use crate::sql::{fmt::Fmt, strand::no_nul_bytes, Graph, Ident, Idiom, Number, Value};
use revision::revisioned;
use serde::{Deserialize, Serialize};
use std::fmt;
use std::str;

#[derive(Clone, Debug, Eq, PartialEq, PartialOrd, Serialize, Deserialize, Hash)]
#[revisioned(revision = 1)]
pub enum Part {
	All,
	Flatten,
	Last,
	First,
	Field(Ident),
	Index(Number),
	Where(Value),
	Graph(Graph),
	Value(Value),
	Start(Value),
	Method(#[serde(with = "no_nul_bytes")] String, Vec<Value>),
}

impl From<i32> for Part {
	fn from(v: i32) -> Self {
		Self::Index(v.into())
	}
}

impl From<isize> for Part {
	fn from(v: isize) -> Self {
		Self::Index(v.into())
	}
}

impl From<usize> for Part {
	fn from(v: usize) -> Self {
		Self::Index(v.into())
	}
}

impl From<String> for Part {
	fn from(v: String) -> Self {
		Self::Field(v.into())
	}
}

impl From<Number> for Part {
	fn from(v: Number) -> Self {
		Self::Index(v)
	}
}

impl From<Ident> for Part {
	fn from(v: Ident) -> Self {
		Self::Field(v)
	}
}

impl From<Graph> for Part {
	fn from(v: Graph) -> Self {
		Self::Graph(v)
	}
}

impl From<&str> for Part {
	fn from(v: &str) -> Self {
		match v.parse::<isize>() {
			Ok(v) => Self::from(v),
			_ => Self::from(v.to_owned()),
		}
	}
}

impl Part {
	/// Check if we require a writeable transaction
	pub(crate) fn writeable(&self) -> bool {
		match self {
			Part::Start(v) => v.writeable(),
			Part::Where(v) => v.writeable(),
			Part::Value(v) => v.writeable(),
			Part::Method(_, v) => v.iter().any(Value::writeable),
			_ => false,
		}
	}
	/// Returns a yield if an alias is specified
	pub(crate) fn alias(&self) -> Option<&Idiom> {
		match self {
			Part::Graph(v) => v.alias.as_ref(),
			_ => None,
		}
	}
}

impl fmt::Display for Part {
	fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
		match self {
			Part::All => f.write_str("[*]"),
			Part::Last => f.write_str("[$]"),
			Part::First => f.write_str("[0]"),
			Part::Start(v) => write!(f, "{v}"),
			Part::Field(v) => write!(f, ".{v}"),
			Part::Flatten => f.write_str("…"),
			Part::Index(v) => write!(f, "[{v}]"),
			Part::Where(v) => write!(f, "[WHERE {v}]"),
			Part::Graph(v) => write!(f, "{v}"),
			Part::Value(v) => write!(f, "[{v}]"),
			Part::Method(v, a) => write!(f, ".{v}({})", Fmt::comma_separated(a)),
		}
	}
}

// ------------------------------

pub trait Next<'a> {
	fn next(&'a self) -> &[Part];
}

impl<'a> Next<'a> for &'a [Part] {
	fn next(&'a self) -> &'a [Part] {
		match self.len() {
			0 => &[],
			_ => &self[1..],
		}
	}
}