from django.db import models

from infrasynth.shared.enums import (
    EntitlementStatus,
    InvoiceStatus,
    MonetizationModel,
    PlanInterval,
    SubscriptionStatus,
)
from infrasynth.tenancy.mixins import TenantOwnedModel


class App(models.Model):
    """A deployed InfraSynth app in the catalog (global)."""

    slug = models.SlugField(max_length=100, unique=True)
    name = models.CharField(max_length=200)
    monetization = models.CharField(max_length=20, choices=MonetizationModel.choices)
    is_active = models.BooleanField(default=True)
    metadata = models.JSONField(default=dict)

    class Meta:
        db_table = "billing_app"

    def __str__(self):
        return self.name


class Plan(models.Model):
    """A purchasable tier of an app (global). Money is integer minor units."""

    app = models.ForeignKey(App, on_delete=models.CASCADE, related_name="plans")
    slug = models.SlugField(max_length=100)
    name = models.CharField(max_length=200)
    price_amount = models.BigIntegerField(help_text="Minor units (cents). Never a float.")
    price_currency = models.CharField(max_length=3, default="USD")
    interval = models.CharField(max_length=20, choices=PlanInterval.choices, default=PlanInterval.MONTHLY)
    trial_days = models.PositiveIntegerField(default=0)
    features = models.JSONField(default=dict)
    limits = models.JSONField(default=dict)
    is_active = models.BooleanField(default=True)
    gateway = models.ForeignKey(
        "PaymentGateway",
        on_delete=models.SET_NULL,
        null=True,
        blank=True,
        related_name="+",
    )
    external_id = models.CharField(max_length=200, blank=True)

    class Meta:
        db_table = "billing_plan"
        constraints = [models.UniqueConstraint(fields=["app", "slug"], name="uniq_plan_slug_per_app")]

    def __str__(self):
        return f"{self.app.slug}:{self.slug}"


class Entitlement(TenantOwnedModel):
    """A tenant's right to use an app under a plan. The unit of enforcement."""

    app = models.ForeignKey(App, on_delete=models.CASCADE, related_name="entitlements")
    plan = models.ForeignKey(Plan, on_delete=models.SET_NULL, null=True, blank=True, related_name="+")
    status = models.CharField(max_length=20, choices=EntitlementStatus.choices, default=EntitlementStatus.ACTIVE)
    started_at = models.DateTimeField(auto_now_add=True)
    current_period_end = models.DateTimeField(null=True, blank=True)
    expires_at = models.DateTimeField(null=True, blank=True)
    cancel_at_period_end = models.BooleanField(default=False)
    source = models.CharField(max_length=20, default="manual")
    metadata = models.JSONField(default=dict)

    class Meta:
        db_table = "billing_entitlement"
        constraints = [
            models.UniqueConstraint(fields=["tenant", "app"], name="uniq_tenant_app_entitlement"),
        ]

    def __str__(self):
        return f"{self.tenant_id}:{self.app.slug}:{self.status}"


class PaymentGateway(models.Model):
    """Platform payment provider account (global). Credentials are Fernet-encrypted."""

    slug = models.SlugField(max_length=100, primary_key=True)
    display_name = models.CharField(max_length=200)
    gateway_class = models.CharField(max_length=500)
    config = models.JSONField(default=dict)
    is_active = models.BooleanField(default=True)
    supported_currencies = models.JSONField(default=list)
    webhook_secret = models.CharField(max_length=500, blank=True)

    class Meta:
        db_table = "billing_gateway"

    def __str__(self):
        return self.display_name


class Subscription(TenantOwnedModel):
    """An active subscription backing an entitlement (tenant-owned)."""

    entitlement = models.ForeignKey(
        Entitlement,
        on_delete=models.SET_NULL,
        null=True,
        blank=True,
        related_name="subscriptions",
    )
    plan = models.ForeignKey(
        Plan,
        on_delete=models.SET_NULL,
        null=True,
        blank=True,
        related_name="+",
    )
    gateway = models.ForeignKey(
        PaymentGateway,
        on_delete=models.SET_NULL,
        null=True,
        blank=True,
        related_name="+",
    )
    external_id = models.CharField(max_length=255, blank=True)
    status = models.CharField(max_length=20, choices=SubscriptionStatus.choices)
    current_period_start = models.DateTimeField(null=True, blank=True)
    current_period_end = models.DateTimeField(null=True, blank=True)
    cancel_at_period_end = models.BooleanField(default=False)
    cancelled_at = models.DateTimeField(null=True, blank=True)
    trial_end = models.DateTimeField(null=True, blank=True)
    metadata = models.JSONField(default=dict)

    class Meta:
        db_table = "billing_subscription"
        indexes = [models.Index(fields=["tenant_id", "status"])]

    def __str__(self):
        return f"{self.tenant_id}#{self.plan}"


class Invoice(TenantOwnedModel):
    """A generated invoice (tenant-owned). Money is integer minor units."""

    subscription = models.ForeignKey(
        Subscription,
        on_delete=models.SET_NULL,
        null=True,
        blank=True,
        related_name="invoices",
    )
    gateway = models.ForeignKey(
        PaymentGateway,
        on_delete=models.SET_NULL,
        null=True,
        blank=True,
        related_name="+",
    )
    external_id = models.CharField(max_length=255, blank=True)
    invoice_number = models.CharField(max_length=100)
    amount = models.BigIntegerField(help_text="Minor units (cents). Never a float.")
    currency = models.CharField(max_length=3, default="USD")
    tax_amount = models.BigIntegerField(default=0)
    tax_name = models.CharField(max_length=100, blank=True)
    status = models.CharField(max_length=20, choices=InvoiceStatus.choices)
    due_date = models.DateTimeField(null=True, blank=True)
    paid_at = models.DateTimeField(null=True, blank=True)
    line_items = models.JSONField(default=list)
    pdf_file = models.ForeignKey(
        "infrasynth_files.StoredFile",
        on_delete=models.SET_NULL,
        null=True,
        blank=True,
        related_name="+",
    )
    metadata = models.JSONField(default=dict)

    class Meta:
        db_table = "billing_invoice"
        constraints = [
            models.UniqueConstraint(fields=["tenant", "invoice_number"], name="uniq_invoice_number_per_tenant"),
        ]

    def __str__(self):
        return self.invoice_number


class PaymentTransaction(TenantOwnedModel):
    """A single payment attempt (tenant-owned)."""

    invoice = models.ForeignKey(
        Invoice,
        on_delete=models.SET_NULL,
        null=True,
        blank=True,
        related_name="transactions",
    )
    gateway = models.ForeignKey(
        PaymentGateway,
        on_delete=models.SET_NULL,
        null=True,
        blank=True,
        related_name="+",
    )
    external_id = models.CharField(max_length=255, blank=True)
    amount = models.BigIntegerField(help_text="Minor units (cents). Never a float.")
    currency = models.CharField(max_length=3, default="USD")
    status = models.CharField(max_length=50, blank=True)
    payment_method = models.CharField(max_length=100, blank=True)
    metadata = models.JSONField(default=dict)
    created_at = models.DateTimeField(auto_now_add=True)

    class Meta:
        db_table = "billing_transaction"
        indexes = [models.Index(fields=["tenant_id", "status"])]

    def __str__(self):
        return f"txn_{self.pk}"