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use super::IsPass;
use crate::ir::editor::Editor;
use serde::{Deserialize, Serialize};

/// This pass will remove all load instructions which are
/// - in same block with a store instruction
/// - after the store instruction.
#[derive(Copy, Clone, Debug, Hash, PartialEq, Eq, Deserialize, Serialize)]
pub struct RemoveLoadDirectlyAfterStore;

impl IsPass for RemoveLoadDirectlyAfterStore {
    fn run(&self, editor: &mut Editor) {
        let mut to_remove = Vec::new();
        let mut to_rename = Vec::new();
        let binding = editor.binded_analyzer();
        let binding = binding.memory_usage();
        let variables = binding.memory_access_variables();
        for variable in variables {
            let binded_analyzer = editor.binded_analyzer();
            let memory_usage = binded_analyzer.memory_usage();
            let memory_access_info = memory_usage.memory_access_info(variable);
            for store_statement_index in &memory_access_info.store {
                let store_statement = editor.content[store_statement_index.clone()].as_store();
                let stored_value = store_statement.source.clone();
                for load_statement_index in
                    memory_access_info.loads_dorminated_by_store_in_block(store_statement_index)
                {
                    let load_statement = editor.content[load_statement_index.clone()].as_load();
                    to_remove.push(load_statement_index);
                    to_rename.push((load_statement.to.clone(), stored_value.clone()));
                }
            }
        }
        editor.remove_statements(to_remove);
        for (from, to) in to_rename {
            editor.rename_local(from, to);
        }
    }

    fn need(&self) -> Vec<super::Pass> {
        Vec::new()
    }

    fn invalidate(&self) -> Vec<super::Pass> {
        Vec::new()
    }
}

#[cfg(test)]
mod tests {
    #![allow(clippy::borrow_interior_mutable_const)]

    use crate::{
        ir::{
            self,
            function::basic_block::BasicBlock,
            statement::{
                calculate::binary::BinaryOperation, Alloca, BinaryCalculate, IRStatement, Jump,
                Load, Ret, Store,
            },
            FunctionDefinition, RegisterName,
        },
        utility::data_type::{self, Type},
    };

    use super::*;

    #[test]
    fn run() {
        let function = FunctionDefinition {
            header: ir::FunctionHeader {
                name: "f".to_string(),
                parameters: Vec::new(),
                return_type: Type::None,
            },
            content: vec![
                BasicBlock {
                    name: Some("bb0".to_string()),
                    content: vec![
                        Alloca {
                            to: RegisterName("0".to_string()),
                            alloc_type: data_type::I32.clone(),
                        }
                        .into(),
                        Alloca {
                            to: RegisterName("1".to_string()),
                            alloc_type: data_type::I32.clone(),
                        }
                        .into(),
                        Store {
                            data_type: data_type::I32.clone(),
                            source: 42.into(),
                            target: RegisterName("0".to_string()).into(),
                        }
                        .into(),
                        Store {
                            data_type: data_type::I32.clone(),
                            source: 43.into(),
                            target: RegisterName("1".to_string()).into(),
                        }
                        .into(),
                        Load {
                            to: RegisterName("3".to_string()),
                            data_type: data_type::I32.clone(),
                            from: RegisterName("0".to_string()).into(),
                        }
                        .into(),
                        BinaryCalculate {
                            operation: BinaryOperation::Add,
                            operand1: RegisterName("3".to_string()).into(),
                            operand2: 44.into(),
                            to: RegisterName("4".to_string()),
                            data_type: data_type::I32.clone(),
                        }
                        .into(),
                        Load {
                            to: RegisterName("5".to_string()),
                            data_type: data_type::I32.clone(),
                            from: RegisterName("0".to_string()).into(),
                        }
                        .into(),
                        BinaryCalculate {
                            operation: BinaryOperation::Add,
                            operand1: RegisterName("5".to_string()).into(),
                            operand2: 45.into(),
                            to: RegisterName("6".to_string()),
                            data_type: data_type::I32.clone(),
                        }
                        .into(),
                        Jump {
                            label: "bb1".to_string(),
                        }
                        .into(),
                    ],
                },
                BasicBlock {
                    name: Some("bb1".to_string()),
                    content: vec![
                        Load {
                            to: RegisterName("2".to_string()),
                            data_type: data_type::I32.clone(),
                            from: RegisterName("0".to_string()).into(),
                        }
                        .into(),
                        BinaryCalculate {
                            operation: BinaryOperation::Add,
                            operand1: RegisterName("2".to_string()).into(),
                            operand2: 46.into(),
                            to: RegisterName("7".to_string()),
                            data_type: data_type::I32.clone(),
                        }
                        .into(),
                        Ret { value: None }.into(),
                    ],
                },
            ],
        };

        let mut editor = Editor::new(function);
        let pass = RemoveLoadDirectlyAfterStore;
        pass.run(&mut editor);

        assert_eq!(editor.content[0].content.len(), 7);
        assert_eq!(
            editor.content[0]
                .content
                .iter()
                .filter(|it| matches!(it, IRStatement::Load(_)))
                .count(),
            0
        );
        assert_eq!(editor.content[1].content.len(), 3);
    }
}