giallo 0.5.0

use crate::grammars::{GlobalRuleRef, GrammarId, ROOT_RULE_ID};
use crate::scope::ScopeListId;

#[cfg(feature = "debug")]
use crate::scope::ScopeInterner;

#[derive(Clone, Debug)]
pub struct StackFrame {
    /// Global rule ref that created this stack element
    pub rule_ref: GlobalRuleRef,
    /// "name" scopes - applied to begin/end delimiters
    /// These scopes are active when matching the rule's boundaries
    pub name_scopes: ScopeListId,
    /// "contentName" scopes - applied to content between delimiters
    /// These scopes are active for the rule's interior content
    pub content_scopes: ScopeListId,
    /// Dynamic end/while pattern resolved with backreferences
    /// For BeginEnd rules: the end pattern with \1, \2, etc. resolved
    /// For BeginWhile rules: the while pattern with backreferences resolved
    pub end_pattern: Option<String>,
    /// The state has entered and captured \n.
    /// This means that the next line should start with an anchor_position of 0.
    pub begin_rule_has_captured_eol: bool,
    /// Where we currently are in a line
    pub anchor_position: Option<usize>,
    /// The position where this rule was entered during current line (for infinite loop detection)
    /// None at beginning of a line
    pub enter_position: Option<usize>,
}

/// Keeps track of nested context as well as how to exit that context and the captures
/// strings used in backreferences.
#[derive(Clone)]
pub struct StateStack {
    /// Stack frames from root to current
    pub frames: Vec<StackFrame>,
}

impl StateStack {
    pub fn new(grammar_id: GrammarId, grammar_scope: ScopeListId) -> Self {
        Self {
            frames: vec![StackFrame {
                rule_ref: GlobalRuleRef {
                    grammar: grammar_id,
                    rule: ROOT_RULE_ID,
                },
                name_scopes: grammar_scope,
                content_scopes: grammar_scope,
                end_pattern: None,
                begin_rule_has_captured_eol: false,
                anchor_position: None,
                enter_position: None,
            }],
        }
    }

    /// Called when entering a nested context: when a BeginEnd or BeginWhile begin pattern matches
    pub fn push(
        &mut self,
        rule_ref: GlobalRuleRef,
        anchor_position: Option<usize>,
        begin_rule_has_captured_eol: bool,
        enter_position: Option<usize>,
    ) {
        let content_scopes = self.top().content_scopes;

        self.frames.push(StackFrame {
            rule_ref,
            // Start with the same scope they will diverge later
            name_scopes: content_scopes,
            content_scopes,
            end_pattern: None,
            begin_rule_has_captured_eol,
            anchor_position,
            enter_position,
        });
    }

    pub fn push_with_scopes(
        &mut self,
        rule_ref: GlobalRuleRef,
        anchor_position: Option<usize>,
        begin_rule_has_captured_eol: bool,
        enter_position: Option<usize>,
        scopes: ScopeListId,
    ) {
        self.frames.push(StackFrame {
            rule_ref,
            name_scopes: scopes,
            content_scopes: scopes,
            end_pattern: None,
            begin_rule_has_captured_eol,
            anchor_position,
            enter_position,
        });
    }

    pub fn set_content_scopes(&mut self, content_scopes: ScopeListId) {
        self.top_mut().content_scopes = content_scopes;
    }

    pub fn set_end_pattern(&mut self, end_pattern: String) {
        self.top_mut().end_pattern = Some(end_pattern);
    }

    /// Exits the current context, getting back to the parent
    pub fn pop(&mut self) -> Option<StackFrame> {
        if self.frames.len() > 1 {
            self.frames.pop()
        } else {
            None
        }
    }

    /// Pop but never go below root state - used in infinite loop protection
    pub fn safe_pop(&mut self) {
        if self.frames.len() > 1 {
            self.frames.pop();
        }
    }

    /// Resets enter_position/anchor_position for all stack elements to None
    pub fn reset(&mut self) {
        for frame in &mut self.frames {
            frame.enter_position = None;
            frame.anchor_position = None;
        }
    }

    /// Access the top frame of the stack
    pub fn top(&self) -> &StackFrame {
        self.frames.last().expect("stack never empty")
    }

    /// Mutable access to the top frame of the stack
    pub fn top_mut(&mut self) -> &mut StackFrame {
        self.frames.last_mut().expect("stack never empty")
    }

    /// We need the interner to show the actual scopes so it's a not a Debug impl
    #[cfg(feature = "debug")]
    pub(crate) fn debug(&self, interner: &ScopeInterner) -> Result<String, std::fmt::Error> {
        use std::fmt::Write;

        let mut f = String::new();
        writeln!(f, "StateStack:")?;

        for (depth, frame) in self.frames.iter().enumerate() {
            // Create indentation
            let indent = "  ".repeat(depth);

            // Format the basic info
            write!(
                f,
                "{}grammar={}, rule={}",
                indent, frame.rule_ref.grammar.0, frame.rule_ref.rule.0
            )?;

            // Add name scopes if not empty
            let name_scopes = interner.get_scopes(frame.name_scopes);
            if !name_scopes.is_empty() {
                write!(f, " name=[")?;
                for (i, scope) in name_scopes.iter().enumerate() {
                    if i > 0 {
                        write!(f, ", ")?;
                    }
                    write!(f, "{}", scope.build_string())?;
                }
                write!(f, "]")?;
            }

            // Add content scopes if not empty
            let content_scopes = interner.get_scopes(frame.content_scopes);
            if !content_scopes.is_empty() {
                write!(f, ", content=[")?;
                for (i, scope) in content_scopes.iter().enumerate() {
                    if i > 0 {
                        write!(f, ", ")?;
                    }
                    write!(f, "{}", scope.build_string())?;
                }
                write!(f, "]")?;
            }

            // Add end_pattern if present
            if let Some(pattern) = &frame.end_pattern {
                write!(f, ", end_pattern=\"{}\"", pattern)?;
            }

            write!(f, ", anchor_pos={:?}", frame.anchor_position)?;

            // Add enter_position if present and different from anchor_position
            if let Some(enter_pos) = frame.enter_position
                && frame.anchor_position != Some(enter_pos)
            {
                write!(f, ", enter_pos={}", enter_pos)?;
            }

            write!(
                f,
                ", begin_rule_has_captured_eol={}",
                frame.begin_rule_has_captured_eol
            )?;

            writeln!(f)?;
        }
        Ok(f)
    }
}