Kingfisher/Sources/General/ImageDataProvider.swift

//
//  ImageDataProvider.swift
//  Kingfisher
//
//  Created by onevcat on 2018/11/13.
//
//  Copyright (c) 2018 Wei Wang <onevcat@gmail.com>
//
//  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.

import Foundation

public protocol ImageDataProvider {
    var cacheKey: String { get }
    func data(handler: (Result<Data, Error>) -> Void)
    var identifier: String {get }
}

public struct LocalFileImageDataProvider: ImageDataProvider {
    public var cacheKey: String

    public func data(handler: (Result<Data, Error>) -> Void) {
        do {
            let data = try Data(contentsOf: fileURL)
            handler(.success(data))
        } catch {
            handler(
                .failure(error)
            )
        }
    }

    public var identifier: String { return fileURL.absoluteString }

    public let fileURL: URL
    public init(fileURL: URL, cacheKey: String? = nil) {
        self.fileURL = fileURL
        self.cacheKey = cacheKey ?? fileURL.absoluteString
    }
}

public struct Base64ImageDataProvider: ImageDataProvider {
    public var cacheKey: String
    public let base64String: String
    public var identifier: String { return cacheKey }

    public init(base64String: String, cacheKey: String) {
        self.base64String = base64String
        self.cacheKey = cacheKey
    }

    public func data(handler: (Result<Data, Error>) -> Void) {
        let data = Data(base64Encoded: base64String)!
        handler(.success(data))
    }

}