using System;
using System.Collections.Generic;

using Avalonia.Collections;

namespace SourceGit.ViewModels
{
    public enum BranchTreeNodeType
    {
        Remote,
        Folder,
        Branch,
    }

    public class BranchTreeNode
    {
        public string Name { get; set; }
        public BranchTreeNodeType Type { get; set; }
        public object Backend { get; set; }
        public bool IsExpanded { get; set; }
        public bool IsFiltered { get; set; }
        public List<BranchTreeNode> Children { get; set; } = new List<BranchTreeNode>();

        public bool IsUpstreamTrackStatusVisible
        {
            get => IsBranch && !string.IsNullOrEmpty((Backend as Models.Branch).UpstreamTrackStatus);
        }

        public string UpstreamTrackStatus
        {
            get => Type == BranchTreeNodeType.Branch ? (Backend as Models.Branch).UpstreamTrackStatus : "";
        }

        public bool IsRemote
        {
            get => Type == BranchTreeNodeType.Remote;
        }

        public bool IsFolder
        {
            get => Type == BranchTreeNodeType.Folder;
        }

        public bool IsBranch
        {
            get => Type == BranchTreeNodeType.Branch;
        }

        public bool IsCurrent
        {
            get => IsBranch && (Backend as Models.Branch).IsCurrent;
        }

        public class Builder
        {
            public List<BranchTreeNode> Locals => _locals;
            public List<BranchTreeNode> Remotes => _remotes;

            public void Run(List<Models.Branch> branches, List<Models.Remote> remotes, bool bForceExpanded)
            {
                foreach (var remote in remotes)
                {
                    var path = $"remote/{remote.Name}";
                    var node = new BranchTreeNode()
                    {
                        Name = remote.Name,
                        Type = BranchTreeNodeType.Remote,
                        Backend = remote,
                        IsExpanded = bForceExpanded || _expanded.Contains(path),
                    };

                    _maps.Add(path, node);
                    _remotes.Add(node);
                }

                foreach (var branch in branches)
                {
                    var isFiltered = _filters.Contains(branch.FullName);
                    if (branch.IsLocal)
                    {
                        MakeBranchNode(branch, _locals, "local", isFiltered, bForceExpanded);
                    }
                    else
                    {
                        var remote = _remotes.Find(x => x.Name == branch.Remote);
                        if (remote != null)
                            MakeBranchNode(branch, remote.Children, $"remote/{remote.Name}", isFiltered, bForceExpanded);
                    }
                }

                SortNodes(_locals);
                SortNodes(_remotes);
            }

            public void SetFilters(AvaloniaList<string> filters)
            {
                _filters.AddRange(filters);
            }

            public void CollectExpandedNodes(List<BranchTreeNode> nodes, bool isLocal)
            {
                CollectExpandedNodes(nodes, isLocal ? "local" : "remote");
            }

            private void CollectExpandedNodes(List<BranchTreeNode> nodes, string prefix)
            {
                foreach (var node in nodes)
                {
                    var path = prefix + "/" + node.Name;
                    if (node.Type != BranchTreeNodeType.Branch && node.IsExpanded)
                        _expanded.Add(path);
                    CollectExpandedNodes(node.Children, path);
                }
            }

            private void MakeBranchNode(Models.Branch branch, List<BranchTreeNode> roots, string prefix, bool isFiltered, bool bForceExpanded)
            {
                var subs = branch.Name.Split(new char[] { '/' }, StringSplitOptions.RemoveEmptyEntries);

                if (subs.Length == 1)
                {
                    var node = new BranchTreeNode()
                    {
                        Name = subs[0],
                        Type = BranchTreeNodeType.Branch,
                        Backend = branch,
                        IsExpanded = false,
                        IsFiltered = isFiltered,
                    };
                    roots.Add(node);
                    return;
                }

                BranchTreeNode lastFolder = null;
                var path = prefix;
                for (var i = 0; i < subs.Length - 1; i++)
                {
                    path = string.Concat(path, "/", subs[i]);
                    if (_maps.TryGetValue(path, out var value))
                    {
                        lastFolder = value;
                    }
                    else if (lastFolder == null)
                    {
                        lastFolder = new BranchTreeNode()
                        {
                            Name = subs[i],
                            Type = BranchTreeNodeType.Folder,
                            IsExpanded = bForceExpanded || branch.IsCurrent || _expanded.Contains(path),
                        };
                        roots.Add(lastFolder);
                        _maps.Add(path, lastFolder);
                    }
                    else
                    {
                        var folder = new BranchTreeNode()
                        {
                            Name = subs[i],
                            Type = BranchTreeNodeType.Folder,
                            IsExpanded = bForceExpanded || branch.IsCurrent || _expanded.Contains(path),
                        };
                        _maps.Add(path, folder);
                        lastFolder.Children.Add(folder);
                        lastFolder = folder;
                    }
                }

                var last = new BranchTreeNode()
                {
                    Name = subs[subs.Length - 1],
                    Type = BranchTreeNodeType.Branch,
                    Backend = branch,
                    IsExpanded = false,
                    IsFiltered = isFiltered,
                };
                lastFolder.Children.Add(last);
            }

            private void SortNodes(List<BranchTreeNode> nodes)
            {
                nodes.Sort((l, r) =>
                {
                    if (l.Type == r.Type)
                    {
                        return l.Name.CompareTo(r.Name);
                    }
                    else
                    {
                        return (int)l.Type - (int)r.Type;
                    }
                });

                foreach (var node in nodes)
                    SortNodes(node.Children);
            }

            private readonly List<BranchTreeNode> _locals = new List<BranchTreeNode>();
            private readonly List<BranchTreeNode> _remotes = new List<BranchTreeNode>();
            private readonly HashSet<string> _expanded = new HashSet<string>();
            private readonly List<string> _filters = new List<string>();
            private readonly Dictionary<string, BranchTreeNode> _maps = new Dictionary<string, BranchTreeNode>();
        }
    }
}