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/*
 * Copyright (C) 2022 Vaticle
 *
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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::{fmt, iter};

use crate::{
    common::{
        error::{collect_err, TypeQLError},
        token,
        validatable::Validatable,
        Result,
    },
    pattern::{Definable, RuleDefinition, TypeVariable},
    write_joined,
};

#[derive(Debug, Default, Eq, PartialEq)]
pub struct TypeQLDefine {
    variables: Vec<TypeVariable>,
    rules: Vec<RuleDefinition>,
}

impl TypeQLDefine {
    pub fn new(definables: Vec<Definable>) -> Self {
        definables.into_iter().fold(TypeQLDefine::default(), |define, definable| match definable {
            Definable::RuleDefinition(rule) => define.add_rule(rule),
            Definable::TypeVariable(var) => define.add_definition(var),
            Definable::RuleDeclaration(r) => {
                panic!("{}", TypeQLError::InvalidRuleWhenMissingPatterns(r.label))
            }
        })
    }

    fn add_definition(mut self, variable: TypeVariable) -> Self {
        self.variables.push(variable);
        self
    }

    fn add_rule(mut self, rule: RuleDefinition) -> Self {
        self.rules.push(rule);
        self
    }
}

impl Validatable for TypeQLDefine {
    fn validate(&self) -> Result<()> {
        collect_err(
            &mut iter::once(expect_non_empty(&self.variables, &self.rules))
                .chain(self.variables.iter().map(Validatable::validate))
                .chain(self.variables.iter().map(TypeVariable::validate_definable))
                .chain(self.rules.iter().map(Validatable::validate)),
        )
    }
}

fn expect_non_empty(variables: &[TypeVariable], rules: &[RuleDefinition]) -> Result<()> {
    if variables.is_empty() && rules.is_empty() {
        Err(TypeQLError::MissingDefinables())?
    }
    Ok(())
}

impl fmt::Display for TypeQLDefine {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        writeln!(f, "{}", token::Command::Define)?;
        write_joined!(f, ";\n", self.variables, self.rules)?;
        f.write_str(";")
    }
}