"""Forms for the ops portal.

The intake form is deliberately **stricter than the model**. ``HarvestIntake``
allows almost everything to be blank, because records also arrive through the
API, and the platform copes by flagging the gaps later: the EUDR completeness
check has an "intake data" test whose whole job is to catch a missing date or
weight. A portal form that let the same blanks through would simply move that
problem to a screen where a person could have prevented it.

So every field the checks read is required here — reference, collector group,
origin zone, date, weight and grade — while the fields that are genuinely
optional at intake (receiving officer, the supporting file's name) stay optional.
"""
from django import forms

from apps.compliance.models import CollectorGroup, HarvestIntake, OriginZone

# The visual grades the product specification defines.
GRADE_CHOICES = [("A", "Grade A"), ("B", "Grade B"), ("C", "Grade C")]


class ZoneChoiceField(forms.ModelChoiceField):
    """Zone dropdown that says which zones are not verified yet.

    Geolocation in the EUDR case passes only for a verified zone, so an operator
    choosing one should be able to see that before it fails a check. It is a
    label, not a block: an intake can legitimately be recorded against a zone
    that is still awaiting verification.
    """

    def label_from_instance(self, zone):
        where = zone.region or zone.country or ""
        mark = ""
        if zone.verification_status != OriginZone.VerificationStatus.VERIFIED:
            mark = f" — {zone.get_verification_status_display().lower()}"
        return f"{zone.zone_code}{f' ({where})' if where else ''}{mark}"


class CollectorGroupChoiceField(forms.ModelChoiceField):
    """Group dropdown that names the zone each group draws from."""

    def label_from_instance(self, group):
        if not group.origin_zone:
            return f"{group.name} — no origin zone set"
        return f"{group.name} — {group.origin_zone.zone_code}"


class HarvestIntakeForm(forms.ModelForm):
    collector_group = CollectorGroupChoiceField(
        queryset=CollectorGroup.objects.select_related("origin_zone").order_by("name"),
        label="Collector group",
        help_text="The registered group that delivered the material.",
        empty_label="Select the collector group",
    )
    origin_zone = ZoneChoiceField(
        queryset=OriginZone.objects.order_by("zone_code"),
        label="Origin zone",
        help_text="Where it was collected. Filled in from the group, and can be changed.",
        empty_label="Select the origin zone",
    )
    grade = forms.ChoiceField(
        choices=GRADE_CHOICES,
        label="Grade",
        help_text="Visual grade recorded at intake, as defined by the product specification.",
        widget=forms.Select(attrs={"class": "form-select"}),
    )

    class Meta:
        model = HarvestIntake
        fields = [
            "intake_reference",
            "collector_group",
            "origin_zone",
            "intake_date",
            "weight_kg",
            "grade",
            "receiving_officer",
            "status",
            "evidence_file",
        ]
        labels = {
            "intake_reference": "Intake reference",
            "intake_date": "Intake date",
            "weight_kg": "Weight (kg)",
            "receiving_officer": "Receiving officer",
            "evidence_file": "Supporting file name",
        }
        help_texts = {
            "intake_reference": "Must be unique. Suggested from the last intake recorded, and can be overwritten to match the weighbridge ticket.",
            "intake_date": "The day the material was received.",
            "weight_kg": "Weight received, in kilograms.",
            "receiving_officer": "Who received and weighed it. Defaults to you.",
            "status": "Received is the normal state for a new intake; Verified is set once the record has been checked.",
            "evidence_file": "The name of the supporting record, typically the weighbridge ticket. Files are not uploaded by the platform yet, so this is the name it is filed under.",
        }
        widgets = {
            "intake_reference": forms.TextInput(
                attrs={"class": "form-control", "autocomplete": "off"}
            ),
            "collector_group": forms.Select(attrs={"class": "form-select"}),
            "origin_zone": forms.Select(attrs={"class": "form-select"}),
            "intake_date": forms.DateInput(
                attrs={"class": "form-control", "type": "date"}
            ),
            "weight_kg": forms.NumberInput(
                attrs={"class": "form-control", "step": "0.01", "min": "0.01"}
            ),
            "receiving_officer": forms.TextInput(attrs={"class": "form-control"}),
            "status": forms.Select(attrs={"class": "form-select"}),
            "evidence_file": forms.TextInput(attrs={"class": "form-control"}),
        }

    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        # The model tolerates blanks; the portal form does not. See the module
        # docstring: these are the fields the completeness checks read.
        for name in ("collector_group", "origin_zone", "intake_date", "weight_kg"):
            self.fields[name].required = True
        self.fields["status"].required = True

    def clean_intake_reference(self):
        reference = (self.cleaned_data["intake_reference"] or "").strip()
        if not reference:
            raise forms.ValidationError("An intake reference is required.")
        clashes = HarvestIntake.objects.filter(intake_reference__iexact=reference)
        if self.instance.pk:
            clashes = clashes.exclude(pk=self.instance.pk)
        if clashes.exists():
            raise forms.ValidationError(
                f"Intake {reference} already exists. References must be unique."
            )
        return reference

    def clean_weight_kg(self):
        weight = self.cleaned_data["weight_kg"]
        if weight is None:
            raise forms.ValidationError("A weight is required.")
        if weight <= 0:
            raise forms.ValidationError("Weight must be greater than zero.")
        return weight

    def clean(self):
        cleaned = super().clean()
        group = cleaned.get("collector_group")
        zone = cleaned.get("origin_zone")
        if group and zone and group.origin_zone_id and group.origin_zone_id != zone.pk:
            # Not an error — a group can deliver from more than one area — but it
            # is worth surfacing, because the two records will disagree.
            self.add_error(
                "origin_zone",
                forms.ValidationError(
                    f"{group.name} is registered to {group.origin_zone.zone_code}, "
                    f"not {zone.zone_code}. Save it this way only if that is intended."
                ),
            )
        return cleaned