use std::collections::BTreeMap;

use serde::{Deserialize, Serialize};
use tree_sitter::Node;

use crate::{
    AbstractTree, BuiltInValue, Error, Expression, Function, Identifier, List, Map, Result,
    Statement, Type, TypeDefinition, Value,
};

#[derive(Debug, Clone, Serialize, Deserialize, Eq, PartialEq, PartialOrd, Ord)]
pub enum ValueNode {
    Boolean(String),
    Float(String),
    Function(Function),
    Integer(String),
    String(String),
    List(Vec<Expression>),
    Option(Option<Box<Expression>>),
    Map(BTreeMap<String, (Statement, Option<Type>)>),
    BuiltInValue(BuiltInValue),
}

impl AbstractTree for ValueNode {
    fn from_syntax_node(source: &str, node: Node, context: &Map) -> Result<Self> {
        Error::expect_syntax_node(source, "value", node)?;

        let child = node.child(0).unwrap();
        let value_node = match child.kind() {
            "boolean" => ValueNode::Boolean(source[child.byte_range()].to_string()),
            "float" => ValueNode::Float(source[child.byte_range()].to_string()),
            "function" => ValueNode::Function(Function::from_syntax_node(source, child, context)?),
            "integer" => ValueNode::Integer(source[child.byte_range()].to_string()),
            "string" => {
                let without_quotes = child.start_byte() + 1..child.end_byte() - 1;

                ValueNode::String(source[without_quotes].to_string())
            }
            "list" => {
                let mut expressions = Vec::new();

                for index in 1..child.child_count() - 1 {
                    let current_node = child.child(index).unwrap();

                    if current_node.is_named() {
                        let expression =
                            Expression::from_syntax_node(source, current_node, context)?;
                        expressions.push(expression);
                    }
                }

                ValueNode::List(expressions)
            }
            "map" => {
                let mut child_nodes = BTreeMap::new();
                let mut current_key = "".to_string();
                let mut current_type = None;

                for index in 0..child.child_count() - 1 {
                    let child_syntax_node = child.child(index).unwrap();

                    if child_syntax_node.kind() == "identifier" {
                        current_key =
                            Identifier::from_syntax_node(source, child_syntax_node, context)?
                                .take_inner();
                        current_type = None;
                    }

                    if child_syntax_node.kind() == "type_definition" {
                        current_type = Some(
                            TypeDefinition::from_syntax_node(source, child_syntax_node, context)?
                                .take_inner(),
                        );
                    }

                    if child_syntax_node.kind() == "statement" {
                        let statement =
                            Statement::from_syntax_node(source, child_syntax_node, context)?;

                        if let Some(type_definition) = &current_type {
                            type_definition.check(&statement.expected_type(context)?)?;
                        }

                        child_nodes.insert(current_key.clone(), (statement, current_type.clone()));
                    }
                }

                ValueNode::Map(child_nodes)
            }
            "option" => {
                let first_grandchild = child.child(0).unwrap();

                if first_grandchild.kind() == "none" {
                    ValueNode::Option(None)
                } else {
                    let expression_node = child.child(2).unwrap();
                    let expression =
                        Expression::from_syntax_node(source, expression_node, context)?;

                    ValueNode::Option(Some(Box::new(expression)))
                }
            }
            "built_in_value" => {
                let built_in_value_node = child.child(0).unwrap();

                ValueNode::BuiltInValue(BuiltInValue::from_syntax_node(
                    source,
                    built_in_value_node,
                    context,
                )?)
            }
            _ => {
                return Err(Error::UnexpectedSyntaxNode {
                    expected: "string, integer, float, boolean, list, map, or option".to_string(),
                    actual: child.kind().to_string(),
                    location: child.start_position(),
                    relevant_source: source[child.byte_range()].to_string(),
                })
            }
        };

        Ok(value_node)
    }

    fn run(&self, source: &str, context: &Map) -> Result<Value> {
        let value = match self {
            ValueNode::Boolean(value_source) => Value::Boolean(value_source.parse().unwrap()),
            ValueNode::Float(value_source) => Value::Float(value_source.parse().unwrap()),
            ValueNode::Function(function) => Value::Function(function.clone()),
            ValueNode::Integer(value_source) => Value::Integer(value_source.parse().unwrap()),
            ValueNode::String(value_source) => Value::string(value_source.clone()),
            ValueNode::List(expressions) => {
                let mut values = Vec::with_capacity(expressions.len());

                for node in expressions {
                    let value = node.run(source, context)?;

                    values.push(value);
                }

                Value::List(List::with_items(values))
            }
            ValueNode::Option(option) => {
                let option_value = if let Some(expression) = option {
                    Some(Box::new(expression.run(source, context)?))
                } else {
                    None
                };

                Value::Option(option_value)
            }
            ValueNode::Map(key_statement_pairs) => {
                let map = Map::new();

                {
                    for (key, (statement, r#type)) in key_statement_pairs {
                        let value = statement.run(source, context)?;

                        map.set(key.clone(), value, r#type.clone())?;
                    }
                }

                Value::Map(map)
            }
            ValueNode::BuiltInValue(built_in_value) => built_in_value.run(source, context)?,
        };

        Ok(value)
    }

    fn expected_type(&self, context: &Map) -> Result<Type> {
        let r#type = match self {
            ValueNode::Boolean(_) => Type::Boolean,
            ValueNode::Float(_) => Type::Float,
            ValueNode::Function(function) => function.r#type().clone(),
            ValueNode::Integer(_) => Type::Integer,
            ValueNode::String(_) => Type::String,
            ValueNode::List(expressions) => {
                let mut previous_type = None;

                for expression in expressions {
                    let expression_type = expression.expected_type(context)?;

                    if let Some(previous) = previous_type {
                        if expression_type != previous {
                            return Ok(Type::List(Box::new(Type::Any)));
                        }
                    }

                    previous_type = Some(expression_type);
                }

                if let Some(previous) = previous_type {
                    Type::List(Box::new(previous))
                } else {
                    Type::List(Box::new(Type::Any))
                }
            }
            ValueNode::Option(option) => {
                if let Some(expression) = option {
                    Type::Option(Box::new(expression.expected_type(context)?))
                } else {
                    Type::None
                }
            }
            ValueNode::Map(_) => Type::Map,
            ValueNode::BuiltInValue(built_in_value) => built_in_value.expected_type(context)?,
        };

        Ok(r#type)
    }
}