// Take a look at the license at the top of the repository in the LICENSE file.

use std::borrow::{Borrow, BorrowMut, ToOwned};
use std::ffi::CStr;
use std::fmt;
use std::mem;
use std::ops::{Deref, DerefMut};
use std::ptr;
use std::str;

use crate::Fraction;

use glib::translate::*;
use glib::value::{FromValue, SendValue, ToSendValue};
use glib::StaticType;

#[derive(Clone, Debug, Eq, PartialEq, thiserror::Error)]
pub enum GetError {
    #[error("GetError: Structure field with name {name} not found")]
    FieldNotFound { name: &'static str },
    #[error("GetError: Structure field with name {name} not retrieved")]
    ValueGetError {
        name: &'static str,
        #[source]
        type_mismatch_error: glib::value::ValueTypeMismatchOrNoneError,
    },
}

impl GetError {
    fn new_field_not_found(name: &'static str) -> Self {
        skip_assert_initialized!();
        GetError::FieldNotFound { name }
    }

    fn from_value_get_error<E: GlibValueError>(name: &'static str, err: E) -> Self {
        skip_assert_initialized!();
        E::from_value_error(name, err)
    }
}

pub trait GlibValueError: 'static {
    fn from_value_error(name: &'static str, err: Self) -> GetError;
}

impl GlibValueError for glib::value::ValueTypeMismatchError {
    fn from_value_error(name: &'static str, err: Self) -> GetError {
        skip_assert_initialized!();
        GetError::ValueGetError {
            name,
            type_mismatch_error: glib::value::ValueTypeMismatchOrNoneError::from(err),
        }
    }
}

impl GlibValueError for glib::value::ValueTypeMismatchOrNoneError {
    fn from_value_error(name: &'static str, err: Self) -> GetError {
        skip_assert_initialized!();
        GetError::ValueGetError {
            name,
            type_mismatch_error: err,
        }
    }
}

/// A [`Structure`][crate::Structure] is a collection of key/value pairs. The keys are expressed as
/// GQuarks and the values can be of any GType.
///
/// In addition to the key/value pairs, a [`Structure`][crate::Structure] also has a name. The name
/// starts with a letter and can be filled by letters, numbers and any of
/// "/-_.:".
///
/// [`Structure`][crate::Structure] is used by various GStreamer subsystems to store information in
/// a flexible and extensible way. A [`Structure`][crate::Structure] does not have a refcount
/// because it usually is part of a higher level object such as [`Caps`][crate::Caps],
/// [`Message`][crate::Message], [`Event`][crate::Event], [`Query`][crate::Query]. It provides a means to enforce mutability
/// using the refcount of the parent with the `gst_structure_set_parent_refcount()`
/// method.
///
/// A [`Structure`][crate::Structure] can be created with [`new_empty()`][Self::new_empty()] or
/// [`new()`][Self::new()], which both take a name and an optional set of key/value
/// pairs along with the types of the values.
///
/// Field values can be changed with `gst_structure_set_value()` or
/// `gst_structure_set()`.
///
/// Field values can be retrieved with `gst_structure_get_value()` or the more
/// convenient gst_structure_get_*() functions.
///
/// Fields can be removed with `gst_structure_remove_field()` or
/// `gst_structure_remove_fields()`.
///
/// Strings in structures must be ASCII or UTF-8 encoded. Other encodings are not
/// allowed. Strings may be [`None`] however.
///
/// ## The serialization format
///
/// GstStructure serialization format serialize the GstStructure name,
/// keys/GType/values in a comma separated list with the structure name as first
/// field without value followed by separated key/value pairs in the form
/// `key=value`, for example:
///
/// ```text
/// a-structure, key=value
/// ````
///
/// The values type will be inferred if not explicitly specified with the
/// `(GTypeName)value` syntax, for example the following struct will have one
/// field called 'is-string' which has the string 'true' as a value:
///
/// ```text
/// a-struct, field-is-string=(string)true, field-is-boolean=true
/// ```
///
/// *Note*: without specifying `(string), `field-is-string` type would have been
/// inferred as boolean.
///
/// *Note*: we specified `(string)` as a type even if `gchararray` is the actual
/// GType name as for convenience some well known types have been aliased or
/// abbreviated.
///
/// To avoid specifying the type, you can give some hints to the "type system".
/// For example to specify a value as a double, you should add a decimal (ie. `1`
/// is an `int` while `1.0` is a `double`).
///
/// *Note*: when a structure is serialized with `gst_structure_to_string`, all
/// values are explicitly typed.
///
/// Some types have special delimiters:
///
/// - [GstValueArray](GST_TYPE_ARRAY) are inside curly brackets (`{` and `}`).
///  For example `a-structure, array={1, 2, 3}`
/// - Ranges are inside brackets (`[` and `]`). For example `a-structure,
///  range=[1, 6, 2]` 1 being the min value, 6 the maximum and 2 the step. To
///  specify a `GST_TYPE_INT64_RANGE` you need to explicitly specify it like:
///  `a-structure, a-int64-range=(gint64) [1, 5]`
/// - [GstValueList](GST_TYPE_LIST) are inside "less and greater than" (`<` and
///  `>`). For example `a-structure, list=<1, 2, 3>
///
/// Structures are delimited either by a null character `\0` or a semicolon `;`
/// the latter allowing to store multiple structures in the same string (see
/// [`Caps`][crate::Caps]).
///
/// Quotes are used as "default" delimiters and can be used around any types that
/// don't use other delimiters (for example `a-struct, i=(int)"1"`). They are use
/// to allow adding spaces or special characters (such as delimiters,
/// semicolumns, etc..) inside strings and you can use backslashes `\` to escape
/// characters inside them, for example:
///
/// ```text
/// a-struct, special="\"{[(;)]}\" can be used inside quotes"
/// ```
///
/// They also allow for nested structure, such as:
///
/// ```text
/// a-struct, nested=(GstStructure)"nested-struct, nested=true"
/// ```
///
/// Since 1.20, nested structures and caps can be specified using brackets (`[`
/// and `]`), for example:
///
/// ```text
/// a-struct, nested=[nested-struct, nested=true]
/// ```
///
/// > *note*: [`to_str()`][Self::to_str()] won't use that syntax for backward
/// > compatibility reason, [`serialize()`][Self::serialize()] has been added for
/// > that purpose.
#[doc(alias = "GstStructure")]
pub struct Structure(ptr::NonNull<ffi::GstStructure>);
unsafe impl Send for Structure {}
unsafe impl Sync for Structure {}

impl Structure {
    pub fn builder(name: &str) -> Builder {
        assert_initialized_main_thread!();
        Builder::new(name)
    }

    /// Creates a new, empty [`Structure`][crate::Structure] with the given `name`.
    ///
    /// See `gst_structure_set_name()` for constraints on the `name` parameter.
    ///
    /// Free-function: gst_structure_free
    /// ## `name`
    /// name of new structure
    ///
    /// # Returns
    ///
    /// a new, empty [`Structure`][crate::Structure]
    #[doc(alias = "gst_structure_new_empty")]
    pub fn new_empty(name: &str) -> Structure {
        assert_initialized_main_thread!();
        unsafe {
            let ptr = ffi::gst_structure_new_empty(name.to_glib_none().0);
            assert!(!ptr.is_null());
            Structure(ptr::NonNull::new_unchecked(ptr))
        }
    }

    /// Creates a new [`Structure`][crate::Structure] with the given name. Parses the
    /// list of variable arguments and sets fields to the values listed.
    /// Variable arguments should be passed as field name, field type,
    /// and value. Last variable argument should be [`None`].
    ///
    /// Free-function: gst_structure_free
    /// ## `name`
    /// name of new structure
    /// ## `firstfield`
    /// name of first field to set
    ///
    /// # Returns
    ///
    /// a new [`Structure`][crate::Structure]
    pub fn new(name: &str, values: &[(&str, &(dyn ToSendValue + Sync))]) -> Structure {
        assert_initialized_main_thread!();
        let mut structure = Structure::new_empty(name);

        for &(f, v) in values {
            structure.set_value(f, v.to_send_value());
        }

        structure
    }

    pub unsafe fn into_ptr(self) -> *mut ffi::GstStructure {
        let s = mem::ManuallyDrop::new(self);
        s.0.as_ptr()
    }

    #[allow(clippy::should_implement_trait)]
    pub fn from_iter<'a, 'b, I>(name: &str, iter: I) -> Structure
    where
        I: IntoIterator<Item = (&'a str, &'b SendValue)>,
    {
        assert_initialized_main_thread!();
        let mut structure = Structure::new_empty(name);

        iter.into_iter().for_each(|(f, v)| unsafe {
            let mut value = v.clone().into_raw();
            ffi::gst_structure_take_value(structure.0.as_mut(), f.to_glib_none().0, &mut value);
        });

        structure
    }
}

impl Deref for Structure {
    type Target = StructureRef;

    fn deref(&self) -> &StructureRef {
        unsafe { &*(self.0.as_ptr() as *const StructureRef) }
    }
}

impl DerefMut for Structure {
    fn deref_mut(&mut self) -> &mut StructureRef {
        unsafe { &mut *(self.0.as_ptr() as *mut StructureRef) }
    }
}

impl AsRef<StructureRef> for Structure {
    fn as_ref(&self) -> &StructureRef {
        self.deref()
    }
}

impl AsMut<StructureRef> for Structure {
    fn as_mut(&mut self) -> &mut StructureRef {
        self.deref_mut()
    }
}

impl Clone for Structure {
    fn clone(&self) -> Self {
        unsafe {
            let ptr = ffi::gst_structure_copy(self.0.as_ref());
            assert!(!ptr.is_null());
            Structure(ptr::NonNull::new_unchecked(ptr))
        }
    }
}

impl Drop for Structure {
    fn drop(&mut self) {
        unsafe { ffi::gst_structure_free(self.0.as_mut()) }
    }
}

impl fmt::Debug for Structure {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        f.debug_tuple("Structure").field(&self.to_string()).finish()
    }
}

impl fmt::Display for Structure {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        // Need to make sure to not call ToString::to_string() here, which
        // we have because of the Display impl. We need StructureRef::to_string()
        f.write_str(&StructureRef::to_string(self.as_ref()))
    }
}

impl PartialEq for Structure {
    fn eq(&self, other: &Structure) -> bool {
        self.as_ref().eq(other)
    }
}

impl PartialEq<StructureRef> for Structure {
    fn eq(&self, other: &StructureRef) -> bool {
        self.as_ref().eq(other)
    }
}

impl Eq for Structure {}

impl str::FromStr for Structure {
    type Err = glib::BoolError;

    #[doc(alias = "gst_structure_from_string")]
    fn from_str(s: &str) -> Result<Self, Self::Err> {
        assert_initialized_main_thread!();
        unsafe {
            let structure = ffi::gst_structure_from_string(s.to_glib_none().0, ptr::null_mut());
            if structure.is_null() {
                Err(glib::bool_error!("Failed to parse structure from string"))
            } else {
                Ok(Self(ptr::NonNull::new_unchecked(structure)))
            }
        }
    }
}

impl Borrow<StructureRef> for Structure {
    fn borrow(&self) -> &StructureRef {
        self.as_ref()
    }
}

impl BorrowMut<StructureRef> for Structure {
    fn borrow_mut(&mut self) -> &mut StructureRef {
        self.as_mut()
    }
}

impl ToOwned for StructureRef {
    type Owned = Structure;

    fn to_owned(&self) -> Structure {
        unsafe {
            let ptr = ffi::gst_structure_copy(&self.0);
            assert!(!ptr.is_null());
            Structure(ptr::NonNull::new_unchecked(ptr))
        }
    }
}

impl glib::types::StaticType for Structure {
    fn static_type() -> glib::types::Type {
        unsafe { from_glib(ffi::gst_structure_get_type()) }
    }
}

impl<'a> ToGlibPtr<'a, *const ffi::GstStructure> for Structure {
    type Storage = &'a Self;

    fn to_glib_none(&'a self) -> Stash<'a, *const ffi::GstStructure, Self> {
        unsafe { Stash(self.0.as_ref(), self) }
    }

    fn to_glib_full(&self) -> *const ffi::GstStructure {
        unsafe { ffi::gst_structure_copy(self.0.as_ref()) }
    }
}

impl<'a> ToGlibPtr<'a, *mut ffi::GstStructure> for Structure {
    type Storage = &'a Self;

    fn to_glib_none(&'a self) -> Stash<'a, *mut ffi::GstStructure, Self> {
        unsafe {
            Stash(
                self.0.as_ref() as *const ffi::GstStructure as *mut ffi::GstStructure,
                self,
            )
        }
    }

    fn to_glib_full(&self) -> *mut ffi::GstStructure {
        unsafe { ffi::gst_structure_copy(self.0.as_ref()) }
    }
}

impl<'a> ToGlibPtrMut<'a, *mut ffi::GstStructure> for Structure {
    type Storage = &'a mut Self;

    fn to_glib_none_mut(&'a mut self) -> StashMut<*mut ffi::GstStructure, Self> {
        unsafe { StashMut(self.0.as_mut(), self) }
    }
}

impl FromGlibPtrNone<*const ffi::GstStructure> for Structure {
    unsafe fn from_glib_none(ptr: *const ffi::GstStructure) -> Self {
        assert!(!ptr.is_null());
        let ptr = ffi::gst_structure_copy(ptr);
        assert!(!ptr.is_null());
        Structure(ptr::NonNull::new_unchecked(ptr))
    }
}

impl FromGlibPtrNone<*mut ffi::GstStructure> for Structure {
    unsafe fn from_glib_none(ptr: *mut ffi::GstStructure) -> Self {
        assert!(!ptr.is_null());
        let ptr = ffi::gst_structure_copy(ptr);
        assert!(!ptr.is_null());
        Structure(ptr::NonNull::new_unchecked(ptr))
    }
}

impl FromGlibPtrFull<*const ffi::GstStructure> for Structure {
    unsafe fn from_glib_full(ptr: *const ffi::GstStructure) -> Self {
        assert!(!ptr.is_null());
        Structure(ptr::NonNull::new_unchecked(ptr as *mut ffi::GstStructure))
    }
}

impl FromGlibPtrFull<*mut ffi::GstStructure> for Structure {
    unsafe fn from_glib_full(ptr: *mut ffi::GstStructure) -> Self {
        assert!(!ptr.is_null());
        Structure(ptr::NonNull::new_unchecked(ptr))
    }
}

impl glib::value::ValueType for Structure {
    type Type = Self;
}

unsafe impl<'a> glib::value::FromValue<'a> for Structure {
    type Checker = glib::value::GenericValueTypeOrNoneChecker<Self>;

    unsafe fn from_value(value: &'a glib::Value) -> Self {
        skip_assert_initialized!();
        from_glib_none(
            glib::gobject_ffi::g_value_get_boxed(value.to_glib_none().0) as *mut ffi::GstStructure
        )
    }
}

impl glib::value::ToValue for Structure {
    fn to_value(&self) -> glib::Value {
        let mut value = glib::Value::for_value_type::<Self>();
        unsafe {
            glib::gobject_ffi::g_value_set_boxed(
                value.to_glib_none_mut().0,
                glib::translate::ToGlibPtr::<*const ffi::GstStructure>::to_glib_none(self).0
                    as *mut _,
            )
        }
        value
    }

    fn value_type(&self) -> glib::Type {
        Self::static_type()
    }
}

impl glib::value::ToValueOptional for Structure {
    fn to_value_optional(s: Option<&Self>) -> glib::Value {
        skip_assert_initialized!();
        let mut value = glib::Value::for_value_type::<Self>();
        unsafe {
            glib::gobject_ffi::g_value_set_boxed(
                value.to_glib_none_mut().0,
                glib::translate::ToGlibPtr::<*const ffi::GstStructure>::to_glib_none(&s).0
                    as *mut _,
            )
        }
        value
    }
}

impl GlibPtrDefault for Structure {
    type GlibType = *mut ffi::GstStructure;
}

#[repr(transparent)]
#[doc(alias = "GstStructure")]
pub struct StructureRef(ffi::GstStructure);

unsafe impl Send for StructureRef {}
unsafe impl Sync for StructureRef {}

impl StructureRef {
    pub unsafe fn from_glib_borrow<'a>(ptr: *const ffi::GstStructure) -> &'a StructureRef {
        assert!(!ptr.is_null());

        &*(ptr as *mut StructureRef)
    }

    pub unsafe fn from_glib_borrow_mut<'a>(ptr: *mut ffi::GstStructure) -> &'a mut StructureRef {
        assert!(!ptr.is_null());

        &mut *(ptr as *mut StructureRef)
    }

    pub unsafe fn as_ptr(&self) -> *const ffi::GstStructure {
        self as *const Self as *const ffi::GstStructure
    }

    pub unsafe fn as_mut_ptr(&self) -> *mut ffi::GstStructure {
        self as *const Self as *mut ffi::GstStructure
    }

    pub fn get<'a, T: FromValue<'a>>(&'a self, name: &str) -> Result<T, GetError>
    where
        <<T as FromValue<'a>>::Checker as glib::value::ValueTypeChecker>::Error: GlibValueError,
    {
        let name = glib::Quark::from_string(name);
        self.get_by_quark(name)
    }

    pub fn get_optional<'a, T: FromValue<'a>>(&'a self, name: &str) -> Result<Option<T>, GetError>
    where
        <<T as FromValue<'a>>::Checker as glib::value::ValueTypeChecker>::Error: GlibValueError,
    {
        let name = glib::Quark::from_string(name);
        self.get_optional_by_quark(name)
    }

    #[doc(alias = "get_value")]
    pub fn value(&self, name: &str) -> Result<&SendValue, GetError> {
        let name = glib::Quark::from_string(name);
        self.value_by_quark(name)
    }

    pub fn get_by_quark<'a, T: FromValue<'a>>(&'a self, name: glib::Quark) -> Result<T, GetError>
    where
        <<T as FromValue<'a>>::Checker as glib::value::ValueTypeChecker>::Error: GlibValueError,
    {
        self.value_by_quark(name)?
            .get()
            .map_err(|err| GetError::from_value_get_error(name.to_string(), err))
    }

    pub fn get_optional_by_quark<'a, T: FromValue<'a>>(
        &'a self,
        name: glib::Quark,
    ) -> Result<Option<T>, GetError>
    where
        <<T as FromValue<'a>>::Checker as glib::value::ValueTypeChecker>::Error: GlibValueError,
    {
        self.value_by_quark(name)
            .ok()
            .map(|v| v.get())
            .transpose()
            .map_err(|err| GetError::from_value_get_error(name.to_string(), err))
    }

    pub fn value_by_quark(&self, name: glib::Quark) -> Result<&SendValue, GetError> {
        unsafe {
            let value = ffi::gst_structure_id_get_value(&self.0, name.into_glib());

            if value.is_null() {
                return Err(GetError::new_field_not_found(name.to_string()));
            }

            Ok(&*(value as *const SendValue))
        }
    }

    pub fn set<T: ToSendValue + Sync>(&mut self, name: &str, value: T) {
        let value = value.to_send_value();
        self.set_value(name, value);
    }

    pub fn set_value(&mut self, name: &str, value: SendValue) {
        unsafe {
            let mut value = value.into_raw();
            ffi::gst_structure_take_value(&mut self.0, name.to_glib_none().0, &mut value);
        }
    }

    pub fn set_by_quark<T: ToSendValue + Sync>(&mut self, name: glib::Quark, value: T) {
        let value = value.to_send_value();
        self.set_value_by_quark(name, value);
    }

    pub fn set_value_by_quark(&mut self, name: glib::Quark, value: SendValue) {
        unsafe {
            let mut value = value.into_raw();
            ffi::gst_structure_id_take_value(&mut self.0, name.into_glib(), &mut value);
        }
    }

    #[doc(alias = "get_name")]
    #[doc(alias = "gst_structure_get_name")]
    pub fn name<'a>(&self) -> &'a str {
        unsafe {
            CStr::from_ptr(ffi::gst_structure_get_name(&self.0))
                .to_str()
                .unwrap()
        }
    }

    pub fn name_quark(&self) -> glib::Quark {
        unsafe { from_glib(ffi::gst_structure_get_name_id(&self.0)) }
    }

    #[doc(alias = "gst_structure_set_name")]
    pub fn set_name(&mut self, name: &str) {
        unsafe { ffi::gst_structure_set_name(&mut self.0, name.to_glib_none().0) }
    }

    #[doc(alias = "gst_structure_has_field")]
    pub fn has_field(&self, field: &str) -> bool {
        unsafe {
            from_glib(ffi::gst_structure_has_field(
                &self.0,
                field.to_glib_none().0,
            ))
        }
    }

    pub fn has_field_with_type(&self, field: &str, type_: glib::Type) -> bool {
        unsafe {
            from_glib(ffi::gst_structure_has_field_typed(
                &self.0,
                field.to_glib_none().0,
                type_.into_glib(),
            ))
        }
    }

    pub fn has_field_by_quark(&self, field: glib::Quark) -> bool {
        unsafe { from_glib(ffi::gst_structure_id_has_field(&self.0, field.into_glib())) }
    }

    pub fn has_field_with_type_by_quark(&self, field: glib::Quark, type_: glib::Type) -> bool {
        unsafe {
            from_glib(ffi::gst_structure_id_has_field_typed(
                &self.0,
                field.into_glib(),
                type_.into_glib(),
            ))
        }
    }

    #[doc(alias = "gst_structure_remove_field")]
    pub fn remove_field(&mut self, field: &str) {
        unsafe {
            ffi::gst_structure_remove_field(&mut self.0, field.to_glib_none().0);
        }
    }

    pub fn remove_fields(&mut self, fields: &[&str]) {
        for f in fields {
            self.remove_field(f)
        }
    }

    #[doc(alias = "gst_structure_remove_all_fields")]
    pub fn remove_all_fields(&mut self) {
        unsafe {
            ffi::gst_structure_remove_all_fields(&mut self.0);
        }
    }

    pub fn fields(&self) -> FieldIterator {
        FieldIterator::new(self)
    }

    pub fn iter(&self) -> Iter {
        Iter::new(self)
    }

    #[doc(alias = "get_nth_field_name")]
    #[doc(alias = "gst_structure_nth_field_name")]
    pub fn nth_field_name<'a>(&self, idx: u32) -> Option<&'a str> {
        unsafe {
            let field_name = ffi::gst_structure_nth_field_name(&self.0, idx);
            if field_name.is_null() {
                return None;
            }

            Some(CStr::from_ptr(field_name).to_str().unwrap())
        }
    }

    #[doc(alias = "gst_structure_n_fields")]
    pub fn n_fields(&self) -> u32 {
        unsafe { ffi::gst_structure_n_fields(&self.0) as u32 }
    }

    #[doc(alias = "gst_structure_can_intersect")]
    pub fn can_intersect(&self, other: &StructureRef) -> bool {
        unsafe { from_glib(ffi::gst_structure_can_intersect(&self.0, &other.0)) }
    }

    #[doc(alias = "gst_structure_intersect")]
    pub fn intersect(&self, other: &StructureRef) -> Option<Structure> {
        unsafe { from_glib_full(ffi::gst_structure_intersect(&self.0, &other.0)) }
    }

    #[doc(alias = "gst_structure_is_subset")]
    pub fn is_subset(&self, superset: &StructureRef) -> bool {
        unsafe { from_glib(ffi::gst_structure_is_subset(&self.0, &superset.0)) }
    }

    #[doc(alias = "gst_structure_fixate")]
    pub fn fixate(&mut self) {
        unsafe { ffi::gst_structure_fixate(&mut self.0) }
    }

    #[doc(alias = "gst_structure_fixate_field")]
    pub fn fixate_field(&mut self, name: &str) -> bool {
        unsafe {
            from_glib(ffi::gst_structure_fixate_field(
                &mut self.0,
                name.to_glib_none().0,
            ))
        }
    }

    #[doc(alias = "gst_structure_fixate_field_boolean")]
    pub fn fixate_field_bool(&mut self, name: &str, target: bool) -> bool {
        unsafe {
            from_glib(ffi::gst_structure_fixate_field_boolean(
                &mut self.0,
                name.to_glib_none().0,
                target.into_glib(),
            ))
        }
    }

    #[doc(alias = "gst_structure_fixate_field_string")]
    pub fn fixate_field_str(&mut self, name: &str, target: &str) -> bool {
        unsafe {
            from_glib(ffi::gst_structure_fixate_field_string(
                &mut self.0,
                name.to_glib_none().0,
                target.to_glib_none().0,
            ))
        }
    }

    #[doc(alias = "gst_structure_fixate_field_nearest_double")]
    pub fn fixate_field_nearest_double(&mut self, name: &str, target: f64) -> bool {
        unsafe {
            from_glib(ffi::gst_structure_fixate_field_nearest_double(
                &mut self.0,
                name.to_glib_none().0,
                target,
            ))
        }
    }

    #[doc(alias = "gst_structure_fixate_field_nearest_fraction")]
    pub fn fixate_field_nearest_fraction<T: Into<Fraction>>(
        &mut self,
        name: &str,
        target: T,
    ) -> bool {
        skip_assert_initialized!();

        let target = target.into();
        unsafe {
            from_glib(ffi::gst_structure_fixate_field_nearest_fraction(
                &mut self.0,
                name.to_glib_none().0,
                *target.numer(),
                *target.denom(),
            ))
        }
    }

    #[doc(alias = "gst_structure_fixate_field_nearest_int")]
    pub fn fixate_field_nearest_int(&mut self, name: &str, target: i32) -> bool {
        unsafe {
            from_glib(ffi::gst_structure_fixate_field_nearest_int(
                &mut self.0,
                name.to_glib_none().0,
                target,
            ))
        }
    }
}

impl fmt::Display for StructureRef {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        let s = unsafe { glib::GString::from_glib_full(ffi::gst_structure_to_string(&self.0)) };
        f.write_str(&s)
    }
}

impl fmt::Debug for StructureRef {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        f.write_str(&self.to_string())
    }
}

impl PartialEq for StructureRef {
    #[doc(alias = "gst_structure_is_equal")]
    fn eq(&self, other: &StructureRef) -> bool {
        unsafe { from_glib(ffi::gst_structure_is_equal(&self.0, &other.0)) }
    }
}

impl Eq for StructureRef {}

impl glib::types::StaticType for StructureRef {
    fn static_type() -> glib::types::Type {
        unsafe { from_glib(ffi::gst_structure_get_type()) }
    }
}

unsafe impl<'a> glib::value::FromValue<'a> for &'a StructureRef {
    type Checker = glib::value::GenericValueTypeOrNoneChecker<Self>;

    unsafe fn from_value(value: &'a glib::Value) -> Self {
        skip_assert_initialized!();
        &*(glib::gobject_ffi::g_value_get_boxed(value.to_glib_none().0) as *const StructureRef)
    }
}

impl glib::value::ToValue for StructureRef {
    fn to_value(&self) -> glib::Value {
        let mut value = glib::Value::for_value_type::<Structure>();
        unsafe {
            glib::gobject_ffi::g_value_set_boxed(
                value.to_glib_none_mut().0,
                self.as_ptr() as *mut _,
            )
        }
        value
    }

    fn value_type(&self) -> glib::Type {
        Self::static_type()
    }
}

impl glib::value::ToValueOptional for StructureRef {
    fn to_value_optional(s: Option<&Self>) -> glib::Value {
        skip_assert_initialized!();
        let mut value = glib::Value::for_value_type::<Structure>();
        unsafe {
            glib::gobject_ffi::g_value_set_boxed(
                value.to_glib_none_mut().0,
                s.map(|s| s.as_ptr()).unwrap_or(ptr::null()) as *mut _,
            )
        }
        value
    }
}

#[derive(Debug)]
pub struct FieldIterator<'a> {
    structure: &'a StructureRef,
    idx: u32,
    n_fields: u32,
}

impl<'a> FieldIterator<'a> {
    fn new(structure: &'a StructureRef) -> FieldIterator<'a> {
        skip_assert_initialized!();
        let n_fields = structure.n_fields();

        FieldIterator {
            structure,
            idx: 0,
            n_fields,
        }
    }
}

impl<'a> Iterator for FieldIterator<'a> {
    type Item = &'static str;

    fn next(&mut self) -> Option<Self::Item> {
        if self.idx >= self.n_fields {
            return None;
        }

        if let Some(field_name) = self.structure.nth_field_name(self.idx) {
            self.idx += 1;
            Some(field_name)
        } else {
            None
        }
    }

    fn size_hint(&self) -> (usize, Option<usize>) {
        if self.idx == self.n_fields {
            return (0, Some(0));
        }

        let remaining = (self.n_fields - self.idx) as usize;

        (remaining, Some(remaining))
    }
}

impl<'a> DoubleEndedIterator for FieldIterator<'a> {
    fn next_back(&mut self) -> Option<Self::Item> {
        if self.idx == self.n_fields {
            return None;
        }

        self.n_fields -= 1;
        self.structure.nth_field_name(self.n_fields)
    }
}

impl<'a> ExactSizeIterator for FieldIterator<'a> {}

#[derive(Debug)]
pub struct Iter<'a> {
    iter: FieldIterator<'a>,
}

impl<'a> Iter<'a> {
    fn new(structure: &'a StructureRef) -> Iter<'a> {
        skip_assert_initialized!();
        Iter {
            iter: FieldIterator::new(structure),
        }
    }
}

impl<'a> Iterator for Iter<'a> {
    type Item = (&'static str, &'a SendValue);

    fn next(&mut self) -> Option<Self::Item> {
        if let Some(f) = self.iter.next() {
            let v = self.iter.structure.value(f);
            Some((f, v.unwrap()))
        } else {
            None
        }
    }

    fn size_hint(&self) -> (usize, Option<usize>) {
        self.iter.size_hint()
    }
}

impl<'a> DoubleEndedIterator for Iter<'a> {
    fn next_back(&mut self) -> Option<Self::Item> {
        if let Some(f) = self.iter.next_back() {
            let v = self.iter.structure.value(f);
            Some((f, v.unwrap()))
        } else {
            None
        }
    }
}

impl<'a> ExactSizeIterator for Iter<'a> {}

#[derive(Debug)]
pub struct Builder {
    s: Structure,
}

impl Builder {
    fn new(name: &str) -> Self {
        skip_assert_initialized!();
        Builder {
            s: Structure::new_empty(name),
        }
    }

    pub fn field<V: ToSendValue + Sync>(mut self, name: &str, value: V) -> Self {
        self.s.set(name, value);
        self
    }

    pub fn build(self) -> Structure {
        self.s
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use std::str::FromStr;

    #[test]
    fn new_set_get() {
        use glib::{value, Type};

        crate::init().unwrap();

        let mut s = Structure::new_empty("test");
        assert_eq!(s.name(), "test");

        s.set("f1", &"abc");
        s.set("f2", &String::from("bcd"));
        s.set("f3", &123i32);

        assert_eq!(s.get::<&str>("f1"), Ok("abc"));
        assert_eq!(s.get::<Option<&str>>("f2"), Ok(Some("bcd")));
        assert_eq!(s.get::<i32>("f3"), Ok(123i32));
        assert_eq!(s.get_optional::<&str>("f1"), Ok(Some("abc")));
        assert_eq!(s.get_optional::<&str>("f4"), Ok(None));
        assert_eq!(s.get_optional::<i32>("f3"), Ok(Some(123i32)));
        assert_eq!(s.get_optional::<i32>("f4"), Ok(None));

        assert_eq!(
            s.get::<i32>("f2"),
            Err(GetError::from_value_get_error(
                "f2",
                value::ValueTypeMismatchError::new(Type::STRING, Type::I32),
            ))
        );
        assert_eq!(
            s.get::<bool>("f3"),
            Err(GetError::from_value_get_error(
                "f3",
                value::ValueTypeMismatchError::new(Type::I32, Type::BOOL),
            ))
        );
        assert_eq!(
            s.get::<&str>("f4"),
            Err(GetError::new_field_not_found("f4"))
        );
        assert_eq!(s.get::<i32>("f4"), Err(GetError::new_field_not_found("f4")));

        assert_eq!(s.fields().collect::<Vec<_>>(), vec!["f1", "f2", "f3"]);

        let v = s.iter().map(|(f, v)| (f, v.clone())).collect::<Vec<_>>();
        assert_eq!(v.len(), 3);
        assert_eq!(v[0].0, "f1");
        assert_eq!(v[0].1.get::<&str>(), Ok("abc"));
        assert_eq!(v[1].0, "f2");
        assert_eq!(v[1].1.get::<&str>(), Ok("bcd"));
        assert_eq!(v[2].0, "f3");
        assert_eq!(v[2].1.get::<i32>(), Ok(123i32));

        let s2 = Structure::new("test", &[("f1", &"abc"), ("f2", &"bcd"), ("f3", &123i32)]);
        assert_eq!(s, s2);
    }

    #[test]
    fn test_builder() {
        crate::init().unwrap();

        let s = Structure::builder("test")
            .field("f1", &"abc")
            .field("f2", &String::from("bcd"))
            .field("f3", &123i32)
            .build();

        assert_eq!(s.name(), "test");
        assert_eq!(s.get::<&str>("f1"), Ok("abc"));
        assert_eq!(s.get::<&str>("f2"), Ok("bcd"));
        assert_eq!(s.get::<i32>("f3"), Ok(123i32));
    }

    #[test]
    fn test_string_conversion() {
        crate::init().unwrap();

        let a = "Test, f1=(string)abc, f2=(uint)123;";

        let s = Structure::from_str(&a).unwrap();
        assert_eq!(s.get::<&str>("f1"), Ok("abc"));
        assert_eq!(s.get::<u32>("f2"), Ok(123));

        assert_eq!(a, s.to_string());
    }

    #[test]
    fn test_from_value_optional() {
        use glib::ToValue;

        crate::init().unwrap();

        let a = None::<&Structure>.to_value();
        assert!(a.get::<Option<Structure>>().unwrap().is_none());
        let b = Structure::from_str(&"foo").unwrap().to_value();
        assert!(b.get::<Option<Structure>>().unwrap().is_some());
    }

    #[test]
    fn test_new_from_iter() {
        crate::init().unwrap();

        let s = Structure::builder("test")
            .field("f1", &"abc")
            .field("f2", &String::from("bcd"))
            .field("f3", &123i32)
            .build();

        let s2 = Structure::from_iter(s.name(), s.iter().filter(|(f, _)| *f == "f1"));

        assert_eq!(s2.name(), "test");
        assert_eq!(s2.get::<&str>("f1"), Ok("abc"));
        assert!(s2.get::<&str>("f2").is_err());
        assert!(s2.get::<&str>("f3").is_err());
    }
}