//
//  NCDataSource.swift
//  Nextcloud
//
//  Created by Marino Faggiana on 06/09/2020.
//  Copyright © 2020 Marino Faggiana. All rights reserved.
//
//  Author Marino Faggiana <marino.faggiana@nextcloud.com>
//
//  This program is free software: you can redistribute it and/or modify
//  it under the terms of the GNU General Public License as published by
//  the Free Software Foundation, either version 3 of the License, or
//  (at your option) any later version.
//
//  This program is distributed in the hope that it will be useful,
//  but WITHOUT ANY WARRANTY; without even the implied warranty of
//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
//  GNU General Public License for more details.
//
//  You should have received a copy of the GNU General Public License
//  along with this program.  If not, see <http://www.gnu.org/licenses/>.
//

import UIKit

class NCDataSource: NSObject {

    public var metadatasForSection: [NCMetadatasForSection] = []

    public var metadatasSource: [tableMetadata] = []
    public var metadataShare: [String: tableShare] = [:]
    public var metadataOffLine: [String] = []
    public var sections: [String] = []

    private var ascending: Bool = true
    private var sort: String = ""
    private var directoryOnTop: Bool = true
    private var favoriteOnTop: Bool = true
    private var filterLivePhoto: Bool = true
    private var groupByField: String = ""

    override init() {
        super.init()
    }

    init(metadatasSource: [tableMetadata], sort: String? = "none", ascending: Bool? = false, directoryOnTop: Bool? = true, favoriteOnTop: Bool? = true, filterLivePhoto: Bool? = true, groupByField: String = "name") {
        super.init()

        self.metadatasSource = metadatasSource
        self.sort = sort ?? "none"
        self.ascending = ascending ?? false
        self.directoryOnTop = directoryOnTop ?? true
        self.favoriteOnTop = favoriteOnTop ?? true
        self.filterLivePhoto = filterLivePhoto ?? true
        self.groupByField = groupByField

        // Create sections && sorted
        self.sections = self.metadatasSource.map { getSectionField(metadata: $0) }
        self.sections = self.sections.sorted {
            if self.ascending {
                return $0 < $1
            } else {
                return $0 > $1
            }
        }

        // Create metadataForSection
        for section in self.sections {
            let metadatas = self.metadatasSource.filter({ getSectionField(metadata: $0) == section})
            let metadataForSection = NCMetadatasForSection.init(section: section, metadatas: metadatas, sort: self.sort, ascending: self.ascending, directoryOnTop: self.directoryOnTop, favoriteOnTop: self.favoriteOnTop, filterLivePhoto: self.filterLivePhoto)
            metadatasForSection.append(metadataForSection)
        }
    }

    // MARK: -

    func getFilesInformation() -> (directories: Int, files: Int, size: Int64) {

        var directories: Int = 0
        var files: Int = 0
        var size: Int64 = 0

        for metadata in self.metadatasSource {
            if metadata.directory {
                directories += 1
            } else {
                files += 1
            }
            size += metadata.size
        }

        return (directories, files, size)
    }

    func deleteMetadata(ocId: String) -> IndexPath? {

        if let indexPath = self.getIndexPathMetadata(ocId: ocId) {
            self.metadatasSource.remove(at: indexPath.row)
            return indexPath
        }

        return nil
    }

    @discardableResult
    func reloadMetadata(ocId: String, ocIdTemp: String? = nil) -> IndexPath? {

        var indexPath: IndexPath?

        if let ocIdTemp = ocIdTemp {
            indexPath = self.getIndexPathMetadata(ocId: ocIdTemp)
        } else {
            indexPath = self.getIndexPathMetadata(ocId: ocId)
        }

        guard let indexPath = indexPath, let metadata = NCManageDatabase.shared.getMetadataFromOcId(ocId) else { return nil }
        self.metadatasSource[indexPath.row] = metadata

        if CCUtility.fileProviderStorageExists(metadata) {
            let tableLocalFile = NCManageDatabase.shared.getTableLocalFile(predicate: NSPredicate(format: "ocId == %@", metadata.ocId))
            if tableLocalFile?.offline ?? false {
                metadataOffLine.append(metadata.ocId)
            }
        }

        return indexPath
    }

    @discardableResult
    func addMetadata(_ metadata: tableMetadata) -> IndexPath? {

        var row: Int = 0

        // Already exists
        for metadataCount in self.metadatasSource {
            if metadataCount.fileNameView == metadata.fileNameView || metadataCount.ocId == metadata.ocId {
                self.metadatasSource[row] = metadata
                let section = getSection(metadata: metadata)
                return IndexPath(row: row, section: section)
            }
            row += 1
        }

        // Append & rebuild
        self.metadatasSource.append(metadata)
        //createMetadatas()

        return getIndexPathMetadata(ocId: metadata.ocId)
    }

    func getIndexPathMetadata(ocId: String) -> IndexPath? {

        var row: Int = 0

        for metadata in self.metadatasSource {
            if metadata.ocId == ocId {
                let section = getSection(metadata: metadata)
                return IndexPath(row: row, section: section)
            }
            row += 1
        }

        return nil
    }

    func numberOfSections() -> Int {

        if sections.count == 0 {
            return 1
        } else {
            return sections.count
        }
    }
    
    func numberOfItemsInSection(_ section: Int) -> Int {

        if self.sections.count == 0 || self.metadatasSource.count == 0 { return 0 }
        let sectionName = self.sections[section]
        let metadatas = self.metadatasSource.filter({ getSectionField(metadata: $0) == sectionName})

        return metadatas.count
    }

    func cellForItemAt(indexPath: IndexPath) -> tableMetadata? {

        let row = indexPath.row
        let sectionName = self.sections[indexPath.section]
        let metadatas = self.metadatasSource.filter({ getSectionField(metadata: $0) == sectionName})

        if row > metadatas.count - 1 {
            return nil
        } else {
            return metadatas[row]
        }
    }

    internal func getSection(metadata: tableMetadata) -> Int {

        let section = self.sections.firstIndex(where: {$0 == getSectionField(metadata: metadata)}) ?? 0
        return section
    }

    internal func getSectionField(metadata: tableMetadata) -> String {

        switch self.groupByField {
        case "name":
            return metadata.name
        default:
            return metadata.name
        }
    }
}

class NCMetadatasForSection: NSObject {

    var section: String
    var metadatas: [tableMetadata]

    var sort : String
    var ascending: Bool
    var directoryOnTop: Bool
    var favoriteOnTop: Bool
    var filterLivePhoto: Bool

    var metadatasSourceSorted: [tableMetadata] = []
    var metadatasFavoriteDirectory: [tableMetadata] = []
    var metadatasFavoriteFile: [tableMetadata] = []
    var metadatasDirectory: [tableMetadata] = []
    var metadatasFile: [tableMetadata] = []
    var metadataShare: [String: tableShare] = [:]
    var metadataOffLine: [String] = []

    init(section: String, metadatas: [tableMetadata], sort: String, ascending: Bool, directoryOnTop: Bool, favoriteOnTop: Bool, filterLivePhoto: Bool) {

        self.section = section
        self.metadatas = metadatas
        self.sort = sort
        self.ascending = ascending
        self.directoryOnTop = directoryOnTop
        self.favoriteOnTop = favoriteOnTop
        self.filterLivePhoto = filterLivePhoto

        super.init()

        createMetadatasForSection()
    }

    private func createMetadatasForSection() {

        /*
        Metadata order
        */

        if sort != "none" && sort != "" {
            metadatasSourceSorted = metadatas.sorted {

                switch sort {
                case "date":
                    if ascending {
                        return ($0.date as Date) < ($1.date as Date)
                    } else {
                        return ($0.date as Date) > ($1.date as Date)
                    }
                case "size":
                    if ascending {
                        return $0.size < $1.size
                    } else {
                        return $0.size > $1.size
                    }
                default:
                    if ascending {
                        return $0.fileNameView.lowercased() < $1.fileNameView.lowercased()
                    } else {
                        return $0.fileNameView.lowercased() > $1.fileNameView.lowercased()
                    }
                }
            }
        } else {
            metadatasSourceSorted = metadatas
        }

        /*
        Initialize datasource
        */

        for metadata in metadatasSourceSorted {

            // skipped the root file
            if metadata.fileName == "." || metadata.serverUrl == ".." {
                continue
            }

            // skipped livePhoto
            if metadata.ext == "mov" && metadata.livePhoto && filterLivePhoto {
                continue
            }

            // share
            let shares = NCManageDatabase.shared.getTableShares(account: metadata.account, serverUrl: metadata.serverUrl, fileName: metadata.fileName)
            if shares.count > 0 {
                metadataShare[metadata.ocId] = shares.first
            }

            // is Local / offline
            if !metadata.directory, CCUtility.fileProviderStorageExists(metadata) {
                let tableLocalFile = NCManageDatabase.shared.getTableLocalFile(predicate: NSPredicate(format: "ocId == %@", metadata.ocId))
                if tableLocalFile == nil {
                    NCManageDatabase.shared.addLocalFile(metadata: metadata)
                }
                if tableLocalFile?.offline ?? false {
                    metadataOffLine.append(metadata.ocId)
                }
            }

            // Organized the metadata
            if metadata.favorite && favoriteOnTop {
                if metadata.directory {
                    metadatasFavoriteDirectory.append(metadata)
                } else {
                    metadatasFavoriteFile.append(metadata)
                }
            } else if  metadata.directory && directoryOnTop {
                metadatasDirectory.append(metadata)
            } else {
                metadatasFile.append(metadata)
            }
        }

        metadatas.removeAll()

        // Struct view : favorite dir -> favorite file -> directory -> files
        metadatas += metadatasFavoriteDirectory
        metadatas += metadatasFavoriteFile
        metadatas += metadatasDirectory
        metadatas += metadatasFile
    }
}