//! Javascript context.

use crate::{
    builtins::{
        self,
        function::{Function, FunctionFlags, NativeFunction},
        iterable::IteratorPrototypes,
        symbol::{Symbol, WellKnownSymbols},
    },
    class::{Class, ClassBuilder},
    exec::Interpreter,
    object::{GcObject, Object, ObjectData, PROTOTYPE},
    property::{Attribute, DataDescriptor, PropertyKey},
    realm::Realm,
    syntax::{
        ast::{
            node::{
                statement_list::RcStatementList, Call, FormalParameter, Identifier, New,
                StatementList,
            },
            Const, Node,
        },
        Parser,
    },
    value::{RcString, RcSymbol, Value},
    BoaProfiler, Executable, Result,
};
use std::result::Result as StdResult;

#[cfg(feature = "console")]
use crate::builtins::console::Console;

#[cfg(feature = "vm")]
use crate::vm::{
    compilation::{CodeGen, Compiler},
    VM,
};

/// Store a builtin constructor (such as `Object`) and its corresponding prototype.
#[derive(Debug, Clone)]
pub struct StandardConstructor {
    pub(crate) constructor: GcObject,
    pub(crate) prototype: GcObject,
}

impl Default for StandardConstructor {
    fn default() -> Self {
        Self {
            constructor: GcObject::new(Object::default()),
            prototype: GcObject::new(Object::default()),
        }
    }
}

impl StandardConstructor {
    /// Build a constructor with a defined prototype.
    fn with_prototype(prototype: Object) -> Self {
        Self {
            constructor: GcObject::new(Object::default()),
            prototype: GcObject::new(prototype),
        }
    }

    /// Return the constructor object.
    ///
    /// This is the same as `Object`, `Array`, etc.
    #[inline]
    pub fn constructor(&self) -> GcObject {
        self.constructor.clone()
    }

    /// Return the prototype of the constructor object.
    ///
    /// This is the same as `Object.prototype`, `Array.prototype`, etc
    #[inline]
    pub fn prototype(&self) -> GcObject {
        self.prototype.clone()
    }
}

/// Cached core standard objects.
#[derive(Debug, Clone)]
pub struct StandardObjects {
    object: StandardConstructor,
    function: StandardConstructor,
    array: StandardConstructor,
    bigint: StandardConstructor,
    number: StandardConstructor,
    boolean: StandardConstructor,
    string: StandardConstructor,
    regexp: StandardConstructor,
    symbol: StandardConstructor,
    error: StandardConstructor,
    type_error: StandardConstructor,
    referece_error: StandardConstructor,
    range_error: StandardConstructor,
    syntax_error: StandardConstructor,
    eval_error: StandardConstructor,
    uri_error: StandardConstructor,
}

impl Default for StandardObjects {
    fn default() -> Self {
        Self {
            object: StandardConstructor::default(),
            function: StandardConstructor::default(),
            array: StandardConstructor::default(),
            bigint: StandardConstructor::default(),
            number: StandardConstructor::with_prototype(Object::number(0.0)),
            boolean: StandardConstructor::with_prototype(Object::boolean(false)),
            string: StandardConstructor::with_prototype(Object::string("")),
            regexp: StandardConstructor::default(),
            symbol: StandardConstructor::default(),
            error: StandardConstructor::default(),
            type_error: StandardConstructor::default(),
            referece_error: StandardConstructor::default(),
            range_error: StandardConstructor::default(),
            syntax_error: StandardConstructor::default(),
            eval_error: StandardConstructor::default(),
            uri_error: StandardConstructor::default(),
        }
    }
}

impl StandardObjects {
    #[inline]
    pub fn object_object(&self) -> &StandardConstructor {
        &self.object
    }

    #[inline]
    pub fn function_object(&self) -> &StandardConstructor {
        &self.function
    }

    #[inline]
    pub fn array_object(&self) -> &StandardConstructor {
        &self.array
    }

    #[inline]
    pub fn bigint_object(&self) -> &StandardConstructor {
        &self.bigint
    }

    #[inline]
    pub fn number_object(&self) -> &StandardConstructor {
        &self.number
    }

    #[inline]
    pub fn boolean_object(&self) -> &StandardConstructor {
        &self.boolean
    }

    #[inline]
    pub fn string_object(&self) -> &StandardConstructor {
        &self.string
    }

    #[inline]
    pub fn regexp_object(&self) -> &StandardConstructor {
        &self.regexp
    }

    #[inline]
    pub fn symbol_object(&self) -> &StandardConstructor {
        &self.symbol
    }

    #[inline]
    pub fn error_object(&self) -> &StandardConstructor {
        &self.error
    }

    #[inline]
    pub fn reference_error_object(&self) -> &StandardConstructor {
        &self.referece_error
    }

    #[inline]
    pub fn type_error_object(&self) -> &StandardConstructor {
        &self.type_error
    }

    #[inline]
    pub fn range_error_object(&self) -> &StandardConstructor {
        &self.range_error
    }

    #[inline]
    pub fn syntax_error_object(&self) -> &StandardConstructor {
        &self.syntax_error
    }

    #[inline]
    pub fn eval_error_object(&self) -> &StandardConstructor {
        &self.eval_error
    }

    pub fn uri_error_object(&self) -> &StandardConstructor {
        &self.uri_error
    }
}

/// Javascript context. It is the primary way to interact with the runtime.
///
/// `Context`s constructed in a thread share the same runtime, therefore it
/// is possible to share objects from one context to another context, but they
/// have to be in the same thread.
#[derive(Debug)]
pub struct Context {
    /// realm holds both the global object and the environment
    realm: Realm,

    /// The current executor.
    executor: Interpreter,

    /// Symbol hash.
    ///
    /// For now this is an incremented u64 number.
    symbol_count: u64,

    /// console object state.
    #[cfg(feature = "console")]
    console: Console,

    /// Cached well known symbols
    well_known_symbols: WellKnownSymbols,

    /// Cached iterator prototypes.
    iterator_prototypes: IteratorPrototypes,

    /// Cached standard objects and their prototypes.
    standard_objects: StandardObjects,

    /// Whether or not to show trace of instructions being ran
    pub trace: bool,
}

impl Default for Context {
    fn default() -> Self {
        let realm = Realm::create();
        let executor = Interpreter::new();
        let (well_known_symbols, symbol_count) = WellKnownSymbols::new();
        let mut context = Self {
            realm,
            executor,
            symbol_count,
            #[cfg(feature = "console")]
            console: Console::default(),
            well_known_symbols,
            iterator_prototypes: IteratorPrototypes::default(),
            standard_objects: Default::default(),
            trace: false,
        };

        // Add new builtIns to Context Realm
        // At a later date this can be removed from here and called explicitly,
        // but for now we almost always want these default builtins
        context.create_intrinsics();
        context.iterator_prototypes = IteratorPrototypes::init(&mut context);
        context
    }
}

impl Context {
    /// Create a new `Context`.
    #[inline]
    pub fn new() -> Self {
        Default::default()
    }

    #[inline]
    pub fn realm(&self) -> &Realm {
        &self.realm
    }

    #[inline]
    pub fn realm_mut(&mut self) -> &mut Realm {
        &mut self.realm
    }

    #[inline]
    pub fn executor(&mut self) -> &mut Interpreter {
        &mut self.executor
    }

    /// A helper function for getting an immutable reference to the `console` object.
    #[cfg(feature = "console")]
    pub(crate) fn console(&self) -> &Console {
        &self.console
    }

    /// A helper function for getting a mutable reference to the `console` object.
    #[cfg(feature = "console")]
    #[inline]
    pub(crate) fn console_mut(&mut self) -> &mut Console {
        &mut self.console
    }

    /// Sets up the default global objects within Global
    #[inline]
    fn create_intrinsics(&mut self) {
        let _timer = BoaProfiler::global().start_event("create_intrinsics", "interpreter");
        // Create intrinsics, add global objects here
        builtins::init(self);
    }

    /// Generates a new `Symbol` internal hash.
    ///
    /// This currently is an incremented value.
    #[inline]
    fn generate_hash(&mut self) -> u64 {
        let hash = self.symbol_count;
        self.symbol_count += 1;
        hash
    }

    /// Construct a new `Symbol` with an optional description.
    #[inline]
    pub fn construct_symbol(&mut self, description: Option<RcString>) -> RcSymbol {
        RcSymbol::from(Symbol::new(self.generate_hash(), description))
    }

    /// Construct an empty object.
    #[inline]
    pub fn construct_object(&self) -> GcObject {
        let object_prototype: Value = self.standard_objects().object_object().prototype().into();
        GcObject::new(Object::create(object_prototype))
    }

    /// <https://tc39.es/ecma262/#sec-call>
    #[inline]
    pub(crate) fn call(&mut self, f: &Value, this: &Value, args: &[Value]) -> Result<Value> {
        match *f {
            Value::Object(ref object) => object.call(this, args, self),
            _ => self.throw_type_error("not a function"),
        }
    }

    /// Return the global object.
    #[inline]
    pub fn global_object(&self) -> &GcObject {
        &self.realm().global_object
    }

    /// Constructs a `RangeError` with the specified message.
    #[inline]
    pub fn construct_range_error<M>(&mut self, message: M) -> Value
    where
        M: Into<Box<str>>,
    {
        // Runs a `new RangeError(message)`.
        New::from(Call::new(
            Identifier::from("RangeError"),
            vec![Const::from(message.into()).into()],
        ))
        .run(self)
        .expect("Into<String> used as message")
    }

    /// Throws a `RangeError` with the specified message.
    #[inline]
    pub fn throw_range_error<M>(&mut self, message: M) -> Result<Value>
    where
        M: Into<Box<str>>,
    {
        Err(self.construct_range_error(message))
    }

    /// Constructs a `TypeError` with the specified message.
    #[inline]
    pub fn construct_type_error<M>(&mut self, message: M) -> Value
    where
        M: Into<Box<str>>,
    {
        // Runs a `new TypeError(message)`.
        New::from(Call::new(
            Identifier::from("TypeError"),
            vec![Const::from(message.into()).into()],
        ))
        .run(self)
        .expect("Into<String> used as message")
    }

    /// Throws a `TypeError` with the specified message.
    #[inline]
    pub fn throw_type_error<M>(&mut self, message: M) -> Result<Value>
    where
        M: Into<Box<str>>,
    {
        Err(self.construct_type_error(message))
    }

    /// Constructs a `ReferenceError` with the specified message.
    #[inline]
    pub fn construct_reference_error<M>(&mut self, message: M) -> Value
    where
        M: Into<Box<str>>,
    {
        New::from(Call::new(
            Identifier::from("ReferenceError"),
            vec![Const::from(message.into()).into()],
        ))
        .run(self)
        .expect("Into<String> used as message")
    }

    /// Throws a `ReferenceError` with the specified message.
    #[inline]
    pub fn throw_reference_error<M>(&mut self, message: M) -> Result<Value>
    where
        M: Into<Box<str>>,
    {
        Err(self.construct_reference_error(message))
    }

    /// Constructs a `SyntaxError` with the specified message.
    #[inline]
    pub fn construct_syntax_error<M>(&mut self, message: M) -> Value
    where
        M: Into<Box<str>>,
    {
        New::from(Call::new(
            Identifier::from("SyntaxError"),
            vec![Const::from(message.into()).into()],
        ))
        .run(self)
        .expect("Into<String> used as message")
    }

    /// Throws a `SyntaxError` with the specified message.
    #[inline]
    pub fn throw_syntax_error<M>(&mut self, message: M) -> Result<Value>
    where
        M: Into<Box<str>>,
    {
        Err(self.construct_syntax_error(message))
    }

    /// Constructs a `EvalError` with the specified message.
    pub fn construct_eval_error<M>(&mut self, message: M) -> Value
    where
        M: Into<Box<str>>,
    {
        New::from(Call::new(
            Identifier::from("EvalError"),
            vec![Const::from(message.into()).into()],
        ))
        .run(self)
        .expect("Into<String> used as message")
    }

    /// Constructs a `URIError` with the specified message.
    pub fn construct_uri_error<M>(&mut self, message: M) -> Value
    where
        M: Into<Box<str>>,
    {
        New::from(Call::new(
            Identifier::from("URIError"),
            vec![Const::from(message.into()).into()],
        ))
        .run(self)
        .expect("Into<String> used as message")
    }

    /// Throws a `EvalError` with the specified message.
    pub fn throw_eval_error<M>(&mut self, message: M) -> Result<Value>
    where
        M: Into<Box<str>>,
    {
        Err(self.construct_eval_error(message))
    }

    /// Throws a `URIError` with the specified message.
    pub fn throw_uri_error<M>(&mut self, message: M) -> Result<Value>
    where
        M: Into<Box<str>>,
    {
        Err(self.construct_uri_error(message))
    }

    /// Utility to create a function Value for Function Declarations, Arrow Functions or Function Expressions
    pub(crate) fn create_function<P, B>(
        &mut self,
        params: P,
        body: B,
        flags: FunctionFlags,
    ) -> Result<Value>
    where
        P: Into<Box<[FormalParameter]>>,
        B: Into<StatementList>,
    {
        let function_prototype: Value =
            self.standard_objects().function_object().prototype().into();

        // Every new function has a prototype property pre-made
        let proto = Value::new_object(self);

        let params = params.into();
        let params_len = params.len();
        let func = Function::Ordinary {
            flags,
            body: RcStatementList::from(body.into()),
            params,
            environment: self.realm.environment.get_current_environment().clone(),
        };

        let new_func = Object::function(func, function_prototype);

        let val = Value::from(new_func);

        // Set constructor field to the newly created Value (function object)
        proto.set_field("constructor", val.clone(), self)?;

        val.set_field(PROTOTYPE, proto, self)?;
        val.set_field("length", Value::from(params_len), self)?;

        Ok(val)
    }

    /// Create a new builin function.
    pub fn create_builtin_function(
        &mut self,
        name: &str,
        length: usize,
        body: NativeFunction,
    ) -> Result<GcObject> {
        let function_prototype: Value = self.standard_objects().object_object().prototype().into();

        // Every new function has a prototype property pre-made
        let proto = Value::new_object(self);
        let mut function = GcObject::new(Object::function(
            Function::BuiltIn(body.into(), FunctionFlags::CALLABLE),
            function_prototype,
        ));
        function.set(PROTOTYPE.into(), proto, function.clone().into(), self)?;
        function.set(
            "length".into(),
            length.into(),
            function.clone().into(),
            self,
        )?;
        function.set("name".into(), name.into(), function.clone().into(), self)?;

        Ok(function)
    }

    /// Register a global function.
    #[inline]
    pub fn register_global_function(
        &mut self,
        name: &str,
        length: usize,
        body: NativeFunction,
    ) -> Result<()> {
        let function = self.create_builtin_function(name, length, body)?;
        let mut global = self.global_object().clone();
        global.insert_property(name, function, Attribute::all());
        Ok(())
    }

    /// Converts an array object into a rust vector of values.
    ///
    /// This is useful for the spread operator, for any other object an `Err` is returned
    /// TODO: Not needed for spread of arrays. Check in the future for Map and remove if necessary
    pub(crate) fn extract_array_properties(
        &mut self,
        value: &Value,
    ) -> Result<StdResult<Vec<Value>, ()>> {
        if let Value::Object(ref x) = value {
            // Check if object is array
            if let ObjectData::Array = x.borrow().data {
                let length = value.get_field("length", self)?.as_number().unwrap() as i32;
                let values = (0..length)
                    .map(|idx| value.get_field(idx, self))
                    .collect::<Result<Vec<_>>>()?;
                return Ok(Ok(values));
            }
            // Check if object is a Map
            else if let ObjectData::Map(ref map) = x.borrow().data {
                let values = map
                    .iter()
                    .map(|(key, value)| {
                        // Construct a new array containing the key-value pair
                        let array = Value::new_object(self);
                        array.set_data(ObjectData::Array);
                        array.as_object().expect("object").set_prototype_instance(
                            self.realm()
                                .environment
                                .get_binding_value("Array")
                                .expect("Array was not initialized")
                                .get_field(PROTOTYPE, self)?,
                        );
                        array.set_field(0, key, self)?;
                        array.set_field(1, value, self)?;
                        array.set_field("length", Value::from(2), self)?;
                        Ok(array)
                    })
                    .collect::<Result<Vec<_>>>()?;
                return Ok(Ok(values));
            }

            return Ok(Err(()));
        }

        Ok(Err(()))
    }

    /// <https://tc39.es/ecma262/#sec-hasproperty>
    #[inline]
    pub(crate) fn has_property(&self, obj: &Value, key: &PropertyKey) -> bool {
        if let Some(obj) = obj.as_object() {
            obj.has_property(key)
        } else {
            false
        }
    }

    #[inline]
    pub(crate) fn set_value(&mut self, node: &Node, value: Value) -> Result<Value> {
        match node {
            Node::Identifier(ref name) => {
                self.realm
                    .environment
                    .set_mutable_binding(name.as_ref(), value.clone(), true)
                    .map_err(|e| e.to_error(self))?;
                Ok(value)
            }
            Node::GetConstField(ref get_const_field_node) => Ok(get_const_field_node
                .obj()
                .run(self)?
                .set_field(get_const_field_node.field(), value, self)?),
            Node::GetField(ref get_field) => {
                let field = get_field.field().run(self)?;
                let key = field.to_property_key(self)?;
                Ok(get_field.obj().run(self)?.set_field(key, value, self)?)
            }
            _ => self.throw_type_error(format!("invalid assignment to {}", node)),
        }
    }

    /// Register a global class of type `T`, where `T` implements `Class`.
    ///
    /// # Example
    /// ```ignore
    /// #[derive(Debug, Trace, Finalize)]
    /// struct MyClass;
    ///
    /// impl Class for MyClass {
    ///    // ...
    /// }
    ///
    /// context.register_global_class::<MyClass>();
    /// ```
    #[inline]
    pub fn register_global_class<T>(&mut self) -> Result<()>
    where
        T: Class,
    {
        let mut class_builder = ClassBuilder::new::<T>(self);
        T::init(&mut class_builder)?;

        let class = class_builder.build();
        let property = DataDescriptor::new(class, T::ATTRIBUTE);
        self.global_object().clone().insert(T::NAME, property);
        Ok(())
    }

    /// Register a global property.
    ///
    /// # Example
    /// ```
    /// use boa::{Context, property::Attribute, object::ObjectInitializer};
    ///
    /// let mut context = Context::new();
    ///
    /// context.register_global_property("myPrimitiveProperty", 10, Attribute::all());
    ///
    /// let object = ObjectInitializer::new(&mut context)
    ///    .property("x", 0, Attribute::all())
    ///    .property("y", 1, Attribute::all())
    ///    .build();
    /// context.register_global_property("myObjectProperty", object, Attribute::all());
    /// ```
    #[inline]
    pub fn register_global_property<K, V>(&mut self, key: K, value: V, attribute: Attribute)
    where
        K: Into<PropertyKey>,
        V: Into<Value>,
    {
        let property = DataDescriptor::new(value, attribute);
        self.global_object().clone().insert(key, property);
    }

    /// Evaluates the given code.
    ///
    /// # Examples
    /// ```
    ///# use boa::Context;
    /// let mut context = Context::new();
    ///
    /// let value = context.eval("1 + 3").unwrap();
    ///
    /// assert!(value.is_number());
    /// assert_eq!(value.as_number().unwrap(), 4.0);
    /// ```
    #[cfg(not(feature = "vm"))]
    #[allow(clippy::unit_arg, clippy::drop_copy)]
    #[inline]
    pub fn eval<T: AsRef<[u8]>>(&mut self, src: T) -> Result<Value> {
        let main_timer = BoaProfiler::global().start_event("Main", "Main");
        let src_bytes: &[u8] = src.as_ref();

        let parsing_result = Parser::new(src_bytes, false)
            .parse_all()
            .map_err(|e| e.to_string());

        let execution_result = match parsing_result {
            Ok(statement_list) => statement_list.run(self),
            Err(e) => self.throw_syntax_error(e),
        };

        // The main_timer needs to be dropped before the BoaProfiler is.
        drop(main_timer);
        BoaProfiler::global().drop();

        execution_result
    }

    /// Evaluates the given code by compiling down to bytecode, then interpreting the bytecode into a value
    ///
    /// # Examples
    /// ```
    ///# use boa::Context;
    /// let mut context = Context::new();
    ///
    /// let value = context.eval("1 + 3").unwrap();
    ///
    /// assert!(value.is_number());
    /// assert_eq!(value.as_number().unwrap(), 4.0);
    /// ```
    #[cfg(feature = "vm")]
    #[allow(clippy::unit_arg, clippy::drop_copy)]
    pub fn eval<T: AsRef<[u8]>>(&mut self, src: T) -> Result<Value> {
        let main_timer = BoaProfiler::global().start_event("Main", "Main");
        let src_bytes: &[u8] = src.as_ref();

        let parsing_result = Parser::new(src_bytes, false)
            .parse_all()
            .map_err(|e| e.to_string());

        let statement_list = match parsing_result {
            Ok(statement_list) => statement_list,
            Err(e) => return self.throw_syntax_error(e),
        };

        let mut compiler = Compiler::default();
        statement_list.compile(&mut compiler);

        let mut vm = VM::new(compiler, self);
        // Generate Bytecode and place it into instruction_stack
        // Interpret the Bytecode
        let result = vm.run();
        // The main_timer needs to be dropped before the BoaProfiler is.
        drop(main_timer);
        BoaProfiler::global().drop();

        result
    }

    /// Returns a structure that contains the JavaScript well known symbols.
    ///
    /// # Examples
    /// ```
    ///# use boa::Context;
    /// let mut context = Context::new();
    ///
    /// let iterator = context.well_known_symbols().iterator_symbol();
    /// assert_eq!(iterator.description(), Some("Symbol.iterator"));
    /// ```
    /// This is equivalent to `let iterator = Symbol.iterator` in JavaScript.
    #[inline]
    pub fn well_known_symbols(&self) -> &WellKnownSymbols {
        &self.well_known_symbols
    }

    /// Return the cached iterator prototypes.
    #[inline]
    pub fn iterator_prototypes(&self) -> &IteratorPrototypes {
        &self.iterator_prototypes
    }

    /// Return the core standard objects.
    #[inline]
    pub fn standard_objects(&self) -> &StandardObjects {
        &self.standard_objects
    }

    /// Set the value of trace on the context
    pub fn set_trace(&mut self, trace: bool) {
        self.trace = trace;
    }
}