ryo-pattern 0.1.0

//! Pattern matcher for PureExpr
//!
//! Matches CodePattern against ryo-source's PureExpr AST nodes.

use crate::{
    ArmPattern, CapturedNode, CodePattern, MatchResult, NameMatcher, NodeKind, PatternExpr, Span,
};
use ryo_source::pure::{PureBlock, PureExpr, PureFn, PureMatchArm, PurePattern, PureStmt};
use std::collections::HashMap;

/// Matcher context for accumulating captures
#[derive(Debug, Default)]
pub struct MatchContext {
    /// Captured nodes during matching
    pub captures: HashMap<String, CapturedNode>,
}

impl MatchContext {
    /// Construct an empty `MatchContext`.
    pub fn new() -> Self {
        Self::default()
    }

    /// Add a capture
    pub fn capture(&mut self, name: impl Into<String>, text: impl Into<String>) {
        let name = name.into();
        self.captures
            .insert(name, CapturedNode::new(Span::point(0, 0), text.into()));
    }

    /// Merge another context's captures
    pub fn merge(&mut self, other: MatchContext) {
        self.captures.extend(other.captures);
    }

    /// Convert to MatchResult
    pub fn into_match_result(self) -> MatchResult {
        let mut result = MatchResult::matched();
        result.captures = self.captures;
        result
    }
}

/// Pattern matcher for expressions
pub struct ExprMatcher<'p> {
    pattern: &'p CodePattern,
}

impl<'p> ExprMatcher<'p> {
    /// Construct a new `ExprMatcher` borrowing the given pattern.
    pub fn new(pattern: &'p CodePattern) -> Self {
        Self { pattern }
    }

    /// Match against a PureExpr
    pub fn matches(&self, expr: &PureExpr) -> Option<MatchContext> {
        let mut ctx = MatchContext::new();

        if self.match_expr(expr, &mut ctx) {
            // Add capture if pattern has capture variable
            if let Some(ref capture_name) = self.pattern.capture {
                ctx.capture(capture_name.clone(), expr_to_string(expr));
            }
            Some(ctx)
        } else {
            None
        }
    }

    /// Match expression against pattern
    fn match_expr(&self, expr: &PureExpr, ctx: &mut MatchContext) -> bool {
        match (&self.pattern.node, expr) {
            // MethodCall pattern
            (
                NodeKind::MethodCall,
                PureExpr::MethodCall {
                    receiver,
                    method,
                    args,
                    ..
                },
            ) => {
                // Check method name if specified
                if let Some(PatternExpr::Name(name_matcher)) = self.pattern.children.get("method") {
                    if !match_name(name_matcher, method) {
                        return false;
                    }
                }

                // Check receiver if specified
                if let Some(receiver_pattern) = self.pattern.children.get("receiver") {
                    if !self.match_pattern_expr(receiver_pattern, receiver, ctx) {
                        return false;
                    }
                }

                // Check args if specified
                if let Some(PatternExpr::Pattern(args_pattern)) = self.pattern.children.get("args")
                {
                    // TODO: Implement args matching
                    let _ = args_pattern;
                    let _ = args;
                }

                true
            }

            // FunctionCall pattern
            (NodeKind::FunctionCall, PureExpr::Call { func, args }) => {
                // Check function name if specified
                if let Some(func_pattern) = self.pattern.children.get("func") {
                    if !self.match_pattern_expr(func_pattern, func, ctx) {
                        return false;
                    }
                }
                let _ = args;
                true
            }

            // MacroCall pattern
            (NodeKind::MacroCall, PureExpr::Macro { name, .. }) => {
                // YAML uses "macro" key (e.g., `macro: "todo"`), not "name"
                if let Some(PatternExpr::Name(name_matcher)) = self.pattern.children.get("macro") {
                    if !match_name(name_matcher, name) {
                        return false;
                    }
                }
                true
            }

            // Try (?) pattern
            (NodeKind::Try, PureExpr::Try(expr)) => {
                if let Some(expr_pattern) = self.pattern.children.get("expr") {
                    if !self.match_pattern_expr(expr_pattern, expr, ctx) {
                        return false;
                    }
                }
                true
            }

            // Await pattern
            (NodeKind::Await, PureExpr::Await(expr)) => {
                if let Some(expr_pattern) = self.pattern.children.get("expr") {
                    if !self.match_pattern_expr(expr_pattern, expr, ctx) {
                        return false;
                    }
                }
                true
            }

            // BinaryOp pattern
            (NodeKind::BinaryOp, PureExpr::Binary { op, left, right }) => {
                if let Some(PatternExpr::Name(name_matcher)) = self.pattern.children.get("op") {
                    if !match_name(name_matcher, op) {
                        return false;
                    }
                }
                if let Some(left_pattern) = self.pattern.children.get("left") {
                    if !self.match_pattern_expr(left_pattern, left, ctx) {
                        return false;
                    }
                }
                if let Some(right_pattern) = self.pattern.children.get("right") {
                    if !self.match_pattern_expr(right_pattern, right, ctx) {
                        return false;
                    }
                }
                true
            }

            // Path pattern (variable/identifier)
            (NodeKind::Path, PureExpr::Path(path)) => {
                if let Some(PatternExpr::Name(name_matcher)) = self.pattern.children.get("path") {
                    if !match_name(name_matcher, path) {
                        return false;
                    }
                }
                true
            }

            // Literal pattern
            (NodeKind::Literal, PureExpr::Lit(lit)) => {
                if let Some(value_pattern) = self.pattern.children.get("value") {
                    match value_pattern {
                        PatternExpr::Literal(expected) => {
                            if let Some(expected_str) = expected.as_str() {
                                if lit != expected_str {
                                    return false;
                                }
                            }
                        }
                        // Handle case where YAML "value: true" is parsed as Name(Exact("true"))
                        // due to serde untagged enum ordering
                        PatternExpr::Name(NameMatcher::Exact(expected_str))
                            if lit != expected_str =>
                        {
                            return false;
                        }
                        _ => {}
                    }
                }
                true
            }

            // Generic Expr matches any expression
            (NodeKind::Expr, _) => true,

            // Block pattern
            (NodeKind::Block, PureExpr::Block { .. }) => true,

            // If pattern
            (
                NodeKind::If,
                PureExpr::If {
                    cond,
                    then_branch,
                    else_branch,
                },
            ) => {
                if let Some(cond_pattern) = self.pattern.children.get("cond") {
                    if !self.match_pattern_expr(cond_pattern, cond, ctx) {
                        return false;
                    }
                }
                let _ = (then_branch, else_branch);
                true
            }

            // Match pattern
            (NodeKind::Match, PureExpr::Match { expr, arms }) => {
                if let Some(expr_pattern) = self.pattern.children.get("expr") {
                    if !self.match_pattern_expr(expr_pattern, expr, ctx) {
                        return false;
                    }
                }
                // Check arm count
                if let Some(expected) = self.pattern.arm_count {
                    if arms.len() != expected {
                        return false;
                    }
                }
                // Check arm patterns (order-independent: each ArmPattern must match some arm)
                if let Some(arm_patterns) = &self.pattern.arms {
                    for ap in arm_patterns {
                        if !arms.iter().any(|arm| match_arm_pattern(ap, arm, ctx)) {
                            return false;
                        }
                    }
                }
                true
            }

            // Return pattern
            (NodeKind::Return, PureExpr::Return(maybe_expr)) => {
                if let Some(expr_pattern) = self.pattern.children.get("expr") {
                    if let Some(expr) = maybe_expr {
                        if !self.match_pattern_expr(expr_pattern, expr, ctx) {
                            return false;
                        }
                    } else {
                        return false;
                    }
                }
                true
            }

            // Loop pattern
            (NodeKind::Loop, PureExpr::Loop { .. }) => true,
            (NodeKind::Loop, PureExpr::While { .. }) => true,
            (NodeKind::Loop, PureExpr::For { .. }) => true,

            // Closure pattern
            (NodeKind::Closure, PureExpr::Closure { .. }) => true,

            // Index pattern (e.g., arr[i])
            (NodeKind::Index, PureExpr::Index { expr, index }) => {
                if let Some(expr_pattern) = self.pattern.children.get("expr") {
                    if !self.match_pattern_expr(expr_pattern, expr, ctx) {
                        return false;
                    }
                }
                if let Some(index_pattern) = self.pattern.children.get("index") {
                    if !self.match_pattern_expr(index_pattern, index, ctx) {
                        return false;
                    }
                }
                true
            }

            _ => false,
        }
    }

    /// Match a PatternExpr against a PureExpr
    fn match_pattern_expr(
        &self,
        pattern: &PatternExpr,
        expr: &PureExpr,
        ctx: &mut MatchContext,
    ) -> bool {
        match pattern {
            PatternExpr::Pattern(nested) => {
                let matcher = ExprMatcher::new(nested);
                if let Some(nested_ctx) = matcher.matches(expr) {
                    ctx.merge(nested_ctx);
                    true
                } else {
                    false
                }
            }
            PatternExpr::Capture(var_name) => {
                // Capture variable matches anything and stores the value
                ctx.capture(var_name.clone(), expr_to_string(expr));
                true
            }
            PatternExpr::Wildcard => true,
            PatternExpr::Name(name_matcher) => {
                if let PureExpr::Path(path) = expr {
                    match_name(name_matcher, path)
                } else {
                    false
                }
            }
            PatternExpr::Literal(expected) => {
                if let PureExpr::Lit(lit) = expr {
                    if let Some(expected_str) = expected.as_str() {
                        lit == expected_str
                    } else {
                        false
                    }
                } else {
                    false
                }
            }
        }
    }
}

/// Match a name against a NameMatcher
fn match_name(matcher: &NameMatcher, name: &str) -> bool {
    match matcher {
        NameMatcher::Exact(expected) => name == expected,
        NameMatcher::Pattern(pattern) => {
            if let Some(ref prefix) = pattern.starts_with {
                if !name.starts_with(prefix) {
                    return false;
                }
            }
            if let Some(ref suffix) = pattern.ends_with {
                if !name.ends_with(suffix) {
                    return false;
                }
            }
            if let Some(ref substr) = pattern.contains {
                if !name.contains(substr) {
                    return false;
                }
            }
            if let Some(ref glob) = pattern.glob {
                if !match_glob(glob, name) {
                    return false;
                }
            }
            true
        }
    }
}

/// Simple glob matching (supports * wildcard)
fn match_glob(pattern: &str, name: &str) -> bool {
    if pattern == "*" {
        return true;
    }
    if let Some(prefix) = pattern.strip_suffix('*') {
        return name.starts_with(prefix);
    }
    if let Some(suffix) = pattern.strip_prefix('*') {
        return name.ends_with(suffix);
    }
    pattern == name
}

/// Check if a PureMatchArm matches an ArmPattern.
fn match_arm_pattern(ap: &ArmPattern, arm: &PureMatchArm, _ctx: &mut MatchContext) -> bool {
    // Check pattern_path: the arm's pattern must contain this path
    if let Some(ref expected_path) = ap.pattern_path {
        if !pattern_contains_path(&arm.pattern, expected_path) {
            return false;
        }
    }
    // Check body: the arm's body must match the CodePattern
    if let Some(ref body_pattern) = ap.body {
        let matcher = ExprMatcher::new(body_pattern);
        if matcher.matches(&arm.body).is_none() {
            return false;
        }
    }
    true
}

/// Check if a PurePattern contains a given path (e.g., "Some", "None").
fn pattern_contains_path(pat: &PurePattern, expected: &str) -> bool {
    match pat {
        PurePattern::Path(p) => p == expected || p.ends_with(&format!("::{}", expected)),
        PurePattern::Struct { path, .. } => {
            path == expected || path.ends_with(&format!("::{}", expected))
        }
        PurePattern::Ident { name, .. } => name == expected,
        PurePattern::Or(patterns) => patterns.iter().any(|p| pattern_contains_path(p, expected)),
        PurePattern::Ref { pattern, .. } => pattern_contains_path(pattern, expected),
        PurePattern::Tuple(patterns) => patterns.iter().any(|p| pattern_contains_path(p, expected)),
        _ => false,
    }
}

/// Convert PureExpr to string representation
pub fn expr_to_string(expr: &PureExpr) -> String {
    match expr {
        PureExpr::Lit(s) => s.clone(),
        PureExpr::Path(s) => s.clone(),
        PureExpr::MethodCall {
            receiver,
            method,
            args,
            turbofish,
        } => {
            let receiver_str = expr_to_string(receiver);
            let turbofish_str = turbofish
                .as_ref()
                .map(|t| format!("::{}", t))
                .unwrap_or_default();
            let args_str = args
                .iter()
                .map(expr_to_string)
                .collect::<Vec<_>>()
                .join(", ");
            format!("{}.{}{}({})", receiver_str, method, turbofish_str, args_str)
        }
        PureExpr::Call { func, args } => {
            let func_str = expr_to_string(func);
            let args_str = args
                .iter()
                .map(expr_to_string)
                .collect::<Vec<_>>()
                .join(", ");
            format!("{}({})", func_str, args_str)
        }
        PureExpr::Binary { op, left, right } => {
            format!("{} {} {}", expr_to_string(left), op, expr_to_string(right))
        }
        PureExpr::Unary { op, expr } => {
            format!("{}{}", op, expr_to_string(expr))
        }
        PureExpr::Try(expr) => {
            format!("{}?", expr_to_string(expr))
        }
        PureExpr::Await(expr) => {
            format!("{}.await", expr_to_string(expr))
        }
        PureExpr::Field { expr, field } => {
            format!("{}.{}", expr_to_string(expr), field)
        }
        PureExpr::Return(Some(e)) => format!("return {}", expr_to_string(e)),
        PureExpr::Return(None) => "return".to_string(),
        PureExpr::Block { .. } => "{ ... }".to_string(),
        PureExpr::If { .. } => "if ...".to_string(),
        PureExpr::Match { .. } => "match ...".to_string(),
        PureExpr::Closure { .. } => "|...| ...".to_string(),
        PureExpr::Tuple(items) => {
            let items_str = items
                .iter()
                .map(expr_to_string)
                .collect::<Vec<_>>()
                .join(", ");
            format!("({})", items_str)
        }
        PureExpr::Array(items) => {
            let items_str = items
                .iter()
                .map(expr_to_string)
                .collect::<Vec<_>>()
                .join(", ");
            format!("[{}]", items_str)
        }
        PureExpr::Macro { name, .. } => format!("{}!(...)", name),
        _ => "<expr>".to_string(),
    }
}

/// Scan a function body for pattern matches
pub struct BodyScanner<'p> {
    pattern: &'p CodePattern,
}

impl<'p> BodyScanner<'p> {
    /// Construct a new `BodyScanner` borrowing the given pattern.
    pub fn new(pattern: &'p CodePattern) -> Self {
        Self { pattern }
    }

    /// Scan a function and return all matches
    pub fn scan_fn(&self, func: &PureFn) -> Vec<MatchResult> {
        let mut results = Vec::new();
        self.scan_block(&func.body, &mut results);
        results
    }

    /// Scan a block for matches
    fn scan_block(&self, block: &PureBlock, results: &mut Vec<MatchResult>) {
        for stmt in &block.stmts {
            self.scan_stmt(stmt, results);
        }
    }

    /// Scan a statement for matches
    fn scan_stmt(&self, stmt: &PureStmt, results: &mut Vec<MatchResult>) {
        match stmt {
            PureStmt::Local {
                init: Some(expr), ..
            } => {
                self.scan_expr(expr, results);
            }
            PureStmt::Semi(expr) | PureStmt::Expr(expr) => {
                self.scan_expr(expr, results);
            }
            _ => {}
        }
    }

    /// Recursively scan an expression
    fn scan_expr(&self, expr: &PureExpr, results: &mut Vec<MatchResult>) {
        // Try to match current expression
        let matcher = ExprMatcher::new(self.pattern);
        if let Some(ctx) = matcher.matches(expr) {
            results.push(ctx.into_match_result());
        }

        // Recursively scan children
        match expr {
            PureExpr::MethodCall { receiver, args, .. } => {
                self.scan_expr(receiver, results);
                for arg in args {
                    self.scan_expr(arg, results);
                }
            }
            PureExpr::Call { func, args } => {
                self.scan_expr(func, results);
                for arg in args {
                    self.scan_expr(arg, results);
                }
            }
            PureExpr::Binary { left, right, .. } => {
                self.scan_expr(left, results);
                self.scan_expr(right, results);
            }
            PureExpr::Unary { expr, .. } => {
                self.scan_expr(expr, results);
            }
            PureExpr::Try(expr) => {
                self.scan_expr(expr, results);
            }
            PureExpr::Await(expr) => {
                self.scan_expr(expr, results);
            }
            PureExpr::Field { expr, .. } => {
                self.scan_expr(expr, results);
            }
            PureExpr::Index { expr, index } => {
                self.scan_expr(expr, results);
                self.scan_expr(index, results);
            }
            PureExpr::Block { block, .. } => {
                self.scan_block(block, results);
            }
            PureExpr::If {
                cond,
                then_branch,
                else_branch,
            } => {
                self.scan_expr(cond, results);
                self.scan_block(then_branch, results);
                if let Some(else_expr) = else_branch {
                    self.scan_expr(else_expr, results);
                }
            }
            PureExpr::Match { expr, arms } => {
                self.scan_expr(expr, results);
                for arm in arms {
                    self.scan_expr(&arm.body, results);
                }
            }
            PureExpr::Loop { body, .. } => {
                self.scan_block(body, results);
            }
            PureExpr::While { cond, body, .. } => {
                self.scan_expr(cond, results);
                self.scan_block(body, results);
            }
            PureExpr::For { expr, body, .. } => {
                self.scan_expr(expr, results);
                self.scan_block(body, results);
            }
            PureExpr::Return(Some(e)) => {
                self.scan_expr(e, results);
            }
            PureExpr::Break { expr: Some(e), .. } => {
                self.scan_expr(e, results);
            }
            PureExpr::Closure { body, .. } => {
                self.scan_expr(body, results);
            }
            PureExpr::Struct { fields, .. } => {
                for (_, field_expr) in fields {
                    self.scan_expr(field_expr, results);
                }
            }
            PureExpr::Tuple(items) | PureExpr::Array(items) => {
                for item in items {
                    self.scan_expr(item, results);
                }
            }
            _ => {}
        }
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use ryo_source::pure::MacroDelimiter;

    #[test]
    fn test_match_method_call() {
        let pattern = CodePattern::new(NodeKind::MethodCall).with_child(
            "method",
            PatternExpr::Name(NameMatcher::Exact("unwrap".into())),
        );

        let expr = PureExpr::MethodCall {
            receiver: Box::new(PureExpr::Path("result".into())),
            method: "unwrap".into(),
            turbofish: None,
            args: vec![],
        };

        let matcher = ExprMatcher::new(&pattern);
        assert!(matcher.matches(&expr).is_some());
    }

    #[test]
    fn test_no_match_different_method() {
        let pattern = CodePattern::new(NodeKind::MethodCall).with_child(
            "method",
            PatternExpr::Name(NameMatcher::Exact("unwrap".into())),
        );

        let expr = PureExpr::MethodCall {
            receiver: Box::new(PureExpr::Path("result".into())),
            method: "expect".into(),
            turbofish: None,
            args: vec![],
        };

        let matcher = ExprMatcher::new(&pattern);
        assert!(matcher.matches(&expr).is_none());
    }

    #[test]
    fn test_capture_receiver() {
        let pattern = CodePattern::new(NodeKind::MethodCall)
            .with_child(
                "method",
                PatternExpr::Name(NameMatcher::Exact("unwrap".into())),
            )
            .with_child("receiver", PatternExpr::Capture("$x".into()))
            .with_capture("$call");

        let expr = PureExpr::MethodCall {
            receiver: Box::new(PureExpr::Path("my_result".into())),
            method: "unwrap".into(),
            turbofish: None,
            args: vec![],
        };

        let matcher = ExprMatcher::new(&pattern);
        let ctx = matcher.matches(&expr).unwrap();

        assert!(ctx.captures.contains_key("$x"));
        assert!(ctx.captures.contains_key("$call"));
        assert_eq!(ctx.captures["$x"].text, "my_result");
    }

    #[test]
    fn test_glob_matching() {
        assert!(match_glob("get_*", "get_name"));
        assert!(match_glob("*_id", "user_id"));
        assert!(match_glob("*", "anything"));
        assert!(!match_glob("get_*", "set_name"));
    }

    #[test]
    fn test_literal_match_with_name_pattern() {
        // Test that PatternExpr::Name(Exact("true")) matches literal "true"
        // This is important because YAML `value: "true"` gets parsed as Name(Exact)
        // due to serde untagged enum ordering
        let pattern = CodePattern::new(NodeKind::Literal).with_child(
            "value",
            PatternExpr::Name(NameMatcher::Exact("true".into())),
        );

        // Should match literal "true"
        let expr_true = PureExpr::Lit("true".into());
        let matcher = ExprMatcher::new(&pattern);
        assert!(matcher.matches(&expr_true).is_some());

        // Should NOT match literal "false"
        let expr_false = PureExpr::Lit("false".into());
        assert!(matcher.matches(&expr_false).is_none());

        // Should NOT match literal "42"
        let expr_num = PureExpr::Lit("42".into());
        assert!(matcher.matches(&expr_num).is_none());
    }

    #[test]
    fn test_literal_match_with_literal_pattern() {
        // Test that PatternExpr::Literal also still works
        let pattern = CodePattern::new(NodeKind::Literal)
            .with_child("value", PatternExpr::Literal(serde_json::json!("true")));

        let expr_true = PureExpr::Lit("true".into());
        let matcher = ExprMatcher::new(&pattern);
        assert!(matcher.matches(&expr_true).is_some());

        let expr_false = PureExpr::Lit("false".into());
        assert!(matcher.matches(&expr_false).is_none());
    }

    #[test]
    fn test_macro_call_match() {
        // Test that MacroCall pattern uses "macro" key (as defined in YAML rules)
        let pattern = CodePattern::new(NodeKind::MacroCall).with_child(
            "macro",
            PatternExpr::Name(NameMatcher::Exact("todo".into())),
        );

        // Should match todo!()
        let expr_todo = PureExpr::Macro {
            name: "todo".into(),
            delimiter: MacroDelimiter::Paren,
            tokens: "".into(),
        };
        let matcher = ExprMatcher::new(&pattern);
        assert!(matcher.matches(&expr_todo).is_some());

        // Should NOT match println!()
        let expr_println = PureExpr::Macro {
            name: "println".into(),
            delimiter: MacroDelimiter::Paren,
            tokens: "".into(),
        };
        assert!(matcher.matches(&expr_println).is_none());

        // Should NOT match vec![]
        let expr_vec = PureExpr::Macro {
            name: "vec".into(),
            delimiter: MacroDelimiter::Bracket,
            tokens: "".into(),
        };
        assert!(matcher.matches(&expr_vec).is_none());
    }

    #[test]
    fn test_macro_call_no_filter_matches_all() {
        // MacroCall without "macro" child should match any macro
        let pattern = CodePattern::new(NodeKind::MacroCall);

        let expr_todo = PureExpr::Macro {
            name: "todo".into(),
            delimiter: MacroDelimiter::Paren,
            tokens: "".into(),
        };
        let matcher = ExprMatcher::new(&pattern);
        assert!(matcher.matches(&expr_todo).is_some());

        let expr_vec = PureExpr::Macro {
            name: "vec".into(),
            delimiter: MacroDelimiter::Bracket,
            tokens: "".into(),
        };
        assert!(matcher.matches(&expr_vec).is_some());
    }

    #[test]
    fn test_path_match_exact() {
        let pattern = CodePattern::new(NodeKind::Path).with_child(
            "path",
            PatternExpr::Name(NameMatcher::Exact("Filter::Recurse".into())),
        );

        let expr_match = PureExpr::Path("Filter::Recurse".into());
        let matcher = ExprMatcher::new(&pattern);
        assert!(matcher.matches(&expr_match).is_some());

        let expr_no_match = PureExpr::Path("Filter::Include".into());
        assert!(matcher.matches(&expr_no_match).is_none());

        let expr_unrelated = PureExpr::Path("something_else".into());
        assert!(matcher.matches(&expr_unrelated).is_none());
    }

    #[test]
    fn test_path_no_filter_matches_all() {
        // Path without "path" child should match any path
        let pattern = CodePattern::new(NodeKind::Path);

        let expr = PureExpr::Path("anything".into());
        let matcher = ExprMatcher::new(&pattern);
        assert!(matcher.matches(&expr).is_some());
    }
}