/* vim: set filetype=rust.rustpeg */

// Copyright 2016 Mozilla
//
// Licensed under the Apache License, Version 2.0 (the "License"); you may not use
// this file except in compliance with the License. You may obtain a copy of the
// License at http://www.apache.org/licenses/LICENSE-2.0
// Unless required by applicable law or agreed to in writing, software distributed
// under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
// CONDITIONS OF ANY KIND, either express or implied. See the License for the
// specific language governing permissions and limitations under the License.

use std::collections::{BTreeSet, BTreeMap, LinkedList};
use std::iter::FromIterator;

use num::BigInt;
use ordered_float::OrderedFloat;
use types;
use types::Value;

// Goal: Be able to parse https://github.com/edn-format/edn
// Also extensible to help parse http://docs.datomic.com/query.html

// Debugging hint: test using `cargo test --features peg/trace -- --nocapture`
// to trace where the parser is failing

// TODO: Support tagged elements
// TODO: Support discard

#[export]
nil -> Value = "nil" {
    Value::Nil
}

#[export]
boolean -> Value =
    "true" { Value::Boolean(true) } /
    "false" { Value::Boolean(false) }

digit = [0-9]
sign = "-" / "+"

#[export]
bigint -> Value = b:$( sign? digit+ ) "N" {
    Value::BigInteger(b.parse::<BigInt>().unwrap())
}

#[export]
integer -> Value = i:$( sign? digit+ ) {
    Value::Integer(i.parse::<i64>().unwrap())
}

frac =     sign? digit+ "." digit+
exp =      sign? digit+            ("e" / "E") sign? digit+
frac_exp = sign? digit+ "." digit+ ("e" / "E") sign? digit+

// The order here is important - frac_exp must come before (exp / frac) or the
// parser assumes exp or frac when the float is really a frac_exp and fails
#[export]
float -> Value = f:$( frac_exp / exp / frac ) {
    Value::Float(OrderedFloat(f.parse::<f64>().unwrap()))
}

// TODO: \newline, \return, \space and \tab
special_char = quote / tab
quote = "\\\""
tab = "\\tab"
char = [^"] / special_char

#[export]
text -> Value = "\"" t:$(  char* ) "\"" {
    Value::Text(t.to_string())
}

namespace_divider = "."
namespace_separator = "/"

// TODO: Be more picky here
symbol_char_initial = [a-z] / [A-Z] / [0-9] / [*!_?$%&=<>]
symbol_char_subsequent = [a-z] / [A-Z] / [0-9] / [-*!_?$%&=<>]

symbol_namespace = symbol_char_initial+ (namespace_divider symbol_char_subsequent+)*
symbol_name = ( symbol_char_initial+ / "." ) ( symbol_char_subsequent* / "." )

keyword_prefix = ":"

// TODO: More chars here?
keyword_namespace_char = [a-z] / [A-Z] / [0-9]
keyword_namespace = keyword_namespace_char+ (namespace_divider keyword_namespace_char+)*

keyword_name_char = [a-z] / [A-Z] / [0-9] / "."
keyword_name = keyword_name_char+

#[export]
symbol -> Value
    = ns:( sns:$(symbol_namespace) namespace_separator { sns })? n:$(symbol_name) {
        types::to_symbol(ns, n)
    }

#[export]
keyword -> Value
    = keyword_prefix ns:( kns:$(keyword_namespace) namespace_separator { kns })? n:$(keyword_name) {
        types::to_keyword(ns, n)
    }

#[export]
list -> Value = "(" __ v:(__ value)* __ ")" {
    Value::List(LinkedList::from_iter(v))
}

#[export]
vector -> Value = "[" __ v:(__ value)* __ "]" {
    Value::Vector(v)
}

#[export]
set -> Value = "#{" __ v:(__ value)* __ "}" {
    Value::Set(BTreeSet::from_iter(v))
}

pair -> (Value, Value) = k:(value) " " v:(value) ", "? {
    (k, v)
}

#[export]
map -> Value = "{" __ v:(pair)* __ "}" {
    Value::Map(BTreeMap::from_iter(v))
}

// It's important that float comes before integer or the parser assumes that
// floats are integers and fails to parse
#[export]
value -> Value
    = nil / boolean / float / bigint / integer / text /
      keyword / symbol /
      list / vector / map / set

whitespace = (" " / "\r" / "\n" / "\t")
comment = ";" [^\r\n]* ("\r" / "\n")?

__ = (whitespace / comment)*