using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Microsoft.Xna.Framework;
using VBXSE;
using System.IO;

namespace SnakeRPG
{
    public static partial class Main
    {
        enum TitleScreenMode
        {
            Selecting,
            NewGame,
            Continue
        }

        const float LOGO_OFFSET = 168;
        const int TITLE_OPTIONS_CENTER = 496;
        const int TITLE_OPTIONS_SPACING = 76;
        const float TITLE_READY = 3f;

        public static bool onTitleScreen = true;
        static float titleScreenTimer = 0f;
        static Sprite titleScreenSprite = null;
        static List<GText> titleScreenOptions = new List<GText>();
        static Sprite titleScreenPointer = null;
        static int titleScreenFirstOptionY = 0;
        static int titleScreenCurrentChoice = 0;
        static TitleScreenMode titleScreenMode = TitleScreenMode.Selecting;

        static void TitleScreenInit()
        {
            titleScreenSprite = SpriteEngine.CreateMultiSprite(new string[] { "title0", "title1", "title2" }, 0, Convert.ToInt32(LOGO_OFFSET), 1f);
            titleScreenSprite.depth = -50000f;
            Audio.Start("startofalegend");

            titleScreenPointer = SpriteEngine.CreateSprite("pointer");
            titleScreenPointer.depth = -52000f;
            titleScreenPointer.enabled = false;

            titleScreenFirstOptionY = TITLE_OPTIONS_CENTER - TITLE_OPTIONS_SPACING / 2;
            for (int i = 0; i < 2; i++)
            {
                string text = "NEW GAME";
                if (i == 1) text = "CONTINUE";
                GText toAdd = SpriteEngine.CreateGText(text, 0, titleScreenFirstOptionY + TITLE_OPTIONS_SPACING * i);
                toAdd.scale = 2f;
                toAdd.depth = -51000f;
                toAdd.SetX(640 - (SpriteEngine.spriteFont.MeasureString(toAdd.text).X));
                toAdd.enabled = false;
                titleScreenOptions.Add(toAdd);
            }

            if (File.Exists("save1.dat")) titleScreenCurrentChoice = 1;
            if (File.Exists("save2.dat")) titleScreenCurrentChoice = 1;
            if (File.Exists("save3.dat")) titleScreenCurrentChoice = 1;
        }

        static void TitleScreenUpdate(float milliseconds)
        {
            float seconds = milliseconds / 1000f;
            titleScreenTimer += seconds;

            if (titleScreenTimer > 0.75f) titleScreenSprite.currentImage = 1;
            if (titleScreenTimer > 1.0f) titleScreenSprite.currentImage = 2;
            //Between 1.5 and 2.5, it should rise slowly
            float diff = titleScreenTimer - 1.5f;
            if (diff < 0) diff = 0;
            if (diff > 1) diff = 1;
            titleScreenSprite.SetY(LOGO_OFFSET - diff * LOGO_OFFSET);
            if (titleScreenTimer > TITLE_READY)
            {
                for (int i = 0; i < titleScreenOptions.Count; i++)
                {
                    titleScreenOptions[i].enabled = true;
                }
                titleScreenPointer.enabled = true;
            }

            int x = 392;
            if (titleScreenMode != TitleScreenMode.Selecting) x = 300;
            titleScreenPointer.SetPosition(x, titleScreenFirstOptionY + titleScreenCurrentChoice * TITLE_OPTIONS_SPACING);
        }

        static void TitleScreenDestroy()
        {
            for (int i = 0; i < titleScreenOptions.Count; i++)
            {
                SpriteEngine.EraseGObject(titleScreenOptions[i]);
            }
            titleScreenOptions.Clear();
            SpriteEngine.EraseGObject(titleScreenSprite);
            SpriteEngine.EraseGObject(titleScreenPointer);
            titleScreenSprite = null;
            titleScreenPointer = null;
            onTitleScreen = false;
        }

        static void TitleScreenMoveSelect(int direction)
        {
            if (titleScreenTimer < TITLE_READY) return;

            if (titleScreenCurrentChoice + direction < titleScreenOptions.Count && titleScreenCurrentChoice + direction > -1)
            {
                titleScreenCurrentChoice += direction;
                Audio.Play("cursor");
            }
        }

        static void TitleScreenConfirm()
        {
            if (titleScreenTimer < TITLE_READY) return;

            if (titleScreenMode == TitleScreenMode.Selecting)
            {
                if (titleScreenCurrentChoice == 0) titleScreenMode = TitleScreenMode.NewGame;
                else titleScreenMode = TitleScreenMode.Continue;
                Audio.Play("select");
                //Erase new game/continue
                for (int i = 0; i < titleScreenOptions.Count; i++)
                {
                    SpriteEngine.EraseGObject(titleScreenOptions[i]);
                }
                titleScreenOptions.Clear();
                //Add file 1/file 2/file 3
                titleScreenFirstOptionY = TITLE_OPTIONS_CENTER - TITLE_OPTIONS_SPACING;
                for (int i = 0; i < 3; i++)
                {
                    string text = "FILE " + (i + 1) + ": ";
                    string filename = "save" + (i + 1) + ".dat";
                    if (!File.Exists(filename)) text += "EMPTY";
                    else
                    {
                        try
                        {
                            FileStream fs = new FileStream(filename, FileMode.Open);
                            BinaryReader br = new BinaryReader(fs);
                            fs.Seek(0x09, SeekOrigin.Begin);
                            int version = br.ReadInt32();
                            if (version > VERSION) text += "<INCOMPATIBLE VERSION>";
                            else
                            {
                                fs.Seek(0x0D, SeekOrigin.Begin);
                                int level = br.ReadInt32();
                                text += "LEVEL " + level;
                            }
                            br.Close();
                            fs.Close();
                        }
                        catch (Exception) { text += "<READ ERROR>"; }
                    }
                    GText toAdd = SpriteEngine.CreateGText(text, 0, titleScreenFirstOptionY + TITLE_OPTIONS_SPACING * i);
                    toAdd.scale = 2f;
                    toAdd.depth = -51000f;
                    toAdd.SetX(640 - (SpriteEngine.spriteFont.MeasureString(toAdd.text).X));
                    toAdd.enabled = false;
                    titleScreenOptions.Add(toAdd);
                }
                titleScreenCurrentChoice = 0;
            }
            else
            {
                Audio.Play("select");
                saveFile = "save" + (titleScreenCurrentChoice + 1) + ".dat";
                saveBackup = "save" + (titleScreenCurrentChoice + 1) + ".bak";
                StartGame();
                if (titleScreenMode == TitleScreenMode.Continue) Load();
                TitleScreenDestroy();
            }
        }
    }
}