from sqlalchemy.sql.expression import text

from common.extensions import db
from datetime import datetime as dt, timezone as tz
from enum import Enum
from sqlalchemy import event
from sqlalchemy.dialects.postgresql import JSONB
from sqlalchemy.ext.hybrid import hybrid_property
from dateutil.relativedelta import relativedelta

from common.utils.database import Database


class BusinessEventLog(db.Model):
    __bind_key__ = 'public'
    __table_args__ = {'schema': 'public'}

    id = db.Column(db.Integer, primary_key=True)
    timestamp = db.Column(db.DateTime, nullable=False)
    event_type = db.Column(db.String(50), nullable=False)
    tenant_id = db.Column(db.Integer, nullable=False)
    trace_id = db.Column(db.String(50), nullable=False)
    span_id = db.Column(db.String(50))
    span_name = db.Column(db.String(255))
    parent_span_id = db.Column(db.String(50))
    document_version_id = db.Column(db.Integer)
    document_version_file_size = db.Column(db.Float)
    specialist_id = db.Column(db.Integer)
    specialist_type = db.Column(db.String(50))
    specialist_type_version = db.Column(db.String(20))
    chat_session_id = db.Column(db.String(50))
    interaction_id = db.Column(db.Integer)
    environment = db.Column(db.String(20))
    llm_metrics_total_tokens = db.Column(db.Integer)
    llm_metrics_prompt_tokens = db.Column(db.Integer)
    llm_metrics_completion_tokens = db.Column(db.Integer)
    llm_metrics_total_time = db.Column(db.Float)
    llm_metrics_nr_of_pages = db.Column(db.Integer)
    llm_metrics_call_count = db.Column(db.Integer)
    llm_interaction_type = db.Column(db.String(20))
    message = db.Column(db.Text)
    license_usage_id = db.Column(db.Integer, db.ForeignKey('public.license_usage.id'), nullable=True)
    license_usage = db.relationship('LicenseUsage', backref='events')


class License(db.Model):
    __bind_key__ = 'public'
    __table_args__ = {'schema': 'public'}

    id = db.Column(db.Integer, primary_key=True)
    tenant_id = db.Column(db.Integer, db.ForeignKey('public.tenant.id'), nullable=False)
    tier_id = db.Column(db.Integer, db.ForeignKey('public.license_tier.id'),nullable=False)  # 'small', 'medium', 'custom'
    start_date = db.Column(db.Date, nullable=False)
    end_date = db.Column(db.Date, nullable=True)
    nr_of_periods = db.Column(db.Integer, nullable=False)
    currency = db.Column(db.String(20), nullable=False)
    yearly_payment = db.Column(db.Boolean, nullable=False, default=False)
    basic_fee = db.Column(db.Float, nullable=False)
    max_storage_mb = db.Column(db.Integer, nullable=False)
    additional_storage_price = db.Column(db.Float, nullable=False)
    additional_storage_bucket = db.Column(db.Integer, nullable=False)
    included_embedding_mb = db.Column(db.Integer, nullable=False)
    additional_embedding_price = db.Column(db.Numeric(10, 4), nullable=False)
    additional_embedding_bucket = db.Column(db.Integer, nullable=False)
    included_interaction_tokens = db.Column(db.Integer, nullable=False)
    additional_interaction_token_price = db.Column(db.Numeric(10, 4), nullable=False)
    additional_interaction_bucket = db.Column(db.Integer, nullable=False)
    overage_embedding = db.Column(db.Float, nullable=False, default=0)
    overage_interaction = db.Column(db.Float, nullable=False, default=0)
    additional_storage_allowed = db.Column(db.Boolean, nullable=False, default=False)
    additional_embedding_allowed = db.Column(db.Boolean, nullable=False, default=False)
    additional_interaction_allowed = db.Column(db.Boolean, nullable=False, default=False)

    # Versioning Information
    created_at = db.Column(db.DateTime, nullable=True, server_default=db.func.now())
    created_by = db.Column(db.Integer, db.ForeignKey('public.user.id'), nullable=True)
    updated_at = db.Column(db.DateTime, nullable=True, server_default=db.func.now(), onupdate=db.func.now())
    updated_by = db.Column(db.Integer, db.ForeignKey('public.user.id'), nullable=True)

    tenant = db.relationship('Tenant', back_populates='licenses')
    license_tier = db.relationship('LicenseTier', back_populates='licenses')
    periods = db.relationship('LicensePeriod', back_populates='license',
                              order_by='LicensePeriod.period_number',
                              cascade='all, delete-orphan')

def calculate_end_date(start_date, nr_of_periods):
    """Utility functie om einddatum te berekenen"""
    if start_date and nr_of_periods:
        return start_date + relativedelta(months=nr_of_periods) - relativedelta(days=1)
    return None

# Luister naar start_date wijzigingen
@event.listens_for(License.start_date, 'set')
def set_start_date(target, value, oldvalue, initiator):
    """Bijwerken van end_date wanneer start_date wordt aangepast"""
    if value and target.nr_of_periods:
        target.end_date = calculate_end_date(value, target.nr_of_periods)

# Luister naar nr_of_periods wijzigingen
@event.listens_for(License.nr_of_periods, 'set')
def set_nr_of_periods(target, value, oldvalue, initiator):
    """Bijwerken van end_date wanneer nr_of_periods wordt aangepast"""
    if value and target.start_date:
        target.end_date = calculate_end_date(target.start_date, value)


class LicenseTier(db.Model):
    __bind_key__ = 'public'
    __table_args__ = {'schema': 'public'}

    id = db.Column(db.Integer, primary_key=True)
    name = db.Column(db.String(50), nullable=False)
    version = db.Column(db.String(50), nullable=False)
    start_date = db.Column(db.Date, nullable=False)
    end_date = db.Column(db.Date, nullable=True)
    basic_fee_d = db.Column(db.Float, nullable=True)
    basic_fee_e = db.Column(db.Float, nullable=True)
    max_storage_mb = db.Column(db.Integer, nullable=False)
    additional_storage_price_d = db.Column(db.Numeric(10, 4), nullable=False)
    additional_storage_price_e = db.Column(db.Numeric(10, 4), nullable=False)
    additional_storage_bucket = db.Column(db.Integer, nullable=False)
    included_embedding_mb = db.Column(db.Integer, nullable=False)
    additional_embedding_price_d = db.Column(db.Numeric(10, 4), nullable=False)
    additional_embedding_price_e = db.Column(db.Numeric(10, 4), nullable=False)
    additional_embedding_bucket = db.Column(db.Integer, nullable=False)
    included_interaction_tokens = db.Column(db.Integer, nullable=False)
    additional_interaction_token_price_d = db.Column(db.Numeric(10, 4), nullable=False)
    additional_interaction_token_price_e = db.Column(db.Numeric(10, 4), nullable=False)
    additional_interaction_bucket = db.Column(db.Integer, nullable=False)
    standard_overage_embedding = db.Column(db.Float, nullable=False, default=0)
    standard_overage_interaction = db.Column(db.Float, nullable=False, default=0)

    # Versioning Information
    created_at = db.Column(db.DateTime, nullable=True, server_default=db.func.now())
    created_by = db.Column(db.Integer, db.ForeignKey('public.user.id'), nullable=True)
    updated_at = db.Column(db.DateTime, nullable=True, server_default=db.func.now(), onupdate=db.func.now())
    updated_by = db.Column(db.Integer, db.ForeignKey('public.user.id'), nullable=True)

    licenses = db.relationship('License', back_populates='license_tier')
    partner_services = db.relationship('PartnerServiceLicenseTier', back_populates='license_tier')


class PartnerServiceLicenseTier(db.Model):
    __bind_key__ = 'public'
    __table_args__ = {'schema': 'public'}

    partner_service_id = db.Column(db.Integer, db.ForeignKey('public.partner_service.id'), primary_key=True,
                                   nullable=False)
    license_tier_id = db.Column(db.Integer, db.ForeignKey('public.license_tier.id'), primary_key=True,
                                nullable=False)

    # Versioning Information
    created_at = db.Column(db.DateTime, nullable=True, server_default=db.func.now())
    created_by = db.Column(db.Integer, db.ForeignKey('public.user.id'), nullable=True)
    updated_at = db.Column(db.DateTime, nullable=True, server_default=db.func.now(), onupdate=db.func.now())
    updated_by = db.Column(db.Integer, db.ForeignKey('public.user.id'), nullable=True)

    license_tier = db.relationship('LicenseTier', back_populates='partner_services')
    partner_service = db.relationship('PartnerService', back_populates='license_tiers')


class PeriodStatus(Enum):
    UPCOMING = "UPCOMING"   # The period is still in the future
    PENDING = "PENDING"     # The period is active, but prepaid is not yet received
    ACTIVE = "ACTIVE"       # The period is active and prepaid has been received
    COMPLETED = "COMPLETED" # The period has been completed, but not yet invoiced
    INVOICED = "INVOICED"   # The period has been completed and invoiced, but overage payment still pending
    CLOSED = "CLOSED"       # The period has been closed, invoiced and fully paid


class LicensePeriod(db.Model):
    __bind_key__ = 'public'
    __table_args__ = {'schema': 'public'}

    id = db.Column(db.Integer, primary_key=True)
    license_id = db.Column(db.Integer, db.ForeignKey('public.license.id'), nullable=False)
    tenant_id = db.Column(db.Integer, db.ForeignKey('public.tenant.id'), nullable=False)

    # Period identification
    period_number = db.Column(db.Integer, nullable=False)
    period_start = db.Column(db.Date, nullable=False)
    period_end = db.Column(db.Date, nullable=False)

    # License configuration snapshot - copied from license when period is created
    currency = db.Column(db.String(20), nullable=True)
    basic_fee = db.Column(db.Float, nullable=True)
    max_storage_mb = db.Column(db.Integer, nullable=True)
    additional_storage_price = db.Column(db.Float, nullable=True)
    additional_storage_bucket = db.Column(db.Integer, nullable=True)
    included_embedding_mb = db.Column(db.Integer, nullable=True)
    additional_embedding_price = db.Column(db.Numeric(10, 4), nullable=True)
    additional_embedding_bucket = db.Column(db.Integer, nullable=True)
    included_interaction_tokens = db.Column(db.Integer, nullable=True)
    additional_interaction_token_price = db.Column(db.Numeric(10, 4), nullable=True)
    additional_interaction_bucket = db.Column(db.Integer, nullable=True)
    
    # Allowance flags - can be changed from False to True within a period
    additional_storage_allowed = db.Column(db.Boolean, nullable=True, default=False)
    additional_embedding_allowed = db.Column(db.Boolean, nullable=True, default=False)
    additional_interaction_allowed = db.Column(db.Boolean, nullable=True, default=False)

    # Status tracking
    status = db.Column(db.Enum(PeriodStatus), nullable=False, default=PeriodStatus.UPCOMING)

    # State transition timestamps
    upcoming_at = db.Column(db.DateTime, nullable=True)
    pending_at = db.Column(db.DateTime, nullable=True)
    active_at = db.Column(db.DateTime, nullable=True)
    completed_at = db.Column(db.DateTime, nullable=True)
    invoiced_at = db.Column(db.DateTime, nullable=True)
    closed_at = db.Column(db.DateTime, nullable=True)

    # Standard audit fields
    created_at = db.Column(db.DateTime, server_default=db.func.now())
    updated_at = db.Column(db.DateTime, server_default=db.func.now(), onupdate=db.func.now())
    created_by = db.Column(db.Integer, db.ForeignKey('public.user.id'))
    updated_by = db.Column(db.Integer, db.ForeignKey('public.user.id'))

    # Relationships
    license = db.relationship('License', back_populates='periods')
    license_usage = db.relationship('LicenseUsage',
                                    uselist=False,  # This makes it one-to-one
                                    back_populates='license_period',
                                    cascade='all, delete-orphan')
    payments = db.relationship('Payment', back_populates='license_period')
    invoices = db.relationship('Invoice', back_populates='license_period',
                               cascade='all, delete-orphan')

    def update_allowance(self, allowance_type, allow_value, user_id=None):
        """
        Update an allowance flag within a period
        Only allows transitioning from False to True
        
        Args:
            allowance_type: One of 'storage', 'embedding', or 'interaction'
            allow_value: The new value (must be True)
            user_id: User ID performing the update
            
        Raises:
            ValueError: If trying to change from True to False, or invalid allowance type
        """
        field_name = f"additional_{allowance_type}_allowed"
        
        # Verify valid field
        if not hasattr(self, field_name):
            raise ValueError(f"Invalid allowance type: {allowance_type}")
            
        # Get current value
        current_value = getattr(self, field_name)
        
        # Only allow False -> True transition
        if current_value is True and allow_value is True:
            # Already True, no change needed
            return
        elif allow_value is False:
            raise ValueError(f"Cannot change {field_name} from {current_value} to False")
        
        # Update the field
        setattr(self, field_name, True)
        self.updated_at = dt.now(tz.utc)
        if user_id:
            self.updated_by = user_id

    @property
    def prepaid_invoice(self):
        """Get the prepaid invoice for this period"""
        return Invoice.query.filter_by(
            license_period_id=self.id,
            invoice_type=PaymentType.PREPAID
        ).first()

    @property
    def overage_invoice(self):
        """Get the overage invoice for this period"""
        return Invoice.query.filter_by(
            license_period_id=self.id,
            invoice_type=PaymentType.POSTPAID
        ).first()

    @property
    def prepaid_payment(self):
        """Get the prepaid payment for this period"""
        return Payment.query.filter_by(
            license_period_id=self.id,
            payment_type=PaymentType.PREPAID
        ).first()

    @property
    def overage_payment(self):
        """Get the overage payment for this period"""
        return Payment.query.filter_by(
            license_period_id=self.id,
            payment_type=PaymentType.POSTPAID
        ).first()

    @property
    def all_invoices(self):
        """Get all invoices for this period"""
        return self.invoices

    @property
    def all_payments(self):
        """Get all payments for this period"""
        return self.payments

    def transition_status(self, new_status: PeriodStatus, user_id: int = None):
        """Transition to a new status with proper validation and logging"""
        if not self.can_transition_to(new_status):
            raise ValueError(f"Invalid status transition from {self.status} to {new_status}")

        self.status = new_status
        self.updated_at = dt.now(tz.utc)
        if user_id:
            self.updated_by = user_id

        # Set appropriate timestamps
        if new_status == PeriodStatus.ACTIVE and not self.prepaid_received_at:
            self.prepaid_received_at = dt.now(tz.utc)
        elif new_status == PeriodStatus.COMPLETED:
            self.completed_at = dt.now(tz.utc)
        elif new_status == PeriodStatus.INVOICED:
            self.invoiced_at = dt.now(tz.utc)
        elif new_status == PeriodStatus.CLOSED:
            self.closed_at = dt.now(tz.utc)

    @property
    def is_overdue(self):
        """Check if a prepaid payment is overdue"""
        return (self.status == PeriodStatus.PENDING and
                self.period_start <= dt.now(tz.utc).date())

    def can_transition_to(self, new_status: PeriodStatus) -> bool:
        """Check if a status transition is valid"""
        valid_transitions = {
            PeriodStatus.UPCOMING: [PeriodStatus.ACTIVE, PeriodStatus.PENDING],
            PeriodStatus.PENDING: [PeriodStatus.ACTIVE],
            PeriodStatus.ACTIVE: [PeriodStatus.COMPLETED],
            PeriodStatus.COMPLETED: [PeriodStatus.INVOICED, PeriodStatus.CLOSED],
            PeriodStatus.INVOICED: [PeriodStatus.CLOSED],
            PeriodStatus.CLOSED: []
        }
        return new_status in valid_transitions.get(self.status, [])

    def __repr__(self):
        return f'<LicensePeriod {self.id}: License {self.license_id}, Period {self.period_number}>'


class LicenseUsage(db.Model):
    __bind_key__ = 'public'
    __table_args__ = {'schema': 'public'}

    id = db.Column(db.Integer, primary_key=True)
    tenant_id = db.Column(db.Integer, db.ForeignKey('public.tenant.id'), nullable=False)
    storage_mb_used = db.Column(db.Float, default=0)
    embedding_mb_used = db.Column(db.Float, default=0)
    embedding_prompt_tokens_used = db.Column(db.Integer, default=0)
    embedding_completion_tokens_used = db.Column(db.Integer, default=0)
    embedding_total_tokens_used = db.Column(db.Integer, default=0)
    interaction_prompt_tokens_used = db.Column(db.Integer, default=0)
    interaction_completion_tokens_used = db.Column(db.Integer, default=0)
    interaction_total_tokens_used = db.Column(db.Integer, default=0)
    license_period_id = db.Column(db.Integer, db.ForeignKey('public.license_period.id'), nullable=False)

    # Standard audit fields
    created_at = db.Column(db.DateTime, server_default=db.func.now())
    updated_at = db.Column(db.DateTime, server_default=db.func.now(), onupdate=db.func.now())
    created_by = db.Column(db.Integer, db.ForeignKey('public.user.id'))
    updated_by = db.Column(db.Integer, db.ForeignKey('public.user.id'))

    license_period = db.relationship('LicensePeriod', back_populates='license_usage')

    def recalculate_storage(self):
        Database(self.tenant_id).switch_schema()
        # Perform a SUM operation to get the total file size from document_versions
        total_storage = db.session.execute(text(f"""
                SELECT SUM(file_size) 
                FROM document_version
            """)).scalar()

        self.storage_mb_used = total_storage


class PaymentType(Enum):
    PREPAID = "PREPAID"
    POSTPAID = "POSTPAID"


class PaymentStatus(Enum):
    PENDING = "PENDING"
    PAID = "PAID"
    FAILED = "FAILED"
    CANCELLED = "CANCELLED"


class Payment(db.Model):
    __bind_key__ = 'public'
    __table_args__ = {'schema': 'public'}

    id = db.Column(db.Integer, primary_key=True)
    license_period_id = db.Column(db.Integer, db.ForeignKey('public.license_period.id'), nullable=True)
    tenant_id = db.Column(db.Integer, db.ForeignKey('public.tenant.id'), nullable=False)

    # Payment details
    payment_type = db.Column(db.Enum(PaymentType), nullable=False)
    amount = db.Column(db.Numeric(10, 2), nullable=False)
    currency = db.Column(db.String(3), nullable=False)
    description = db.Column(db.Text, nullable=True)

    # Status tracking
    status = db.Column(db.Enum(PaymentStatus), nullable=False, default=PaymentStatus.PENDING)

    # External provider information
    external_payment_id = db.Column(db.String(255), nullable=True)
    payment_method = db.Column(db.String(50), nullable=True)  # credit_card, bank_transfer, etc.
    provider_data = db.Column(JSONB, nullable=True)  # Provider-specific data

    # Payment information
    paid_at = db.Column(db.DateTime, nullable=True)

    # Standard audit fields
    created_at = db.Column(db.DateTime, server_default=db.func.now())
    created_by = db.Column(db.Integer, db.ForeignKey('public.user.id'))
    updated_at = db.Column(db.DateTime, server_default=db.func.now(), onupdate=db.func.now())
    updated_by = db.Column(db.Integer, db.ForeignKey('public.user.id'))

    # Relationships
    license_period = db.relationship('LicensePeriod', back_populates='payments')
    invoice = db.relationship('Invoice', back_populates='payment', uselist=False)

    @property
    def is_overdue(self):
        """Check if payment is overdue"""
        if self.status != PaymentStatus.PENDING:
            return False

        # For prepaid payments, check if period start has passed
        if (self.payment_type == PaymentType.PREPAID and
                self.license_period_id):
            return self.license_period.period_start <= dt.now(tz.utc).date()

        # For postpaid, check against due date (would be on invoice)
        return False

    def __repr__(self):
        return f'<Payment {self.id}: {self.payment_type} {self.amount} {self.currency}>'


class InvoiceStatus(Enum):
    DRAFT = "DRAFT"
    SENT = "SENT"
    PAID = "PAID"
    OVERDUE = "OVERDUE"
    CANCELLED = "CANCELLED"


class Invoice(db.Model):
    __bind_key__ = 'public'
    __table_args__ = {'schema': 'public'}

    id = db.Column(db.Integer, primary_key=True)
    license_period_id = db.Column(db.Integer, db.ForeignKey('public.license_period.id'), nullable=False)
    payment_id = db.Column(db.Integer, db.ForeignKey('public.payment.id'), nullable=True)
    tenant_id = db.Column(db.Integer, db.ForeignKey('public.tenant.id'), nullable=False)

    # Invoice details
    invoice_type = db.Column(db.Enum(PaymentType), nullable=False)
    invoice_number = db.Column(db.String(50), unique=True, nullable=False)
    invoice_date = db.Column(db.Date, nullable=False)
    due_date = db.Column(db.Date, nullable=False)

    # Financial details
    amount = db.Column(db.Numeric(10, 2), nullable=False)
    currency = db.Column(db.String(3), nullable=False)
    tax_amount = db.Column(db.Numeric(10, 2), default=0)

    # Descriptive fields
    description = db.Column(db.Text, nullable=True)
    status = db.Column(db.Enum(InvoiceStatus), nullable=False, default=InvoiceStatus.DRAFT)

    # Timestamps
    sent_at = db.Column(db.DateTime, nullable=True)
    paid_at = db.Column(db.DateTime, nullable=True)

    # Standard audit fields
    created_at = db.Column(db.DateTime, server_default=db.func.now())
    created_by = db.Column(db.Integer, db.ForeignKey('public.user.id'))
    updated_at = db.Column(db.DateTime, server_default=db.func.now(), onupdate=db.func.now())
    updated_by = db.Column(db.Integer, db.ForeignKey('public.user.id'))

    # Relationships
    license_period = db.relationship('LicensePeriod', back_populates='invoices')
    payment = db.relationship('Payment', back_populates='invoice')

    def __repr__(self):
        return f'<Invoice {self.invoice_number}: {self.amount} {self.currency}>'


class LicenseChangeLog(db.Model):
    """
    Log of changes to license configurations
    Used for auditing and tracking when/why license details changed
    """
    __bind_key__ = 'public'
    __table_args__ = {'schema': 'public'}
    
    id = db.Column(db.Integer, primary_key=True)
    license_id = db.Column(db.Integer, db.ForeignKey('public.license.id'), nullable=False)
    changed_at = db.Column(db.DateTime, nullable=False, default=lambda: dt.now(tz.utc))
    
    # What changed
    field_name = db.Column(db.String(100), nullable=False)
    old_value = db.Column(db.String(255), nullable=True)
    new_value = db.Column(db.String(255), nullable=False)
    
    # Why it changed
    reason = db.Column(db.Text, nullable=True)
    
    # Standard audit fields
    created_by = db.Column(db.Integer, db.ForeignKey('public.user.id'), nullable=True)
    
    # Relationships
    license = db.relationship('License', backref=db.backref('change_logs', order_by='LicenseChangeLog.changed_at'))
    
    def __repr__(self):
        return f'<LicenseChangeLog: {self.license_id} {self.field_name} {self.old_value} -> {self.new_value}>'