//
//  Attachment.swift
//  Pachyderm
//
//  Created by Shadowfacts on 9/9/18.
//  Copyright © 2018 Shadowfacts. All rights reserved.
//

import Foundation

public class Attachment: Decodable {
    public let id: String
    public let kind: Kind
    public let url: URL
    public let remoteURL: URL?
    public let previewURL: URL
    public let textURL: URL?
    public let meta: Metadata?
    public let description: String?
    
    public static func update(_ attachment: Attachment, focus: (Float, Float)?, description: String?) -> Request<Attachment> {
        return Request<Attachment>(method: .put, path: "/api/v1/media/\(attachment.id)", body: .formData([
                "description" => (description ?? attachment.description),
                "focus" => focus
            ], nil))
    }
    
    required public init(from decoder: Decoder) throws {
        let container = try decoder.container(keyedBy: CodingKeys.self)
        self.id = try container.decode(String.self, forKey: .id)
        self.kind = try container.decode(Kind.self, forKey: .kind)
        self.url = URL(lenient: try container.decode(String.self, forKey: .url))!
        if let remote = try? container.decode(String.self, forKey: .remoteURL) {
            self.remoteURL = URL(lenient: remote.replacingOccurrences(of: " ", with: "%20"))
        } else {
            self.remoteURL = nil
        }
        self.previewURL = URL(lenient: try container.decode(String.self, forKey: .previewURL).replacingOccurrences(of: " ", with: "%20"))!
        if let text = try? container.decode(String.self, forKey: .textURL) {
            self.textURL = URL(lenient: text.replacingOccurrences(of: " ", with: "%20"))
        } else {
            self.textURL = nil
        }
        self.meta = try? container.decode(Metadata.self, forKey: .meta)
        self.description = try? container.decode(String.self, forKey: .description)
    }
    
    private enum CodingKeys: String, CodingKey {
        case id
        case kind = "type"
        case url
        case remoteURL = "remote_url"
        case previewURL = "preview_url"
        case textURL = "text_url"
        case meta
        case description
    }
}

extension Attachment {
    public enum Kind: String, Decodable {
        case image
        case video
        case gifv
        case audio
        case unknown
        
        // we need a custom decoder, because all API-compatible implementations don't return some data in the same format
        public init(from decoder: Decoder) throws {
            let container = try decoder.singleValueContainer()
            let str = try container.decode(String.self)
            if let kind = Kind(rawValue: str.lowercased()) {
                self = kind
            } else {
                throw DecodingError.dataCorruptedError(in: container, debugDescription: "Attachment type must be one of image, video, gifv, audio, or unknown.")
            }
        }
    }
}

extension Attachment {
    public class Metadata: Decodable {
        public let length: String?
        public let duration: Float?
        public let audioEncoding: String?
        public let audioBitrate: String?
        public let audioChannels: String?
        public let fps: Float?
        public let width: Int?
        public let height: Int?
        public let size: String?
        public let aspect: Float?
        
        public let small: ImageMetadata?
        public let original: ImageMetadata?
        
        private enum CodingKeys: String, CodingKey {
            case length
            case duration
            case audioEncoding = "audio_encode"
            case audioBitrate = "audio_bitrate"
            case audioChannels = "audio_channels"
            case fps
            case width
            case height
            case size
            case aspect
            case small
            case original
        }
    }
    
    public class ImageMetadata: Decodable {
        public let width: Int?
        public let height: Int?
        public let size: String?
        public let aspect: Float?
        
        private enum CodingKeys: String, CodingKey {
            case width
            case height
            case size
            case aspect
        }
    }
}

fileprivate extension URL {
    private static let allowedChars = CharacterSet.urlHostAllowed.union(.urlPathAllowed).union(.urlQueryAllowed)
    
    init?(lenient string: String) {
        guard let escaped = string.addingPercentEncoding(withAllowedCharacters: URL.allowedChars) else {
            return nil
        }
        self.init(string: escaped)
    }
}