// LLSD for Rust - Parser and Writer for the LLSD format.
// Copyright (C) 2017-2018  Leonardo Schwarz <mail@leoschwarz.com>
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

//! The data types to be used.

pub mod scalar;

use byteorder::{BigEndian, ByteOrder};
use chrono::{NaiveDateTime, Utc};
use regex::Regex;
use std::collections::HashMap;
pub use url::ParseError as UrlParseError;
pub use url::Url;
pub use uuid::Uuid;

lazy_static! {
    static ref RE_INTEGER: Regex = Regex::new(r"(-?\d+)").unwrap();
    static ref RE_REAL: Regex = Regex::new(r"((-?\d+\.?\d*)|nan)").unwrap();
}

#[derive(Clone, Debug, PartialEq)]
pub enum Scalar {
    Boolean(bool),
    Integer(i32),
    Real(f64),
    Uuid(Uuid),
    String(String),
    Date(scalar::Date),
    // TODO: Consider renaming variant to `Url`.
    Uri(scalar::Url),
    Binary(Vec<u8>),
    Undefined,
}

#[allow(dead_code)]
#[derive(Debug, Eq, PartialEq)]
pub(crate) enum ScalarType {
    Boolean,
    Integer,
    Real,
    Uuid,
    String,
    Date,
    // TODO: Consider renaming variant to `Url`.
    Uri,
    Binary,
    Undefined,
}

impl ScalarType {
    /// Parse a scalar from the specified data into a scalar with the variant
    /// specified by this Self instance.
    pub(crate) fn parse_scalar(&self, source: &[u8]) -> Option<Scalar> {
        let s_value = Scalar::String(String::from_utf8_lossy(source).to_string());
        match *self {
            ScalarType::Boolean => s_value.as_bool().map(|b| Scalar::Boolean(b)),
            ScalarType::Integer => s_value.as_int().map(|i| Scalar::Integer(i)),
            ScalarType::Real => s_value.as_real().map(|r| Scalar::Real(r)),
            ScalarType::Uuid => s_value.as_uuid().map(|u| Scalar::Uuid(u)),
            ScalarType::String => Some(s_value),
            ScalarType::Date => s_value.as_date().map(|d| Scalar::Date(d)),
            ScalarType::Uri => s_value.as_uri().map(|u| Scalar::Uri(u)),
            ScalarType::Binary => None,
            ScalarType::Undefined => None,
        }
    }
}

pub type Map = HashMap<String, Value>;
pub type Array = Vec<Value>;

#[derive(Debug, PartialEq)]
pub enum Value {
    Scalar(Scalar),
    Map(Map),
    Array(Array),
}

impl Value {
    pub fn scalar(self) -> Option<Scalar> {
        match self {
            Value::Scalar(s) => Some(s),
            _ => None,
        }
    }

    pub fn scalar_ref(&self) -> Option<&Scalar> {
        match *self {
            Value::Scalar(ref s) => Some(s),
            _ => None,
        }
    }

    pub fn map(self) -> Option<Map> {
        match self {
            Value::Map(m) => Some(m),
            _ => None,
        }
    }

    pub fn map_ref(&self) -> Option<&Map> {
        match *self {
            Value::Map(ref m) => Some(m),
            _ => None,
        }
    }

    pub fn array(self) -> Option<Array> {
        match self {
            Value::Array(a) => Some(a),
            _ => None,
        }
    }

    pub fn array_ref(&self) -> Option<&Array> {
        match *self {
            Value::Array(ref a) => Some(a),
            _ => None,
        }
    }

    pub fn new_boolean(b: bool) -> Self {
        Value::Scalar(Scalar::Boolean(b))
    }

    pub fn new_integer(i: i32) -> Self {
        Value::Scalar(Scalar::Integer(i))
    }

    pub fn new_real(r: f64) -> Self {
        Value::Scalar(Scalar::Real(r))
    }

    pub fn new_uuid(u: Uuid) -> Self {
        Value::Scalar(Scalar::Uuid(u))
    }

    pub fn new_string<S: Into<String>>(s: S) -> Self {
        Value::Scalar(Scalar::String(s.into()))
    }

    pub fn new_date(d: scalar::Date) -> Self {
        Value::Scalar(Scalar::Date(d))
    }

    pub fn new_uri<U: Into<scalar::Url>>(u: U) -> Self {
        Value::Scalar(Scalar::Uri(u.into()))
    }

    pub fn new_binary(b: Vec<u8>) -> Self {
        Value::Scalar(Scalar::Binary(b))
    }
}

impl Scalar {
    pub fn as_bool(&self) -> Option<bool> {
        match *self {
            Scalar::Boolean(ref b) => Some(*b),
            Scalar::Integer(ref i) => Some(*i != 0),
            Scalar::Real(ref r) => Some(*r != 0.),
            Scalar::Uuid(ref u) => Some(*u != Uuid::nil()),
            Scalar::String(ref s) => match s.as_str() {
                "1" | "true" => Some(true),
                _ => Some(false),
            },
            Scalar::Date(_) => None,
            Scalar::Uri(_) => None,
            Scalar::Binary(ref b) => Some(!b.is_empty()),
            Scalar::Undefined => None,
        }
    }

    pub fn as_int(&self) -> Option<i32> {
        match *self {
            Scalar::Boolean(ref b) => if *b {
                Some(1)
            } else {
                Some(0)
            },
            Scalar::Integer(ref i) => Some(*i),
            // Note: this can overflow, but never panics.
            Scalar::Real(ref r) => Some(r.round() as i32),
            Scalar::Uuid(_) => None,
            Scalar::String(ref s) => {
                for cap in RE_INTEGER.captures_iter(s) {
                    return Some(cap[1].parse().unwrap());
                }
                None
            }
            Scalar::Date(ref d) => Some(d.timestamp() as i32),
            Scalar::Uri(_) => None,
            Scalar::Binary(ref b) => if b.len() < 4 {
                None
            } else {
                Some(BigEndian::read_i32(&b[0..4]))
            },
            Scalar::Undefined => None,
        }
    }

    pub fn as_real(&self) -> Option<f64> {
        match *self {
            Scalar::Boolean(ref b) => if *b {
                Some(1.)
            } else {
                Some(0.)
            },
            Scalar::Integer(ref i) => Some(*i as f64),
            Scalar::Real(ref r) => Some(*r),
            Scalar::Uuid(_) => None,
            Scalar::String(ref s) => {
                for cap in RE_REAL.captures_iter(s) {
                    return match &cap[1] {
                        "nan" => Some(::std::f64::NAN),
                        s => Some(s.parse().unwrap()),
                    };
                }
                None
            }
            Scalar::Date(ref d) => Some(d.timestamp() as f64),
            Scalar::Uri(_) => None,
            Scalar::Binary(ref b) => if b.len() < 8 {
                None
            } else {
                Some(BigEndian::read_f64(&b[0..8]))
            },
            Scalar::Undefined => None,
        }
    }

    pub fn as_uuid(&self) -> Option<Uuid> {
        match *self {
            Scalar::Boolean(_) => None,
            Scalar::Integer(_) => None,
            Scalar::Real(_) => None,
            Scalar::Uuid(ref u) => Some(u.clone()),
            // TODO: This doesn't correctly implement the spec, as the spec says only the
            // conversion of hyphenated UUIDs should succeed, every other should fail,
            // but this method is agnostic of the hyphens.
            Scalar::String(ref s) => Uuid::parse_str(s.as_str()).ok(),
            Scalar::Date(_) => None,
            Scalar::Uri(_) => None,
            Scalar::Binary(ref b) => {
                if b.len() < 16 {
                    None
                } else {
                    // TODO: This should never error.
                    Uuid::from_slice(&b[0..16]).ok()
                }
            }
            Scalar::Undefined => None,
        }
    }

    pub fn as_string(&self) -> Option<String> {
        match *self {
            Scalar::Boolean(ref b) => if *b {
                Some("true".to_string())
            } else {
                Some("false".to_string())
            },
            Scalar::Integer(ref i) => Some(format!("{}", i)),
            Scalar::Real(ref r) => Some(format!("{}", r)),
            Scalar::Uuid(ref u) => Some(u.to_hyphenated().to_string()),
            Scalar::String(ref s) => Some(s.clone()),
            Scalar::Date(ref d) => Some(d.to_rfc3339()),
            Scalar::Uri(ref u) => Some(u.clone().into_string()),
            Scalar::Binary(ref b) => Some(String::from_utf8_lossy(b).to_string()),
            Scalar::Undefined => None,
        }
    }

    pub fn as_date(&self) -> Option<scalar::Date> {
        match *self {
            Scalar::Boolean(_) => None,
            // TODO: I can't imagine anyone ever wants to use this with a i32, maybe this is
            // another error in the documentation?
            Scalar::Integer(ref i) => Some(scalar::Date::from_utc(
                NaiveDateTime::from_timestamp(*i as i64, 0),
                Utc,
            )),
            Scalar::Real(ref f) => Some(scalar::Date::from_utc(
                NaiveDateTime::from_timestamp(*f as i64, 0),
                Utc,
            )),
            Scalar::Uuid(_) => None,
            Scalar::String(ref s) => s.parse().ok(),
            Scalar::Date(ref d) => Some(d.clone()),
            Scalar::Uri(_) => None,
            Scalar::Binary(_) => None,
            Scalar::Undefined => None,
        }
    }

    pub fn as_uri(&self) -> Option<scalar::Url> {
        match *self {
            Scalar::Boolean(_) => None,
            Scalar::Integer(_) => None,
            Scalar::Real(_) => None,
            Scalar::Uuid(_) => None,
            Scalar::String(ref s) => Some(s.as_str().into()),
            Scalar::Date(_) => None,
            Scalar::Uri(ref u) => Some(u.clone()),
            Scalar::Binary(ref b) => Some(String::from_utf8_lossy(b).to_string().into()),
            Scalar::Undefined => None,
        }
    }

    pub fn as_binary(&self) -> Option<Vec<u8>> {
        match *self {
            Scalar::Boolean(ref b) => if *b {
                Some(vec![1])
            } else {
                Some(vec![0])
            },
            Scalar::Integer(ref i) => {
                let mut buf = Vec::new();
                BigEndian::write_i32(&mut buf, *i);
                Some(buf)
            }
            Scalar::Real(ref r) => {
                let mut buf = Vec::new();
                BigEndian::write_f64(&mut buf, *r);
                Some(buf)
            }
            Scalar::Uuid(ref u) => Some(u.as_bytes().to_vec()),
            Scalar::String(ref s) => Some(s.as_bytes().to_vec()),
            Scalar::Date(_) => None,
            Scalar::Uri(_) => None,
            Scalar::Binary(ref b) => Some(b.clone()),
            Scalar::Undefined => None,
        }
    }
}