//! Pattern Recognition Helpers
//!
//! Phase 140-P4-B: This module now delegates to SSOT implementations in ast_feature_extractor.
//! Provides backward-compatible wrappers for existing callsites.

use crate::ast::ASTNode;
use crate::mir::{detect_skip_whitespace_pattern as ast_detect, SkipWhitespaceInfo};

// ============================================================================
// Skip Whitespace Pattern (Phase 140-P4-B SSOT Wrapper)
// ============================================================================

/// Try to extract skip_whitespace pattern from loop
///
/// Pattern structure:
/// ```
/// loop(cond) {
///     // ... optional body statements (Body)
///     if check_cond {
///         carrier = carrier + const
///     } else {
///         break
///     }
/// }
/// ```
///
/// Returns (carrier_name, delta, body_stmts) if pattern matches.
///
/// # Phase 140-P4-B: SSOT Migration
///
/// This function now delegates to `ast_feature_extractor::detect_skip_whitespace_pattern`
/// for SSOT implementation. This wrapper maintains backward compatibility for existing callsites.
pub fn try_extract_skip_whitespace_pattern(
    body: &[ASTNode],
) -> Option<(String, i64, Vec<ASTNode>)> {
    ast_detect(body).map(|info| (info.carrier_name, info.delta, info.body_stmts))
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::ast::{BinaryOperator, LiteralValue, Span};

    #[test]
    fn test_skip_whitespace_basic_pattern() {
        // Build: if is_ws { p = p + 1 } else { break }
        let body = vec![ASTNode::If {
            condition: Box::new(ASTNode::Variable {
                name: "is_ws".to_string(),
                span: Span::unknown(),
            }),
            then_body: vec![ASTNode::Assignment {
                target: Box::new(ASTNode::Variable {
                    name: "p".to_string(),
                    span: Span::unknown(),
                }),
                value: Box::new(ASTNode::BinaryOp {
                    operator: BinaryOperator::Add,
                    left: Box::new(ASTNode::Variable {
                        name: "p".to_string(),
                        span: Span::unknown(),
                    }),
                    right: Box::new(ASTNode::Literal {
                        value: LiteralValue::Integer(1),
                        span: Span::unknown(),
                    }),
                    span: Span::unknown(),
                }),
                span: Span::unknown(),
            }],
            else_body: Some(vec![ASTNode::Break {
                span: Span::unknown(),
            }]),
            span: Span::unknown(),
        }];

        let result = try_extract_skip_whitespace_pattern(&body);
        assert!(result.is_some());

        let (carrier_name, delta, body_stmts) = result.unwrap();
        assert_eq!(carrier_name, "p");
        assert_eq!(delta, 1);
        assert_eq!(body_stmts.len(), 0);
    }

    #[test]
    fn test_skip_whitespace_with_body() {
        // Build: local ch = get_char(p); if is_ws { p = p + 1 } else { break }
        let body = vec![
            ASTNode::Assignment {
                target: Box::new(ASTNode::Variable {
                    name: "ch".to_string(),
                    span: Span::unknown(),
                }),
                value: Box::new(ASTNode::FunctionCall {
                    name: "get_char".to_string(),
                    arguments: vec![ASTNode::Variable {
                        name: "p".to_string(),
                        span: Span::unknown(),
                    }],
                    span: Span::unknown(),
                }),
                span: Span::unknown(),
            },
            ASTNode::If {
                condition: Box::new(ASTNode::Variable {
                    name: "is_ws".to_string(),
                    span: Span::unknown(),
                }),
                then_body: vec![ASTNode::Assignment {
                    target: Box::new(ASTNode::Variable {
                        name: "p".to_string(),
                        span: Span::unknown(),
                    }),
                    value: Box::new(ASTNode::BinaryOp {
                        operator: BinaryOperator::Add,
                        left: Box::new(ASTNode::Variable {
                            name: "p".to_string(),
                            span: Span::unknown(),
                        }),
                        right: Box::new(ASTNode::Literal {
                            value: LiteralValue::Integer(1),
                            span: Span::unknown(),
                        }),
                        span: Span::unknown(),
                    }),
                    span: Span::unknown(),
                }],
                else_body: Some(vec![ASTNode::Break {
                    span: Span::unknown(),
                }]),
                span: Span::unknown(),
            },
        ];

        let result = try_extract_skip_whitespace_pattern(&body);
        assert!(result.is_some());

        let (carrier_name, delta, body_stmts) = result.unwrap();
        assert_eq!(carrier_name, "p");
        assert_eq!(delta, 1);
        assert_eq!(body_stmts.len(), 1); // The assignment before the if
    }

    #[test]
    fn test_skip_whitespace_rejects_no_else() {
        // Build: if is_ws { p = p + 1 } (no else)
        let body = vec![ASTNode::If {
            condition: Box::new(ASTNode::Variable {
                name: "is_ws".to_string(),
                span: Span::unknown(),
            }),
            then_body: vec![ASTNode::Assignment {
                target: Box::new(ASTNode::Variable {
                    name: "p".to_string(),
                    span: Span::unknown(),
                }),
                value: Box::new(ASTNode::BinaryOp {
                    operator: BinaryOperator::Add,
                    left: Box::new(ASTNode::Variable {
                        name: "p".to_string(),
                        span: Span::unknown(),
                    }),
                    right: Box::new(ASTNode::Literal {
                        value: LiteralValue::Integer(1),
                        span: Span::unknown(),
                    }),
                    span: Span::unknown(),
                }),
                span: Span::unknown(),
            }],
            else_body: None,
            span: Span::unknown(),
        }];

        let result = try_extract_skip_whitespace_pattern(&body);
        assert!(result.is_none());
    }
}