use nom::combinator::eof;

use super::exiting::ExitClass;
use super::global_settings::GlobalSettings;
use super::list::List;
use super::list::ListType;
use super::DynContextMatcher;
use super::RefContext;
use crate::error::Res;
use crate::parser::OrgSource;
use crate::types::Object;

// type Matcher =
//     dyn for<'r, 's> Fn(Context<'r, 's>, OrgSource<'s>) -> Res<OrgSource<'s>, OrgSource<'s>>;

// #[derive(Debug, Clone)]
// pub struct ContextTree<'r, 's> {
//     tree: List<ContextElement<'r, 's>>,
// }

// impl<'r, 's> ContextTree<'r, 's> {
//     pub fn new() -> Self {
//         ContextTree { tree: List::new() }
//     }

//     pub fn branch_from(trunk: &Rc<Node<ContextElement<'r, 's>>>) -> Self {
//         ContextTree {
//             tree: List::branch_from(trunk),
//         }
//     }

//     #[allow(dead_code)]
//     pub fn ptr_eq<'x, 'y>(&self, other: &ContextTree<'x, 'y>) -> bool {
//         self.tree.ptr_eq(&other.tree)
//     }

//     pub fn with_additional_node(&self, data: ContextElement<'r, 's>) -> ContextTree<'r, 's> {
//         let new_list = self.tree.push_front(data);
//         ContextTree { tree: new_list }
//     }

//     pub fn iter(&self) -> impl Iterator<Item = &Rc<Node<ContextElement<'r, 's>>>> {
//         self.tree.iter()
//     }

//     #[cfg_attr(feature = "tracing", tracing::instrument(ret, level = "debug"))]
//     pub fn check_exit_matcher(
//         &'r self,
//         i: OrgSource<'s>,
//     ) -> IResult<OrgSource<'s>, OrgSource<'s>, CustomError<OrgSource<'s>>> {
//         // Special check for EOF. We don't just make this a document-level exit matcher since the IgnoreParent ChainBehavior could cause early exit matchers to not run.
//         let at_end_of_file = eof(i);
//         if at_end_of_file.is_ok() {
//             return at_end_of_file;
//         }

//         let mut current_class_filter = ExitClass::Gamma;
//         for current_node in self.iter() {
//             let context_element = current_node.get_data();
//             match context_element {
//                 ContextElement::ExitMatcherNode(exit_matcher) => {
//                     if exit_matcher.class as u32 <= current_class_filter as u32 {
//                         current_class_filter = exit_matcher.class;
//                         let local_context = ContextTree::branch_from(current_node);
//                         let local_result = (exit_matcher.exit_matcher)(&local_context, i);
//                         if local_result.is_ok() {
//                             return local_result;
//                         }
//                     }
//                 }
//                 _ => {}
//             };
//         }
//         // TODO: Make this a specific error instead of just a generic MyError
//         return Err(nom::Err::Error(CustomError::MyError(MyError(
//             "NoExit".into(),
//         ))));
//     }

//     /// Indicates if elements should consume the whitespace after them.
//     ///
//     /// Defaults to true.
//     pub fn should_consume_trailing_whitespace(&self) -> bool {
//         self._should_consume_trailing_whitespace().unwrap_or(true)
//     }

//     fn _should_consume_trailing_whitespace(&self) -> Option<bool> {
//         for current_node in self.iter() {
//             let context_element = current_node.get_data();
//             match context_element {
//                 ContextElement::ConsumeTrailingWhitespace(should) => {
//                     return Some(*should);
//                 }
//                 _ => {}
//             }
//         }
//         None
//     }
// }

#[derive(Debug)]
pub enum ContextElement<'r, 's> {
    /// Stores a parser that indicates that children should exit upon matching an exit matcher.
    ExitMatcherNode(ExitMatcherNode<'r>),

    /// Stores the name of the current element to prevent directly nesting elements of the same type.
    Context(&'r str),

    /// Indicates if elements should consume the whitespace after them.
    ConsumeTrailingWhitespace(bool),

    /// The contents of a radio target.
    ///
    /// If any are found, this will force a 2nd parse through the
    /// org-mode document since text needs to be re-parsed to look for
    /// radio links matching the contents of radio targets.
    RadioTarget(Vec<&'r Vec<Object<'s>>>),
}

pub struct ExitMatcherNode<'r> {
    // TODO: Should this be "&'r DynContextMatcher<'c>" ?
    pub exit_matcher: &'r DynContextMatcher<'r>,
    pub class: ExitClass,
}

impl<'r> std::fmt::Debug for ExitMatcherNode<'r> {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        let mut formatter = f.debug_struct("ExitMatcherNode");
        formatter.field("class", &self.class.to_string());
        formatter.finish()
    }
}

#[derive(Debug)]
pub struct Context<'r, 's> {
    global_settings: &'s GlobalSettings<'s>,
    tree: &'r List<'r, ContextElement<'r, 's>>,
}

impl<'r, 's> Context<'r, 's> {
    pub fn new(
        global_settings: &'s GlobalSettings<'s>,
        tree: &'r List<'r, ContextElement<'r, 's>>,
    ) -> Self {
        Self {
            global_settings,
            tree,
        }
    }

    pub fn with_additional_node(&self, data: ContextElement<'r, 's>) -> Self {
        let new_tree = self.tree.push(data);
        Self {
            global_settings: self.global_settings,
            tree: new_tree,
        }
    }

    pub fn iter(&self) -> super::list::Iter<'r, ContextElement<'r, 's>> {
        self.tree.iter()
    }

    pub fn iter_context(&self) -> Iter<'r, 's> {
        Iter {
            next: self.tree.iter_list(),
            global_settings: self.global_settings,
        }
    }

    pub fn get_parent(&self) -> Option<Self> {
        self.tree.get_parent().map(|parent_tree| Self {
            global_settings: self.global_settings,
            tree: parent_tree,
        })
    }
}

#[cfg_attr(feature = "tracing", tracing::instrument(ret, level = "debug"))]
fn document_end<'r, 's>(
    _context: RefContext<'r, 's>,
    input: OrgSource<'s>,
) -> Res<OrgSource<'s>, OrgSource<'s>> {
    eof(input)
}

pub struct Iter<'r, 's> {
    global_settings: &'s GlobalSettings<'s>,
    next: super::list::IterList<'r, ContextElement<'r, 's>>,
}

impl<'r, 's> Iterator for Iter<'r, 's> {
    type Item = Context<'r, 's>;

    fn next(&mut self) -> Option<Self::Item> {
        let next_tree = self.next.next();
        let ret = next_tree.map(|parent_tree| Context::new(self.global_settings, parent_tree));
        ret
    }
}

impl<'r, 's> ContextElement<'r, 's> {
    pub fn document_context() -> Self {
        Self::ExitMatcherNode(ExitMatcherNode {
            exit_matcher: &document_end,
            class: ExitClass::Document,
        })
    }
}