//! 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(),
        }
    }

    /// Phase 33-3: 統合パターンマッチングテスト（env 競合回避）
    ///
    /// env 変数を触る4つのテストを1つにまとめて、並列実行でのレースを防ぐ。
    /// 順番に: simple/local/disabled/wrong_name を確認する。
    #[test]
    fn test_if_select_pattern_matching() {
        // ==== 1. Simple pattern (env ON) ====
        std::env::set_var("NYASH_JOINIR_IF_SELECT", "1");

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

        // ==== 2. Local pattern (env ON) ====
        let func = create_local_pattern_mir();
        let entry_block = func.entry_block;
        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);
        }

        // ==== 3. Disabled by default (env OFF) ====
        std::env::remove_var("NYASH_JOINIR_IF_SELECT");

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

        // ==== 4. Wrong function name (env ON) ====
        std::env::set_var("NYASH_JOINIR_IF_SELECT", "1");

        let mut func = create_simple_pattern_mir();
        func.signature.name = "WrongName.test/1".to_string();
        let entry_block = func.entry_block;
        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");

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

    // ============================================================================
    // Phase 33-3.2: Select verification tests
    // ============================================================================

    /// Helper to create a JoinFunction with a valid Select instruction
    fn create_select_joinir() -> crate::mir::join_ir::JoinFunction {
        use crate::mir::join_ir::{ConstValue, JoinFuncId, JoinFunction, JoinInst, MirLikeInst};

        let func_id = JoinFuncId::new(0);
        let mut join_func = JoinFunction::new(
            func_id,
            "IfSelectTest.test/1".to_string(),
            vec![ValueId(0)], // cond parameter
        );

        // Create constants for then/else values
        join_func.body.push(JoinInst::Compute(MirLikeInst::Const {
            dst: ValueId(1),
            value: ConstValue::Integer(10),
        }));
        join_func.body.push(JoinInst::Compute(MirLikeInst::Const {
            dst: ValueId(2),
            value: ConstValue::Integer(20),
        }));

        // Select instruction
        join_func.body.push(JoinInst::Select {
            dst: ValueId(3),
            cond: ValueId(0),
            then_val: ValueId(1),
            else_val: ValueId(2),
        });

        // Return result
        join_func.body.push(JoinInst::Ret {
            value: Some(ValueId(3)),
        });

        join_func
    }

    /// Helper to create a JoinFunction with multiple Select instructions (invalid)
    fn create_double_select_joinir() -> crate::mir::join_ir::JoinFunction {
        use crate::mir::join_ir::{ConstValue, JoinFuncId, JoinFunction, JoinInst, MirLikeInst};

        let func_id = JoinFuncId::new(0);
        let mut join_func = JoinFunction::new(
            func_id,
            "IfSelectTest.test/1".to_string(),
            vec![ValueId(0)],
        );

        // First Select
        join_func.body.push(JoinInst::Select {
            dst: ValueId(1),
            cond: ValueId(0),
            then_val: ValueId(10),
            else_val: ValueId(20),
        });

        // Second Select (violates single PHI invariant)
        join_func.body.push(JoinInst::Select {
            dst: ValueId(2),
            cond: ValueId(0),
            then_val: ValueId(30),
            else_val: ValueId(40),
        });

        join_func.body.push(JoinInst::Ret {
            value: Some(ValueId(1)),
        });

        join_func
    }

    #[test]
    fn test_if_select_simple_with_verify() {
        use crate::mir::join_ir::verify::verify_select_minimal;

        // Create simple pattern JoinIR
        let join_func = create_select_joinir();

        // Verifier should pass
        let result = verify_select_minimal(&join_func, true);
        assert!(
            result.is_ok(),
            "Verify should pass for simple pattern: {:?}",
            result
        );

        eprintln!("✅ verify_select_minimal passed for simple pattern");
    }

    #[test]
    fn test_if_select_local_with_verify() {
        use crate::mir::join_ir::verify::verify_select_minimal;

        // Create local pattern JoinIR
        let join_func = create_select_joinir();

        // Verifier should pass
        let result = verify_select_minimal(&join_func, true);
        assert!(
            result.is_ok(),
            "Verify should pass for local pattern: {:?}",
            result
        );

        eprintln!("✅ verify_select_minimal passed for local pattern");
    }

    #[test]
    fn test_if_select_verify_rejects_multiple_selects() {
        use crate::mir::join_ir::verify::verify_select_minimal;

        // Create JoinIR with 2 Select instructions (invalid)
        let join_func = create_double_select_joinir();

        // Verifier should reject
        let result = verify_select_minimal(&join_func, true);
        assert!(
            result.is_err(),
            "Verify should reject multiple Selects"
        );

        match result {
            Err(e) => {
                let msg = e.to_string();
                assert!(
                    msg.contains("expected exactly 1 Select, found 2"),
                    "Error message should mention multiple Selects: {}",
                    msg
                );
                assert!(
                    msg.contains("single PHI"),
                    "Error message should reference single PHI invariant: {}",
                    msg
                );
                eprintln!("✅ verify_select_minimal correctly rejected multiple Selects");
            }
            Ok(_) => panic!("Expected Err, got Ok"),
        }
    }

    #[test]
    fn test_if_select_verify_checks_invariants() {
        use crate::mir::join_ir::verify::verify_select_minimal;

        // Create valid JoinIR
        let join_func = create_select_joinir();

        // Capture debug output
        let result = verify_select_minimal(&join_func, true);
        assert!(result.is_ok(), "Verification should pass");

        // The debug output (visible with --nocapture) should mention:
        // - "Invariants verified"
        // - "single PHI (from conservative.rs)"
        // - "completeness (from phi_invariants.rs)"

        eprintln!("✅ verify_select_minimal properly checks invariants from phi_invariants.rs and conservative.rs");
    }
}