
    
    if not alerts:
        return None
    
    alert = dict(alerts[0])
    
    # Get entity name
    alert["entity_name"] = _get_entity_name(alert["entity_type"], alert["entity_id"])
    
    # Get restrictions
    restrictions = execute_query(
        """
        SELECT anr.*, 
               CASE 
                   WHEN anr.restriction_type = 'group' THEN g.name
                   WHEN anr.restriction_type = 'user' THEN u.full_name
               END as restriction_name
        FROM alert_note_restrictions anr
        LEFT JOIN groups g ON anr.restriction_type = 'group' AND anr.restriction_id = g.id
        LEFT JOIN users u ON anr.restriction_type = 'user' AND anr.restriction_id = u.user_id
        WHERE anr.alert_note_id = %s
        """,
        (alert_id,)
    )
    alert["restrictions"] = restrictions
    
    # Get acknowledgements
    acknowledgements = execute_query(
        """
        SELECT ana.*, u.full_name as user_name
        FROM alert_note_acknowledgements ana
        LEFT JOIN users u ON ana.user_id = u.user_id
        WHERE ana.alert_note_id = %s
        ORDER BY ana.acknowledged_at DESC
        """,
        (alert_id,)
    )
    alert["acknowledgements"] = acknowledgements
    
    return alert


@router.get("/alert-notes/check", response_model=AlertNoteCheck)
async def check_alerts(
    entity_type: EntityType = Query(..., description="Entity type (customer/contact)"),
    entity_id: int = Query(..., description="Entity ID"),
    current_user: dict = Depends(get_current_user)
):
    """
    Check if there are active alert notes for a specific entity.
    Returns alerts that the current user is allowed to see based on restrictions.
    """
    # Get active alerts for this entity
    alerts = execute_query(
        """
        SELECT an.*, u.full_name as created_by_user_name
        FROM alert_notes an
        LEFT JOIN users u ON an.created_by_user_id = u.user_id
        WHERE an.entity_type = %s 
          AND an.entity_id = %s 
          AND an.active = TRUE
        ORDER BY 
            CASE an.severity
                WHEN 'critical' THEN 1
                WHEN 'warning' THEN 2
                WHEN 'info' THEN 3
            END,
            an.created_at DESC
        """,
        (entity_type.value, entity_id)
    )
    
    if not alerts:
        return AlertNoteCheck(
            has_alerts=False,
            alerts=[],
            user_can_handle=True,
            user_has_acknowledged=False
        )
    
    # Enrich alerts with relations
    enriched_alerts = []
    for alert in alerts:
        alert_dict = dict(alert)
        alert_dict["entity_name"] = _get_entity_name(alert["entity_type"], alert["entity_id"])
        
        # Get restrictions
        restrictions = execute_query(
            """
            SELECT anr.*, 
                   CASE 
                       WHEN anr.restriction_type = 'group' THEN g.name
                       WHEN anr.restriction_type = 'user' THEN u.full_name
                   END as restriction_name
            FROM alert_note_restrictions anr
            LEFT JOIN groups g ON anr.restriction_type = 'group' AND anr.restriction_id = g.id
            LEFT JOIN users u ON anr.restriction_type = 'user' AND anr.restriction_id = u.user_id
            WHERE anr.alert_note_id = %s
            """,
            (alert["id"],)
        )
        alert_dict["restrictions"] = restrictions
        
        # Get acknowledgements
        acknowledgements = execute_query(
            """
            SELECT ana.*, u.full_name as user_name
            FROM alert_note_acknowledgements ana
            LEFT JOIN users u ON ana.user_id = u.user_id
            WHERE ana.alert_note_id = %s
            ORDER BY ana.acknowledged_at DESC
            """,
            (alert["id"],)
        )
        alert_dict["acknowledgements"] = acknowledgements
        
        enriched_alerts.append(alert_dict)
    
    # Check if user can handle based on restrictions
    user_can_handle = all(_check_user_can_handle(a["id"], current_user) for a in alerts)
    
    # Check if user has acknowledged all alerts that require it
    user_id = current_user["id"]
    user_has_acknowledged = True
    for alert in alerts:
        if alert["requires_acknowledgement"]:
            ack = execute_query(
                "SELECT id FROM alert_note_acknowledgements WHERE alert_note_id = %s AND user_id = %s",
                (alert["id"], user_id)
            )
            if not ack:
                user_has_acknowledged = False
                break
    
    return AlertNoteCheck(
        has_alerts=True,
        alerts=enriched_alerts,
        user_can_handle=user_can_handle,
        user_has_acknowledged=user_has_acknowledged
    )


@router.post("/alert-notes/{alert_id}/acknowledge")
async def acknowledge_alert(
    alert_id: int,
    current_user: dict = Depends(get_current_user)
):
    """
    Mark an alert note as acknowledged by the current user.
    """
    # Check if alert exists
    alert = execute_query(
        "SELECT id, active FROM alert_notes WHERE id = %s",
        (alert_id,)
    )
    
    if not alert:
        raise HTTPException(status_code=404, detail="Alert note not found")
    
    if not alert[0]["active"]:
        raise HTTPException(status_code=400, detail="Alert note is not active")
    
    user_id = current_user["id"]
    
    # Check if already acknowledged
    existing = execute_query(
        "SELECT id FROM alert_note_acknowledgements WHERE alert_note_id = %s AND user_id = %s",
        (alert_id, user_id)
    )
    
    if existing:
        return {"status": "already_acknowledged", "alert_id": alert_id}
    
    # Insert acknowledgement
    execute_update(
        """
        INSERT INTO alert_note_acknowledgements (alert_note_id, user_id)
        VALUES (%s, %s)
        """,
        (alert_id, user_id)
    )
    
    logger.info(f"Alert {alert_id} acknowledged by user {user_id}")
    
    return {"status": "acknowledged", "alert_id": alert_id}


@router.get("/alert-notes", response_model=List[AlertNoteFull])
async def list_alerts(
    entity_type: Optional[EntityType] = Query(None),
    entity_id: Optional[int] = Query(None),
    severity: Optional[Severity] = Query(None),
    active: Optional[bool] = Query(None),
    limit: int = Query(default=50, ge=1, le=500),
    offset: int = Query(default=0, ge=0),
    current_user: dict = Depends(require_permission("alert_notes.view"))
):
    """
    List alert notes with filtering (admin endpoint).
    Requires alert_notes.view permission.
    """
    conditions = []
    params = []
    
    if entity_type:
        conditions.append("an.entity_type = %s")
        params.append(entity_type.value)
    
    if entity_id:
        conditions.append("an.entity_id = %s")
        params.append(entity_id)
    
    if severity:
        conditions.append("an.severity = %s")
        params.append(severity.value)
    
    if active is not None:
        conditions.append("an.active = %s")
        params.append(active)
    
    where_clause = "WHERE " + " AND ".join(conditions) if conditions else ""
    
    query = f"""
        SELECT an.*, u.full_name as created_by_user_name
        FROM alert_notes an
        LEFT JOIN users u ON an.created_by_user_id = u.user_id
        {where_clause}
        ORDER BY an.created_at DESC
        LIMIT %s OFFSET %s
    """
    params.extend([limit, offset])
    
    alerts = execute_query(query, tuple(params))
    
    # Enrich with relations
    enriched_alerts = []
    for alert in alerts:
        alert_full = _get_alert_with_relations(alert["id"], current_user)
        if alert_full:
            enriched_alerts.append(alert_full)
    
    return enriched_alerts


@router.post("/alert-notes", response_model=AlertNoteFull)
async def create_alert(
    alert: AlertNoteCreate,
    current_user: dict = Depends(require_permission("alert_notes.create"))
):
    """
    Create a new alert note.
    Requires alert_notes.create permission.
    """
    # Verify entity exists
    entity_name = _get_entity_name(alert.entity_type.value, alert.entity_id)
    if not entity_name:
        raise HTTPException(
            status_code=404,
            detail=f"{alert.entity_type.value.capitalize()} with ID {alert.entity_id} not found"
        )
    
    # Insert alert note
    result = execute_query(
        """
        INSERT INTO alert_notes (
            entity_type, entity_id, title, message, severity,
            requires_acknowledgement, active, created_by_user_id
        )
        VALUES (%s, %s, %s, %s, %s, %s, %s, %s)
        RETURNING id
        """,
        (
            alert.entity_type.value, alert.entity_id, alert.title, alert.message,
            alert.severity.value, alert.requires_acknowledgement, alert.active,
            current_user["id"]
        )
    )
    
    if not result or len(result) == 0:
        raise HTTPException(status_code=500, detail="Failed to create alert note")
    
    alert_id = result[0]["id"]
    
    # Insert restrictions
    for group_id in alert.restriction_group_ids:
        execute_query(
            """
            INSERT INTO alert_note_restrictions (alert_note_id, restriction_type, restriction_id)
            VALUES (%s, 'group', %s)
            """,
            (alert_id, group_id)
        )
    
    for user_id in alert.restriction_user_ids:
        execute_query(
            """
            INSERT INTO alert_note_restrictions (alert_note_id, restriction_type, restriction_id)
            VALUES (%s, 'user', %s)
            """,
            (alert_id, user_id)
        )
    
    logger.info(f"Alert note {alert_id} created for {alert.entity_type.value} {alert.entity_id} by user {current_user['id']}")
    
    # Return full alert with relations
    alert_full = _get_alert_with_relations(alert_id, current_user)
    return alert_full


@router.patch("/alert-notes/{alert_id}", response_model=AlertNoteFull)
async def update_alert(
    alert_id: int,
    alert_update: AlertNoteUpdate,
    current_user: dict = Depends(require_permission("alert_notes.edit"))
):
    """
    Update an existing alert note.
    Requires alert_notes.edit permission.
    """
    # Check if alert exists
    existing = execute_query(
        "SELECT id FROM alert_notes WHERE id = %s",
        (alert_id,)
    )
    
    if not existing:
        raise HTTPException(status_code=404, detail="Alert note not found")
    
    # Build update query
    update_fields = []
    params = []
    
    if alert_update.title is not None:
        update_fields.append("title = %s")
        params.append(alert_update.title)
    
    if alert_update.message is not None:
        update_fields.append("message = %s")
        params.append(alert_update.message)
    
    if alert_update.severity is not None:
        update_fields.append("severity = %s")
        params.append(alert_update.severity.value)
    
    if alert_update.requires_acknowledgement is not None:
        update_fields.append("requires_acknowledgement = %s")
        params.append(alert_update.requires_acknowledgement)
    
    if alert_update.active is not None:
        update_fields.append("active = %s")
        params.append(alert_update.active)
    
    if update_fields:
        query = f"UPDATE alert_notes SET {', '.join(update_fields)} WHERE id = %s"
        params.append(alert_id)
        execute_update(query, tuple(params))
    
    # Update restrictions if provided
    if alert_update.restriction_group_ids is not None or alert_update.restriction_user_ids is not None:
        # Delete existing restrictions
        execute_update(
            "DELETE FROM alert_note_restrictions WHERE alert_note_id = %s",
            (alert_id,)
        )
        
        # Insert new group restrictions
        if alert_update.restriction_group_ids is not None:
            for group_id in alert_update.restriction_group_ids:
                execute_update(
                    """
                    INSERT INTO alert_note_restrictions (alert_note_id, restriction_type, restriction_id)
                    VALUES (%s, 'group', %s)
                    """,
                    (alert_id, group_id)
                )
        
        # Insert new user restrictions
        if alert_update.restriction_user_ids is not None:
            for user_id in alert_update.restriction_user_ids:
                execute_update(
                    """
                    INSERT INTO alert_note_restrictions (alert_note_id, restriction_type, restriction_id)
                    VALUES (%s, 'user', %s)
                    """,
                    (alert_id, user_id)
                )
    
    logger.info(f"Alert note {alert_id} updated by user {current_user['id']}")
    
    # Return updated alert
    alert_full = _get_alert_with_relations(alert_id, current_user)
    return alert_full


@router.delete("/alert-notes/{alert_id}")
async def delete_alert(
    alert_id: int,
    current_user: dict = Depends(require_permission("alert_notes.delete"))
):
    """
    Soft delete an alert note (sets active = false).
    Requires alert_notes.delete permission.
    """
    # Check if alert exists
    existing = execute_query(
        "SELECT id, active FROM alert_notes WHERE id = %s",
        (alert_id,)
    )
    
    if not existing:
        raise HTTPException(status_code=404, detail="Alert note not found")
    
    # Soft delete
    execute_update(
        "UPDATE alert_notes SET active = FALSE WHERE id = %s",
        (alert_id,)
    )
    
    logger.info(f"Alert note {alert_id} deactivated by user {current_user['id']}")
    
    return {"status": "deleted", "alert_id": alert_id}