ryo-executor 0.1.0

//! V2 ASTRegApply implementation for MapUnwrapOrMutation
//!
//! Converts `.map().unwrap_or()` chains to `.map_or()`:
//! - `opt.map(f).unwrap_or(default)` → `opt.map_or(default, f)`
//! - `opt.map(f).unwrap_or_else(g)` → `opt.map_or_else(g, f)`
//! - `opt.map(f).unwrap_or(None)` → `opt.and_then(f)`

use ryo_analysis::SymbolKind;
use ryo_mutations::idiom::MapUnwrapOrMutation;
use ryo_mutations::{Mutation, MutationResult};
use ryo_source::pure::{PureImplItem, PureItem};

use crate::engine::{ASTMutationContext, ASTRegApply};

impl ASTRegApply for MapUnwrapOrMutation {
    fn apply_to_registry(&self, ctx: &mut ASTMutationContext) -> MutationResult {
        let mut total_changes = 0;

        if let Some(target_id) = self.target_fn {
            // Target function specified: direct lookup
            if let Some(PureItem::Fn(f)) = ctx.ast_registry.get_mut(target_id) {
                total_changes += self.transform_block(&mut f.body);
            }
        } else {
            // No target: process all functions
            let fn_ids: Vec<_> = ctx
                .symbol_registry
                .iter()
                .filter(|(id, _)| {
                    matches!(ctx.symbol_registry.kind(*id), Some(SymbolKind::Function))
                })
                .map(|(id, _)| id)
                .collect();

            for id in fn_ids {
                if let Some(PureItem::Fn(f)) = ctx.ast_registry.get_mut(id) {
                    total_changes += self.transform_block(&mut f.body);
                }
            }

            // Process impl blocks (methods)
            let impl_ids: Vec<_> = ctx
                .symbol_registry
                .iter()
                .filter(|(id, _)| matches!(ctx.symbol_registry.kind(*id), Some(SymbolKind::Impl)))
                .map(|(id, _)| id)
                .collect();

            for id in impl_ids {
                if let Some(PureItem::Impl(imp)) = ctx.ast_registry.get_mut(id) {
                    for impl_item in &mut imp.items {
                        if let PureImplItem::Fn(f) = impl_item {
                            total_changes += self.transform_block(&mut f.body);
                        }
                    }
                }
            }
        }

        MutationResult {
            mutation_type: self.mutation_type().to_string(),
            changes: total_changes,
            description: if total_changes > 0 {
                format!(
                    "Converted {} .map().unwrap_or() chain(s) to .map_or()",
                    total_changes
                )
            } else {
                "No map().unwrap_or() chains found".to_string()
            },
        }
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::engine::ASTMutationEngine;
    use ryo_analysis::testing::ContextBuilder;

    #[test]
    fn test_v2_map_unwrap_or_basic() {
        let mut ctx = ContextBuilder::new()
            .with_file(
                "src/lib.rs",
                r#"
fn get_length(opt: Option<String>) -> usize {
    opt.map(|s| s.len()).unwrap_or(0)
}
"#,
            )
            .build();

        let mutation = MapUnwrapOrMutation::new();
        let result = ASTMutationEngine::execute_ast_reg(&mutation, &mut ctx);

        assert_eq!(result.result.changes, 1);
    }

    #[test]
    fn test_v2_map_unwrap_or_else() {
        let mut ctx = ContextBuilder::new()
            .with_file(
                "src/lib.rs",
                r#"
fn get_length(opt: Option<String>) -> usize {
    opt.map(|s| s.len()).unwrap_or_else(|| compute_default())
}

fn compute_default() -> usize { 0 }
"#,
            )
            .build();

        let mutation = MapUnwrapOrMutation::new();
        let result = ASTMutationEngine::execute_ast_reg(&mutation, &mut ctx);

        assert_eq!(result.result.changes, 1);
    }

    #[test]
    fn test_v2_map_unwrap_or_no_changes() {
        let mut ctx = ContextBuilder::new()
            .with_file(
                "src/lib.rs",
                r#"
fn get_length(opt: Option<String>) -> usize {
    opt.map_or(0, |s| s.len())
}
"#,
            )
            .build();

        let mutation = MapUnwrapOrMutation::new();
        let result = ASTMutationEngine::execute_ast_reg(&mutation, &mut ctx);

        assert_eq!(result.result.changes, 0);
    }
}