use std::collections::HashMap;
use serde_json::{json, Value};
use crate::{
	parameter::Parameter,
	PResult,
	perr
};

#[derive(Debug, PartialEq, Eq, Clone, Hash)]
pub struct EntityType(pub String);

#[derive(Debug, Clone, Copy, Hash, PartialEq, Eq)]
pub enum SaveOption {
	Default,
	False,
	Always
}

#[derive(Debug, Clone, PartialEq)]
pub struct Template {
	pub name: EntityType,
	pub args: Vec<Parameter>,
	pub kwargs: HashMap<String, Parameter>,
	pub save: SaveOption,
}


impl Template {
	
	pub fn new(name: &str, kwargs: HashMap<String, Parameter>) -> Self {
		Self {
			name: EntityType(name.to_string()),
			args: Vec::new(),
			kwargs,
			save: SaveOption::Default
		}
	}
	
	pub fn empty(name: &str) -> Self {
		Self::new(name, HashMap::new())
	}
	
	pub fn should_save(&self) -> bool {
		match self.save {
			SaveOption::Default | SaveOption::Always => true,
			SaveOption::False => false
		}
	}
	
	pub fn from_entity_type(typ: EntityType) -> Self {
		Self {
			name: typ,
			args: Vec::new(),
			kwargs: HashMap::new(),
			save: SaveOption::Default
		}
	}
	
	pub fn unsaved(mut self) -> Self {
		if self.save == SaveOption::Default {
			self.save = SaveOption::False
		}
		self
	}
	
	pub fn merge(mut self, other: Template) -> Self {
		if self.save == SaveOption::Default {
			self.save = other.save;
		}
		for (key, value) in other.kwargs {
			self.kwargs.entry(key).or_insert(value);
		}
		self
	}
	
	pub fn from_json(v: &Value) -> PResult<Template> {
		let val = match v {
			Value::String(s) => json!({"type": s}),
			Value::Array(_) => json!({
				"type": v.get(0).ok_or(perr!("index 0 not in template array {:?}", v))?,
				"kwargs": v.get(1).ok_or(perr!("index 1 not in template array {:?}", v))?
			}),
			Value::Object(_) => v.clone(),
			_ => return Err(perr!("invalid template {:?}", v))
		};
			
		let name = EntityType(val.get("type").ok_or(perr!("template doesn't have 'type'"))?.as_str().ok_or(perr!("template type not a string"))?.to_string());
		let mut args = Vec::new();
		for arg in val.get("args").unwrap_or(&json!([])).as_array().ok_or(perr!("template args not an array"))? {
			args.push(Parameter::guess_from_json(arg)?);
		}
		let mut kwargs = HashMap::new();
		for (key, arg) in val.get("kwargs").unwrap_or(&json!({})).as_object().ok_or(perr!("template kwargs not a json object"))? {
			kwargs.insert(key.to_string(), Parameter::guess_from_json(arg)?);
		}
		let save = 
			if let Some(saveval) = val.get("save") {
				if saveval.as_bool().ok_or(perr!("save not a bool"))? {
					SaveOption::Always
				} else {
					SaveOption::False
				}
			} else {
				SaveOption::Default
			};
		Ok(Template {name, args, kwargs, save})
	}
	
	pub fn to_json(&self) -> Value {
		if self.args.is_empty() && self.kwargs.is_empty() {
			return json!(self.name.0);
		}
		let jsonargs: Vec<Value> = self.args.iter().map(|a| a.to_json()).collect();
		let jsonkwargs: HashMap<&String, Value> = self.kwargs.iter().map(|(k, a)| (k, a.to_json())).collect();
		json!({
			"type": self.name.0,
			"args": jsonargs,
			"kwargs": jsonkwargs
		})
	}
}