// The Swift Programming Language
// https://docs.swift.org/swift-book

import SDL
import Foundation

guard SDL_Init(SDL_INIT_VIDEO) == 0 else {
    fatalError("SDL could not initialize! SDL_Error: \(String(cString: SDL_GetError()))")
}

let window = SDL_CreateWindow(
    "SwiftNES",
    Int32(SDL_WINDOWPOS_CENTERED_MASK), Int32(SDL_WINDOWPOS_CENTERED_MASK),
    Int32(256.0 * 3.0), Int32(240.0 * 3.0),
    SDL_WINDOW_SHOWN.rawValue)

let canvas = SDL_CreateRenderer(window, -1, SDL_RENDERER_PRESENTVSYNC.rawValue)

SDL_RenderSetScale(canvas, 3.0, 3.0)

var texture = SDL_CreateTexture(canvas, SDL_PIXELFORMAT_RGB24.rawValue, Int32(SDL_TEXTUREACCESS_TARGET.rawValue), 256, 240)

var event = SDL_Event()
var quit = false

// func handleUserInput(_ cpu: CPU, event: inout SDL_Event) {
//     while SDL_PollEvent(&event) > 0 {
//         if event.type == SDL_QUIT.rawValue {
//             SDL_DestroyWindow(window)
//             SDL_Quit()
//             exit(0)
//         }
//         if event.type == SDL_KEYDOWN.rawValue {
//             switch SDL_KeyCode(UInt32(event.key.keysym.sym)) {
//             case SDLK_ESCAPE:
//                 SDL_DestroyWindow(window)
//                 SDL_Quit()
//                 exit(0)
//             case SDLK_w:
//                 cpu.memWrite(0xff, data: 0x77)
//             case SDLK_a:
//                 cpu.memWrite(0xff, data: 0x61)
//             case SDLK_s:
//                 cpu.memWrite(0xff, data: 0x73)
//             case SDLK_d:
//                 cpu.memWrite(0xff, data: 0x64)
//             default:
//                 continue
//             }
//         }
//     }
// }

// func color(_ byte: UInt8) -> SDL_Color {
//     switch byte{
//     case 0:
//         return SDL_Color(r: 0, g: 0, b: 0, a: 255)
//     case 1:
//         return SDL_Color(r: 255, g: 255, b: 255, a: 255)
//     case 2, 9:
//         return SDL_Color(r: 128, g: 128, b: 128, a: 255)
//     case 3, 10:
//         return SDL_Color(r: 255, g: 0, b: 0, a: 255)
//     case 4, 11:
//         return SDL_Color(r: 0, g: 255, b: 0, a: 255)
//     case 5, 12:
//         return SDL_Color(r: 0, g: 0, b: 255, a: 255)
//     case 6, 13:
//         return SDL_Color(r: 255, g: 0, b: 255, a: 255)
//     case 7, 14:
//         return SDL_Color(r: 255, g: 255, b: 0, a: 255)
//     default:
//         return SDL_Color(r: 0, g: 255, b: 255, a: 255)

//     }
// }

// func readScreenState(_ cpu: CPU, frame: inout [UInt8]) -> Bool {

//     var frame_idx = 0
//     var update = false
//     for i in 0x0200..<0x600 {
//         let color_idx = cpu.memRead(UInt16(i))
//         let color = color(color_idx)
//         let (b1, b2, b3) = (color.r, color.b, color.g)
//         if frame[frame_idx] != b1 || frame[frame_idx + 1] != b2 || frame[frame_idx + 2] != b3 {
//            frame[frame_idx] = b1;
//            frame[frame_idx + 1] = b2;
//            frame[frame_idx + 2] = b3;
//            update = true;
//        }
//         frame_idx += 3
//     }
//     return update
// }

guard let bytes = NSData(contentsOfFile: "pacman.nes") else { fatalError("Rom not found") }
var gameCode = [UInt8](repeating: 0, count: bytes.length)
bytes.getBytes(&gameCode, length: bytes.length)

let rom = try Rom(gameCode)

var frame = Frame()
let bus = Bus(rom) { ppu in
    Render.render(ppu, frame: frame)
    SDL_UpdateTexture(texture, nil, frame.data, 256 * 3)
    SDL_RenderCopy(canvas, texture, nil, nil)
    SDL_RenderPresent(canvas)

    while SDL_PollEvent(&event) > 0 {
        if event.type == SDL_QUIT.rawValue {
             SDL_DestroyWindow(window)
             SDL_Quit()
             exit(0)
         }
        if event.type == SDL_KEYDOWN.rawValue {
            switch SDL_KeyCode(UInt32(event.key.keysym.sym)) {
            case SDLK_ESCAPE:
                SDL_DestroyWindow(window)
                SDL_Quit()
                exit(0)
            default:
                continue
            }
        }
    }
}

let cpu = CPU(bus: bus)
cpu.reset()
cpu.run()

// let tileFrame = TileViewer.showTile(chrRom: rom.character, bank: 1, tileNum: 0)
// let tileFrame = TileViewer.showTileBank(chrRom: rom.character, bank: 1)

// SDL_UpdateTexture(texture, nil, tileFrame.data, 256 * 3)
// SDL_RenderCopy(canvas, texture, nil, nil)
// SDL_RenderPresent(canvas)

// while true {
//     while SDL_PollEvent(&event) > 0 {
//         if event.type == SDL_QUIT.rawValue {
//              SDL_DestroyWindow(window)
//              SDL_Quit()
//              exit(0)
//          }
//         if event.type == SDL_KEYDOWN.rawValue {
//             switch SDL_KeyCode(UInt32(event.key.keysym.sym)) {
//             case SDLK_ESCAPE:
//                 SDL_DestroyWindow(window)
//                 SDL_Quit()
//                 exit(0)
//             default:
//                 continue
//             }
//         }
//     }
// }

// let bus = Bus(try! Rom(gameCode))

//var cpu = CPU(bus: bus)
//cpu.load(gameCode)
//cpu.reset()
//cpu.programCounter = 0xC000

// var screenState = [UInt8](repeating: 0, count: 32 * 3 * 32)
// var rng = SystemRandomNumberGenerator()
// cpu.run(onCycle: {
//     //print(dumpCpuState(cpu))
//     handleUserInput(cpu, event: &event)
//     cpu.memWrite(0xfe, data: UInt8.random(in: 1...16, using: &rng))

//     if readScreenState(cpu, frame: &screenState) {
//         SDL_UpdateTexture(texture, nil, screenState, 32 * 3)
//         SDL_RenderCopy(canvas, texture, nil, nil)
//         SDL_RenderPresent(canvas)
//     }

//     usleep(70)
// }, onComplete: {
//     SDL_DestroyWindow(window)
//     SDL_Quit()
//     exit(0)
// })

// Infinite loop otherwise the program will exit prematurely
// RunLoop.main.run()