import uuid
from django.conf import settings
from django.db import models


class ProductSpecification(models.Model):
    class Status(models.TextChoices):
        DRAFT = "draft", "Draft"
        APPROVED = "approved", "Approved"
        SUPERSEDED = "superseded", "Superseded"

    id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)
    product = models.CharField(max_length=100)
    version = models.CharField(max_length=20)
    status = models.CharField(max_length=20, choices=Status.choices, default=Status.DRAFT)
    effective_from = models.DateField(null=True, blank=True)
    effective_to = models.DateField(null=True, blank=True)
    is_current = models.BooleanField(default=False)
    approved_by = models.ForeignKey(
        settings.AUTH_USER_MODEL, on_delete=models.SET_NULL, null=True, blank=True,
        related_name="specs_approved",
    )
    approved_at = models.DateTimeField(null=True, blank=True)
    created_at = models.DateTimeField(auto_now_add=True)
    updated_at = models.DateTimeField(auto_now=True)

    class Meta:
        db_table = "product_specifications"
        unique_together = [("product", "version")]
        ordering = ["product", "-version"]

    def __str__(self):
        return f"{self.product} v{self.version} ({self.status})"

    @classmethod
    def current(cls, product):
        return cls.objects.filter(product=product, status=cls.Status.APPROVED, is_current=True).first()


class SpecParameter(models.Model):
    class Parameter(models.TextChoices):
        FFA = "ffa", "Free Fatty Acid"
        MOISTURE = "moisture", "Moisture"
        PEROXIDE = "peroxide", "Peroxide Value"
        VISUAL = "visual", "Visual Grade"

    id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)
    spec = models.ForeignKey(ProductSpecification, on_delete=models.CASCADE, related_name="parameters")
    parameter = models.CharField(max_length=20, choices=Parameter.choices)
    unit = models.CharField(max_length=50, blank=True)
    min_value = models.DecimalField(max_digits=8, decimal_places=3, null=True, blank=True)
    max_value = models.DecimalField(max_digits=8, decimal_places=3, null=True, blank=True)
    allowed_values = models.CharField(max_length=255, blank=True)
    required = models.BooleanField(default=True)
    sort_order = models.IntegerField(default=0)

    class Meta:
        db_table = "spec_parameters"
        unique_together = [("spec", "parameter")]
        ordering = ["sort_order"]

    def __str__(self):
        return f"{self.get_parameter_display()} ({self.unit})"

    def check_value(self, value):
        if value is None or value == "":
            if self.required:
                return ("missing", "Value required")
            return ("within", "Optional value absent")

        if self.parameter == self.Parameter.VISUAL:
            allowed = [v.strip() for v in self.allowed_values.split(",") if v.strip()]
            if allowed and str(value) not in allowed:
                return ("outside", f"Visual grade '{value}' not in allowed values: {', '.join(allowed)}")
            return ("within", "Within specification")

        try:
            numeric = float(value)
        except (TypeError, ValueError):
            return ("missing", "Non-numeric value")

        if self.min_value is not None and numeric < float(self.min_value):
            return ("outside", f"{value} below minimum {self.min_value} {self.unit}")
        if self.max_value is not None and numeric > float(self.max_value):
            return ("outside", f"{value} above maximum {self.max_value} {self.unit}")
        return ("within", "Within specification")


class Facility(models.Model):
    class FacilityType(models.TextChoices):
        PRODUCTION = "production", "Production"
        PROCESSING = "processing", "Processing"

    id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)
    name = models.CharField(max_length=255)
    country = models.CharField(max_length=100)
    region = models.CharField(max_length=100, blank=True)
    address = models.TextField(blank=True)
    facility_type = models.CharField(max_length=20, choices=FacilityType.choices, default=FacilityType.PRODUCTION)
    is_active = models.BooleanField(default=True)
    created_at = models.DateTimeField(auto_now_add=True)

    class Meta:
        db_table = "facilities"

    def __str__(self):
        return self.name


class OriginZone(models.Model):
    class VerificationStatus(models.TextChoices):
        UNVERIFIED = "unverified", "Unverified"
        VERIFIED = "verified", "Verified"
        REJECTED = "rejected", "Rejected"

    id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)
    facility = models.ForeignKey(Facility, on_delete=models.CASCADE, related_name="origin_zones")
    zone_code = models.CharField(max_length=100, unique=True)
    country = models.CharField(max_length=100)
    region = models.CharField(max_length=100, blank=True)
    geometry = models.JSONField(default=dict, blank=True)
    coordinate_source = models.CharField(max_length=255, blank=True)
    coordinates_collected_by = models.CharField(max_length=255, blank=True)
    coordinates_collected_at = models.DateField(null=True, blank=True)
    evidence_file = models.CharField(max_length=255, blank=True)
    verification_status = models.CharField(
        max_length=20, choices=VerificationStatus.choices, default=VerificationStatus.UNVERIFIED
    )
    verified_by = models.ForeignKey(
        settings.AUTH_USER_MODEL, on_delete=models.SET_NULL, null=True, blank=True, related_name="zones_verified"
    )
    verified_at = models.DateTimeField(null=True, blank=True)
    created_at = models.DateTimeField(auto_now_add=True)

    class Meta:
        db_table = "origin_zones"

    def __str__(self):
        return f"{self.zone_code} ({self.country})"


class CollectorGroup(models.Model):
    id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)
    name = models.CharField(max_length=255)
    contact_reference = models.CharField(max_length=255, blank=True)
    origin_zone = models.ForeignKey(
        OriginZone, on_delete=models.SET_NULL, null=True, blank=True, related_name="collector_groups"
    )
    notes = models.TextField(blank=True)
    created_at = models.DateTimeField(auto_now_add=True)

    class Meta:
        db_table = "collector_groups"

    def __str__(self):
        return self.name


class HarvestIntake(models.Model):
    class Status(models.TextChoices):
        DRAFT = "draft", "Draft"
        RECEIVED = "received", "Received"
        VERIFIED = "verified", "Verified"
        REJECTED = "rejected", "Rejected"

    id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)
    intake_reference = models.CharField(max_length=100, unique=True)
    collector_group = models.ForeignKey(
        CollectorGroup, on_delete=models.SET_NULL, null=True, blank=True, related_name="intakes"
    )
    origin_zone = models.ForeignKey(
        OriginZone, on_delete=models.SET_NULL, null=True, blank=True, related_name="intakes"
    )
    intake_date = models.DateField(null=True, blank=True)
    weight_kg = models.DecimalField(max_digits=10, decimal_places=2, null=True, blank=True)
    grade = models.CharField(max_length=5, blank=True)
    receiving_officer = models.CharField(max_length=255, blank=True)
    status = models.CharField(max_length=20, choices=Status.choices, default=Status.DRAFT)
    evidence_file = models.CharField(max_length=255, blank=True)
    created_at = models.DateTimeField(auto_now_add=True)

    class Meta:
        db_table = "harvest_intakes"

    def __str__(self):
        return self.intake_reference


class IntakeBatchLineage(models.Model):
    id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)
    batch = models.ForeignKey("batches.ProcessingBatch", on_delete=models.CASCADE, related_name="intake_lineage")
    harvest_intake = models.ForeignKey(HarvestIntake, on_delete=models.CASCADE, related_name="batch_lineage")
    weight_allocated_kg = models.DecimalField(max_digits=10, decimal_places=2, null=True, blank=True)
    created_at = models.DateTimeField(auto_now_add=True)

    class Meta:
        db_table = "intake_batch_lineage"
        unique_together = [("batch", "harvest_intake")]

    def __str__(self):
        return f"{self.batch.batch_reference} <- {self.harvest_intake.intake_reference}"


class DueDiligenceCase(models.Model):
    class Status(models.TextChoices):
        INCOMPLETE = "incomplete", "Incomplete"
        COMPLETE_FOR_REVIEW = "complete_for_review", "Complete for Review"
        RISK_IDENTIFIED = "risk_identified", "Risk Identified"
        MITIGATION_REQUIRED = "mitigation_required", "Mitigation Required"
        APPROVED = "approved", "Approved"
        REJECTED = "rejected", "Rejected"

    class RiskLevel(models.TextChoices):
        LOW = "low", "Low"
        STANDARD = "standard", "Standard"
        HIGH = "high", "High"

    id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)
    batch = models.OneToOneField("batches.ProcessingBatch", on_delete=models.CASCADE, related_name="due_diligence_case")
    status = models.CharField(max_length=30, choices=Status.choices, default=Status.INCOMPLETE)
    risk_level = models.CharField(max_length=20, choices=RiskLevel.choices, default=RiskLevel.STANDARD)
    completeness_results = models.JSONField(default=dict, blank=True)
    assessed_by = models.ForeignKey(
        settings.AUTH_USER_MODEL, on_delete=models.SET_NULL, null=True, blank=True, related_name="eudr_cases_assessed"
    )
    assessed_at = models.DateTimeField(null=True, blank=True)
    approved_by = models.ForeignKey(
        settings.AUTH_USER_MODEL, on_delete=models.SET_NULL, null=True, blank=True, related_name="eudr_cases_approved"
    )
    approved_at = models.DateTimeField(null=True, blank=True)
    rejected_reason = models.TextField(blank=True)
    created_at = models.DateTimeField(auto_now_add=True)
    updated_at = models.DateTimeField(auto_now=True)

    class Meta:
        db_table = "due_diligence_cases"

    def __str__(self):
        return f"EUDR case - {self.batch.batch_reference} ({self.status})"


class EUDREvidence(models.Model):
    class EvidenceType(models.TextChoices):
        GEOLOCATION = "geolocation", "Geolocation"
        HARVEST_DOCUMENT = "harvest_document", "Harvest Document"
        SUPPLIER_IDENTITY = "supplier_identity", "Supplier Identity"
        LEGALITY = "legality", "Legality"
        OTHER = "other", "Other"

    id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)
    case = models.ForeignKey(DueDiligenceCase, on_delete=models.CASCADE, related_name="evidence")
    evidence_type = models.CharField(max_length=30, choices=EvidenceType.choices, default=EvidenceType.OTHER)
    file = models.CharField(max_length=255)
    source = models.CharField(max_length=255, blank=True)
    collected_at = models.DateField(null=True, blank=True)
    verified_by = models.ForeignKey(
        settings.AUTH_USER_MODEL, on_delete=models.SET_NULL, null=True, blank=True, related_name="eudr_evidence_verified"
    )
    verified_at = models.DateTimeField(null=True, blank=True)
    notes = models.TextField(blank=True)
    created_at = models.DateTimeField(auto_now_add=True)

    class Meta:
        db_table = "eudr_evidence"

    def __str__(self):
        return f"{self.get_evidence_type_display()} - {self.case.batch.batch_reference}"


class RiskAssessment(models.Model):
    id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)
    case = models.ForeignKey(DueDiligenceCase, on_delete=models.CASCADE, related_name="risk_assessments")
    risk_level = models.CharField(max_length=20, choices=DueDiligenceCase.RiskLevel.choices, default=DueDiligenceCase.RiskLevel.STANDARD)
    basis = models.TextField(blank=True)
    findings = models.TextField(blank=True)
    assessed_by = models.ForeignKey(
        settings.AUTH_USER_MODEL, on_delete=models.SET_NULL, null=True, blank=True, related_name="risk_assessments"
    )
    assessed_at = models.DateTimeField(auto_now_add=True)

    class Meta:
        db_table = "risk_assessments"
        ordering = ["-assessed_at"]

    def __str__(self):
        return f"Risk {self.risk_level} - {self.case.batch.batch_reference}"


class MitigationAction(models.Model):
    class Status(models.TextChoices):
        OPEN = "open", "Open"
        IN_PROGRESS = "in_progress", "In Progress"
        COMPLETED = "completed", "Completed"
        VERIFIED = "verified", "Verified"

    id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)
    case = models.ForeignKey(DueDiligenceCase, on_delete=models.CASCADE, related_name="mitigation_actions")
    action = models.TextField()
    status = models.CharField(max_length=20, choices=Status.choices, default=Status.OPEN)
    owner = models.CharField(max_length=255, blank=True)
    due_date = models.DateField(null=True, blank=True)
    evidence_file = models.CharField(max_length=255, blank=True)
    completed_at = models.DateTimeField(null=True, blank=True)
    created_at = models.DateTimeField(auto_now_add=True)

    class Meta:
        db_table = "mitigation_actions"

    def __str__(self):
        return f"Mitigation - {self.case.batch.batch_reference} ({self.status})"


class DueDiligenceStatementReference(models.Model):
    class ReconciliationStatus(models.TextChoices):
        PENDING = "pending", "Pending"
        RECONCILED = "reconciled", "Reconciled"

    id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)
    case = models.ForeignKey(DueDiligenceCase, on_delete=models.CASCADE, related_name="statement_references")
    dds_reference = models.CharField(max_length=255, blank=True)
    submission_date = models.DateField(null=True, blank=True)
    submitted_by = models.ForeignKey(
        settings.AUTH_USER_MODEL, on_delete=models.SET_NULL, null=True, blank=True, related_name="dds_submissions"
    )
    reconciliation_status = models.CharField(
        max_length=20, choices=ReconciliationStatus.choices, default=ReconciliationStatus.PENDING
    )
    notes = models.TextField(blank=True)
    created_at = models.DateTimeField(auto_now_add=True)

    class Meta:
        db_table = "due_diligence_statement_references"

    def __str__(self):
        return f"DDS {self.dds_reference or '-'} - {self.case.batch.batch_reference}"