using System.Collections.Generic;
using System.Text;

namespace SourceGit.Models {
    public class DiffOption {
        public Change WorkingCopyChange => _workingCopyChange;
        public bool IsUnstaged => _isUnstaged;
        public List<string> Revisions => _revisions;
        public string Path => _path;
        public string OrgPath => _orgPath;

        /// <summary>
        ///     Only used for working copy changes
        /// </summary>
        /// <param name="change"></param>
        /// <param name="isUnstaged"></param>
        public DiffOption(Change change, bool isUnstaged) {
            _workingCopyChange = change;
            _isUnstaged = isUnstaged;

            if (isUnstaged) {
                switch (change.WorkTree) {
                case ChangeState.Added:
                case ChangeState.Untracked:
                    _extra = "--no-index";
                    _path = change.Path;
                    _orgPath = "/dev/null";
                    break;
                default:
                    _path = change.Path;
                    _orgPath = change.OriginalPath;
                    break;
                }
            } else {
                _extra = "--cached";
                _path = change.Path;
                _orgPath = change.OriginalPath;
            }
        }

        /// <summary>
        ///     Only used for commit changes.
        /// </summary>
        /// <param name="commit"></param>
        /// <param name="change"></param>
        public DiffOption(Commit commit, Change change) {
            var baseRevision = commit.Parents.Count == 0 ? "4b825dc642cb6eb9a060e54bf8d69288fbee4904" : $"{commit.SHA}^";
            _revisions.Add(baseRevision);
            _revisions.Add(commit.SHA);
            _path = change.Path;
            _orgPath = change.OriginalPath;
        }

        /// <summary>
        ///     Diff with filepath. Used by FileHistories
        /// </summary>
        /// <param name="commit"></param>
        /// <param name="file"></param>
        public DiffOption(Commit commit, string file) {
            var baseRevision = commit.Parents.Count == 0 ? "4b825dc642cb6eb9a060e54bf8d69288fbee4904" : $"{commit.SHA}^";
            _revisions.Add(baseRevision);
            _revisions.Add(commit.SHA);
            _path = file;
        }

        /// <summary>
        ///     Used to show differences between two revisions.
        /// </summary>
        /// <param name="baseRevision"></param>
        /// <param name="targetRevision"></param>
        /// <param name="change"></param>
        public DiffOption(string baseRevision, string targetRevision, Change change) {
            _revisions.Add(baseRevision);
            _revisions.Add(targetRevision);
            _path = change.Path;
            _orgPath = change.OriginalPath;
        }

        /// <summary>
        ///     Converts to diff command arguments.
        /// </summary>
        /// <returns></returns>
        public override string ToString() {
            var builder = new StringBuilder();
            if (!string.IsNullOrEmpty(_extra)) builder.Append($"{_extra} ");
            foreach (var r in _revisions) builder.Append($"{r} ");

            builder.Append("-- ");
            if (!string.IsNullOrEmpty(_orgPath)) builder.Append($"\"{_orgPath}\" ");
            builder.Append($"\"{_path}\"");

            return builder.ToString();
        }

        private Change _workingCopyChange = null;
        private bool _isUnstaged = false;
        private string _orgPath = string.Empty;
        private string _path = string.Empty;
        private string _extra = string.Empty;
        private List<string> _revisions = new List<string>();
    }
}