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// The MIT License (MIT)
//
// Copyright (c) 2017 Doublify Technologies
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
mod parser;
mod scanner;
mod tokenizer;

pub use filtering::parser::{Expression, InExpression, Literal, OrExpression, VariableDeclaration,
                            VariableDeclarationKind, parse};
pub use filtering::scanner::{Kind, Token, scan};
pub use filtering::tokenizer::tokenize;

use std::collections::HashMap;

/// Type of operation
#[derive(Debug, PartialEq)]
pub enum Operation {
  /// =
  Equal,
  /// {}
  Or,
  /// ()
  In,
}

/// Filter
#[derive(Debug, PartialEq)]
pub struct Filter {
  /// Type of operation
  pub operation: Operation,
  /// Values
  pub bindings: Vec<Literal>,
}

/// Query
#[derive(Debug, PartialEq)]
pub struct Query {
  /// Map of filters
  pub bindings: HashMap<String, Filter>,
}

/// Traverses identifier
///
/// Checks if identifier is reserved keyword (`IsKeyword` or `NotKeyword`)
/// and returns identifier in initializer or identifier name.
fn traverse_identifier(name: &Literal, children: &Option<Box<Expression>>) -> String {
  let default = &String::new();
  let new_name = if let Some(box Expression::Literal(Literal::Identifier(ref name))) = *children {
    name
  } else if let Literal::Identifier(ref name) = *name {
    name
  } else {
    default
  };

  new_name.to_owned()
}

/// Traverses children of array-like expression (`InExpression` or `OrExpression`)
fn traverse_children(filter: &mut Filter, children: &Vec<Box<Expression>>) {
  for child in children {
    match *child {
      box Expression::Literal(ref binding) => filter.bindings.push(binding.to_owned()),
      _ => {}
    }
  }
}

/// Traverses variable declaration
fn traverse_variable_declaration(VariableDeclaration { ref mut kind, ref name, ref mut children }: VariableDeclaration) -> (String, Filter){
  let new_name = traverse_identifier(name, children);

  let mut filter = Filter {
    operation: Operation::Equal,
    bindings: vec![],
  };

  children
    .take()
    .map(
      |expr| match expr {
        box Expression::OrExpression(OrExpression { ref children }) => {
          filter.operation = Operation::Or;
          traverse_children(&mut filter, children);
        }
        box Expression::InExpression(InExpression { ref children }) => {
          filter.operation = Operation::In;
          traverse_children(&mut filter, children);
        }
        box Expression::Literal(binding) => {
          use self::VariableDeclarationKind::*;

          let traverse = |kind| {
            Literal::Boolean(
              match kind {
                IsKeyword => true,
                NotKeyword => false,
              },
            )
          };

          filter
            .bindings
            .push(kind.take().map_or(binding, traverse))
        }
        _ => {}
      },
    );

  (new_name, filter)
}

/// Parses query
pub fn parse_query(raw_query: &str) -> Query {
  let tokens = tokenize(raw_query);
  let source = parse(tokens);
  let mut bindings: HashMap<String, Filter> = HashMap::new();

  for node in source.body {
    if let Expression::VariableDeclaration(variable_declaration) = *node {
      let (name, filter) = traverse_variable_declaration(variable_declaration);

      bindings.insert(name, filter);
    }
  }

  Query { bindings: bindings }
}