use proc_macro2::{Ident, Literal, TokenStream, TokenTree};
use quote::quote;

use crate::config::{global_attrs, SELF_CLOSING};
use crate::error::ParseError;
use crate::ident;
use crate::lexer::{Lexer, Token};
use crate::map::StringyMap;
use crate::parser;

// State

pub struct Declare {
    pub name: Ident,
    pub attrs: StringyMap<Ident, TokenStream>,
    pub req_children: Vec<Ident>,
    pub opt_children: Option<TokenStream>,
    pub traits: Vec<TokenStream>,
}

impl Declare {
    pub fn new(name: Ident) -> Self {
        Declare {
            attrs: global_attrs(name.span()),
            req_children: Vec::new(),
            opt_children: None,
            traits: Vec::new(),
            name,
        }
    }

    fn elem_name(&self) -> TokenTree {
        Ident::new(&self.name.to_string(), self.name.span()).into()
    }

    fn attr_type_name(&self) -> TokenTree {
        Ident::new(&format!("Attrs_{}", self.name), self.name.span()).into()
    }

    fn attrs(&self) -> impl Iterator<Item = (TokenTree, TokenStream, TokenTree)> + '_ {
        self.attrs.iter().map(|(key, value)| {
            let attr_name: TokenTree = ident::new_raw(&key.to_string(), key.span()).into();
            let attr_type = value.clone();
            let attr_str = Literal::string(&key.to_string()).into();
            (attr_name, attr_type, attr_str)
        })
    }

    fn req_children(&self) -> impl Iterator<Item = (TokenTree, TokenTree, TokenTree)> + '_ {
        self.req_children.iter().map(|child| {
            let child_name: TokenTree =
                Ident::new(&format!("child_{}", child), child.span()).into();
            let child_type: TokenTree = Ident::new(&child.to_string(), child.span()).into();
            let child_str = Literal::string(&child.to_string()).into();
            (child_name, child_type, child_str)
        })
    }

    pub fn into_token_stream(self) -> TokenStream {
        let mut stream = TokenStream::new();
        stream.extend(self.attr_struct());
        stream.extend(self.struct_());
        stream.extend(self.impl_());
        stream.extend(self.impl_node());
        stream.extend(self.impl_element());
        stream.extend(self.impl_marker_traits());
        stream.extend(self.impl_display());
        stream.extend(self.impl_into_iter());
        stream
    }

    fn attr_struct(&self) -> TokenStream {
        let mut body = TokenStream::new();
        for (attr_name, attr_type, _) in self.attrs() {
            body.extend(quote!( pub #attr_name: Option<#attr_type>, ));
        }

        let attr_type_name = self.attr_type_name();
        quote!(
            pub struct #attr_type_name {
                #body
            }
        )
    }

    fn struct_(&self) -> TokenStream {
        let elem_name = self.elem_name();
        let attr_type_name = self.attr_type_name();

        let mut body = TokenStream::new();

        for (child_name, child_type, _) in self.req_children() {
            body.extend(quote!( pub #child_name: Box<#child_type<T>>, ));
        }

        if let Some(child_constraint) = &self.opt_children {
            let child_constraint = child_constraint.clone();
            body.extend(quote!(pub children: Vec<Box<#child_constraint<T>>>,));
        }

        quote!(
            pub struct #elem_name<T> where T: crate::OutputType + Send {
                pub attrs: #attr_type_name,
                pub data_attributes: Vec<(&'static str, String)>,
                pub aria_attributes: Vec<(&'static str, String)>,
                pub events: T::Events,
                #body
            }
        )
    }

    fn impl_(&self) -> TokenStream {
        let elem_name = self.elem_name();
        let attr_type_name = self.attr_type_name();

        let mut args = TokenStream::new();
        for (child_name, child_type, _) in self.req_children() {
            args.extend(quote!( #child_name: Box<#child_type<T>>, ));
        }

        let mut attrs = TokenStream::new();
        for (attr_name, _, _) in self.attrs() {
            attrs.extend(quote!( #attr_name: None, ));
        }

        let mut body = TokenStream::new();
        body.extend(quote!(
            attrs: #attr_type_name { #attrs },
        ));
        body.extend(quote!(data_attributes: Vec::new(),));
        body.extend(quote!(aria_attributes: Vec::new(),));

        for (child_name, _, _) in self.req_children() {
            body.extend(quote!( #child_name, ));
        }
        if self.opt_children.is_some() {
            body.extend(quote!(children: Vec::new()));
        }

        quote!(
            impl<T> #elem_name<T> where T: crate::OutputType + Send {
                pub fn new(#args) -> Self {
                    #elem_name {
                        events: T::Events::default(),
                        #body
                    }
                }
            }
        )
    }

    fn impl_vnode(&self) -> TokenStream {
        let elem_name = TokenTree::Literal(Literal::string(self.name.to_string().as_str()));
        let mut req_children = TokenStream::new();
        for (child_name, _, _) in self.req_children() {
            req_children.extend(quote!(
                children.push(self.#child_name.vnode());
            ));
        }
        let mut opt_children = TokenStream::new();
        if self.opt_children.is_some() {
            opt_children.extend(quote!(for child in &mut self.children {
                children.push(child.vnode());
            }));
        }

        let mut push_attrs = TokenStream::new();
        for (attr_name, _, attr_str) in self.attrs() {
            push_attrs.extend(quote!(
                if let Some(ref value) = self.attrs.#attr_name {
                    attributes.push((#attr_str, value.to_string()));
                }
            ));
        }

        quote!(
            let mut attributes = Vec::new();
            #push_attrs
            attributes.extend(self.data_attributes.clone());
            attributes.extend(self.aria_attributes.clone());

            let mut children = Vec::new();
            #req_children
            #opt_children

            crate::dom::VNode::Element(crate::dom::VElement {
                name: #elem_name,
                attributes,
                events: &mut self.events,
                children
            })
        )
    }

    fn impl_node(&self) -> TokenStream {
        let elem_name = self.elem_name();
        let vnode = self.impl_vnode();
        quote!(
            impl<T> crate::dom::Node<T> for #elem_name<T> where T: crate::OutputType + Send {
                fn vnode(&'_ mut self) -> crate::dom::VNode<'_, T> {
                    #vnode
                }
            }
        )
    }

    fn impl_element(&self) -> TokenStream {
        let name: TokenTree = Literal::string(&self.name.to_string()).into();
        let elem_name = self.elem_name();

        let attrs: TokenStream = self.attrs().map(|(_, _, name)| quote!( #name, )).collect();
        let reqs: TokenStream = self
            .req_children()
            .map(|(_, _, name)| quote!( #name, ))
            .collect();

        let mut push_attrs = TokenStream::new();
        for (attr_name, _, attr_str) in self.attrs() {
            push_attrs.extend(quote!(
                if let Some(ref value) = self.attrs.#attr_name {
                    out.push((#attr_str, value.to_string()));
                }
            ));
        }

        quote!(
            impl<T> crate::dom::Element<T> for #elem_name<T> where T: crate::OutputType + Send {
                fn name() -> &'static str {
                    #name
                }

                fn attribute_names() -> &'static [&'static str] {
                    &[ #attrs ]
                }

                fn required_children() -> &'static [&'static str] {
                    &[ #reqs ]
                }

                fn attributes(&self) -> Vec<(&'static str, String)> {
                    let mut out = Vec::new();
                    #push_attrs
                    for (key, value) in &self.data_attributes {
                        out.push((key, value.to_string()));
                    }

                    for (key, value) in &self.aria_attributes {
                        out.push((key, value.to_string()));
                    }
                    out
                }
            }
        )
    }

    fn impl_marker_traits(&self) -> TokenStream {
        let elem_name = self.elem_name();
        let mut body = TokenStream::new();
        for t in &self.traits {
            let name = t.clone();
            body.extend(quote!(
                impl<T> #name<T> for #elem_name<T> where T: crate::OutputType + Send {}
            ));
        }
        body
    }

    fn impl_into_iter(&self) -> TokenStream {
        let elem_name = self.elem_name();
        quote!(
            impl<T> IntoIterator for #elem_name<T> where T: crate::OutputType + Send {
                type Item = #elem_name<T>;
                type IntoIter = std::vec::IntoIter<#elem_name<T>>;
                fn into_iter(self) -> Self::IntoIter {
                    vec![self].into_iter()
                }
            }

            impl<T> IntoIterator for Box<#elem_name<T>> where T: crate::OutputType + Send {
                type Item = Box<#elem_name<T>>;
                type IntoIter = std::vec::IntoIter<Box<#elem_name<T>>>;
                fn into_iter(self) -> Self::IntoIter {
                    vec![self].into_iter()
                }
            }
        )
    }

    fn impl_display(&self) -> TokenStream {
        let elem_name = self.elem_name();
        let name: TokenTree = Literal::string(&self.name.to_string()).into();

        let print_opt_children = if self.opt_children.is_some() {
            quote!(for child in &self.children {
                child.fmt(f)?;
            })
        } else {
            TokenStream::new()
        };

        let mut print_req_children = TokenStream::new();
        for (child_name, _, _) in self.req_children() {
            print_req_children.extend(quote!(
                self.#child_name.fmt(f)?;
            ));
        }

        let print_children = if self.req_children.is_empty() {
            if self.opt_children.is_some() {
                if !SELF_CLOSING.contains(&elem_name.to_string().as_str()) {
                    quote!(
                        write!(f, ">")?;
                        #print_opt_children
                        write!(f, "</{}>", #name)
                    )
                } else {
                    quote!(if self.children.is_empty() {
                        write!(f, " />")
                    } else {
                        write!(f, ">")?;
                        #print_opt_children
                        write!(f, "</{}>", #name)
                    })
                }
            } else if !SELF_CLOSING.contains(&elem_name.to_string().as_str()) {
                quote!(write!(f, "></{}>", #name))
            } else {
                quote!(write!(f, "/>"))
            }
        } else {
            quote!(
                write!(f, ">")?;
                #print_req_children
                #print_opt_children
                write!(f, "</{}>", #name)
            )
        };

        let mut print_attrs = TokenStream::new();
        for (attr_name, _, attr_str) in self.attrs() {
            print_attrs.extend(quote!(
                if let Some(ref value) = self.attrs.#attr_name {
                    let value = crate::escape_html_attribute(value.to_string());
                    if !value.is_empty() {
                        write!(f, " {}=\"{}\"", #attr_str, value)?;
                    }
                }
            ));
        }

        quote!(
            impl<T> std::fmt::Display for #elem_name<T>
            where
                T: crate::OutputType + Send,
            {
                fn fmt(&self, f: &mut std::fmt::Formatter) -> Result<(), std::fmt::Error> {
                    write!(f, "<{}", #name)?;
                    #print_attrs
                    for (key, value) in &self.data_attributes {
                        write!(f, " data-{}=\"{}\"", key,
                               crate::escape_html_attribute(value.to_string()))?;
                    }
                    for (key, value) in &self.aria_attributes {
                        write!(f, " aria-{}=\"{}\"", key,
                               crate::escape_html_attribute(value.to_string()))?;
                    }
                    write!(f, "{}", self.events)?;
                    #print_children
                }
            }
        )
    }
}

pub fn expand_declare(input: &[Token]) -> Result<Vec<Declare>, ParseError> {
    parser::grammar::DeclarationsParser::new().parse(Lexer::new(input))
}