use std::fmt;
use std::fmt::Debug;
use std::fmt::Formatter;

use crate::reflect::map::empty::DynamicEmptyMap;
use crate::reflect::reflect_eq::ReflectEq;
use crate::reflect::reflect_eq::ReflectEqMode;
use crate::reflect::ReflectValueBox;
use crate::reflect::ReflectValueRef;
use crate::reflect::RuntimeType;

mod empty;
mod generated;

/// Implemented for `HashMap` with appropriate keys and values
pub(crate) trait ReflectMap: Debug + Send + Sync + 'static {
    fn reflect_iter(&self) -> ReflectMapIter;

    fn len(&self) -> usize;

    fn is_empty(&self) -> bool;

    fn get<'a>(&'a self, key: ReflectValueRef) -> Option<ReflectValueRef<'a>>;

    fn insert(&mut self, key: ReflectValueBox, value: ReflectValueBox);

    fn clear(&mut self);

    fn key_type(&self) -> RuntimeType;

    fn value_type(&self) -> RuntimeType;
}

pub(crate) trait ReflectMapIterTrait<'a> {
    fn next(&mut self) -> Option<(ReflectValueRef<'a>, ReflectValueRef<'a>)>;
    fn key_type(&self) -> RuntimeType;
    fn value_type(&self) -> RuntimeType;
}

pub struct ReflectMapIter<'a> {
    imp: Box<dyn ReflectMapIterTrait<'a> + 'a>,
}

impl<'a> ReflectMapIter<'a> {
    pub(crate) fn new<I: ReflectMapIterTrait<'a> + 'a>(imp: I) -> ReflectMapIter<'a> {
        ReflectMapIter { imp: Box::new(imp) }
    }
}

impl<'a> Iterator for ReflectMapIter<'a> {
    type Item = (ReflectValueRef<'a>, ReflectValueRef<'a>);

    fn next(&mut self) -> Option<(ReflectValueRef<'a>, ReflectValueRef<'a>)> {
        self.imp.next()
    }
}

impl<'a> IntoIterator for &'a dyn ReflectMap {
    type Item = (ReflectValueRef<'a>, ReflectValueRef<'a>);
    type IntoIter = ReflectMapIter<'a>;

    fn into_iter(self) -> Self::IntoIter {
        self.reflect_iter()
    }
}

#[derive(Clone)]
enum ReflectMapRefImpl<'a> {
    Generated(&'a dyn ReflectMap),
    DynamicEmpty(DynamicEmptyMap),
}

impl<'a> fmt::Debug for ReflectMapRefImpl<'a> {
    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
        match self {
            ReflectMapRefImpl::Generated(m) => fmt::Debug::fmt(m, f),
            ReflectMapRefImpl::DynamicEmpty(m) => fmt::Debug::fmt(m, f),
        }
    }
}

/// Dynamic reference to `map` field
#[derive(Clone)]
pub struct ReflectMapRef<'a> {
    imp: ReflectMapRefImpl<'a>,
}

/// Dynamic mutable reference to `map` field
pub struct ReflectMapMut<'a> {
    map: &'a mut dyn ReflectMap,
}

impl<'a> fmt::Debug for ReflectMapRef<'a> {
    fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
        fmt::Debug::fmt(&self.imp, f)
    }
}

impl<'a> fmt::Debug for ReflectMapMut<'a> {
    fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
        fmt::Debug::fmt(&self.map, f)
    }
}

impl<'a> ReflectMapRef<'a> {
    pub(crate) fn new(map: &'a dyn ReflectMap) -> ReflectMapRef<'a> {
        ReflectMapRef {
            imp: ReflectMapRefImpl::Generated(map),
        }
    }

    pub(crate) fn new_empty(key: RuntimeType, value: RuntimeType) -> ReflectMapRef<'a> {
        ReflectMapRef {
            imp: ReflectMapRefImpl::DynamicEmpty(DynamicEmptyMap::new(key, value)),
        }
    }

    /// Size of the map
    pub fn len(&self) -> usize {
        match &self.imp {
            ReflectMapRefImpl::Generated(map) => map.len(),
            ReflectMapRefImpl::DynamicEmpty(map) => map.len(),
        }
    }

    /// Is map empty?
    pub fn is_empty(&self) -> bool {
        match &self.imp {
            ReflectMapRefImpl::Generated(map) => map.is_empty(),
            ReflectMapRefImpl::DynamicEmpty(map) => map.is_empty(),
        }
    }

    /// Find a value by given key.
    pub fn get(&self, key: ReflectValueRef) -> Option<ReflectValueRef> {
        match &self.imp {
            ReflectMapRefImpl::Generated(map) => map.get(key),
            ReflectMapRefImpl::DynamicEmpty(map) => map.get(key),
        }
    }

    /// Map key type
    pub fn key_type(&self) -> RuntimeType {
        match &self.imp {
            ReflectMapRefImpl::Generated(map) => map.key_type(),
            ReflectMapRefImpl::DynamicEmpty(map) => map.key_type(),
        }
    }

    /// Map value type
    pub fn value_type(&self) -> RuntimeType {
        match &self.imp {
            ReflectMapRefImpl::Generated(map) => map.value_type(),
            ReflectMapRefImpl::DynamicEmpty(map) => map.value_type(),
        }
    }
}

impl<'a> PartialEq for ReflectMapRef<'a> {
    fn eq(&self, other: &Self) -> bool {
        self.reflect_eq(other, &ReflectEqMode::default())
    }
}

impl<'a> ReflectEq for ReflectMapRef<'a> {
    fn reflect_eq(&self, that: &Self, mode: &ReflectEqMode) -> bool {
        let len = self.len();

        if len != that.len() {
            return false;
        }

        if self.key_type() != that.key_type() {
            return false;
        }
        if self.value_type() != that.value_type() {
            return false;
        }

        for (k, va) in self {
            let vb = match that.get(k) {
                Some(v) => v,
                None => return false,
            };

            if !va.reflect_eq(&vb, mode) {
                return false;
            }
        }

        true
    }
}

impl<'a> ReflectMapMut<'a> {
    pub(crate) fn new(map: &'a mut dyn ReflectMap) -> ReflectMapMut<'a> {
        ReflectMapMut { map }
    }

    fn as_ref(&'a self) -> ReflectMapRef<'a> {
        ReflectMapRef::new(self.map)
    }

    /// Map key type
    pub fn key_type(&self) -> RuntimeType {
        self.map.key_type()
    }

    /// Map value type
    pub fn value_type(&self) -> RuntimeType {
        self.map.value_type()
    }

    /// Number of map entries
    pub fn len(&self) -> usize {
        self.as_ref().len()
    }

    /// Is this map empty?
    pub fn is_empty(&self) -> bool {
        self.as_ref().is_empty()
    }

    /// Find a value for given key
    pub fn get(&self, key: ReflectValueRef) -> Option<ReflectValueRef> {
        self.map.get(key)
    }

    /// Insert a value into the map.
    ///
    /// # Panics
    ///
    /// If given key has an incompatible key type.
    pub fn insert(&mut self, key: ReflectValueBox, value: ReflectValueBox) {
        self.map.insert(key, value)
    }

    /// Clear
    pub fn clear(&mut self) {
        self.map.clear();
    }
}

/// Iterator over map
pub struct ReflectMapRefIter<'a> {
    iter: ReflectMapIter<'a>,
}

impl<'a> ReflectMapRefIter<'a> {
    fn _key_type(&self) -> RuntimeType {
        self.iter.imp.key_type()
    }

    fn _value_type(&self) -> RuntimeType {
        self.iter.imp.value_type()
    }
}

impl<'a> Iterator for ReflectMapRefIter<'a> {
    type Item = (ReflectValueRef<'a>, ReflectValueRef<'a>);

    fn next(&mut self) -> Option<(ReflectValueRef<'a>, ReflectValueRef<'a>)> {
        self.iter.next()
    }
}

impl<'a, 'b: 'a> IntoIterator for &'b ReflectMapRef<'a> {
    type Item = (ReflectValueRef<'a>, ReflectValueRef<'a>);
    type IntoIter = ReflectMapRefIter<'a>;

    fn into_iter(self) -> ReflectMapRefIter<'a> {
        match &self.imp {
            ReflectMapRefImpl::Generated(map) => ReflectMapRefIter {
                iter: map.reflect_iter(),
            },
            ReflectMapRefImpl::DynamicEmpty(map) => ReflectMapRefIter {
                iter: map.reflect_iter(),
            },
        }
    }
}