/*!
 * LLVM Compiler Implementation - Compile MIR to LLVM IR and native code
 */

use crate::mir::function::MirModule;
use crate::mir::instruction::{MirInstruction, ConstValue, BinaryOp, UnaryOp, CompareOp};
use crate::mir::ValueId;
use crate::box_trait::{NyashBox, IntegerBox, FloatBox, StringBox, BoolBox, NullBox};
use super::context::CodegenContext;
use std::collections::HashMap;

/// Mock LLVM Compiler with MIR interpreter for demonstration
/// This simulates LLVM behavior by interpreting MIR instructions
pub struct LLVMCompiler {
    /// Values stored during mock execution
    values: HashMap<ValueId, Box<dyn NyashBox>>,
}

impl LLVMCompiler {
    pub fn new() -> Result<Self, String> {
        Ok(Self {
            values: HashMap::new(),
        })
    }
    
    pub fn compile_module(
        &self,
        mir_module: &MirModule,
        output_path: &str,
    ) -> Result<(), String> {
        // Mock implementation - in a real scenario this would:
        // 1. Create LLVM context and module
        // 2. Convert MIR instructions to LLVM IR
        // 3. Generate object file
        
        println!("🔧 Mock LLVM Compilation:");
        println!("   Module: {}", mir_module.name);
        println!("   Functions: {}", mir_module.functions.len());
        println!("   Output: {}", output_path);
        
        // Find main function 
        let main_func = mir_module.functions.get("Main.main")
            .ok_or("Main.main function not found")?;
            
        println!("   Main function found with {} blocks", main_func.blocks.len());
        
        // Simulate object file generation
        std::fs::write(output_path, b"Mock object file")?;
        println!("   ✅ Mock object file created");
        
        Ok(())
    }
    
    pub fn compile_and_execute(
        &mut self,
        mir_module: &MirModule,
        temp_path: &str,
    ) -> Result<Box<dyn NyashBox>, String> {
        // Mock implementation - interprets MIR instructions to simulate execution
        
        println!("🚀 Mock LLVM Compile & Execute (MIR Interpreter Mode):");
        
        // 1. Mock object file generation
        let obj_path = format!("{}.o", temp_path);
        self.compile_module(mir_module, &obj_path)?;
        
        // 2. Find and execute main function
        let main_func = mir_module.functions.get("Main.main")
            .ok_or("Main.main function not found")?;
        
        println!("   ⚡ Interpreting MIR instructions...");
        
        // 3. Execute MIR instructions
        let result = self.interpret_function(main_func)?;
        
        // 4. Cleanup mock files
        let _ = std::fs::remove_file(&obj_path);
        
        Ok(result)
    }
    
    /// Interpret a MIR function by executing its instructions
    fn interpret_function(
        &mut self,
        func: &crate::mir::function::MirFunction,
    ) -> Result<Box<dyn NyashBox>, String> {
        // Clear value storage
        self.values.clear();
        
        // For now, just execute the entry block
        if let Some(entry_block) = func.blocks.get(&0) {
            for inst in &entry_block.instructions {
                match inst {
                    MirInstruction::Const { dst, value } => {
                        let nyash_value = match value {
                            ConstValue::Integer(i) => Box::new(IntegerBox::new(*i)) as Box<dyn NyashBox>,
                            ConstValue::Float(f) => Box::new(FloatBox::new(*f)) as Box<dyn NyashBox>,
                            ConstValue::String(s) => Box::new(StringBox::new(s.clone())) as Box<dyn NyashBox>,
                            ConstValue::Bool(b) => Box::new(BoolBox::new(*b)) as Box<dyn NyashBox>,
                            ConstValue::Null => Box::new(NullBox::new()) as Box<dyn NyashBox>,
                        };
                        self.values.insert(*dst, nyash_value);
                        println!("   📝 %{} = const {:?}", dst.0, value);
                    }
                    
                    MirInstruction::BinOp { dst, op, lhs, rhs } => {
                        // Get operands
                        let left = self.values.get(lhs)
                            .ok_or_else(|| format!("Value %{} not found", lhs.0))?;
                        let right = self.values.get(rhs)
                            .ok_or_else(|| format!("Value %{} not found", rhs.0))?;
                        
                        // Simple integer arithmetic for now
                        if let (Some(l), Some(r)) = (left.as_any().downcast_ref::<IntegerBox>(), 
                                                      right.as_any().downcast_ref::<IntegerBox>()) {
                            let result = match op {
                                BinaryOp::Add => l.value() + r.value(),
                                BinaryOp::Sub => l.value() - r.value(),
                                BinaryOp::Mul => l.value() * r.value(),
                                BinaryOp::Div => {
                                    if r.value() == 0 {
                                        return Err("Division by zero".to_string());
                                    }
                                    l.value() / r.value()
                                }
                                BinaryOp::Mod => l.value() % r.value(),
                            };
                            self.values.insert(*dst, Box::new(IntegerBox::new(result)));
                            println!("   📊 %{} = %{} {:?} %{} = {}", dst.0, lhs.0, op, rhs.0, result);
                        } else {
                            return Err("Binary operation on non-integer values not supported in mock".to_string());
                        }
                    }
                    
                    MirInstruction::Return { value } => {
                        if let Some(val_id) = value {
                            let result = self.values.get(val_id)
                                .ok_or_else(|| format!("Return value %{} not found", val_id.0))?
                                .clone_box();
                            println!("   ✅ Returning value from %{}", val_id.0);
                            return Ok(result);
                        } else {
                            println!("   ✅ Void return");
                            return Ok(Box::new(IntegerBox::new(0)));
                        }
                    }
                    
                    _ => {
                        // Other instructions not yet implemented
                        println!("   ⚠️  Skipping instruction: {:?}", inst);
                    }
                }
            }
        }
        
        // Default return
        Ok(Box::new(IntegerBox::new(0)))
    }
}

// The real implementation would look like this with proper LLVM libraries:
/*
#[cfg(feature = "llvm")]
use inkwell::context::Context;

#[cfg(feature = "llvm")]
pub struct LLVMCompiler {
    context: Context,
}

#[cfg(feature = "llvm")]
impl LLVMCompiler {
    pub fn new() -> Result<Self, String> {
        Ok(Self {
            context: Context::create(),
        })
    }
    
    pub fn compile_module(
        &self,
        mir_module: &MirModule,
        output_path: &str,
    ) -> Result<(), String> {
        let codegen = CodegenContext::new(&self.context, "nyash_module")?;
        
        // 1. main関数を探す
        let main_func = mir_module.functions.get("Main.main")
            .ok_or("Main.main function not found")?;
        
        // 2. LLVM関数を作成
        let i32_type = codegen.context.i32_type();
        let fn_type = i32_type.fn_type(&[], false);
        let llvm_func = codegen.module.add_function("main", fn_type, None);
        
        // 3. エントリブロックを作成
        let entry = codegen.context.append_basic_block(llvm_func, "entry");
        codegen.builder.position_at_end(entry);
        
        // 4. MIR命令を処理
        for (_block_id, block) in &main_func.blocks {
            for inst in &block.instructions {
                match inst {
                    MirInstruction::Return { value: Some(_value_id) } => {
                        let ret_val = i32_type.const_int(42, false);
                        codegen.builder.build_return(Some(&ret_val)).unwrap();
                    }
                    MirInstruction::Return { value: None } => {
                        let ret_val = i32_type.const_int(0, false);
                        codegen.builder.build_return(Some(&ret_val)).unwrap();
                    }
                    _ => {
                        // 他の命令は今回スキップ
                    }
                }
            }
        }
        
        // 5. 検証
        if !llvm_func.verify(true) {
            return Err("Function verification failed".to_string());
        }
        
        // 6. オブジェクトファイル生成
        codegen.target_machine
            .write_to_file(&codegen.module, 
                         inkwell::targets::FileType::Object, 
                         output_path.as_ref())
            .map_err(|e| format!("Failed to write object file: {}", e))?;
        
        Ok(())
    }
    
    // ... rest of implementation
}
*/

#[cfg(test)]
mod tests {
    use super::*;
    
    #[test]
    fn test_compiler_creation() {
        let compiler = LLVMCompiler::new();
        assert!(compiler.is_ok());
    }
}