// Copyright (c) 2019, OpenEmu Team
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
//     * Redistributions of source code must retain the above copyright
//       notice, this list of conditions and the following disclaimer.
//     * Redistributions in binary form must reproduce the above copyright
//       notice, this list of conditions and the following disclaimer in the
//       documentation and/or other materials provided with the distribution.
//     * Neither the name of the OpenEmu Team nor the
//       names of its contributors may be used to endorse or promote products
//       derived from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY OpenEmu Team ''AS IS'' AND ANY
// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
// WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
// DISCLAIMED. IN NO EVENT SHALL OpenEmu Team BE LIABLE FOR ANY
// DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
// (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
// LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
// ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
// SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

import Foundation
import OpenEmuBase
import OpenEmuShaders

@objc
public class OEShadersModel : NSObject {
    // MARK: Notifications
    
    @objc public static let shaderModelCustomShadersDidChange = Notification.Name("OEShaderModelCustomShadersDidChangeNotification")
    
    public enum Preferences {
        case global
        case system(String)
        
        public var key: String {
            get {
                switch self {
                case .global:
                    return "videoShader"
                case .system(let identifier):
                    return "videoShader.\(identifier)"
                }
            }
        }
    }
    
    private let store: UserDefaults
    private let userPathName: String
    private let bundle: Bundle
    
    private var systemShaders = [OEShaderModel]()
    private var customShaders = [OEShaderModel]()
    
    
    /// Creates a shader model used for accessing shaders and their user state.
    /// - Parameters:
    ///   - store: The user defaults store to read and write to.
    ///   - bundle: The main bundle used to locate shaders.
    ///   - name: The name of the path used to read and write user-specified shaders,
    ///     from within the application support directory. A `nil`
    ///     value will use the `kCFBundleNameKey` from the main bundle; otherwise, `OpenEmuKit` will be used.
    @objc public init(store: UserDefaults, bundle: Bundle = .main, userPathName name: String? = nil) {
        self.store          = store
        self.bundle         = bundle
        self.userPathName   = name ?? bundle.infoDictionary?[kCFBundleNameKey as String] as? String ?? "OpenEmuKit"
        super.init()
        
        self.systemShaders  = loadSystemShaders()
        self.customShaders  = loadCustomShaders()
    }
    
    @objc public func reload() {
        customShaders       = loadCustomShaders()
        _allShaderNames     = nil
        _customShaderNames  = nil
        NotificationCenter.default.post(name: Self.shaderModelCustomShadersDidChange, object: nil)
    }
    
    private var _systemShaderNames: [String]?
    
    @objc public var systemShaderNames: [String] {
        if _systemShaderNames == nil {
            _systemShaderNames = systemShaders.map(\.name)
        }
        return _systemShaderNames!
    }
    
    private var _customShaderNames: [String]?
    
    @objc public var customShaderNames: [String] {
        if _customShaderNames == nil {
            _customShaderNames = customShaders.map(\.name)
        }
        return _customShaderNames!
    }
    
    private var _allShaderNames: [String]?
    
    @objc public var allShaderNames: [String] {
        if _allShaderNames == nil {
            
        }
        return _allShaderNames!
    }
    
    @objc public var defaultShader: OEShaderModel {
        get {
            if let name = store.string(forKey: Preferences.global.key),
               let shader = self[name] {
                return shader
            }
            
            return self["Pixellate"]!
        }
        
        set {
            store.set(newValue.name, forKey: Preferences.global.key)
        }
    }
    
    @objc public func shader(withName name: String) -> OEShaderModel? {
        return self[name]
    }
    
    @objc public func shader(forSystem identifier: String) -> OEShaderModel? {
        guard let name = store.string(forKey: Preferences.system(identifier).key) else {
            return defaultShader
        }
        return self[name]
    }
    
    @objc public func shader(forURL url: URL) -> OEShaderModel? {
        return OEShaderModel(url: url, store: store)
    }
    
    subscript(name: String) -> OEShaderModel? {
        return systemShaders.first(where: { $0.name == name }) ?? customShaders.first(where: { $0.name == name })
    }
    
    // MARK: - helpers
    
    private func loadSystemShaders() -> [OEShaderModel] {
        if let path = bundle.resourcePath {
            let url = URL(fileURLWithPath: path, isDirectory: true).appendingPathComponent("Shaders", isDirectory: true)
            let urls = Self.urlsForShaders(at: url)
            return urls.map { OEShaderModel(url: $0, store: store) }
        }
        return []
    }
    
    private func loadCustomShaders() -> [OEShaderModel] {
        guard let path = userShadersPath else { return [] }
        return Self.urlsForShaders(at: path).map { OEShaderModel(url: $0, store: store) }
    }
    
    private static func urlsForShaders(at url: URL) -> [URL] {
        var res = [URL]()
        
        let fm = FileManager.default
        
        guard
            let urls = try? fm.contentsOfDirectory(at: url, includingPropertiesForKeys: [.isDirectoryKey], options: .skipsSubdirectoryDescendants)
        else { return [] }
        
        let dirs = urls.filter({ (try? $0.resourceValues(forKeys: [.isDirectoryKey]).isDirectory) ?? false })
        for dir in dirs {
            guard
                let files = try? fm.contentsOfDirectory(at: dir, includingPropertiesForKeys: nil, options: [.skipsHiddenFiles, .skipsSubdirectoryDescendants])
            else { continue }
            if let slangp = files.first(where: { $0.pathExtension == "slangp" }) {
                // we have a file!
                res.append(slangp)
            }
        }
        
        return res
    }
    
    @objc public var userShadersPath: URL? {
        guard
            let path = try? FileManager.default.url(for: .applicationSupportDirectory, in: .userDomainMask, appropriateFor: nil, create: false)
        else { return nil }
        
        return path.appendingPathComponent(userPathName, isDirectory: true).appendingPathComponent("Shaders", isDirectory: true)
    }
    
    @objc public var shadersCachePath: URL? {
        guard
            let path = try? FileManager.default.url(for: .cachesDirectory, in: .userDomainMask, appropriateFor: nil, create: false)
        else { return nil }
        
        return path.appendingPathComponent(userPathName, isDirectory: true).appendingPathComponent("Shaders", isDirectory: true)
    }
    
    // MARK: - Shader Model
    
    @objc(OEShaderModel)
    @objcMembers
    public class OEShaderModel: NSObject {
        public enum Params {
            case global(String)
            case system(String, String)
            
            public var key: String {
                get {
                    switch self {
                    case .global(let shader):
                        return "videoShader.\(shader).params"
                    case .system(let shader, let identifier):
                        return "videoShader.\(identifier).\(shader).params"
                    }
                }
            }
        }
        
        private let store: UserDefaults
        public var name: String
        public var url: URL
        
        init(url: URL, store: UserDefaults) {
            self.store  = store
            self.name   = url.deletingLastPathComponent().lastPathComponent
            self.url    = url
        }
        
        @objc
        public func parameters(forIdentifier identifier: String) -> [String: Double]? {
            if let state = store.string(forKey: Params.system(self.name, identifier).key) {
                var res = [String:Double]()
                for param in state.split(separator: ";") {
                    let vals = param.split(separator: "=")
                    if let d = Double(vals[1]) {
                        res[String(vals[0])] = d
                    }
                }
                return res
            }
            
            return nil
        }
        
        @objc
        public func write(parameters params: [OEShaderParamValue], identifier: String) {
            var state = [String]()
            
            for p in params.filter({ !$0.isInitial }) {
                state.append("\(p.name)=\(p.value)")
            }
            if state.isEmpty {
                store.removeObject(forKey: Params.system(self.name, identifier).key)
            } else {
                store.set(state.joined(separator: ";"), forKey: Params.system(self.name, identifier).key)
            }
        }
        
        override public var description: String {
            return self.name
        }
        
        public override var debugDescription: String {
            return "\(name) \(url.absoluteString)"
        }
    }
}

extension OEShadersModel.OEShaderModel {
    public func readGroups() -> [OEShaderParamGroupValue] {
        guard let ss = try? SlangShader(fromURL: url) else { return [] }
        
        if let groups = readGroupsModel() {
            var all = ss.parameters
            var dg: OEShaderParamGroupValue?
            
            let res: [OEShaderParamGroupValue] = groups.enumerated().map { (i, g) in
                let gv = OEShaderParamGroupValue()
                gv.index = i
                gv.name = g.name
                gv.desc = g.desc
                gv.hidden = g.hidden
                
                if g.name == "default" {
                    dg = gv
                }
                
                // return a list of parameters from SlangShader in same order as g.parameters
                let p = g.parameters.compactMap { name in
                    all.first { $0.name == name }
                }
                all.removeAll { p.contains($0) }
                
                gv.parameters = OEShaderParamValue.withParameters(p)
                return gv
            }
            
            if let dg = dg, !all.isEmpty {
                dg.parameters = OEShaderParamValue.withParameters(all)
            }
            
            return res
        }
        
        let gv = OEShaderParamGroupValue()
        gv.index = 0
        gv.name = "default"
        gv.desc = "Default"
        gv.parameters = OEShaderParamValue.withParameters(ss.parameters)
        return [gv]
    }
    
    func readGroupsModel() -> [ShaderParameterGroupModel]? {
        let groupsURL = url.deletingLastPathComponent().appendingPathComponent("parameterGroups.plist")
        guard let data = try? Data(contentsOf: groupsURL) else { return nil }
        
        let dec = PropertyListDecoder()
        return try? dec.decode([ShaderParameterGroupModel].self, from: data)
    }
}