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//! Defines the [PdfFormRadioButtonField] struct, exposing functionality related to a single
//! form field of type `PdfFormFieldType::RadioButton`.

use crate::bindgen::{FPDF_ANNOTATION, FPDF_FORMHANDLE};
use crate::bindings::PdfiumLibraryBindings;
use crate::error::PdfiumError;
use crate::form_field_private::internal::PdfFormFieldPrivate;

/// A single `PdfFormField` of type `PdfFormFieldType::RadioButton`. The form field object defines
/// an interactive radio button widget that can be toggled by the user.
///
/// Form fields in Pdfium are wrapped inside page annotations of type `PdfPageAnnotationType::Widget`
/// or `PdfPageAnnotationType::XfaWidget`. User-specified values can be retrieved directly from
/// each form field object by unwrapping the form field from the annotation, or in bulk from the
/// `PdfForm::field_values()` function.
pub struct PdfFormRadioButtonField<'a> {
    form_handle: FPDF_FORMHANDLE,
    annotation_handle: FPDF_ANNOTATION,
    bindings: &'a dyn PdfiumLibraryBindings,
}

impl<'a> PdfFormRadioButtonField<'a> {
    #[inline]
    pub(crate) fn from_pdfium(
        form_handle: FPDF_FORMHANDLE,
        annotation_handle: FPDF_ANNOTATION,
        bindings: &'a dyn PdfiumLibraryBindings,
    ) -> Self {
        PdfFormRadioButtonField {
            form_handle,
            annotation_handle,
            bindings,
        }
    }

    /// Returns the [PdfiumLibraryBindings] used by this [PdfFormRadioButtonField] object.
    #[inline]
    pub fn bindings(&self) -> &'a dyn PdfiumLibraryBindings {
        self.bindings
    }

    /// Returns the index of this [PdfFormRadioButtonField] in its control group.
    ///
    /// Control groups are used to group related interactive fields together. Checkboxes and
    /// radio buttons can be grouped such that only a single button can be selected within
    /// the control group. Each field within the group has a unique group index.
    #[inline]
    pub fn index_in_group(&self) -> u32 {
        self.index_in_group_impl()
    }

    /// Returns the value set for the control group containing this [PdfFormRadioButtonField].
    ///
    /// Control groups are used to group related interactive fields together. Checkboxes and
    /// radio buttons can be grouped such that only a single button can be selected within
    /// the control group. In this case, a single value can be shared by the group, indicating
    /// the value of the currently selected field within the group.
    #[inline]
    pub fn group_value(&self) -> Option<String> {
        self.value_impl()
    }

    /// Returns `true` if this [PdfFormRadioButtonField] object has its radio button selected.
    #[inline]
    pub fn is_checked(&self) -> Result<bool, PdfiumError> {
        // The PDF Reference manual, version 1.7, states that a selected radio button can indicate
        // its selected appearance by setting a custom appearance stream; this appearance stream
        // value will then become the group value. Pdfium's FPDFAnnot_IsChecked()
        // function doesn't check for this; so if FPDFAnnot_IsChecked() comes back with
        // anything other than Ok(true), we also check the appearance stream.

        match self.is_checked_impl() {
            Ok(true) => Ok(true),
            Ok(false) => Ok(self.group_value() == self.appearance_stream_impl()),
            Err(err) => match self.group_value() {
                None => Err(err),
                group_value => Ok(group_value == self.appearance_stream_impl()),
            },
        }
    }
}

impl<'a> PdfFormFieldPrivate<'a> for PdfFormRadioButtonField<'a> {
    #[inline]
    fn form_handle(&self) -> &FPDF_FORMHANDLE {
        &self.form_handle
    }

    #[inline]
    fn annotation_handle(&self) -> &FPDF_ANNOTATION {
        &self.annotation_handle
    }

    #[inline]
    fn bindings(&self) -> &dyn PdfiumLibraryBindings {
        self.bindings
    }
}