use std::collections::VecDeque;

use super::value::*;

use super::store::*;

use super::error::*;

use crate::protocol::*;

use crate::protocol::ast::*;

use crate::protocol::type_table::*;

macro_rules! debug_log {

    ($format:literal) => {

    };

    ($format:literal, $($args:expr),*) => {

    };

}

#[derive(Debug, Clone)]

pub(crate) enum ExprInstruction {

    EvalExpr(ExpressionId),

    PushValToFront,

}

#[derive(Debug, Clone)]

pub(crate) struct Frame {

    pub(crate) definition: ProcedureDefinitionId,

    pub(crate) monomorph_type_id: TypeId,

    pub(crate) monomorph_index: usize,

    pub(crate) position: StatementId,

    pub(crate) expr_stack: VecDeque<ExprInstruction>, // hack for expression evaluation, evaluated by popping from back

    pub(crate) expr_values: VecDeque<Value>, // hack for expression results, evaluated by popping from front/back

    pub(crate) max_stack_size: u32,

}

impl Frame {

    /// Creates a new execution frame. Does not modify the stack in any way.

    pub fn new(heap: &Heap, definition_id: ProcedureDefinitionId, monomorph_type_id: TypeId, monomorph_index: u32) -> Self {

        let definition = &heap[definition_id];

        let outer_scope_id = definition.scope;

        let first_statement_id = definition.body;

        // Another not-so-pretty thing that has to be replaced somewhere in the

        // future...

        fn determine_max_stack_size(heap: &Heap, scope_id: ScopeId, max_size: &mut u32) {

            let scope = &heap[scope_id];

            // Check current block

            let cur_size = scope.next_unique_id_in_scope as u32;

            if cur_size > *max_size { *max_size = cur_size; }

            // And child blocks

            for child_scope in &scope.nested {

                determine_max_stack_size(heap, *child_scope, max_size);

            }

        }

        let mut max_stack_size = 0;

        determine_max_stack_size(heap, outer_scope_id, &mut max_stack_size);

        Frame{

            definition: definition_id,

            monomorph_type_id,

        // array into a heap region (e.g. constructing arrays or structs).

        fn transfer_expression_values_front_into_heap(cur_frame: &mut Frame, store: &mut Store, num_values: usize) -> HeapPos {

            let heap_pos = store.alloc_heap();

            // Do the transformation first (because Rust...)

            for val_idx in 0..num_values {

                cur_frame.expr_values[val_idx] = store.read_take_ownership(cur_frame.expr_values[val_idx].clone());

            }

            // And now transfer to the heap region

            let values = &mut store.heap_regions[heap_pos as usize].values;

            debug_assert!(values.is_empty());

            values.reserve(num_values);

            for _ in 0..num_values {

                values.push(cur_frame.expr_values.pop_front().unwrap());

            }

            heap_pos

        }

        // Helper function to make sure that an index into an aray is valid.

        fn array_inclusive_index_is_invalid(store: &Store, array_heap_pos: u32, idx: i64) -> bool {

            let array_len = store.heap_regions[array_heap_pos as usize].values.len();

            return idx < 0 || idx >= array_len as i64;

        }

        fn array_exclusive_index_is_invalid(store: &Store, array_heap_pos: u32, idx: i64) -> bool {

            let array_len = store.heap_regions[array_heap_pos as usize].values.len();

            return idx < 0 || idx > array_len as i64;

        }

        fn construct_array_error(prompt: &Prompt, modules: &[Module], heap: &Heap, expr_id: ExpressionId, heap_pos: u32, idx: i64) -> EvalError {

            let array_len = prompt.store.heap_regions[heap_pos as usize].values.len();

            return EvalError::new_error_at_expr(

                prompt, modules, heap, expr_id,

                format!("index {} is out of bounds: array length is {}", idx, array_len)

            )

        }

        // Checking if we're at the end of execution

        let cur_frame = self.frames.last_mut().unwrap();

        if cur_frame.position.is_invalid() {

            if heap[cur_frame.definition].kind == ProcedureKind::Function {

                todo!("End of function without return, return an evaluation error");

            }

            return Ok(EvalContinuation::ComponentTerminated);

        }

        // Execute all pending expressions

        while !cur_frame.expr_stack.is_empty() {

            let next = cur_frame.expr_stack.pop_back().unwrap();

            debug_log!("Expr stack: {:?}", next);

            match next {

                ExprInstruction::PushValToFront => {

                    cur_frame.expr_values.rotate_right(1);

                },

                ExprInstruction::EvalExpr(expr_id) => {

                    let expr = &heap[expr_id];

                    match expr {

                        Expression::Assignment(expr) => {

                            let to = cur_frame.expr_values.pop_back().unwrap().as_ref();

                            let rhs = cur_frame.expr_values.pop_back().unwrap();

                            // Note: although not pretty, the assignment operator takes ownership

                            // of the right-hand side value when possible. So we do not drop the

                            // rhs's optionally owned heap data.

                            let rhs = self.store.read_take_ownership(rhs);

                            apply_assignment_operator(&mut self.store, to, expr.operation, rhs);

                        },

                        Expression::Binding(_expr) => {

                            let bind_to = cur_frame.expr_values.pop_back().unwrap();

                            let bind_from = cur_frame.expr_values.pop_back().unwrap();

                            let bind_to_heap_pos = bind_to.get_heap_pos();

                            let bind_from_heap_pos = bind_from.get_heap_pos();

                            let result = apply_binding_operator(&mut self.store, bind_to, bind_from);

                            self.store.drop_value(bind_to_heap_pos);

                            self.store.drop_value(bind_from_heap_pos);

                            cur_frame.expr_values.push_back(Value::Bool(result));

                        },

                        Expression::Conditional(expr) => {

                            // Evaluate testing expression, then extend the

                            // expression stack with the appropriate expression

                            let test_result = cur_frame.expr_values.pop_back().unwrap().as_bool();

                            if test_result {

                                cur_frame.serialize_expression(heap, expr.true_expression);

                            } else {

                                cur_frame.serialize_expression(heap, expr.false_expression);

                            }

                        },

                        Expression::Binary(expr) => {

                            let lhs = cur_frame.expr_values.pop_back().unwrap();

                            let rhs = cur_frame.expr_values.pop_back().unwrap();

                            let result = apply_binary_operator(&mut self.store, &lhs, expr.operation, &rhs);

                            cur_frame.expr_values.push_back(result);

pub(crate) mod ast_printer;

use std::sync::Mutex;

use crate::collections::{StringPool, StringRef};

use crate::protocol::ast::*;

use crate::protocol::eval::*;

use crate::protocol::input_source::*;

use crate::protocol::parser::*;

use crate::protocol::type_table::*;

pub use parser::type_table::TypeId;

/// A protocol description module

pub struct Module {

    pub(crate) source: InputSource,

    pub(crate) root_id: RootId,

    pub(crate) name: Option<StringRef<'static>>,

}

/// Description of a protocol object, used to configure new connectors.

#[repr(C)]

pub struct ProtocolDescription {

    pub(crate) modules: Vec<Module>,

    pub(crate) heap: Heap,

    pub(crate) types: TypeTable,

    pub(crate) pool: Mutex<StringPool>,

}

#[derive(Debug, Clone)]

pub(crate) struct ComponentState {

    pub(crate) prompt: Prompt,

}

#[derive(Debug)]

pub enum ComponentCreationError {

    ModuleDoesntExist,

    DefinitionDoesntExist,

    DefinitionNotComponent,

    InvalidNumArguments,

    InvalidArgumentType(usize),

    UnownedPort,

    InSync,

}

impl ProtocolDescription {

    pub fn parse(buffer: &[u8]) -> Result<Self, String> {

        let source = InputSource::new(String::new(), Vec::from(buffer));

        let mut parser = Parser::new();

        parser.feed(source).expect("failed to feed source");

        if let Err(err) = parser.parse() {

            println!("ERROR:\n{}", err);

            return Err(format!("{}", err))

        }

        debug_assert_eq!(parser.modules.len(), 1, "only supporting one module here for now");

        let modules: Vec<Module> = parser.modules.into_iter()

            .map(|module| Module{

                source: module.source,

                root_id: module.root_id,

                name: module.name.map(|(_, name)| name)

            })

            .collect();

        return Ok(ProtocolDescription {

            modules,

            heap: parser.heap,

            types: parser.type_table,

            pool: Mutex::new(parser.string_pool),

        });

    }

    pub(crate) fn new_component(

        &self, module_name: &[u8], identifier: &[u8], arguments: ValueGroup

    ) -> Result<Prompt, ComponentCreationError> {

        // Find the module in which the definition can be found

        let module_root = self.lookup_module_root(module_name);

        if module_root.is_none() {

            return Err(ComponentCreationError::ModuleDoesntExist);

        }

        let module_root = module_root.unwrap();

        let root = &self.heap[module_root];

        let definition_id = root.get_definition_ident(&self.heap, identifier);

        if definition_id.is_none() {

            return Err(ComponentCreationError::DefinitionDoesntExist);

        }

        let definition_id = definition_id.unwrap();

        let ast_definition = &self.heap[definition_id];

        if !ast_definition.is_procedure() {

            return Err(ComponentCreationError::DefinitionNotComponent);

        }

        // Make sure that the types of the provided value group matches that of

        // the expected types.

        let ast_definition = ast_definition.as_procedure();

        if !ast_definition.poly_vars.is_empty() || ast_definition.kind == ProcedureKind::Function {

            EC::BlockGet(port_id) => {

                debug_assert_eq!(self.mode, Mode::Sync);

                debug_assert!(self.exec_ctx.stmt.is_none());

                let port_id = port_id_from_eval(port_id);

                let port_handle = comp_ctx.get_port_handle(port_id);

                let port_index = comp_ctx.get_port_index(port_handle);

                if let Some(message) = &self.inbox_main[port_index] {

                    // Check if we can actually receive the message

                    if self.consensus.try_receive_data_message(sched_ctx, comp_ctx, message) {

                        // Message was received. Make sure any blocked peers and

                        // pending messages are handled.

                        let message = self.inbox_main[port_index].take().unwrap();

                        self.handle_received_data_message(sched_ctx, comp_ctx, port_handle);

                        self.exec_ctx.stmt = ExecStmt::PerformedGet(message.content);

                        return Ok(CompScheduling::Immediate);

                    } else {

                        todo!("handle sync failure due to message deadlock");

                        return Ok(CompScheduling::Sleep);

                    }

                } else {

                    // We need to wait

                    self.mode = Mode::BlockedGet;

                    self.mode_port = port_id;

                    return Ok(CompScheduling::Sleep);

                }

            },

            EC::Put(port_id, value) => {

                debug_assert_eq!(self.mode, Mode::Sync);

                sched_ctx.log(&format!("Putting value {:?}", value));

                let port_id = port_id_from_eval(port_id);

                let port_handle = comp_ctx.get_port_handle(port_id);

                let port_info = comp_ctx.get_port(port_handle);

                if port_info.state.is_blocked() {

                    self.mode = Mode::BlockedPut;

                    self.mode_port = port_id;

                    self.mode_value = value;

                    self.exec_ctx.stmt = ExecStmt::PerformedPut; // prepare for when we become unblocked

                    return Ok(CompScheduling::Sleep);

                } else {

                    self.send_data_message_and_wake_up(sched_ctx, comp_ctx, port_handle, value);

                    self.exec_ctx.stmt = ExecStmt::PerformedPut;

                    return Ok(CompScheduling::Immediate);

                }

            },

            EC::SelectStart(num_cases, _num_ports) => {

                debug_assert_eq!(self.mode, Mode::Sync);

                self.select.handle_select_start(num_cases);

                return Ok(CompScheduling::Requeue);

            },

            EC::SelectRegisterPort(case_index, port_index, port_id) => {

                debug_assert_eq!(self.mode, Mode::Sync);

                let port_id = port_id_from_eval(port_id);

                if let Err(_err) = self.select.register_select_case_port(comp_ctx, case_index, port_index, port_id) {

                    todo!("handle registering a port multiple times");

                }

                return Ok(CompScheduling::Immediate);

            },

            EC::SelectWait => {

                debug_assert_eq!(self.mode, Mode::Sync);

                let select_decision = self.select.handle_select_waiting_point(&self.inbox_main, comp_ctx);

                if let SelectDecision::Case(case_index) = select_decision {

                    // Reached a conclusion, so we can continue immediately

                    self.exec_ctx.stmt = ExecStmt::PerformedSelectWait(case_index);

                    self.mode = Mode::Sync;

                    return Ok(CompScheduling::Immediate);

                } else {

                    // No decision yet

                    self.mode = Mode::BlockedSelect;

                    return Ok(CompScheduling::Sleep);

                }

            },

            // Results that can be returned outside of sync mode

            EC::ComponentTerminated => {

                self.mode = Mode::StartExit; // next call we'll take care of the exit

                return Ok(CompScheduling::Immediate);

            },

            EC::SyncBlockStart => {

                debug_assert_eq!(self.mode, Mode::NonSync);

                self.handle_sync_start(sched_ctx, comp_ctx);

                return Ok(CompScheduling::Immediate);

            },

            EC::NewComponent(definition_id, type_id, arguments) => {

                debug_assert_eq!(self.mode, Mode::NonSync);

                self.create_component_and_transfer_ports(

                    sched_ctx, comp_ctx,

                    definition_id, type_id, arguments

                );

                return Ok(CompScheduling::Requeue);

            },

            EC::NewChannel => {

                debug_assert_eq!(self.mode, Mode::NonSync);

                debug_assert!(self.exec_ctx.stmt.is_none());

                let channel = comp_ctx.create_channel();

                self.exec_ctx.stmt = ExecStmt::CreatedChannel((

                    Value::Output(port_id_to_eval(channel.putter_id)),

                    Value::Input(port_id_to_eval(channel.getter_id))

                ));

                self.inbox_main.push(None);

                self.inbox_main.push(None);

                return Ok(CompScheduling::Immediate);

            }

        }

    }

    fn execute_prompt(&mut self, sched_ctx: &SchedulerCtx) -> EvalResult {

        let mut step_result = EvalContinuation::Stepping;

        while let EvalContinuation::Stepping = step_result {

#[test]

fn test_simple_select() {

    let pd = ProtocolDescription::parse(b"

    func infinite_assert<T>(T val, T expected) -> () {

        while (val != expected) { print(\"nope!\"); }

        return ();

    }

    primitive receiver(in<u32> in_a, in<u32> in_b, u32 num_sends) {

        auto num_from_a = 0;

        auto num_from_b = 0;

        while (num_from_a + num_from_b < 2 * num_sends) {

            sync select {

                auto v = get(in_a) -> {

                    print(\"got something from A\");

                    auto _ = infinite_assert(v, num_from_a);

                    num_from_a += 1;

                }

                auto v = get(in_b) -> {

                    print(\"got something from B\");

                    auto _ = infinite_assert(v, num_from_b);

                    num_from_b += 1;

                }

            }

        }

    }

    primitive sender(out<u32> tx, u32 num_sends) {

        auto index = 0;

        while (index < num_sends) {

            sync {

                put(tx, index);

                index += 1;

            }

        }

    }

    composite constructor() {

        auto num_sends = 15;

        channel tx_a -> rx_a;

        channel tx_b -> rx_b;

        new sender(tx_a, num_sends);

        new receiver(rx_a, rx_b, num_sends);

        new sender(tx_b, num_sends);

    }

    ").expect("compilation");

    let rt = Runtime::new(3, false, pd);

    create_component(&rt, "", "constructor", no_args());

}