surrealdb-core 3.2.1

use anyhow::{Result, bail, ensure};
use chrono::{TimeZone, Utc};
use rand::Rng;
use rand::distr::{Alphanumeric, SampleString};
use rand::seq::{IndexedRandom, IteratorRandom};
use ulid::Ulid;

use super::args::{Any, Args, Arity, FromArg, Optional};
use crate::cnf::ID_CHARS;
use crate::err::Error;
use crate::val::{Datetime, Duration, Number, Uuid, Value};

pub fn rand(_: ()) -> Result<Value> {
	Ok(crate::rnd::with_rng(|rng| rng.random::<f64>()).into())
}

pub fn bool(_: ()) -> Result<Value> {
	Ok(crate::rnd::with_rng(|rng| rng.random::<bool>()).into())
}

pub fn r#enum(Any(mut args): Any) -> Result<Value> {
	Ok(match args.len() {
		0 => Value::None,
		1 => match args.remove(0) {
			Value::Array(v) => {
				crate::rnd::with_rng(|rng| v.into_iter().choose(rng)).unwrap_or(Value::None)
			}
			v => v,
		},
		_ => crate::rnd::with_rng(|rng| args.into_iter().choose(rng)).expect("non-empty args"),
	})
}

pub struct NoneOrRange<T>(Option<(T, T)>);

impl<T: FromArg> FromArg for NoneOrRange<T> {
	fn arity() -> Arity {
		Arity {
			lower: 0,
			upper: Some(2),
		}
	}

	fn from_arg(name: &str, args: &mut Args) -> Result<Self> {
		if !args.has_next() {
			return Ok(NoneOrRange(None));
		}

		let a = T::from_arg(name, args)?;

		ensure!(
			args.has_next(),
			Error::InvalidFunctionArguments {
				name: name.to_owned(),
				message: "Expected 0 or 2 arguments".to_string(),
			}
		);

		let b = T::from_arg(name, args)?;

		Ok(NoneOrRange(Some((a, b))))
	}
}

// TODO (Delskayn): Don't agree with the inclusive ranges in the functions here,
// seems inconsistent with general use of ranges not including the upperbound.
// These should probably all be exclusive.
pub fn float((NoneOrRange(range),): (NoneOrRange<f64>,)) -> Result<Value> {
	let v = if let Some((min, max)) = range {
		ensure!(
			min <= max,
			Error::InvalidFunctionArguments {
				name: String::from("rand::float"),
				message: "Lowerbound of the range must be less than or equal to the upperbound."
					.to_string(),
			}
		);
		crate::rnd::with_rng(|rng| rng.random_range(min..=max))
	} else {
		crate::rnd::with_rng(|rng| rng.random::<f64>())
	};
	Ok(Value::from(v))
}

// Without this check, a negative length wraps to a huge `usize` and either
// panics `random_range` ("cannot sample empty range") or OOMs the allocator
// when used as a string length.
fn to_random_len(name: &str, val: i64) -> Result<usize> {
	usize::try_from(val).map_err(|_| {
		anyhow::Error::new(Error::ArithmeticNegativeOverflow(format!("{name}({val})")))
	})
}

pub fn id((Optional(arg1), Optional(arg2)): (Optional<i64>, Optional<i64>)) -> Result<Value> {
	// Set a reasonable maximum length
	const LIMIT: i64 = 64;

	// rand::id(NULL,10) is not allowed by the calling infrastructure.
	let lower = arg1.unwrap_or(20);
	let len = if let Some(upper) = arg2 {
		ensure!(
			lower <= upper,
			Error::InvalidFunctionArguments {
				name: String::from("rand::id"),
				message: "Lowerbound of number of characters must be less then the upperbound."
					.to_string(),
			}
		);
		ensure!(
			upper <= LIMIT,
			Error::InvalidFunctionArguments {
				name: String::from("rand::id"),
				message: format!(
					"To generate a string of X characters in length, the argument must be a positive number and no higher than {LIMIT}."
				),
			}
		);
		let lower = to_random_len("rand::id", lower)?;
		let upper = to_random_len("rand::id", upper)?;
		crate::rnd::with_rng(|rng| rng.random_range(lower..=upper))
	} else {
		ensure!(
			lower <= LIMIT,
			Error::InvalidFunctionArguments {
				name: String::from("rand::id"),
				message: format!(
					"To generate a string of X characters in length, the argument must be a positive number and no higher than {LIMIT}."
				),
			}
		);
		to_random_len("rand::id", lower)?
	};

	// Generate the random id
	let id: String = crate::rnd::with_rng(|rng| {
		(0..len).map(|_| *ID_CHARS[..].choose(&mut *rng).unwrap_or(&'0')).collect()
	});
	Ok(Value::from(id))
}

pub fn int((NoneOrRange(range),): (NoneOrRange<i64>,)) -> Result<Value> {
	Ok(if let Some((min, max)) = range {
		ensure!(
			min <= max,
			Error::InvalidFunctionArguments {
				name: String::from("rand::int"),
				message: "Lowerbound of the range must be less than or equal to the upperbound."
					.to_string(),
			}
		);
		crate::rnd::with_rng(|rng| rng.random_range(min..=max))
	} else {
		crate::rnd::with_rng(|rng| rng.random::<i64>())
	}
	.into())
}

pub fn string((Optional(arg1), Optional(arg2)): (Optional<i64>, Optional<i64>)) -> Result<Value> {
	// Set a reasonable maximum length
	const LIMIT: i64 = 65536;
	// rand::string(NULL,10) is not allowed by the calling infrastructure.
	let lower = arg1.unwrap_or(32);
	let len = if let Some(upper) = arg2 {
		ensure!(
			lower <= upper,
			Error::InvalidFunctionArguments {
				name: String::from("rand::string"),
				message: "Lowerbound of number of characters must be less then the upperbound."
					.to_string(),
			}
		);
		ensure!(
			upper <= LIMIT,
			Error::InvalidFunctionArguments {
				name: String::from("rand::string"),
				message: format!(
					"To generate a string of X characters in length, the argument must be a positive number and no higher than {LIMIT}."
				),
			}
		);
		let lower = to_random_len("rand::string", lower)?;
		let upper = to_random_len("rand::string", upper)?;
		crate::rnd::with_rng(|rng| rng.random_range(lower..=upper))
	} else {
		ensure!(
			lower <= LIMIT,
			Error::InvalidFunctionArguments {
				name: String::from("rand::string"),
				message: format!(
					"To generate a string of X characters in length, the argument must be a positive number and no higher than {LIMIT}."
				),
			}
		);
		to_random_len("rand::string", lower)?
	};
	// Generate the random string
	Ok(crate::rnd::with_rng(|rng| Alphanumeric.sample_string(rng, len)).into())
}

pub fn duration((dur1, dur2): (Duration, Duration)) -> Result<Value> {
	ensure!(
		dur1 <= dur2,
		Error::InvalidFunctionArguments {
			name: String::from("rand::duration"),
			message: "Lowerbound of the range must be less than or equal to the upperbound."
				.to_string(),
		}
	);

	let rand = crate::rnd::with_rng(|rng| rng.random_range(dur1.as_nanos()..=dur2.as_nanos()));

	let nanos = (rand % 1_000_000_000) as u32;

	// Max Duration is made of (u64::MAX, NANOS_PER_SEC - 1) so will never overflow
	let Ok(secs) = u64::try_from(rand / 1_000_000_000) else {
		fail!("Overflow inside rand::duration()");
	};

	Ok(Value::Duration(Duration::new(secs, nanos)))
}

pub fn time((NoneOrRange(range),): (NoneOrRange<Value>,)) -> Result<Value> {
	// Process the arguments
	let range = match range {
		None => None,
		Some((Value::Number(Number::Int(min)), Value::Number(Number::Int(max)))) => {
			Some((min, max))
		}
		Some((Value::Datetime(min), Value::Datetime(max))) => Some((min.to_secs(), max.to_secs())),
		Some((Value::Number(Number::Int(min)), Value::Datetime(max))) => Some((min, max.to_secs())),
		Some((Value::Datetime(min), Value::Number(Number::Int(max)))) => Some((min.to_secs(), max)),
		_ => {
			bail!(Error::InvalidFunctionArguments {
				name: String::from("rand::time"),
				message: String::from("Expected two arguments of type datetime or int"),
			})
		}
	};

	// Set the minimum valid seconds
	const MINIMUM: i64 = -8334601228800;
	// Set the maximum valid seconds
	const LIMIT: i64 = 8210266876799;

	// Check the function input arguments
	let (min, max) = if let Some((min, max)) = range {
		ensure!(
			(MINIMUM..=LIMIT).contains(&min) && (MINIMUM..=LIMIT).contains(&max),
			Error::InvalidFunctionArguments {
				name: String::from("rand::time"),
				message: format!(
					"To generate a random time, the 2 arguments must be numbers between {MINIMUM} and {LIMIT} seconds from the UNIX epoch or a 'datetime' within the range d'-262143-01-01T00:00:00Z' and +262142-12-31T23:59:59Z'."
				),
			}
		);
		ensure!(
			min <= max,
			Error::InvalidFunctionArguments {
				name: String::from("rand::time"),
				message: "Lowerbound of the range must be less than or equal to the upperbound."
					.to_string(),
			}
		);
		(min, max)
	} else {
		// Datetime between d'0000-01-01T00:00:00Z' and d'9999-12-31T23:59:59Z'
		(-62167219200, 253402300799)
	};
	// Generate the random time, try up to 5 times
	for _ in 0..5 {
		let val = crate::rnd::with_rng(|rng| rng.random_range(min..=max));
		if let Some(v) = Utc.timestamp_opt(val, 0).earliest() {
			return Ok(v.into());
		}
	}
	// We were unable to generate a valid random datetime
	fail!("Expected a valid datetime, but were unable to generate one")
}

pub fn ulid((Optional(timestamp),): (Optional<Datetime>,)) -> Result<Value> {
	let ulid = match timestamp {
		Some(timestamp) => {
			#[cfg(target_family = "wasm")]
			ensure!(
				timestamp.0 >= chrono::DateTime::UNIX_EPOCH,
				Error::InvalidFunctionArguments {
					name: String::from("rand::ulid"),
					message: format!(
						"To generate a ULID from a datetime, it must be a time beyond UNIX epoch."
					),
				}
			);

			Ulid::from_datetime(timestamp.0.into())
		}
		None => Ulid::new(),
	};

	Ok(ulid.to_string().into())
}

pub fn uuid((Optional(timestamp),): (Optional<Datetime>,)) -> Result<Value> {
	let uuid = match timestamp {
		Some(timestamp) => {
			#[cfg(target_family = "wasm")]
			ensure!(
				timestamp.0 >= chrono::DateTime::UNIX_EPOCH,
				Error::InvalidFunctionArguments {
					name: String::from("rand::ulid"),
					message: format!(
						"To generate a ULID from a datetime, it must be a time beyond UNIX epoch."
					),
				}
			);

			Uuid::new_v7_from_datetime(timestamp)
		}
		None => Uuid::new(),
	};
	Ok(uuid.into())
}

#[cfg(test)]
mod tests {
	use std::thread;

	use super::*;

	#[test]
	fn test_rand_id_concurrency() {
		let mut handles = vec![];
		for _ in 0..100 {
			handles.push(thread::spawn(|| {
				for _ in 0..1000 {
					let _ = id((Optional(Some(0)), Optional(Some(10)))).unwrap();
				}
			}));
		}
		for handle in handles {
			handle.join().unwrap();
		}
	}

	#[test]
	fn test_rand_id_len_0() {
		let res = id((Optional(Some(0)), Optional(Some(0)))).unwrap();
		assert_eq!(res, Value::from(""));
	}
}

pub mod uuid {

	use anyhow::Result;

	use crate::fnc::args::Optional;
	use crate::val::{Datetime, Uuid, Value};

	pub fn v4(_: ()) -> Result<Value> {
		Ok(Uuid::new_v4().into())
	}

	pub fn v7((Optional(timestamp),): (Optional<Datetime>,)) -> Result<Value> {
		let uuid = match timestamp {
			Some(timestamp) => {
				#[cfg(target_family = "wasm")]
				anyhow::ensure!(
					timestamp.0 >= chrono::DateTime::UNIX_EPOCH,
					crate::err::Error::InvalidFunctionArguments {
						name: String::from("rand::ulid"),
						message: format!(
							"To generate a ULID from a datetime, it must be a time beyond UNIX epoch."
						),
					}
				);

				Uuid::new_v7_from_datetime(timestamp)
			}
			None => Uuid::new(),
		};
		Ok(uuid.into())
	}
}