using System;
using System.Collections.Generic;
using Jovian.PopupSystem.UI;
using UnityEngine;
using Object = UnityEngine.Object;

namespace Jovian.PopupSystem {
    public sealed class PopupSystem : IPopupSystem {
        readonly PopupSettings settings;
        readonly PopupView viewPrefab;
        readonly Func<IPopupAnimator> animatorFactory;
        readonly Dictionary<PopupCategory, ViewState> categories = new();

        public PopupSystem(PopupSettings settings, PopupView viewPrefab, Func<IPopupAnimator> animatorFactory = null) {
            this.settings = settings;
            this.viewPrefab = viewPrefab;
            this.animatorFactory = animatorFactory ?? (() => new FadePopupAnimator());
        }

        public void RegisterCategory(PopupCategory category, int priority = 0) {
            if(categories.ContainsKey(category)) {
                return;
            }
            var effectivePriority = settings.GetPriority(category);
            if(effectivePriority == 0) {
                effectivePriority = priority;
            }
            categories[category] = new ViewState {
                priority = effectivePriority,
                delay = settings.GetDelay(category),
                animator = animatorFactory()
            };
        }

        public void Show(PopupCategory category, Action<PopupContentBuilder> buildContent,
                         RectTransform anchor = null, AnchorSide? anchorSide = null) {
            if(!categories.TryGetValue(category, out var state)) {
                return;
            }

            DismissLowerPriority(state.priority);

            state.pendingBuild = buildContent;
            state.pendingAnchor = anchor;
            state.pendingAnchorSide = anchorSide ?? settings.defaultAnchorSide;
            state.pendingScreenPos = null;
            state.delayTimer = state.delay;
            state.isPending = true;
        }

        public void ShowAtPosition(PopupCategory category, Action<PopupContentBuilder> buildContent,
                                   Vector2 screenPosition) {
            if(!categories.TryGetValue(category, out var state)) {
                return;
            }

            DismissLowerPriority(state.priority);

            state.pendingBuild = buildContent;
            state.pendingAnchor = null;
            state.pendingScreenPos = screenPosition;
            state.delayTimer = state.delay;
            state.isPending = true;
        }

        public void Hide(PopupCategory category) {
            if(!categories.TryGetValue(category, out var state)) {
                return;
            }

            state.isPending = false;
            if(state.view != null && state.view.IsVisible) {
                state.animator.Hide(state.view.CanvasGroup, settings.fadeDuration, () => {
                    state.view.SetVisible(false);
                });
            }
        }

        public void HideAll() {
            foreach(var kvp in categories) {
                Hide(kvp.Key);
            }
        }

        public void Tick(float deltaTime) {
            foreach(var kvp in categories) {
                kvp.Value.animator.Tick(deltaTime);
            }

            foreach(var kvp in categories) {
                var state = kvp.Value;
                if(!state.isPending) {
                    continue;
                }

                state.delayTimer -= deltaTime;
                if(state.delayTimer > 0f) {
                    continue;
                }

                state.isPending = false;
                ShowImmediate(state);
            }

            foreach(var kvp in categories) {
                var state = kvp.Value;
                if(state.view != null && state.view.IsVisible && state.isFollowMouse) {
                    state.view.UpdatePosition();
                }
            }
        }

        public void Dispose() {
            foreach(var kvp in categories) {
                if(kvp.Value.view != null) {
                    Object.Destroy(kvp.Value.view.gameObject);
                }
            }
            categories.Clear();
        }

        private void ShowImmediate(ViewState state) {
            EnsureView(state);
            state.view.ClearContent();

            var builder = new PopupContentBuilder(state.view);
            state.pendingBuild?.Invoke(builder);

            if(state.pendingScreenPos.HasValue) {
                state.view.SetFixedPosition(state.pendingScreenPos.Value, settings.screenEdgePadding);
                state.isFollowMouse = false;
            }
            else if(state.pendingAnchor != null) {
                state.view.SetAnchorMode(state.pendingAnchor, state.pendingAnchorSide, settings.screenEdgePadding);
                state.isFollowMouse = false;
            }
            else {
                state.view.SetFollowMouseMode(settings.followMouseOffset, settings.screenEdgePadding);
                state.isFollowMouse = true;
            }

            state.view.SetVisible(true);
            state.view.UpdatePosition();
            state.animator.Show(state.view.CanvasGroup, settings.fadeDuration, null);
        }

        private void EnsureView(ViewState state) {
            if(state.view != null) {
                return;
            }
            state.view = Object.Instantiate(viewPrefab);
            state.view.SetVisible(false);
            state.view.SetMaxWidth(settings.maxPopupWidth);

            var canvas = state.view.GetComponent<Canvas>();
            if(canvas != null) {
                canvas.sortingOrder = settings.sortingOrder;
            }
        }

        private void DismissLowerPriority(int showingPriority) {
            foreach(var kvp in categories) {
                var state = kvp.Value;
                if(state.priority < showingPriority && state.view != null && state.view.IsVisible) {
                    state.isPending = false;
                    state.animator.Hide(state.view.CanvasGroup, settings.fadeDuration, () => {
                        state.view.SetVisible(false);
                    });
                }
            }
        }

        private sealed class ViewState {
            public PopupView view;
            public IPopupAnimator animator;
            public int priority;
            public float delay;
            public float delayTimer;
            public bool isPending;
            public bool isFollowMouse;
            public Action<PopupContentBuilder> pendingBuild;
            public RectTransform pendingAnchor;
            public AnchorSide pendingAnchorSide;
            public Vector2? pendingScreenPos;
        }
    }
}