from datetime import datetime, timedelta, timezone
from app import db
from app.config import Config
from app.utils.timezone import utc_to_local, local_to_utc

def local_now():
    """Get current time in local timezone as naive datetime (for database storage)"""
    from app.utils.timezone import get_timezone_obj
    tz = get_timezone_obj()
    now = datetime.now(tz)
    return now.replace(tzinfo=None)

class TimeEntry(db.Model):
    """Time entry model for manual and automatic time tracking"""
    
    __tablename__ = 'time_entries'
    
    id = db.Column(db.Integer, primary_key=True)
    user_id = db.Column(db.Integer, db.ForeignKey('users.id'), nullable=False, index=True)
    project_id = db.Column(db.Integer, db.ForeignKey('projects.id'), nullable=False, index=True)
    task_id = db.Column(db.Integer, db.ForeignKey('tasks.id'), nullable=True, index=True)
    start_time = db.Column(db.DateTime, nullable=False, index=True)
    end_time = db.Column(db.DateTime, nullable=True, index=True)
    duration_seconds = db.Column(db.Integer, nullable=True)
    notes = db.Column(db.Text, nullable=True)
    tags = db.Column(db.String(500), nullable=True)  # Comma-separated tags
    source = db.Column(db.String(20), default='manual', nullable=False)  # 'manual' or 'auto'
    billable = db.Column(db.Boolean, default=True, nullable=False)
    created_at = db.Column(db.DateTime, default=local_now, nullable=False)
    updated_at = db.Column(db.DateTime, default=local_now, onupdate=local_now, nullable=False)
    
    # Relationships
    # user and project relationships are defined via backref in their respective models
    # task relationship is defined via backref in Task model
    
    def __init__(self, user_id, project_id, start_time, end_time=None, task_id=None, notes=None, tags=None, source='manual', billable=True):
        self.user_id = user_id
        self.project_id = project_id
        self.task_id = task_id
        self.start_time = start_time
        self.end_time = end_time
        self.notes = notes.strip() if notes else None
        self.tags = tags.strip() if tags else None
        self.source = source
        self.billable = billable
        
        # Calculate duration if end time is provided
        if self.end_time:
            self.calculate_duration()
    
    def __repr__(self):
        return f'<TimeEntry {self.id}: {self.user.username} on {self.project.name}>'
    
    @property
    def is_active(self):
        """Check if this is an active timer (no end time)"""
        return self.end_time is None
    
    @property
    def duration_hours(self):
        """Get duration in hours"""
        if not self.duration_seconds:
            return 0
        return round(self.duration_seconds / 3600, 2)
    
    @property
    def duration_formatted(self):
        """Get duration formatted as HH:MM:SS"""
        if not self.duration_seconds:
            return "00:00:00"
        
        hours = self.duration_seconds // 3600
        minutes = (self.duration_seconds % 3600) // 60
        seconds = self.duration_seconds % 60
        
        return f"{hours:02d}:{minutes:02d}:{seconds:02d}"
    
    @property
    def tag_list(self):
        """Get tags as a list"""
        if not self.tags:
            return []
        return [tag.strip() for tag in self.tags.split(',') if tag.strip()]
    
    @property
    def current_duration_seconds(self):
        """Calculate current duration for active timers"""
        if self.end_time:
            return self.duration_seconds or 0
        
        # For active timers, calculate from start time to now
        # Since we store everything in local timezone, we can work with naive datetimes
        # as long as we treat them as local time
        
        # Get current time in local timezone (naive, matching database storage)
        now_local = local_now()
        
        # Calculate duration (both times are treated as local time)
        duration = now_local - self.start_time
        return int(duration.total_seconds())
    
    def calculate_duration(self):
        """Calculate and set duration in seconds with rounding"""
        if not self.end_time:
            return
        
        # Since we store everything in local timezone, we can work with naive datetimes
        # as long as we treat them as local time
        
        # Calculate raw duration (both times are treated as local time)
        duration = self.end_time - self.start_time
        raw_seconds = int(duration.total_seconds())
        
        # Apply rounding
        rounding_minutes = Config.ROUNDING_MINUTES
        if rounding_minutes > 1:
            # Round to nearest interval
            minutes = raw_seconds / 60
            rounded_minutes = round(minutes / rounding_minutes) * rounding_minutes
            self.duration_seconds = int(rounded_minutes * 60)
        else:
            self.duration_seconds = raw_seconds
    
    def stop_timer(self, end_time=None):
        """Stop an active timer"""
        if self.end_time:
            raise ValueError("Timer is already stopped")
        
        # Use local timezone for consistency with database storage
        if end_time:
            self.end_time = end_time
        else:
            self.end_time = local_now()
        
        self.calculate_duration()
        self.updated_at = local_now()
        
        db.session.commit()
    
    def update_notes(self, notes):
        """Update notes for this entry"""
        self.notes = notes.strip() if notes else None
        self.updated_at = local_now()
        db.session.commit()
    
    def update_tags(self, tags):
        """Update tags for this entry"""
        self.tags = tags.strip() if tags else None
        self.updated_at = local_now()
        db.session.commit()
    
    def set_billable(self, billable):
        """Set billable status"""
        self.billable = billable
        self.updated_at = local_now()
        db.session.commit()
    
    def to_dict(self):
        """Convert time entry to dictionary for API responses"""
        return {
            'id': self.id,
            'user_id': self.user_id,
            'project_id': self.project_id,
            'task_id': self.task_id,
            'start_time': self.start_time.isoformat() if self.start_time else None,
            'end_time': self.end_time.isoformat() if self.end_time else None,
            'duration_seconds': self.duration_seconds,
            'duration_hours': self.duration_hours,
            'duration_formatted': self.duration_formatted,
            'notes': self.notes,
            'tags': self.tags,
            'tag_list': self.tag_list,
            'source': self.source,
            'billable': self.billable,
            'is_active': self.is_active,
            'created_at': self.created_at.isoformat() if self.created_at else None,
            'updated_at': self.updated_at.isoformat() if self.updated_at else None,
            'user': self.user.username if self.user else None,
            'project': self.project.name if self.project else None,
            'task': self.task.name if self.task else None
        }
    
    @classmethod
    def get_active_timers(cls):
        """Get all active timers"""
        return cls.query.filter_by(end_time=None).all()
    
    @classmethod
    def get_user_active_timer(cls, user_id):
        """Get active timer for a specific user"""
        return cls.query.filter_by(user_id=user_id, end_time=None).first()
    
    @classmethod
    def get_entries_for_period(cls, start_date=None, end_date=None, user_id=None, project_id=None):
        """Get time entries for a specific period with optional filters"""
        query = cls.query.filter(cls.end_time.isnot(None))
        
        if start_date:
            query = query.filter(cls.start_time >= start_date)
        
        if end_date:
            query = query.filter(cls.start_time <= end_date)
        
        if user_id:
            query = query.filter(cls.user_id == user_id)
        
        if project_id:
            query = query.filter(cls.project_id == project_id)
        
        return query.order_by(cls.start_time.desc()).all()
    
    @classmethod
    def get_total_hours_for_period(cls, start_date=None, end_date=None, user_id=None, project_id=None, billable_only=False):
        """Calculate total hours for a period with optional filters"""
        query = db.session.query(db.func.sum(cls.duration_seconds))
        
        if start_date:
            query = query.filter(cls.start_time >= start_date)
        
        if end_date:
            query = query.filter(cls.start_time <= end_date)
        
        if user_id:
            query = query.filter(cls.user_id == user_id)
        
        if project_id:
            query = query.filter(cls.project_id == project_id)
        
        if billable_only:
            query = query.filter(cls.billable == True)
        
        total_seconds = query.scalar() or 0
        return round(total_seconds / 3600, 2)