using System.Collections.Generic;
using UnityEditor;
using UnityEngine;
using UnityEditor.SceneManagement;

namespace GitMerge {
    /// <summary>
    /// The window that lets you perform merges on scenes and prefabs.
    /// </summary>
    public class GitMergeWindow : EditorWindow {
        private VCS vcs = new VCSGit ();

        //EditorPrefs keys for settings
        private const string epAutomerge = "GitMerge_automerge";
        private const string epAutofocus = "GitMerge_autofocus";

        //Settings
        public static bool automerge { private set; get; }
        public static bool autofocus { private set; get; }

        //The MergeManager that has the actual merging logic
        private MergeManager manager;

        public bool mergeInProgress {
            get {
                return manager != null;
            }
        }

        private Vector2 scrollPosition = Vector2.zero;
        private int tab = 0;

        [MenuItem ("Window/GitMerge")]
        static void OpenEditor () {
            var window = EditorWindow.GetWindow (typeof (GitMergeWindow), false, "GitMerge");
            //In case we're merging and the scene becomes edited,
            //the shown SerializedProperties should be repainted
            window.autoRepaintOnSceneChange = true;
            window.minSize = new Vector2 (500, 100);
        }

        void OnEnable () {
            LoadSettings ();
        }

        private static void LoadSettings () {
            if (EditorPrefs.HasKey (epAutomerge)) {
                automerge = EditorPrefs.GetBool (epAutomerge);
            } else {
                automerge = true;
            }
            if (EditorPrefs.HasKey (epAutofocus)) {
                autofocus = EditorPrefs.GetBool (epAutofocus);
            } else {
                autofocus = true;
            }
        }

        void OnHierarchyChange () {
            //Repaint if we changed the scene
            this.Repaint ();
        }

        //Always check for editor state changes, and abort the active merge process if needed
        void Update () {
            if (MergeAction.inMergePhase &&
                (EditorApplication.isCompiling ||
                    EditorApplication.isPlayingOrWillChangePlaymode)) {
                ShowNotification (new GUIContent ("Aborting merge due to editor state change."));
                AbortMerge ();
            }
        }

        private void AbortMerge () {
            manager.AbortMerge ();
            manager = null;
        }

        void OnGUI () {
            Resources.DrawLogo ();
            DrawTabButtons ();

            switch (tab) {
                case 0:
                    OnGUISceneTab ();
                    break;

                case 1:
                    OnGUIPrefabTab ();
                    break;

                default:
                    OnGUISettingsTab ();
                    break;
            }
        }

        /// <summary>
        /// Tab that offers scene merging.
        /// </summary>
        private void OnGUISceneTab () {
            GUILayout.Label ("Open Scene: " + EditorSceneManager.GetActiveScene().ToString());
            if (EditorSceneManager.GetActiveScene().ToString() != "" &&
                !mergeInProgress &&
                GUILayout.Button ("Start merging this scene", GUILayout.Height (80))) {
                var mm = new MergeManagerScene (this, vcs);
                if (mm.InitializeMerge ()) {
                    manager = mm;
                }
            }

            DisplayMergeProcess ();
        }

        /// <summary>
        /// Tab that offers prefab merging.
        /// </summary>
        private void OnGUIPrefabTab () {
            GameObject prefab;
            if (!mergeInProgress) {
                GUILayout.Label ("Drag your prefab here to start merging:");
                if (prefab = EditorGUILayout.ObjectField (null, typeof (GameObject), false, GUILayout.Height (60)) as GameObject) {
                    var mm = new MergeManagerPrefab (this, vcs);
                    if (mm.InitializeMerge (prefab)) {
                        manager = mm;
                    }
                }
            }

            DisplayMergeProcess ();
        }

        /// <summary>
        /// Tab that offers various settings for the tool.
        /// </summary>
        private void OnGUISettingsTab () {
            var vcsPath = vcs.exe ();
            var vcsPathNew = EditorGUILayout.TextField ("Path to git.exe", vcsPath);
            if (vcsPath != vcsPathNew) {
                vcs.SetPath (vcsPathNew);
            }

            var amNew = EditorGUILayout.Toggle ("Automerge", automerge);
            if (automerge != amNew) {
                automerge = amNew;
                EditorPrefs.SetBool (epAutomerge, automerge);
            }
            GUILayout.Label ("(Automerge new/deleted GameObjects/Components upon merge start)");

            var afNew = EditorGUILayout.Toggle ("Auto Highlight", autofocus);
            if (autofocus != afNew) {
                autofocus = afNew;
                EditorPrefs.SetBool (epAutofocus, autofocus);
            }
            GUILayout.Label ("(Highlight GameObjects when applying a MergeAction to it)");
        }

        /// <summary>
        /// If no merge is in progress, draws the buttons to switch between tabs.
        /// Otherwise, draws the "abort merge" button.
        /// </summary>
        private void DrawTabButtons () {
            if (!mergeInProgress) {
                string[] tabs = { "Merge Scene", "Merge Prefab", "Settings" };
                tab = GUI.SelectionGrid (new Rect (72, 36, 300, 22), tab, tabs, 3);
            } else {
                GUI.backgroundColor = new Color (1, 0.4f, 0.4f, 1);
                if (GUI.Button (new Rect (72, 36, 300, 22), "Abort merge")) {
                    manager.AbortMerge ();
                    manager = null;
                }
                GUI.backgroundColor = Color.white;
            }
        }

        /// <summary>
        /// Displays all MergeActions and the "apply merge" button if a merge is in progress.
        /// </summary>
        private void DisplayMergeProcess () {
            if (mergeInProgress) {
                var done = DisplayMergeActions ();
                GUILayout.BeginHorizontal ();
                if (done && GUILayout.Button ("Apply merge")) {
                    manager.CompleteMerge ();
                    manager = null;
                }
                GUILayout.EndHorizontal ();
            }
        }

        /// <summary>
        /// Displays all GameObjectMergeActions.
        /// </summary>
        /// <returns>True, if all MergeActions are flagged as "merged".</returns>
        private bool DisplayMergeActions () {
            scrollPosition = GUILayout.BeginScrollView (scrollPosition, false, true);
            GUILayout.BeginVertical (GUILayout.MinWidth (480));

            var textColor = GUI.skin.label.normal.textColor;
            GUI.skin.label.normal.textColor = Color.black;

            var done = true;
            foreach (var actions in manager.allMergeActions) {
                actions.OnGUI ();
                done = done && actions.merged;
            }

            GUI.skin.label.normal.textColor = textColor;

            GUILayout.EndVertical ();
            GUILayout.EndScrollView ();
            return done;
        }
    }
}