from datetime import datetime
from flask_login import UserMixin
from werkzeug.security import generate_password_hash, check_password_hash
from app import db


# ─── Enumerations ────────────────────────────────────────────────────────────

class UserRole:
    EMPLOYEE = 'employee'
    IT_STAFF  = 'it_staff'
    ADMIN     = 'admin'

class TicketStatus:
    OPEN        = 'open'
    IN_PROGRESS = 'in_progress'
    PENDING     = 'pending'
    RESOLVED    = 'resolved'
    CLOSED      = 'closed'

class TicketPriority:
    LOW      = 'low'
    MEDIUM   = 'medium'
    HIGH     = 'high'
    CRITICAL = 'critical'

class TicketCategory:
    HARDWARE       = 'hardware'
    SOFTWARE       = 'software'
    NETWORK        = 'network'
    ACCESS         = 'access'
    EMAIL          = 'email'
    PRINTER        = 'printer'
    PHONE          = 'phone'
    SECURITY       = 'security'
    OTHER          = 'other'

class NotificationType:
    TICKET_CREATED   = 'ticket_created'
    TICKET_UPDATED   = 'ticket_updated'
    TICKET_ASSIGNED  = 'ticket_assigned'
    COMMENT_ADDED    = 'comment_added'
    STATUS_CHANGED   = 'status_changed'
    TICKET_RESOLVED  = 'ticket_resolved'
    TICKET_CLOSED    = 'ticket_closed'
    MENTION          = 'mention'


# ─── Models ──────────────────────────────────────────────────────────────────

class User(UserMixin, db.Model):
    __tablename__ = 'users'

    id           = db.Column(db.Integer, primary_key=True)
    email        = db.Column(db.String(120), unique=True, nullable=False, index=True)
    username     = db.Column(db.String(64), unique=True, nullable=False, index=True)
    full_name    = db.Column(db.String(128), nullable=False)
    password_hash= db.Column(db.String(256), nullable=False)
    role         = db.Column(db.String(20), default=UserRole.EMPLOYEE, nullable=False)
    department   = db.Column(db.String(100))
    phone        = db.Column(db.String(20))
    avatar_url   = db.Column(db.String(256))
    is_active    = db.Column(db.Boolean, default=True, nullable=False)
    email_notif  = db.Column(db.Boolean, default=True, nullable=False)
    web_notif    = db.Column(db.Boolean, default=True, nullable=False)
    created_at   = db.Column(db.DateTime, default=datetime.utcnow)
    last_login   = db.Column(db.DateTime)

    # Relationships
    created_tickets  = db.relationship('Ticket', foreign_keys='Ticket.created_by_id', backref='creator', lazy='dynamic')
    assigned_tickets = db.relationship('Ticket', foreign_keys='Ticket.assigned_to_id', backref='assignee', lazy='dynamic')
    comments         = db.relationship('Comment', backref='author', lazy='dynamic')
    notifications    = db.relationship('Notification', backref='recipient', lazy='dynamic')
    activity_logs    = db.relationship('ActivityLog', backref='user', lazy='dynamic')

    def set_password(self, password):
        self.password_hash = generate_password_hash(password)

    def check_password(self, password):
        return check_password_hash(self.password_hash, password)

    @property
    def is_it_staff(self):
        return self.role in (UserRole.IT_STAFF, UserRole.ADMIN)

    @property
    def is_admin(self):
        return self.role == UserRole.ADMIN

    def __repr__(self):
        return f'<User {self.username}>'


class Ticket(db.Model):
    __tablename__ = 'tickets'

    id            = db.Column(db.Integer, primary_key=True)
    ticket_number = db.Column(db.String(20), unique=True, nullable=False, index=True)
    title         = db.Column(db.String(200), nullable=False)
    description   = db.Column(db.Text, nullable=False)
    category      = db.Column(db.String(50), default=TicketCategory.OTHER, nullable=False)
    priority      = db.Column(db.String(20), default=TicketPriority.MEDIUM, nullable=False)
    status        = db.Column(db.String(20), default=TicketStatus.OPEN, nullable=False, index=True)
    location      = db.Column(db.String(100))
    asset_tag     = db.Column(db.String(50))

    created_by_id  = db.Column(db.Integer, db.ForeignKey('users.id'), nullable=False)
    assigned_to_id = db.Column(db.Integer, db.ForeignKey('users.id'))

    created_at     = db.Column(db.DateTime, default=datetime.utcnow, index=True)
    updated_at     = db.Column(db.DateTime, default=datetime.utcnow, onupdate=datetime.utcnow)
    resolved_at    = db.Column(db.DateTime)
    closed_at      = db.Column(db.DateTime)
    due_date       = db.Column(db.DateTime)

    ai_generated   = db.Column(db.Boolean, default=False)
    internal_notes = db.Column(db.Text)
    resolution_notes = db.Column(db.Text)

    # Relationships
    comments     = db.relationship('Comment', backref='ticket', lazy='dynamic', cascade='all, delete-orphan')
    attachments  = db.relationship('Attachment', backref='ticket', lazy='dynamic', cascade='all, delete-orphan')
    notifications= db.relationship('Notification', backref='ticket', lazy='dynamic', cascade='all, delete-orphan')
    history      = db.relationship('TicketHistory', backref='ticket', lazy='dynamic', cascade='all, delete-orphan')

    def generate_ticket_number(self):
        """Generate unique ticket number like TKT-20240101-0001"""
        date_str = datetime.utcnow().strftime('%Y%m%d')
        last = Ticket.query.filter(
            Ticket.ticket_number.like(f'TKT-{date_str}-%')
        ).order_by(Ticket.id.desc()).first()
        if last:
            seq = int(last.ticket_number.split('-')[-1]) + 1
        else:
            seq = 1
        return f'TKT-{date_str}-{seq:04d}'

    @property
    def priority_color(self):
        return {
            TicketPriority.LOW:      'success',
            TicketPriority.MEDIUM:   'warning',
            TicketPriority.HIGH:     'danger',
            TicketPriority.CRITICAL: 'dark',
        }.get(self.priority, 'secondary')

    @property
    def status_color(self):
        return {
            TicketStatus.OPEN:        'primary',
            TicketStatus.IN_PROGRESS: 'info',
            TicketStatus.PENDING:     'warning',
            TicketStatus.RESOLVED:    'success',
            TicketStatus.CLOSED:      'secondary',
        }.get(self.status, 'secondary')

    def __repr__(self):
        return f'<Ticket {self.ticket_number}>'


class Comment(db.Model):
    __tablename__ = 'comments'

    id          = db.Column(db.Integer, primary_key=True)
    ticket_id   = db.Column(db.Integer, db.ForeignKey('tickets.id'), nullable=False)
    author_id   = db.Column(db.Integer, db.ForeignKey('users.id'), nullable=False)
    body        = db.Column(db.Text, nullable=False)
    is_internal = db.Column(db.Boolean, default=False)  # IT-only internal note
    created_at  = db.Column(db.DateTime, default=datetime.utcnow)
    updated_at  = db.Column(db.DateTime, default=datetime.utcnow, onupdate=datetime.utcnow)

    attachments = db.relationship('Attachment', backref='comment', lazy='dynamic')

    def __repr__(self):
        return f'<Comment {self.id} on Ticket {self.ticket_id}>'


class Attachment(db.Model):
    __tablename__ = 'attachments'

    id          = db.Column(db.Integer, primary_key=True)
    ticket_id   = db.Column(db.Integer, db.ForeignKey('tickets.id'))
    comment_id  = db.Column(db.Integer, db.ForeignKey('comments.id'))
    filename    = db.Column(db.String(256), nullable=False)
    stored_name = db.Column(db.String(256), nullable=False)
    file_size   = db.Column(db.Integer)
    mime_type   = db.Column(db.String(100))
    uploaded_by = db.Column(db.Integer, db.ForeignKey('users.id'))
    uploaded_at = db.Column(db.DateTime, default=datetime.utcnow)

    uploader    = db.relationship('User', foreign_keys=[uploaded_by])

    def __repr__(self):
        return f'<Attachment {self.filename}>'


class Notification(db.Model):
    __tablename__ = 'notifications'

    id          = db.Column(db.Integer, primary_key=True)
    user_id     = db.Column(db.Integer, db.ForeignKey('users.id'), nullable=False)
    ticket_id   = db.Column(db.Integer, db.ForeignKey('tickets.id'))
    type        = db.Column(db.String(50), nullable=False)
    title       = db.Column(db.String(200), nullable=False)
    message     = db.Column(db.Text)
    is_read     = db.Column(db.Boolean, default=False, index=True)
    created_at  = db.Column(db.DateTime, default=datetime.utcnow, index=True)
    link        = db.Column(db.String(256))

    def __repr__(self):
        return f'<Notification {self.id} for User {self.user_id}>'


class TicketHistory(db.Model):
    __tablename__ = 'ticket_history'

    id          = db.Column(db.Integer, primary_key=True)
    ticket_id   = db.Column(db.Integer, db.ForeignKey('tickets.id'), nullable=False)
    changed_by  = db.Column(db.Integer, db.ForeignKey('users.id'), nullable=False)
    field_name  = db.Column(db.String(50), nullable=False)
    old_value   = db.Column(db.String(200))
    new_value   = db.Column(db.String(200))
    changed_at  = db.Column(db.DateTime, default=datetime.utcnow)

    changer     = db.relationship('User', foreign_keys=[changed_by])

    def __repr__(self):
        return f'<TicketHistory {self.id}>'


class ActivityLog(db.Model):
    __tablename__ = 'activity_logs'

    id          = db.Column(db.Integer, primary_key=True)
    user_id     = db.Column(db.Integer, db.ForeignKey('users.id'))
    action      = db.Column(db.String(100), nullable=False)
    entity_type = db.Column(db.String(50))
    entity_id   = db.Column(db.Integer)
    details     = db.Column(db.Text)
    ip_address  = db.Column(db.String(45))
    created_at  = db.Column(db.DateTime, default=datetime.utcnow, index=True)

    def __repr__(self):
        return f'<ActivityLog {self.action} by User {self.user_id}>'


class KnowledgeBase(db.Model):
    __tablename__ = 'knowledge_base'

    id          = db.Column(db.Integer, primary_key=True)
    title       = db.Column(db.String(200), nullable=False)
    body        = db.Column(db.Text, nullable=False)
    category    = db.Column(db.String(50))
    tags        = db.Column(db.String(256))
    author_id   = db.Column(db.Integer, db.ForeignKey('users.id'))
    is_published= db.Column(db.Boolean, default=True)
    view_count  = db.Column(db.Integer, default=0)
    created_at  = db.Column(db.DateTime, default=datetime.utcnow)
    updated_at  = db.Column(db.DateTime, default=datetime.utcnow, onupdate=datetime.utcnow)

    author      = db.relationship('User', foreign_keys=[author_id])

    def __repr__(self):
        return f'<KnowledgeBase {self.title}>'