//! Phase 33-3: If/Else → Select lowering integration tests
//!
//! Tests the pattern matching and lowering of if/else to JoinIR Select instruction.

#[cfg(test)]
mod tests {
    use crate::mir::join_ir::lowering::try_lower_if_to_joinir;
    use crate::mir::join_ir::JoinInst;
    use crate::mir::{
        BasicBlock, BasicBlockId, MirFunction, MirInstruction, MirModule, ValueId,
    };
    use std::collections::BTreeMap;

    /// Helper to create a simple if/else function matching the "simple" pattern
    fn create_simple_pattern_mir() -> MirFunction {
        let mut blocks = BTreeMap::new();

        // Entry block (bb0): branch on cond
        let mut entry = BasicBlock::new(BasicBlockId::new(0));
        entry.terminator = Some(MirInstruction::Branch {
            condition: ValueId(0), // cond parameter
            then_bb: BasicBlockId::new(1),
            else_bb: BasicBlockId::new(2),
        });
        blocks.insert(BasicBlockId::new(0), entry);

        // Then block (bb1): return 10
        // NOTE: Pattern matcher expects empty blocks (Return only)
        let mut then_block = BasicBlock::new(BasicBlockId::new(1));
        then_block.terminator = Some(MirInstruction::Return {
            value: Some(ValueId(1)), // Assumes ValueId(1) is const 10
        });
        blocks.insert(BasicBlockId::new(1), then_block);

        // Else block (bb2): return 20
        // NOTE: Pattern matcher expects empty blocks (Return only)
        let mut else_block = BasicBlock::new(BasicBlockId::new(2));
        else_block.terminator = Some(MirInstruction::Return {
            value: Some(ValueId(2)), // Assumes ValueId(2) is const 20
        });
        blocks.insert(BasicBlockId::new(2), else_block);

        use crate::mir::{EffectMask, MirType};
        use crate::mir::function::FunctionMetadata;
        use std::collections::HashMap;

        MirFunction {
            signature: crate::mir::FunctionSignature {
                name: "IfSelectTest.test/1".to_string(),
                params: vec![MirType::Unknown],
                return_type: MirType::Integer,
                effects: EffectMask::PURE,
            },
            entry_block: BasicBlockId::new(0),
            blocks: blocks.into_iter().collect(),
            locals: vec![],
            params: vec![ValueId(0)],
            next_value_id: 3,
            metadata: FunctionMetadata::default(),
        }
    }

    /// Helper to create a local pattern function
    fn create_local_pattern_mir() -> MirFunction {
        let mut blocks = BTreeMap::new();

        // Entry block (bb0): branch on cond
        let mut entry = BasicBlock::new(BasicBlockId::new(0));
        entry.terminator = Some(MirInstruction::Branch {
            condition: ValueId(0), // cond
            then_bb: BasicBlockId::new(1),
            else_bb: BasicBlockId::new(2),
        });
        blocks.insert(BasicBlockId::new(0), entry);

        // Then block (bb1): x = 100; jump merge
        // NOTE: Pattern matcher expects exactly 1 Copy instruction
        let mut then_block = BasicBlock::new(BasicBlockId::new(1));
        then_block.instructions.push(MirInstruction::Copy {
            dst: ValueId(3), // x
            src: ValueId(10), // Assumes ValueId(10) is const 100
        });
        then_block.terminator = Some(MirInstruction::Jump {
            target: BasicBlockId::new(3),
        });
        blocks.insert(BasicBlockId::new(1), then_block);

        // Else block (bb2): x = 200; jump merge
        // NOTE: Pattern matcher expects exactly 1 Copy instruction
        let mut else_block = BasicBlock::new(BasicBlockId::new(2));
        else_block.instructions.push(MirInstruction::Copy {
            dst: ValueId(3), // x
            src: ValueId(20), // Assumes ValueId(20) is const 200
        });
        else_block.terminator = Some(MirInstruction::Jump {
            target: BasicBlockId::new(3),
        });
        blocks.insert(BasicBlockId::new(2), else_block);

        // Merge block (bb3): return x
        let mut merge_block = BasicBlock::new(BasicBlockId::new(3));
        merge_block.terminator = Some(MirInstruction::Return {
            value: Some(ValueId(3)),
        });
        blocks.insert(BasicBlockId::new(3), merge_block);

        use crate::mir::{EffectMask, MirType};
        use crate::mir::function::FunctionMetadata;
        use std::collections::HashMap;

        MirFunction {
            signature: crate::mir::FunctionSignature {
                name: "IfSelectTest.main/0".to_string(),
                params: vec![],
                return_type: MirType::Integer,
                effects: EffectMask::PURE,
            },
            entry_block: BasicBlockId::new(0),
            blocks: blocks.into_iter().collect(),
            locals: vec![],
            params: vec![],
            next_value_id: 21,
            metadata: FunctionMetadata::default(),
        }
    }

    #[test]
    fn test_if_select_simple_pattern() {
        // Set environment variable for this test
        std::env::set_var("NYASH_JOINIR_IF_SELECT", "1");

        let func = create_simple_pattern_mir();
        let entry_block = func.entry_block;

        // Try to lower to JoinIR
        let result = try_lower_if_to_joinir(&func, entry_block, true);

        assert!(
            result.is_some(),
            "Expected simple pattern to be lowered to Select"
        );

        if let Some(JoinInst::Select {
            dst,
            cond,
            then_val,
            else_val,
        }) = result
        {
            eprintln!("✅ Simple pattern successfully lowered to Select");
            eprintln!("   dst: {:?}, cond: {:?}, then: {:?}, else: {:?}", dst, cond, then_val, else_val);
        } else {
            panic!("Expected JoinInst::Select, got {:?}", result);
        }

        // Clean up
        std::env::remove_var("NYASH_JOINIR_IF_SELECT");
    }

    #[test]
    fn test_if_select_local_pattern() {
        std::env::set_var("NYASH_JOINIR_IF_SELECT", "1");

        let func = create_local_pattern_mir();
        let entry_block = func.entry_block;

        // Try to lower to JoinIR
        let result = try_lower_if_to_joinir(&func, entry_block, true);

        assert!(
            result.is_some(),
            "Expected local pattern to be lowered to Select"
        );

        if let Some(JoinInst::Select {
            dst,
            cond,
            then_val,
            else_val,
        }) = result
        {
            eprintln!("✅ Local pattern successfully lowered to Select");
            eprintln!("   dst: {:?}, cond: {:?}, then: {:?}, else: {:?}", dst, cond, then_val, else_val);
        } else {
            panic!("Expected JoinInst::Select, got {:?}", result);
        }

        std::env::remove_var("NYASH_JOINIR_IF_SELECT");
    }

    #[test]
    fn test_if_select_disabled_by_default() {
        // Ensure environment variable is NOT set
        std::env::remove_var("NYASH_JOINIR_IF_SELECT");

        let func = create_simple_pattern_mir();
        let entry_block = func.entry_block;

        // Should return None when disabled
        let result = try_lower_if_to_joinir(&func, entry_block, false);

        assert!(
            result.is_none(),
            "Expected None when NYASH_JOINIR_IF_SELECT is not set"
        );

        eprintln!("✅ If/Select lowering correctly disabled by default");
    }

    #[test]
    fn test_if_select_wrong_function_name() {
        std::env::set_var("NYASH_JOINIR_IF_SELECT", "1");

        // Create function with wrong name (not IfSelectTest.*)
        let mut func = create_simple_pattern_mir();
        func.signature.name = "WrongName.test/1".to_string();

        let entry_block = func.entry_block;

        // Should return None for non-IfSelectTest functions
        let result = try_lower_if_to_joinir(&func, entry_block, true);

        assert!(
            result.is_none(),
            "Expected None for non-IfSelectTest functions"
        );

        eprintln!("✅ Function name filter working correctly");

        std::env::remove_var("NYASH_JOINIR_IF_SELECT");
    }
}