import json

from django import forms
from django.contrib.admin.utils import (
    display_for_field,
    flatten_fieldsets,
    help_text_for_field,
    label_for_field,
    lookup_field,
    quote,
)
from django.core.exceptions import ObjectDoesNotExist
from django.db.models.fields.related import (
    ForeignObjectRel,
    ManyToManyRel,
    OneToOneField,
)
from django.forms.utils import flatatt
from django.template.defaultfilters import capfirst, linebreaksbr
from django.urls import NoReverseMatch, reverse
from django.utils.functional import cached_property
from django.utils.html import conditional_escape, format_html
from django.utils.safestring import mark_safe
from django.utils.translation import gettext
from django.utils.translation import gettext_lazy as _

ACTION_CHECKBOX_NAME = "_selected_action"


class ActionForm(forms.Form):
    action = forms.ChoiceField(label=_("Action:"))
    select_across = forms.BooleanField(
        label="",
        required=False,
        initial=0,
        widget=forms.HiddenInput({"class": "select-across"}),
    )


class AdminForm:
    def __init__(
        self,
        form,
        fieldsets,
        prepopulated_fields,
        readonly_fields=None,
        model_admin=None,
    ):
        self.form, self.fieldsets = form, fieldsets
        self.prepopulated_fields = [
            {"field": form[field_name], "dependencies": [form[f] for f in dependencies]}
            for field_name, dependencies in prepopulated_fields.items()
        ]
        self.model_admin = model_admin
        if readonly_fields is None:
            readonly_fields = ()
        self.readonly_fields = readonly_fields

    def __repr__(self):
        return (
            f"<{self.__class__.__qualname__}: "
            f"form={self.form.__class__.__qualname__} "
            f"fieldsets={self.fieldsets!r}>"
        )

    def __iter__(self):
        for name, options in self.fieldsets:
            yield Fieldset(
                self.form,
                name,
                readonly_fields=self.readonly_fields,
                model_admin=self.model_admin,
                **options,
            )

    @property
    def errors(self):
        return self.form.errors

    @property
    def non_field_errors(self):
        return self.form.non_field_errors

    @property
    def fields(self):
        return self.form.fields

    @property
    def is_bound(self):
        return self.form.is_bound

    @property
    def media(self):
        media = self.form.media
        for fs in self:
            media += fs.media
        return media


class Fieldset:
    def __init__(
        self,
        form,
        name=None,
        readonly_fields=(),
        fields=(),
        classes=(),
        description=None,
        model_admin=None,
    ):
        self.form = form
        self.name, self.fields = name, fields
        self.classes = " ".join(classes)
        self.description = description
        self.model_admin = model_admin
        self.readonly_fields = readonly_fields

    @property
    def media(self):
        return forms.Media()

    @cached_property
    def is_collapsible(self):
        if any([field in self.fields for field in self.form.errors]):
            return False
        return "collapse" in self.classes

    def __iter__(self):
        for field in self.fields:
            yield Fieldline(
                self.form, field, self.readonly_fields, model_admin=self.model_admin
            )


class Fieldline:
    def __init__(self, form, field, readonly_fields=None, model_admin=None):
        self.form = form  # A django.forms.Form instance
        if not hasattr(field, "__iter__") or isinstance(field, str):
            self.fields = [field]
        else:
            self.fields = field
        self.has_visible_field = not all(
            field in self.form.fields and self.form.fields[field].widget.is_hidden
            for field in self.fields
        )
        self.model_admin = model_admin
        if readonly_fields is None:
            readonly_fields = ()
        self.readonly_fields = readonly_fields

    def __iter__(self):
        for i, field in enumerate(self.fields):
            if field in self.readonly_fields:
                yield AdminReadonlyField(
                    self.form, field, is_first=(i == 0), model_admin=self.model_admin
                )
            else:
                yield AdminField(self.form, field, is_first=(i == 0))

    def errors(self):
        return mark_safe(
            "\n".join(
                self.form[f].errors.as_ul()
                for f in self.fields
                if f not in self.readonly_fields
            ).strip("\n")
        )


class AdminField:
    def __init__(self, form, field, is_first):
        self.field = form[field]  # A django.forms.BoundField instance
        self.is_first = is_first  # Whether this field is first on the line
        self.is_checkbox = isinstance(self.field.field.widget, forms.CheckboxInput)
        self.is_readonly = False

    def label_tag(self):
        classes = []
        contents = conditional_escape(self.field.label)
        if self.is_checkbox:
            classes.append("vCheckboxLabel")

        if self.field.field.required:
            classes.append("required")
        if not self.is_first:
            classes.append("inline")
        attrs = {"class": " ".join(classes)} if classes else {}
        # checkboxes should not have a label suffix as the checkbox appears
        # to the left of the label.
        return self.field.label_tag(
            contents=mark_safe(contents),
            attrs=attrs,
            label_suffix="" if self.is_checkbox else None,
        )

    def errors(self):
        return mark_safe(self.field.errors.as_ul())


class AdminReadonlyField:
    def __init__(self, form, field, is_first, model_admin=None):
        # Make self.field look a little bit like a field. This means that
        # {{ field.name }} must be a useful class name to identify the field.
        # For convenience, store other field-related data here too.
        if callable(field):
            class_name = field.__name__ if field.__name__ != "<lambda>" else ""
        else:
            class_name = field

        if form._meta.labels and class_name in form._meta.labels:
            label = form._meta.labels[class_name]
        else:
            label = label_for_field(field, form._meta.model, model_admin, form=form)

        if form._meta.help_texts and class_name in form._meta.help_texts:
            help_text = form._meta.help_texts[class_name]
        else:
            help_text = help_text_for_field(class_name, form._meta.model)

        if field in form.fields:
            is_hidden = form.fields[field].widget.is_hidden
        else:
            is_hidden = False

        self.field = {
            "name": class_name,
            "label": label,
            "help_text": help_text,
            "field": field,
            "is_hidden": is_hidden,
        }
        self.form = form
        self.model_admin = model_admin
        self.is_first = is_first
        self.is_checkbox = False
        self.is_readonly = True
        self.empty_value_display = model_admin.get_empty_value_display()

    def label_tag(self):
        attrs = {}
        if not self.is_first:
            attrs["class"] = "inline"
        label = self.field["label"]
        return format_html(
            "<label{}>{}{}</label>",
            flatatt(attrs),
            capfirst(label),
            self.form.label_suffix,
        )

    def get_admin_url(self, remote_field, remote_obj):
        url_name = "admin:%s_%s_change" % (
            remote_field.model._meta.app_label,
            remote_field.model._meta.model_name,
        )
        try:
            url = reverse(
                url_name,
                args=[quote(remote_obj.pk)],
                current_app=self.model_admin.admin_site.name,
            )
            return format_html('<a href="{}">{}</a>', url, remote_obj)
        except NoReverseMatch:
            return str(remote_obj)

    def contents(self):
        from django.contrib.admin.templatetags.admin_list import _boolean_icon

        field, obj, model_admin = (
            self.field["field"],
            self.form.instance,
            self.model_admin,
        )
        try:
            f, attr, value = lookup_field(field, obj, model_admin)
        except (AttributeError, ValueError, ObjectDoesNotExist):
            result_repr = self.empty_value_display
        else:
            if field in self.form.fields:
                widget = self.form[field].field.widget
                # This isn't elegant but suffices for contrib.auth's
                # ReadOnlyPasswordHashWidget.
                if getattr(widget, "read_only", False):
                    return widget.render(field, value)
            if f is None:
                if getattr(attr, "boolean", False):
                    result_repr = _boolean_icon(value)
                else:
                    if hasattr(value, "__html__"):
                        result_repr = value
                    else:
                        result_repr = linebreaksbr(value)
            else:
                if isinstance(f.remote_field, ManyToManyRel) and value is not None:
                    result_repr = ", ".join(map(str, value.all()))
                elif (
                    isinstance(f.remote_field, (ForeignObjectRel, OneToOneField))
                    and value is not None
                ):
                    result_repr = self.get_admin_url(f.remote_field, value)
                else:
                    result_repr = display_for_field(value, f, self.empty_value_display)
                result_repr = linebreaksbr(result_repr)
        return conditional_escape(result_repr)


class InlineAdminFormSet:
    """
    A wrapper around an inline formset for use in the admin system.
    """

    def __init__(
        self,
        inline,
        formset,
        fieldsets,
        prepopulated_fields=None,
        readonly_fields=None,
        model_admin=None,
        has_add_permission=True,
        has_change_permission=True,
        has_delete_permission=True,
        has_view_permission=True,
    ):
        self.opts = inline
        self.formset = formset
        self.fieldsets = fieldsets
        self.model_admin = model_admin
        if readonly_fields is None:
            readonly_fields = ()
        self.readonly_fields = readonly_fields
        if prepopulated_fields is None:
            prepopulated_fields = {}
        self.prepopulated_fields = prepopulated_fields
        self.classes = " ".join(inline.classes) if inline.classes else ""
        self.has_add_permission = has_add_permission
        self.has_change_permission = has_change_permission
        self.has_delete_permission = has_delete_permission
        self.has_view_permission = has_view_permission

    def __iter__(self):
        if self.has_change_permission:
            readonly_fields_for_editing = self.readonly_fields
        else:
            readonly_fields_for_editing = self.readonly_fields + flatten_fieldsets(
                self.fieldsets
            )

        for form, original in zip(
            self.formset.initial_forms, self.formset.get_queryset()
        ):
            view_on_site_url = self.opts.get_view_on_site_url(original)
            yield InlineAdminForm(
                self.formset,
                form,
                self.fieldsets,
                self.prepopulated_fields,
                original,
                readonly_fields_for_editing,
                model_admin=self.opts,
                view_on_site_url=view_on_site_url,
            )
        for form in self.formset.extra_forms:
            yield InlineAdminForm(
                self.formset,
                form,
                self.fieldsets,
                self.prepopulated_fields,
                None,
                self.readonly_fields,
                model_admin=self.opts,
            )
        if self.has_add_permission:
            yield InlineAdminForm(
                self.formset,
                self.formset.empty_form,
                self.fieldsets,
                self.prepopulated_fields,
                None,
                self.readonly_fields,
                model_admin=self.opts,
            )

    def fields(self):
        fk = getattr(self.formset, "fk", None)
        empty_form = self.formset.empty_form
        meta_labels = empty_form._meta.labels or {}
        meta_help_texts = empty_form._meta.help_texts or {}
        for i, field_name in enumerate(flatten_fieldsets(self.fieldsets)):
            if fk and fk.name == field_name:
                continue
            if not self.has_change_permission or field_name in self.readonly_fields:
                form_field = empty_form.fields.get(field_name)
                widget_is_hidden = False
                if form_field is not None:
                    widget_is_hidden = form_field.widget.is_hidden
                yield {
                    "name": field_name,
                    "label": meta_labels.get(field_name)
                    or label_for_field(
                        field_name,
                        self.opts.model,
                        self.opts,
                        form=empty_form,
                    ),
                    "widget": {"is_hidden": widget_is_hidden},
                    "required": False,
                    "help_text": meta_help_texts.get(field_name)
                    or help_text_for_field(field_name, self.opts.model),
                }
            else:
                form_field = empty_form.fields[field_name]
                label = form_field.label
                if label is None:
                    label = label_for_field(
                        field_name, self.opts.model, self.opts, form=empty_form
                    )
                yield {
                    "name": field_name,
                    "label": label,
                    "widget": form_field.widget,
                    "required": form_field.required,
                    "help_text": form_field.help_text,
                }

    def inline_formset_data(self):
        verbose_name = self.opts.verbose_name
        return json.dumps(
            {
                "name": "#%s" % self.formset.prefix,
                "options": {
                    "prefix": self.formset.prefix,
                    "addText": gettext("Add another %(verbose_name)s")
                    % {
                        "verbose_name": capfirst(verbose_name),
                    },
                    "deleteText": gettext("Remove"),
                },
            }
        )

    @property
    def forms(self):
        return self.formset.forms

    @cached_property
    def is_collapsible(self):
        if any(self.formset.errors):
            return False
        return "collapse" in self.classes

    def non_form_errors(self):
        return self.formset.non_form_errors()

    @property
    def is_bound(self):
        return self.formset.is_bound

    @property
    def total_form_count(self):
        return self.formset.total_form_count

    @property
    def media(self):
        media = self.opts.media + self.formset.media
        for fs in self:
            media += fs.media
        return media


class InlineAdminForm(AdminForm):
    """
    A wrapper around an inline form for use in the admin system.
    """

    def __init__(
        self,
        formset,
        form,
        fieldsets,
        prepopulated_fields,
        original,
        readonly_fields=None,
        model_admin=None,
        view_on_site_url=None,
    ):
        self.formset = formset
        self.model_admin = model_admin
        self.original = original
        self.show_url = original and view_on_site_url is not None
        self.absolute_url = view_on_site_url
        super().__init__(
            form, fieldsets, prepopulated_fields, readonly_fields, model_admin
        )

    def __iter__(self):
        for name, options in self.fieldsets:
            yield InlineFieldset(
                self.formset,
                self.form,
                name,
                self.readonly_fields,
                model_admin=self.model_admin,
                **options,
            )

    def needs_explicit_pk_field(self):
        return (
            # Auto fields are editable, so check for auto or non-editable pk.
            self.form._meta.model._meta.auto_field
            or not self.form._meta.model._meta.pk.editable
            # The pk can be editable, but excluded from the inline.
            or (
                self.form._meta.exclude
                and self.form._meta.model._meta.pk.name in self.form._meta.exclude
            )
            or
            # Also search any parents for an auto field. (The pk info is
            # propagated to child models so that does not need to be checked
            # in parents.)
            any(
                parent._meta.auto_field or not parent._meta.model._meta.pk.editable
                for parent in self.form._meta.model._meta.all_parents
            )
        )

    def pk_field(self):
        return AdminField(self.form, self.formset._pk_field.name, False)

    def fk_field(self):
        fk = getattr(self.formset, "fk", None)
        if fk:
            return AdminField(self.form, fk.name, False)
        else:
            return ""

    def deletion_field(self):
        from django.forms.formsets import DELETION_FIELD_NAME

        return AdminField(self.form, DELETION_FIELD_NAME, False)


class InlineFieldset(Fieldset):
    def __init__(self, formset, *args, **kwargs):
        self.formset = formset
        super().__init__(*args, **kwargs)

    def __iter__(self):
        fk = getattr(self.formset, "fk", None)
        for field in self.fields:
            if not fk or fk.name != field:
                yield Fieldline(
                    self.form, field, self.readonly_fields, model_admin=self.model_admin
                )


class AdminErrorList(forms.utils.ErrorList):
    """Store errors for the form/formsets in an add/change view."""

    def __init__(self, form, inline_formsets):
        super().__init__()

        if form.is_bound:
            self.extend(form.errors.values())
            for inline_formset in inline_formsets:
                self.extend(inline_formset.non_form_errors())
                for errors_in_inline_form in inline_formset.errors:
                    self.extend(errors_in_inline_form.values())
