from django import forms
from django.utils.translation import gettext as _
from django.utils.translation import ngettext

from misago.admin.forms import YesNoSwitch

__all__ = ["ChangeSettingsForm"]


class ValidateChoicesNum(object):
    def __init__(self, min_choices=0, max_choices=0):
        self.min_choices = min_choices
        self.max_choices = max_choices

    def __call__(self, data):
        data_len = len(data)

        if self.min_choices and self.min_choices > data_len:
            message = ngettext(
                "You have to select at least %(choices)d option.",
                "You have to select at least %(choices)d options.",
                self.min_choices,
            )
            raise forms.ValidationError(message % {"choices": self.min_choices})

        if self.max_choices and self.max_choices < data_len:
            message = ngettext(
                "You cannot select more than %(choices)d option.",
                "You cannot select more than %(choices)d options.",
                self.max_choices,
            )
            raise forms.ValidationError(message % {"choices": self.max_choices})

        return data


def basic_kwargs(setting, extra):
    kwargs = {
        "label": _(setting.name),
        "initial": setting.value,
        "required": extra.get("min_length") or extra.get("min"),
    }

    if setting.description:
        kwargs["help_text"] = _(setting.description)

    if setting.form_field == "yesno":
        # YesNoSwitch is int-base and setting is bool based
        # this means we need to do quick conversion
        kwargs["initial"] = 1 if kwargs["initial"] else 0

    if kwargs["required"]:
        if kwargs.get("help_text"):
            format = {"help_text": kwargs["help_text"]}
            kwargs["help_text"] = _("Required. %(help_text)s") % format
        else:
            kwargs["help_text"] = _("This field is required.")

    return kwargs


def localise_choices(extra):
    return [(v, _(l)) for v, l in extra.get("choices", [])]


def create_checkbox(setting, kwargs, extra):
    kwargs["widget"] = forms.CheckboxSelectMultiple()
    kwargs["choices"] = localise_choices(extra)

    if extra.get("min") or extra.get("max"):
        kwargs["validators"] = [
            ValidateChoicesNum(extra.pop("min", 0), extra.pop("max", 0))
        ]

    if setting.python_type == "int":
        return forms.TypedMultipleChoiceField(coerce="int", **kwargs)
    else:
        return forms.MultipleChoiceField(**kwargs)


def create_choice(setting, kwargs, extra):
    if setting.form_field == "choice":
        kwargs["widget"] = forms.RadioSelect()
    else:
        kwargs["widget"] = forms.Select()

    kwargs["choices"] = localise_choices(extra)

    if setting.python_type == "int":
        return forms.TypedChoiceField(coerce="int", **kwargs)
    else:
        return forms.ChoiceField(**kwargs)


def create_text(setting, kwargs, extra):
    kwargs.update(extra)
    if setting.python_type == "int":
        return forms.IntegerField(**kwargs)
    else:
        return forms.CharField(**kwargs)


def create_textarea(setting, kwargs, extra):
    widget_kwargs = {}
    if extra.get("min_length", 0) == 0:
        kwargs["required"] = False
    if extra.get("rows", 0):
        widget_kwargs["attrs"] = {"rows": extra.pop("rows")}

    kwargs["widget"] = forms.Textarea(**widget_kwargs)
    return forms.CharField(**kwargs)


def create_yesno(setting, kwargs, extra):
    return YesNoSwitch(**kwargs)


FIELD_STYPES = {
    "checkbox": create_checkbox,
    "radio": create_choice,
    "select": create_choice,
    "text": create_text,
    "textarea": create_textarea,
    "yesno": create_yesno,
}


def setting_field(FormType, setting):
    field_factory = FIELD_STYPES[setting.form_field]
    field_extra = setting.field_extra

    form_field = field_factory(setting, basic_kwargs(setting, field_extra), field_extra)

    FormType = type(
        "FormType%s" % setting.pk, (FormType,), {setting.setting: form_field}
    )

    return FormType


def ChangeSettingsForm(data=None, group=None):
    """factory method that builds valid form for settings group"""

    class FormType(forms.Form):
        pass

    fieldsets = []

    fieldset_legend = None
    fieldset_form = FormType
    fieldset_fields = False
    for setting in group.setting_set.order_by("order"):
        if setting.legend and setting.legend != fieldset_legend:
            if fieldset_fields:
                fieldsets.append(
                    {"legend": fieldset_legend, "form": fieldset_form(data)}
                )
            fieldset_legend = setting.legend
            fieldset_form = FormType
            fieldset_fields = False
        fieldset_fields = True
        fieldset_form = setting_field(fieldset_form, setting)

    if fieldset_fields:
        fieldsets.append({"legend": fieldset_legend, "form": fieldset_form(data)})

    return fieldsets