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// Copyright 2023 Datafuse Labs.
//
// 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::HashMap;
use std::env;

use crate::raw::*;
use crate::*;

/// Builder will build an accessor;
pub trait Builder: Default {
    /// Associated scheme for this builder.
    const SCHEME: Scheme;
    /// The accessor that built by this builder.
    type Accessor: Accessor;

    /// Construct a builder from given map.
    fn from_map(map: HashMap<String, String>) -> Self;

    /// Construct a builder from given iterator.
    fn from_iter(iter: impl Iterator<Item = (String, String)>) -> Self
    where
        Self: Sized,
    {
        Self::from_map(iter.collect())
    }

    /// Construct a builder from envs.
    fn from_env() -> Self
    where
        Self: Sized,
    {
        let prefix = format!("opendal_{}_", Self::SCHEME);
        let envs = env::vars()
            .filter_map(move |(k, v)| {
                k.to_lowercase()
                    .strip_prefix(&prefix)
                    .map(|k| (k.to_string(), v))
            })
            .collect();

        Self::from_map(envs)
    }

    /// Consume the accessor builder to build a service.
    fn build(&mut self) -> Result<Self::Accessor>;
}