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// 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.

#[derive(Debug,Clone)]
pub enum DataType {
    Boolean,
    Int8,
    Int16,
    Int32,
    Int64,
    UInt8,
    UInt16,
    UInt32,
    UInt64,
    Float32,
    Float64,
    Utf8,
    Struct(Vec<Field>)
}

#[derive(Debug,Clone)]
pub struct Field {
    pub name: String,
    pub data_type: DataType,
    pub nullable: bool
}

impl Field {

    pub fn new(name: &str, data_type: DataType, nullable: bool) -> Self {
        Field {
            name: name.to_string(),
            data_type: data_type,
            nullable: nullable
        }
    }

    pub fn to_string(&self) -> String {
        format!("{}: {:?}", self.name, self.data_type)
    }
}

#[derive(Debug,Clone)]
pub struct Schema {
    pub columns: Vec<Field>
}

impl Schema {

    /// create an empty schema
    pub fn empty() -> Self { Schema { columns: vec![] } }

    pub fn new(columns: Vec<Field>) -> Self { Schema { columns: columns } }

    /// look up a column by name and return a reference to the column along with it's index
    pub fn column(&self, name: &str) -> Option<(usize, &Field)> {
        self.columns.iter()
            .enumerate()
            .find(|&(_,c)| c.name == name)
    }

    pub fn to_string(&self) -> String {
        let s : Vec<String> = self.columns.iter()
            .map(|c| c.to_string())
            .collect();
        s.join(",")
    }

}