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use std::fmt::{Display, Formatter};

use crate::dfa::DFA;
use crate::dfa_state::DFAState;
use crate::lexer_atn_simulator::ERROR_DFA_STATE_REF;

pub struct DFASerializer<'a, 'b> {
    dfa: &'a DFA,
    get_edge_label: &'b dyn Fn(usize) -> String,
}

impl Display for DFASerializer<'_, '_> {
    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
        let dfa = &self.dfa.states;
        for source in dfa.iter() {
            for (i, edge) in source.edges.iter().copied().enumerate() {
                if edge != 0 && edge != ERROR_DFA_STATE_REF {
                    let target = &dfa[edge];
                    f.write_fmt(format_args!(
                        "{}-{}->{}\n",
                        self.get_state_string(source),
                        (self.get_edge_label)(i),
                        self.get_state_string(target)
                    ))?;
                }
            }
        }
        Ok(())
    }
}

impl DFASerializer<'_, '_> {
    pub fn new<'a, 'b>(
        dfa: &'a DFA,
        get_edge_label: &'b dyn Fn(usize) -> String,
    ) -> DFASerializer<'a, 'b> {
        DFASerializer {
            dfa,
            get_edge_label,
        }
    }

    fn get_state_string(&self, state: &DFAState) -> String {
        let mut base_str = format!(
            "{}s{}{}",
            if state.is_accept_state { ":" } else { "" },
            state.state_number - 1,
            if state.requires_full_context { "^" } else { "" },
        );
        if state.is_accept_state {
            base_str = if !state.predicates.is_empty() {
                unimplemented!()
            //                format!("{}=>{:?}", base_str, state.predicates)
            } else {
                format!("{}=>{}", base_str, state.prediction)
            };
        }
        base_str
    }
}