use std::collections::HashMap;

use xml::attribute::OwnedAttribute;

use crate::{
    parse_properties,
    util::{get_attrs, map_wrapper, parse_tag, XmlEventResult},
    Color, Error, MapTilesetGid, Object, ObjectData, Properties, Result,
};

/// Raw data referring to a map object layer or tile collision data.
#[derive(Debug, PartialEq, Clone)]
pub struct ObjectLayerData {
    objects: Vec<ObjectData>,
    /// The color used in the editor to display objects in this layer.
    pub colour: Option<Color>,
}

impl ObjectLayerData {
    /// If it is known that there are no objects with tile images in it (i.e. collision data)
    /// then we can pass in [`None`] as the tilesets
    pub(crate) fn new(
        parser: &mut impl Iterator<Item = XmlEventResult>,
        attrs: Vec<OwnedAttribute>,
        tilesets: Option<&[MapTilesetGid]>,
    ) -> Result<(ObjectLayerData, Properties)> {
        let c = get_attrs!(
            attrs,
            optionals: [
                ("color", colour, |v:String| v.parse().ok()),
            ]
        );
        let mut objects = Vec::new();
        let mut properties = HashMap::new();
        parse_tag!(parser, "objectgroup", {
            "object" => |attrs| {
                objects.push(ObjectData::new(parser, attrs, tilesets)?);
                Ok(())
            },
            "properties" => |_| {
                properties = parse_properties(parser)?;
                Ok(())
            },
        });
        Ok((ObjectLayerData { objects, colour: c }, properties))
    }

    /// Returns the data belonging to the objects contained within the layer, in the order they were
    /// declared in the TMX file.
    #[inline]
    pub fn object_data(&self) -> &[ObjectData] {
        self.objects.as_ref()
    }
}

map_wrapper!(
    #[doc = "Also called an \"object group\". Used for storing [`Object`]s in a map."]
    ObjectLayer => ObjectLayerData);

impl<'map> ObjectLayer<'map> {
    /// Obtains the object corresponding to the index given.
    pub fn get_object(&self, idx: usize) -> Option<Object<'map>> {
        self.data
            .objects
            .get(idx)
            .map(|data| Object::new(self.map, data))
    }

    /// Returns an iterator over the objects present in this layer, in the order they were declared
    /// in in the TMX file.
    /// 
    /// ## Example
    /// ```
    /// # use tiled::Loader;
    /// use tiled::Object;
    ///
    /// # fn main() {
    /// # let map = Loader::new()
    /// #     .load_tmx_map("assets/tiled_group_layers.tmx")
    /// #     .unwrap();
    /// # 
    /// let spawnpoints: Vec<Object> = map
    ///     .layers()
    ///     .filter_map(|layer| match layer.layer_type() {
    ///         tiled::LayerType::ObjectLayer(layer) => Some(layer),
    ///         _ => None,
    ///     })
    ///     .flat_map(|layer| layer.objects())
    ///     .filter(|object| object.obj_type == "spawn")
    ///     .collect();
    ///
    /// dbg!(spawnpoints);
    /// # }
    /// ```
    #[inline]
    pub fn objects(&self) -> impl ExactSizeIterator<Item = Object<'map>> + 'map {
        let map: &'map crate::Map = self.map;
        self.data
            .objects
            .iter()
            .map(move |object| Object::new(map, object))
    }
}