primitive m3u8 encoder-decoder

m3u8_primitive_swift_encoder_decoder.swift

//  License: MIT
//  2023 Ivan Oparin
//
//  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

enum m3u8 {
	static func encode(_ playlist: HLSPlaylist, to url: URL) throws {
		let lines = playlist.entries.map { entry -> String in
			switch entry {
				case .directive(let directive):
					return directive
				case .segment(let segment):
					return segment
			}
		}
		
		let text = lines.joined(separator: "\n")
		try text.write(to: url, atomically: true, encoding: .utf8)
	}
	
	static func decode(_ playlist: URL) throws -> HLSPlaylist {
		let text = try String(contentsOf: playlist, encoding: .utf8)
		let lines = text.split(separator: "\n")
		
		var playlist = HLSPlaylist()
		
		for line in lines {
			if line.hasPrefix("#") {
				// This is a directive
				playlist.entries.append(.directive(String(line)))
			} else {
				// This is a URI for a media segment or sub-playlist
				playlist.entries.append(.segment(String(line)))
			}
		}
		
		return playlist
	}
	
	static func decode(_ playlist: URL, prependingUrl components: URL) throws -> HLSPlaylist {
		let text = try String(contentsOf: playlist, encoding: .utf8)
		let lines = text.split(separator: "\n")
		
		var playlist = HLSPlaylist()
		
		for line in lines {
			if line.hasPrefix("#") {
				// This is a directive
				playlist.entries.append(.directive(String(line)))
			} else {
				// This is a URI for a media segment or sub-playlist
				playlist.entries.append(.segment("\(components.path)\(String(line))"))
			}
		}
		
		return playlist
	}
	
	enum PlaylistEntry: Equatable {
		case directive(String)
		case segment(String)
		
		var isSegment: Bool {
			switch self {
				case .directive:
					return false
				case .segment:
					return true
			}
		}
		
		var value: String {
			switch self {
				case let .directive(value):
					return value
				case let .segment(value):
					return value
			}
		}
	}
	
	struct HLSPlaylist {
		var entries: [PlaylistEntry] = []
	}
	
}