from django.db import models
from django.core.exceptions import ValidationError
from django.urls import reverse
from django.utils.text import slugify
from django_prose_editor.fields import ProseEditorField
from django.core.validators import URLValidator


def validate_image_size(value):
    filesize = value.size
    if filesize > 1 * 1024 * 1024:  # 1MB
        raise ValidationError("Maximum file size is 1MB")


class ReusableText(models.Model):
    name = models.CharField(max_length=100)
    textsnippet = models.ForeignKey(
        "self",
        on_delete=models.SET_NULL,
        null=True,
        blank=True,
        related_name="children",
    )
    text = ProseEditorField()

    class Meta:
        ordering = ["name"]

    def __str__(self):
        return self.name

    def get_full_text(self):
        """Returns the text with all nested textsnippet content recursively included in reverse order"""
        text_parts = []

        # Recursively collect all text parts
        def collect_text(snippet):
            if snippet is None:
                return
            collect_text(snippet.textsnippet)  # Collect deepest snippets first
            text_parts.append(snippet.text)

        # Start collection with the deepest snippets
        collect_text(self.textsnippet)

        # Add the main text at the end
        text_parts.append(self.text)

        # Join all text parts
        return "".join(text_parts)


class Category(models.Model):
    name = models.CharField(max_length=100)
    slug = models.SlugField(unique=True)
    parent = models.ForeignKey(
        "self", on_delete=models.CASCADE, null=True, blank=True, related_name="children"
    )
    description = models.TextField(blank=True)
    order = models.IntegerField(default=0)

    class Meta:
        verbose_name = "Service Category"
        verbose_name_plural = "Service Categories"
        ordering = ["order", "name"]

    def __str__(self):
        if self.parent:
            return f"{self.parent} > {self.name}"
        return self.name

    def save(self, *args, **kwargs):
        if not self.slug:
            self.slug = slugify(self.name)
        super().save(*args, **kwargs)

    @property
    def full_path(self):
        path = [self.name]
        parent = self.parent
        while parent:
            path.append(parent.name)
            parent = parent.parent
        return " > ".join(reversed(path))


class CloudProvider(models.Model):
    name = models.CharField(max_length=100)
    slug = models.SlugField(unique=True)
    description = ProseEditorField()
    website = models.URLField()
    linkedin = models.URLField(blank=True)
    phone = models.CharField(max_length=25, blank=True, null=True)
    email = models.EmailField(max_length=254, blank=True, null=True)
    address = models.TextField(max_length=250, blank=True, null=True)
    logo = models.ImageField(
        upload_to="cloud_provider_logos/",
        validators=[validate_image_size],
        null=True,
        blank=True,
    )
    order = models.IntegerField(default=0)
    is_featured = models.BooleanField(default=False)
    disable_listing = models.BooleanField(default=False)

    class Meta:
        ordering = ["order"]

    def __str__(self):
        return self.name

    def save(self, *args, **kwargs):
        if not self.slug:
            self.slug = slugify(self.name)
        super().save(*args, **kwargs)

    def get_absolute_url(self):
        return reverse("services:provider_detail", kwargs={"slug": self.slug})


class Service(models.Model):
    name = models.CharField(max_length=200)
    slug = models.SlugField(max_length=250, unique=True)
    description = ProseEditorField()
    tagline = models.TextField(max_length=500, blank=True, null=True)
    logo = models.ImageField(
        upload_to="service_logos/",
        validators=[validate_image_size],
        null=True,
        blank=True,
    )
    categories = models.ManyToManyField(Category, related_name="services")
    features = ProseEditorField()
    is_featured = models.BooleanField(default=False)
    is_coming_soon = models.BooleanField(default=False)
    disable_listing = models.BooleanField(default=False)

    created_at = models.DateTimeField(auto_now_add=True)
    updated_at = models.DateTimeField(auto_now=True)

    def __str__(self):
        return self.name

    def clean(self):
        if self.is_featured and self.is_coming_soon:
            raise ValidationError(
                "A service cannot be both featured and coming soon simultaneously."
            )
        super().clean()

    def save(self, *args, **kwargs):
        self.clean()  # Ensure validation runs on save
        if not self.slug:
            self.slug = slugify(self.name)
            counter = 1
            while Service.objects.filter(slug=self.slug).exists():
                self.slug = f"{slugify(self.name)}-{counter}"
                counter += 1
        super().save(*args, **kwargs)

    def get_absolute_url(self):
        return reverse("services:service_detail", kwargs={"slug": self.slug})


class ConsultingPartner(models.Model):
    name = models.CharField(max_length=200)
    slug = models.SlugField(unique=True)
    description = ProseEditorField()
    logo = models.ImageField(
        upload_to="partner_logos/",
        validators=[validate_image_size],
        null=True,
        blank=True,
    )
    website = models.URLField(blank=True)
    linkedin = models.URLField(blank=True)
    phone = models.CharField(max_length=25, blank=True, null=True)
    email = models.EmailField(max_length=254, blank=True, null=True)
    address = models.TextField(max_length=250, blank=True, null=True)

    services = models.ManyToManyField(
        Service, related_name="consulting_partners", blank=True
    )
    cloud_providers = models.ManyToManyField(
        CloudProvider, related_name="consulting_partners", blank=True
    )

    order = models.IntegerField(default=0)
    is_featured = models.BooleanField(default=False)
    disable_listing = models.BooleanField(default=False)

    created_at = models.DateTimeField(auto_now_add=True)
    updated_at = models.DateTimeField(auto_now=True)

    class Meta:
        ordering = ["order"]

    def __str__(self):
        return self.name

    def save(self, *args, **kwargs):
        if not self.slug:
            self.slug = slugify(self.name)
        super().save(*args, **kwargs)

    def get_absolute_url(self):
        return reverse("services:partner_detail", kwargs={"slug": self.slug})


class ServiceOffering(models.Model):
    service = models.ForeignKey(
        Service, on_delete=models.CASCADE, related_name="offerings"
    )
    cloud_provider = models.ForeignKey(
        CloudProvider, on_delete=models.CASCADE, related_name="offerings"
    )
    description = ProseEditorField(blank=True, null=True)
    offer_description = models.ForeignKey(
        ReusableText,
        on_delete=models.PROTECT,
        related_name="offer_descriptions",
        blank=True,
        null=True,
    )

    disable_listing = models.BooleanField(default=False)

    created_at = models.DateTimeField(auto_now_add=True)
    updated_at = models.DateTimeField(auto_now=True)

    class Meta:
        unique_together = ["service", "cloud_provider"]
        ordering = ["service__name", "cloud_provider__name"]

    def __str__(self):
        return f"{self.service.name} on {self.cloud_provider.name}"

    def get_absolute_url(self):
        return reverse(
            "services:offering_detail",
            kwargs={
                "provider_slug": self.cloud_provider.slug,
                "service_slug": self.service.slug,
            },
        )


class Plan(models.Model):
    name = models.CharField(max_length=100)
    description = ProseEditorField(blank=True, null=True)
    pricing = ProseEditorField(blank=True, null=True)
    plan_description = models.ForeignKey(
        ReusableText,
        on_delete=models.PROTECT,
        related_name="plan_descriptions",
        blank=True,
        null=True,
    )
    offering = models.ForeignKey(
        ServiceOffering, on_delete=models.CASCADE, related_name="plans"
    )

    created_at = models.DateTimeField(auto_now_add=True)
    updated_at = models.DateTimeField(auto_now=True)

    class Meta:
        ordering = ["name"]
        unique_together = [["offering", "name"]]

    def __str__(self):
        return f"{self.offering} - {self.name}"


class ExternalLinkOffering(models.Model):
    offering = models.ForeignKey(
        ServiceOffering, on_delete=models.CASCADE, related_name="external_links"
    )
    url = models.URLField()
    description = models.CharField(max_length=200)
    order = models.IntegerField(default=0)
    created_at = models.DateTimeField(auto_now_add=True)
    updated_at = models.DateTimeField(auto_now=True)

    class Meta:
        ordering = ["order", "description"]
        verbose_name = "External Link"
        verbose_name_plural = "External Links"

    def __str__(self):
        return f"{self.description} ({self.url})"

    def clean(self):
        validate = URLValidator()
        try:
            validate(self.url)
        except ValidationError:
            raise ValidationError({"url": "Enter a valid URL."})


class ExternalLink(models.Model):
    service = models.ForeignKey(
        Service, on_delete=models.CASCADE, related_name="external_links"
    )
    url = models.URLField()
    description = models.CharField(max_length=200)
    order = models.IntegerField(default=0)
    created_at = models.DateTimeField(auto_now_add=True)
    updated_at = models.DateTimeField(auto_now=True)

    class Meta:
        ordering = ["order", "description"]
        verbose_name = "External Link"
        verbose_name_plural = "External Links"

    def __str__(self):
        return f"{self.description} ({self.url})"

    def clean(self):
        validate = URLValidator()
        try:
            validate(self.url)
        except ValidationError:
            raise ValidationError({"url": "Enter a valid URL."})


class Lead(models.Model):
    name = models.CharField(max_length=200)
    email = models.EmailField()
    company = models.CharField(max_length=200, null=True, blank=True)
    phone = models.CharField(max_length=50, null=True, blank=True)
    message = models.TextField(blank=True, null=True, max_length=1000)
    odoo_lead_id = models.IntegerField(null=True, blank=True)

    service = models.ForeignKey(
        Service, on_delete=models.SET_NULL, null=True, blank=True
    )
    offering = models.ForeignKey(
        ServiceOffering, on_delete=models.SET_NULL, null=True, blank=True
    )
    plan = models.ForeignKey(Plan, on_delete=models.SET_NULL, null=True, blank=True)

    created_at = models.DateTimeField(auto_now_add=True)

    def __str__(self):
        return f"{self.name} - {self.company} ({self.service})"


class WebsiteFaq(models.Model):
    question = models.CharField(max_length=200)
    answer = ProseEditorField()
    order = models.IntegerField(default=0)

    class Meta:
        ordering = ["order"]

    def __str__(self):
        return self.question


class Currency(models.TextChoices):
    CHF = "CHF", "Swiss Franc"
    EUR = "EUR", "Euro"
    USD = "USD", "US Dollar"


class Term(models.TextChoices):
    MTH = "MTH", "per Month (30d)"
    DAY = "DAY", "per Day"
    HR = "HR", "per Hour"
    MIN = "MIN", "per Minute"


class Unit(models.TextChoices):
    GIB = "GIB", "GiB"
    MIB = "MIB", "MiB"
    CPU = "CPU", "vCPU"


class ComputePlanPrice(models.Model):
    compute_plan = models.ForeignKey(
        "ComputePlan", on_delete=models.CASCADE, related_name="prices"
    )
    currency = models.CharField(
        max_length=3,
        choices=Currency.choices,
    )
    amount = models.DecimalField(
        max_digits=10,
        decimal_places=2,
        help_text="Price in the specified currency, excl. VAT",
    )

    class Meta:
        unique_together = ("compute_plan", "currency")
        ordering = ["currency"]

    def __str__(self):
        return f"{self.compute_plan.name} - {self.amount} {self.currency}"


class ComputePlan(models.Model):
    name = models.CharField(max_length=200)
    vcpus = models.FloatField(help_text="Number of available vCPUs")
    ram = models.FloatField(help_text="Amount of RAM available")
    cpu_mem_ratio = models.FloatField(
        help_text="vCPU to Memory ratio. How much vCPU per GiB RAM is available?"
    )
    active = models.BooleanField(default=True, help_text="Is the plan active?")
    term = models.CharField(
        max_length=3,
        default=Term.MTH,
        choices=Term.choices,
    )

    cloud_provider = models.ForeignKey(
        CloudProvider, on_delete=models.CASCADE, related_name="compute_plans"
    )

    valid_from = models.DateTimeField(blank=True, null=True)
    valid_to = models.DateTimeField(blank=True, null=True)

    class Meta:
        ordering = ["name"]

    def __str__(self):
        return self.name

    def get_price(self, currency_code: str):
        try:
            return self.prices.get(currency=currency_code).amount
        except ComputePlanPrice.DoesNotExist:
            return None


class StoragePlanPrice(models.Model):
    storage_plan = models.ForeignKey(
        "StoragePlan", on_delete=models.CASCADE, related_name="prices"
    )
    currency = models.CharField(
        max_length=3,
        choices=Currency.choices,
    )
    amount = models.DecimalField(
        max_digits=10,
        decimal_places=2,
        help_text="Price in the specified currency, excl. VAT",
    )

    class Meta:
        unique_together = ("storage_plan", "currency")
        ordering = ["currency"]

    def __str__(self):
        return f"{self.storage_plan.name} - {self.amount} {self.currency}"


class StoragePlan(models.Model):
    name = models.CharField(max_length=200)
    cloud_provider = models.ForeignKey(
        CloudProvider, on_delete=models.CASCADE, related_name="storage_plans"
    )
    term = models.CharField(
        max_length=3,
        default=Term.MTH,
        choices=Term.choices,
    )
    unit = models.CharField(
        max_length=3,
        default=Unit.GIB,
        choices=Unit.choices,
    )

    valid_from = models.DateTimeField(blank=True, null=True)
    valid_to = models.DateTimeField(blank=True, null=True)

    class Meta:
        unique_together = ("cloud_provider", "term", "unit", "valid_from", "valid_to")
        ordering = ["name"]

    def __str__(self):
        return self.name

    def get_price(self, currency_code: str):
        try:
            return self.prices.get(currency=currency_code).amount
        except ComputePlanPrice.DoesNotExist:
            return None


class VSHNAppCatBaseFee(models.Model):
    vshn_appcat_price_config = models.ForeignKey(
        "VSHNAppCatPrice", on_delete=models.CASCADE, related_name="base_fees"
    )
    currency = models.CharField(
        max_length=3,
        choices=Currency.choices,
    )
    amount = models.DecimalField(
        max_digits=10,
        decimal_places=2,
        help_text="Base fee in the specified currency, excl. VAT",
    )

    class Meta:
        verbose_name = "Service Base Fee"
        unique_together = ("vshn_appcat_price_config", "currency")
        ordering = ["currency"]

    def __str__(self):
        return f"{self.vshn_appcat_price_config.service.name} Base Fee - {self.amount} {self.currency}"


class ProgressiveDiscountModel(models.Model):
    name = models.CharField(max_length=100)
    description = models.TextField(blank=True)
    active = models.BooleanField(default=True)

    class Meta:
        verbose_name = "Discount Model"

    def __str__(self):
        return self.name

    def calculate_discount(self, base_rate, units):
        """Calculate price using progressive percentage discounts."""
        final_price = 0
        remaining_units = units
        processed_units = 0

        # Get all tiers sorted by threshold
        discount_tiers = self.tiers.all().order_by("threshold")

        for i, tier in enumerate(discount_tiers):
            # Calculate how many units fall into this tier
            if i < discount_tiers.count() - 1:
                next_threshold = discount_tiers[i + 1].threshold
                tier_units = min(remaining_units, next_threshold - processed_units)
            else:
                # Last tier handles all remaining units
                tier_units = remaining_units

            # Calculate discounted rate for this tier
            discounted_rate = base_rate * (1 - tier.discount_percent / 100)

            # Add the price for units in this tier
            final_price += discounted_rate * tier_units

            # Update tracking variables
            remaining_units -= tier_units
            processed_units += tier_units

            # Exit if all units have been processed
            if remaining_units <= 0:
                break

        return final_price


class DiscountTier(models.Model):
    discount_model = models.ForeignKey(
        ProgressiveDiscountModel, on_delete=models.CASCADE, related_name="tiers"
    )
    threshold = models.PositiveIntegerField(
        help_text="Starting unit count for this tier"
    )
    discount_percent = models.DecimalField(
        max_digits=5, decimal_places=2, help_text="Percentage discount applied (0-100)"
    )

    class Meta:
        ordering = ["threshold"]
        unique_together = ["discount_model", "threshold"]

    def __str__(self):
        return f"{self.discount_model.name}: {self.threshold}+ units → {self.discount_percent}% discount"


class VSHNAppCatPrice(models.Model):
    class VariableUnit(models.TextChoices):
        RAM = "RAM", "Memory (RAM)"
        CPU = "CPU", "CPU (vCPU)"
        USER = "USR", "Users"

    class ServiceLevel(models.TextChoices):
        BEST_EFFORT = "BE", "Best Effort"
        GUARANTEED = "GA", "Guaranteed Availability"

    service = models.ForeignKey(
        Service, on_delete=models.CASCADE, related_name="vshn_appcat_price"
    )
    variable_unit = models.CharField(
        max_length=3,
        choices=VariableUnit.choices,
        default=VariableUnit.RAM,
    )
    term = models.CharField(
        max_length=3,
        default=Term.MTH,
        choices=Term.choices,
    )
    discount_model = models.ForeignKey(
        ProgressiveDiscountModel,
        on_delete=models.SET_NULL,
        null=True,
        blank=True,
        related_name="price_configs",
    )

    ha_replica_min = models.IntegerField(
        default=1, help_text="Minimum of replicas for HA"
    )
    ha_replica_max = models.IntegerField(
        default=1, help_text="Maximum supported replicas"
    )

    valid_from = models.DateTimeField(blank=True, null=True)
    valid_to = models.DateTimeField(blank=True, null=True)

    class Meta:
        verbose_name = "AppCat Price"

    def __str__(self):
        return f"{self.service.name} - {self.get_variable_unit_display()} based pricing"

    def get_base_fee(self, currency_code: str):
        try:
            return self.base_fees.get(currency=currency_code).amount
        except VSHNAppCatBaseFee.DoesNotExist:
            return None

    def get_unit_rate(self, currency_code: str, service_level: str):
        try:
            return self.unit_rates.get(
                currency=currency_code, service_level=service_level
            ).amount
        except VSHNAppCatUnitRate.DoesNotExist:
            return None

    def calculate_final_price(
        self, currency_code: str, service_level: str, number_of_units: int
    ):
        base_fee = self.get_base_fee(currency_code)
        unit_rate = self.get_unit_rate(currency_code, service_level)

        if base_fee is None or unit_rate is None:
            return None

        if number_of_units < 0:
            raise ValueError("Number of units cannot be negative")

        # Apply discount model if available
        if self.discount_model and self.discount_model.active:
            discounted_price = self.discount_model.calculate_discount(
                unit_rate, number_of_units
            )
            total_price = base_fee + discounted_price
        else:
            total_price = base_fee + (unit_rate * number_of_units)

        return total_price


class VSHNAppCatUnitRate(models.Model):
    vshn_appcat_price_config = models.ForeignKey(
        VSHNAppCatPrice, on_delete=models.CASCADE, related_name="unit_rates"
    )
    currency = models.CharField(
        max_length=3,
        choices=Currency.choices,
    )
    service_level = models.CharField(
        max_length=2,
        choices=VSHNAppCatPrice.ServiceLevel.choices,
    )
    amount = models.DecimalField(
        max_digits=10,
        decimal_places=4,
        help_text="Price per unit in the specified currency and service level, excl. VAT",
    )

    class Meta:
        verbose_name = "Service Unit Rate"
        unique_together = ("vshn_appcat_price_config", "currency", "service_level")
        ordering = ["currency", "service_level"]

    def __str__(self):
        return f"{self.vshn_appcat_price_config.service.name} - {self.get_service_level_display()} Unit Rate - {self.amount} {self.currency}"