use std::collections::HashMap;

use num::One;
use rand::{random, thread_rng, Rng};
use twenty_first::shared_math::b_field_element::BFieldElement;
use twenty_first::shared_math::other::random_elements;

use crate::rust_shadowing_helper_functions::unsafe_list::untyped_unsafe_insert_random_list;
use crate::snippet::{DataType, Snippet};
use crate::snippet_state::SnippetState;
use crate::{get_init_tvm_stack, ExecutionState};

#[derive(Clone, Debug)]
pub struct UnsafePush(pub DataType);

/// A parameterized version of `Push` where `N` is the size of an element in the list
impl Snippet for UnsafePush {
    fn inputs(&self) -> Vec<String> {
        let element_size = self.0.get_size();

        // _ *list, elem{{N - 1}}, elem{{N - 2}}, ..., elem{{0}}
        let mut ret = vec!["*list".to_string()];
        for i in 0..element_size {
            ret.push(format!("element_{}", element_size - 1 - i));
        }

        ret
    }

    fn outputs(&self) -> Vec<String> {
        vec![]
    }

    fn input_types(&self) -> Vec<crate::snippet::DataType> {
        vec![DataType::List(Box::new(self.0.clone())), self.0.clone()]
    }

    fn output_types(&self) -> Vec<crate::snippet::DataType> {
        vec![]
    }

    fn crash_conditions(&self) -> Vec<String> {
        vec![]
    }

    fn gen_input_states(&self) -> Vec<ExecutionState> {
        vec![
            prepare_state(&self.0),
            prepare_state(&self.0),
            prepare_state(&self.0),
            prepare_state(&self.0),
        ]
    }

    fn stack_diff(&self) -> isize {
        -(self.0.get_size() as isize) - 1
    }

    fn entrypoint(&self) -> String {
        format!("tasm_list_unsafe_u32_push_{}", self.0.label_friendly_name())
    }

    // Push *one* element of size N to stack
    fn function_code(&self, _library: &mut SnippetState) -> String {
        let element_size = self.0.get_size();
        // write the elements to memory
        // Start and end of this loop: _  *list, [elements..], address_of_next_element -- top of stack is where we will store elements
        let mut write_elements_to_memory_code = String::default();
        for i in 0..element_size {
            write_elements_to_memory_code.push_str("swap 1\n");
            write_elements_to_memory_code.push_str("write_mem\n");
            if i != element_size - 1 {
                // Prepare for next write. Not needed for last iteration.
                write_elements_to_memory_code.push_str("push 1\n");
                write_elements_to_memory_code.push_str("add\n");
            }
        }

        let mul_with_size = if element_size != 1 {
            format!("push {element_size}\n mul\n")
        } else {
            String::default()
        };

        let entry_point = self.entrypoint();
        format!(
            "
            // Before: _ *list, elem{{N - 1}}, elem{{N - 2}}, ..., elem{{0}}
            // After: _
            {entry_point}:
                dup {element_size}
                // stack : _  *list, elem{{N - 1}}, elem{{N - 2}}, ..., elem{{0}}, *list

                read_mem
                // stack : _  *list, elem{{N - 1}}, elem{{N - 2}}, ..., elem{{0}}, *list, length

                {mul_with_size}
                // stack : _  *list, elem{{N - 1}}, elem{{N - 2}}, ..., elem{{0}}, *list, length * elem_size

                push 1
                add
                // stack : _  *list, elem{{N - 1}}, elem{{N - 2}}, ..., elem{{0}}, *list, length * elem_size + 1 -- top of stack is offset for where we will store elements

                add
                // stack : _  *list, elem{{N - 1}}, elem{{N - 2}}, ..., elem{{0}}, *list + length * elem_size + 1 -- top of stack is where we will store elements

                {write_elements_to_memory_code}
                // stack : _  *list, *list + length * elem_size + 1

                pop
                // stack : _  *list

                // Increase length indicator by one
                read_mem
                push 1
                add
                // stack : _  *list, length + 1

                write_mem
                pop
                // stack : _

                return
                "
        )
    }

    fn rust_shadowing(
        &self,
        stack: &mut Vec<BFieldElement>,
        _std_in: Vec<BFieldElement>,
        _secret_in: Vec<BFieldElement>,
        memory: &mut HashMap<BFieldElement, BFieldElement>,
    ) {
        let list_address = stack[stack.len() - 1 - self.0.get_size()];
        let initial_list_length = memory[&list_address];

        let mut next_free_address = list_address
            + initial_list_length * BFieldElement::new(self.0.get_size() as u64)
            + BFieldElement::one();

        for _ in 0..self.0.get_size() {
            let elem = stack.pop().unwrap();
            memory.insert(next_free_address, elem);
            next_free_address += BFieldElement::one();
        }

        // Remove list pointer
        stack.pop().unwrap();

        // Update length indicator
        memory.insert(list_address, initial_list_length + BFieldElement::one());
    }

    fn common_case_input_state(&self) -> ExecutionState {
        prepare_state(&self.0)
    }

    fn worst_case_input_state(&self) -> ExecutionState {
        prepare_state(&self.0)
    }
}

fn prepare_state(data_type: &DataType) -> ExecutionState {
    let list_pointer: u32 = random();
    let list_pointer = BFieldElement::new(list_pointer as u64);
    let init_length: usize = thread_rng().gen_range(0..100);
    let mut stack = get_init_tvm_stack();
    stack.push(list_pointer);
    let mut push_value: Vec<BFieldElement> = random_elements(data_type.get_size());
    while let Some(element) = push_value.pop() {
        stack.push(element);
    }

    let mut memory = HashMap::default();
    untyped_unsafe_insert_random_list(list_pointer, init_length, &mut memory, data_type.get_size());
    ExecutionState::with_stack_and_memory(stack, memory, 0)
}

#[cfg(test)]
mod tests {
    use twenty_first::shared_math::b_field_element::BFieldElement;

    use crate::get_init_tvm_stack;

    use crate::test_helpers::{
        test_rust_equivalence_given_input_values, test_rust_equivalence_multiple,
    };

    use super::*;

    #[test]
    fn new_snippet_test() {
        test_rust_equivalence_multiple(&UnsafePush(DataType::Bool), true);
        test_rust_equivalence_multiple(&UnsafePush(DataType::U64), true);
        test_rust_equivalence_multiple(&UnsafePush(DataType::XFE), true);
        test_rust_equivalence_multiple(&UnsafePush(DataType::Digest), true);
    }

    #[test]
    fn list_u32_n_is_one_push() {
        let list_address = BFieldElement::new(48);
        let push_value = vec![BFieldElement::new(1337)];
        prop_push(DataType::BFE, list_address, 20, push_value);
    }

    #[test]
    fn list_u32_n_is_two_push() {
        let list_address = BFieldElement::new(1841);
        let push_value = vec![BFieldElement::new(133700), BFieldElement::new(32)];
        prop_push(DataType::U64, list_address, 20, push_value);
    }

    #[test]
    fn list_u32_n_is_five_push() {
        let list_address = BFieldElement::new(558);
        let push_value = vec![
            BFieldElement::new(133700),
            BFieldElement::new(32),
            BFieldElement::new(133700),
            BFieldElement::new(19990),
            BFieldElement::new(88888888),
        ];
        prop_push(DataType::Digest, list_address, 2313, push_value);
    }

    fn prop_push(
        data_type: DataType,
        list_address: BFieldElement,
        init_list_length: u32,
        push_value: Vec<BFieldElement>,
    ) {
        assert_eq!(
            data_type.get_size(),
            push_value.len(),
            "Push value length must match data size"
        );
        let expected_end_stack = get_init_tvm_stack();
        let mut init_stack = get_init_tvm_stack();
        init_stack.push(list_address);

        for i in 0..data_type.get_size() {
            init_stack.push(push_value[data_type.get_size() - 1 - i]);
        }
        let mut memory = HashMap::default();

        untyped_unsafe_insert_random_list(
            list_address,
            init_list_length as usize,
            &mut memory,
            data_type.get_size(),
        );

        test_rust_equivalence_given_input_values(
            &UnsafePush(data_type.clone()),
            &init_stack,
            &[],
            &[],
            &mut memory,
            0,
            Some(&expected_end_stack),
        );

        // Verify that length indicator has increased by one
        assert_eq!(
            BFieldElement::new((init_list_length + 1) as u64),
            memory[&list_address]
        );

        // verify that value was inserted at expected place
        for i in 0..data_type.get_size() {
            assert_eq!(
                push_value[i],
                memory[&BFieldElement::new(
                    list_address.value()
                        + 1
                        + data_type.get_size() as u64 * init_list_length as u64
                        + i as u64
                )]
            );
        }
    }
}

#[cfg(test)]
mod benches {
    use super::*;
    use crate::snippet_bencher::bench_and_write;

    #[test]
    fn unsafe_push_benchmark() {
        bench_and_write(UnsafePush(DataType::Digest));
    }
}