package application

import (
	"errors"
	"io/fs"
	"os"
	"path/filepath"
	"time"

	"github.com/go-gl/gl/v3.3-core/gl"
	"github.com/veandco/go-sdl2/sdl"
	"github.com/veandco/go-sdl2/ttf"
	"gorm.io/gorm"
	"rhemawavetech.com/rhemawave/internal/assets"
	"rhemawavetech.com/rhemawave/internal/db"
	"rhemawavetech.com/rhemawave/internal/download"
	"rhemawavetech.com/rhemawave/internal/fontManager"
	"rhemawavetech.com/rhemawave/internal/graphics"
	"rhemawavetech.com/rhemawave/internal/keybinds"
	"rhemawavetech.com/rhemawave/internal/license"
	"rhemawavetech.com/rhemawave/internal/logger"
	"rhemawavetech.com/rhemawave/internal/mixer"
	"rhemawavetech.com/rhemawave/internal/network"
	"rhemawavetech.com/rhemawave/internal/page"
	"rhemawavetech.com/rhemawave/internal/shaderManager"
	"rhemawavetech.com/rhemawave/internal/sync"
)

const (
	targetFPS          = 60.0
	openGLMajorVersion = 3
	openGLMinorVersion = 3
	// volumeStepSize     = 16
	// apiURL             = "https://portal.rhemawavetech.com/api/v1"
)

type State int

const (
	FIRST_RUN State = iota
	NEEDS_INTERNET
	NEEDS_LICENSE_KEY
	NEEDS_EMAIL_ADDRESS
	DOWNLOADING_ASSETS
	READY
)

type Application struct {
	Window             *sdl.Window
	License            *license.Response
	pageStack          []page.Page
	pendingAction      func()
	running            bool
	DB                 *gorm.DB
	PageRouter         *page.Router
	state              State
	downloadsComplete  bool
	downloadFailed     bool
}

var lastNetworkCheckTime time.Time
var networkIsUp bool

// DataDirFor returns the per-user data directory for the application.
func DataDirFor(homeDir string) string {
	return filepath.Join(homeDir, ".local", "share", "radiantwave")
}

// ----------------------------------------------------------------------------
// Main Entry Point
// ----------------------------------------------------------------------------

func Run(bundled fs.FS) {
	var err error
	var homeDir string
	var dataDir string
	var DB *gorm.DB

	networkIsUp = false

	logger.Info("Starting Application")

	homeDir, err = os.UserHomeDir()
	if err != nil {
		logger.Error("unable to fetch user $HOME directory: %v", err)
		return
	}

	dataDir = DataDirFor(homeDir)
	if err := os.MkdirAll(dataDir, 0755); err != nil {
		logger.Error("unable to create data directory %s %v", dataDir, err)
		return
	}

	testFile := filepath.Join(dataDir, ".access_test")
	f, err := os.Create(testFile)
	if err != nil {
		logger.Error("data %s is not writeable: %v", dataDir, err)
		return
	}
	f.Close()
	os.Remove(testFile)

	logger.AddFile(filepath.Join(dataDir, "log.txt"))
	logger.SetLevel = logger.LevelInfo

	DB, err = db.Connect(filepath.Join(dataDir, "database.sqlite"))
	if err != nil {
		logger.Error("application failed to connect to the database: %v", err)
		return
	}

	if err = db.Migrate(DB); err != nil {
		logger.Error("application failed to perform database migrations: %v", err)
		return
	}

	firstRun := false

	// Populate the initial Config cache OR create defaults
	cfg, err := db.GetConfig(DB)
	if err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			firstRun = true
			cfg = &db.AppConfig{
				Model:               gorm.Model{ID: 1},
				DataDir:             dataDir,
				AssetsDir:           dataDir,
				SystemLevel:         "BASIC",
				SelectedAudioDevice: "default",
				InitialFontSize:     128,
				StandardFontSize:    32,
				LinePattern:         "fibonacci",
				AudioEnabled:        true,
				SavedVolume:         1.0,
			}

			if err := DB.Create(cfg).Error; err != nil {
				logger.Error("failed to create config: %v", err)
				return
			}
		}
	}

	logger.AddDatabase(DB)

	// Ensure bundled static assets (fonts, shaders, tos) are present in the
	// assets directory before any manager tries to load them.
	config, err := db.GetConfig(DB)
	if err != nil {
		panic(err)
	}
	if err := assets.Provision(bundled, config.AssetsDir); err != nil {
		logger.Error("failed to provision bundled assets into %s: %v", config.AssetsDir, err)
	}

	app := &Application{
		DB: DB,
	}

	logger.Debug("==== Debug Statement ====")

	if firstRun {
		app.state = FIRST_RUN
	}

	w, h := app.initializeSDLAndOpenGL()
	defer app.cleanup()

	app.initializeManagers()
	app.initializeAudio()
	// Create a buffered channel so log writes don't slow down downloads.
	downloadProgressChan := make(chan download.DownloadStatus, 1000)
	downloadDone := make(chan struct{})

	app.PageRouter = page.NewRouter(page.PageCtx{
		DbPtr:          app.DB,
		W:              w,
		H:              h,
		MessageChannel: downloadProgressChan,
		DownloadDone:   downloadDone,
	})

	// Sync the proclamations from the API to the Database
	sync.SyncProclamations(DB)
	sync.SyncCategories(DB)
	sync.SyncFrequencies(DB)

	// audioFileNames := []string{
	// 	"OriginalAudio.wav",
	// 	"174Hz.wav",
	// 	"396Hz.wav",
	// 	"417Hz.wav",
	// 	"432Hz.wav",
	// 	"639Hz.wav",
	// 	"741Hz.wav",
	// 	"852Hz.wav",
	// 	"963Hz.wav",
	// 	"1111Hz.wav",
	// 	"14Hz_Binaural.wav",
	// 	"40Hz_Binaural.wav",
	// 	"AlphaWaves.wav",
	// 	"PinealGland.wav",
	// }

	audioDir := filepath.Join(homeDir, ".radiantwave", "audio")

	_, err = os.Stat(audioDir)
	if os.IsNotExist(err) {
		if err = os.MkdirAll(audioDir, 0755); err != nil {
			logger.Error("unable to create audio directory: %v", err)
		}
	}

	go download.DownloadAudioFiles(app.PageRouter.Context.MessageChannel, app.DB, audioDir, "https://files.radiantwavetech.com/audio/")

	app.runEventLoop()
}

// computeState determines what state the application should be in based on
// current conditions, without performing any navigation. It returns the first
// unmet prerequisite in priority order: network > email > license > downloads > ready.
func (app *Application) computeState() State {
	if app.state == READY {
		return READY
	}

	// Check if downloads have finished (non-blocking)
	if !app.downloadsComplete {
		select {
		case <-app.PageRouter.Context.DownloadDone:
			app.downloadsComplete = true
		default:
		}
	}

	// Check if there is an internet connection
	if !networkIsUp {
		if lastNetworkCheckTime.IsZero() || time.Since(lastNetworkCheckTime) >= time.Second {
			lastNetworkCheckTime = time.Now()
			if !network.HasInternet() {
				return NEEDS_INTERNET
			}
			networkIsUp = true // internet confirmed, don't check again
		} else {
			return app.state // throttled, can't determine yet
		}
	}

	// Check for email address
	config, err := db.GetConfig(app.DB)
	if err != nil {
		panic(err)
	}

	// A rather annoying, insecure, but sometimes necessary "print the config" statement
	// data, err := json.MarshalIndent(config, "", " ")
	// if err != nil {
	// 	logger.Error("failed to marshal config: %v", err)
	// } else {
	// 	logger.Debug("AppConfig: %s", data)
	// }

	if config.EmailAddress == "" {
		return NEEDS_EMAIL_ADDRESS
	}

	// Check for license key
	config, err = db.GetConfig(app.DB)
	if err != nil {
		panic(err)
	}
	if config.LicenseKey == "" {
		return NEEDS_LICENSE_KEY
	}

	// All config prerequisites met -- now wait for downloads to finish
	if !app.downloadsComplete {
		return DOWNLOADING_ASSETS
	}

	return READY
}

// checkState keeps watch of the application state and sets pages
// accordingly. This function runs once per frame.
func (app *Application) checkState() {
	newState := app.computeState()

	if newState == app.state {
		return
	}

	oldState := app.state
	app.state = newState

	// Both DOWNLOADING_ASSETS and READY map to the HOME page.
	// Skip re-navigation when transitioning between them to avoid
	// destroying and recreating the Home page (which would close
	// the already-closed DownloadDone channel).
	oldIsHome := oldState == DOWNLOADING_ASSETS || oldState == READY
	newIsHome := newState == DOWNLOADING_ASSETS || newState == READY
	if oldIsHome && newIsHome {
		return
	}

	switch newState {
	case NEEDS_INTERNET:
		app.PageRouter.NavigateTo(page.WIFI)
	case NEEDS_EMAIL_ADDRESS:
		logger.Warning("No email address detected")
		app.PageRouter.NavigateTo(page.EMAIL_ADDRESS)
	case NEEDS_LICENSE_KEY:
		app.PageRouter.NavigateTo(page.LICENSE_KEY)
	case DOWNLOADING_ASSETS, READY:
		app.PageRouter.NavigateTo(page.HOME)
	}
}

func (app *Application) initializeSDLAndOpenGL() (W, H int32) {
	logger.Info("Initializing SDL")
	if err := sdl.Init(sdl.INIT_VIDEO | sdl.INIT_AUDIO); err != nil {
		logger.Fatal("SDL init failed: %v", err)
	}

	logger.Info("Initializing TTF")
	if err := ttf.Init(); err != nil {
		logger.Fatal("TTF init failed: %v", err)
	}

	sdl.GLSetAttribute(sdl.GL_CONTEXT_MAJOR_VERSION, openGLMajorVersion)
	sdl.GLSetAttribute(sdl.GL_CONTEXT_MINOR_VERSION, openGLMinorVersion)
	sdl.GLSetAttribute(sdl.GL_CONTEXT_PROFILE_MASK, sdl.GL_CONTEXT_PROFILE_CORE)
	sdl.ShowCursor(sdl.DISABLE)
	sdl.SetRelativeMouseMode(true)

	logger.Info("Querying display mode")
	displayMode, err := sdl.GetDisplayMode(0, 0)
	if err != nil {
		logger.Fatal("Display mode query failed: %v", err)
	}
	if displayMode.W == 0 || displayMode.H == 0 {
		logger.Fatal("Invalid display dimensions: %dx%d", displayMode.W, displayMode.H)
	}
	logger.Info("Display: %dx%d @ %dHz", displayMode.W, displayMode.H, displayMode.RefreshRate)

	logger.Info("Creating window")
	window, err := sdl.CreateWindow(
		"Rhema Wave",
		sdl.WINDOWPOS_UNDEFINED,
		sdl.WINDOWPOS_UNDEFINED,
		displayMode.W,
		displayMode.H,
		sdl.WINDOW_OPENGL|sdl.WINDOW_FULLSCREEN_DESKTOP|sdl.WINDOW_SHOWN,
	)
	if err != nil {
		logger.Fatal("Window creation failed: %v", err)
	}
	app.Window = window

	logger.Info("Creating OpenGL context")
	if _, err := app.Window.GLCreateContext(); err != nil {
		logger.Fatal("OpenGL context creation failed: %v", err)
	}

	logger.Info("Initializing go-gl")
	if err := gl.InitWithProcAddrFunc(sdl.GLGetProcAddress); err != nil {
		logger.Fatal("go-gl initialization failed: %v", err)
	}

	logger.Info("OpenGL version: %s", gl.GoStr(gl.GetString(gl.VERSION)))
	logger.Info("OpenGL renderer: %s", gl.GoStr(gl.GetString(gl.RENDERER)))

	if err := sdl.GLSetSwapInterval(1); err != nil {
		logger.Warning("Failed to enable vsync: %v", err)
	}

	w, h := app.Window.GLGetDrawableSize()
	logger.Info("Drawable size: %dx%d", w, h)

	logger.Info("Initializing virtual framebuffer (%dx%d -> %dx%d)",
		graphics.VirtualWidth, graphics.VirtualHeight, w, h)
	if err := graphics.InitVirtualFramebuffer(w, h); err != nil {
		logger.Fatal("Virtual framebuffer init failed: %v", err)
	}

	app.initKeybinds()
	logger.Info("SDL and OpenGL initialization complete")
	return graphics.VirtualWidth, graphics.VirtualHeight
}

func (app *Application) initializeManagers() {
	logger.Info("Initializing ShaderManager")
	config, err := db.GetConfig(app.DB)
	if err != nil {
		panic(err)
	}
	shaderDir := filepath.Join(config.AssetsDir, "shaders")
	logger.Info("Loading shaders from %s", shaderDir)
	if err := shaderManager.InitShaderManager(shaderDir); err != nil {
		logger.Fatal("ShaderManager initialization failed: %v", err)
	}

	logger.Info("Initializing FontManager")
	if err := fontManager.InitFontManager(config); err != nil {
		logger.Fatal("FontManager initialization failed: %v", err)
	}
}

func (app *Application) initializeAudio() {
	logger.Info("Initializing audio")
	config, err := db.GetConfig(app.DB)
	if err != nil {
		panic(err)
	}
	if err := mixer.Init(config, app.refreshCache); err != nil {
		logger.Error("Unable to initialize audio device '%s': %v", config.SelectedAudioDevice, err)
		logger.Error("Audio will be unavailable until a device is configured")
	} else {
		logger.Info("Audio initialized with device: '%s'", config.SelectedAudioDevice)
	}
}

func (app *Application) refreshCache() {}

func (app *Application) cleanup() {
	logger.Info("Cleaning up")

	if app.PageRouter != nil && app.PageRouter.ActivePage != nil {
		app.PageRouter.ActivePage.Destroy()
	}

	graphics.DestroyVirtualFramebuffer()

	if app.Window != nil {
		app.Window.Destroy()
	}

	ttf.Quit()
	sdl.Quit()
	logger.Info("Cleanup complete")
	logger.Close()
}

// ----------------------------------------------------------------------------
// Event Loop
// ----------------------------------------------------------------------------

func (app *Application) runEventLoop() {
	if app.PageRouter == nil || app.PageRouter.ActivePage == nil {
		logger.Fatal("No initial page loaded, Router is empty")
	}
	const frameDelay = time.Second / targetFPS
	app.running = true
	lastTime := time.Now()
	logger.Info("Entering event loop")

	for app.running {
		frameStart := time.Now()

		app.checkState()
		app.handleEvents()
		if !app.running {
			break
		}

		deltaTime := float32(time.Since(lastTime).Seconds())
		lastTime = time.Now()

		app.updateCurrentPage(deltaTime)
		app.renderFrame()

		frameTime := time.Since(frameStart)
		if frameTime < frameDelay {
			time.Sleep(frameDelay - frameTime)
		}
	}

	logger.Info("Event loop exited")
}

func (app *Application) handleEvents() {
	for event := sdl.PollEvent(); event != nil; event = sdl.PollEvent() {
		switch e := event.(type) {
		case *sdl.QuitEvent:
			app.running = false
			return

		case *sdl.KeyboardEvent:
			if e.Type == sdl.KEYDOWN && e.Repeat == 0 {
				isCtrlPressed := (e.Keysym.Mod&sdl.KMOD_CTRL) != 0 || (e.Keysym.Mod&sdl.KMOD_GUI) != 0
				if e.Keysym.Sym == sdl.K_c && isCtrlPressed {
					continue
				}
				keybinds.PerformAction(e)
			}
		}

		if currentPage := app.PageRouter.ActivePage; currentPage != nil {
			if err := currentPage.HandleEvent(&event); err != nil {
				logger.Error("Page event handler error: %v", err)
			}
		}
	}
}

func (app *Application) updateCurrentPage(deltaTime float32) {
	if currentPage := app.PageRouter.ActivePage; currentPage != nil {
		currentPage.Update(deltaTime)
	}
}

func (app *Application) renderFrame() {
	graphics.BeginVirtualRender()
	gl.ClearColor(0.0, 0.0, 0.0, 1.0)
	gl.Clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT)

	if currentPage := app.PageRouter.ActivePage; currentPage != nil {
		currentPage.Render()
	}

	graphics.BlitToScreen()
	app.Window.GLSwap()
}

// ----------------------------------------------------------------------------
// Keybind Registration
// ----------------------------------------------------------------------------

func (app *Application) initKeybinds() {
	keybinds.Register(sdl.K_F3, sdl.KMOD_NONE, func() {
		if app.state != READY && app.state != DOWNLOADING_ASSETS {
			return
		}
		app.PageRouter.NavigateTo(page.SETTINGS)
	})

	keybinds.Register(sdl.K_F2, sdl.KMOD_NONE, func() {
		if app.state != READY && app.state != DOWNLOADING_ASSETS {
			return
		}
		app.PageRouter.NavigateTo(page.SCROLLER)
	})

	keybinds.Register(sdl.K_F1, sdl.KMOD_NONE, func() {
		if app.state != READY && app.state != DOWNLOADING_ASSETS {
			return
		}
		app.PageRouter.NavigateTo(page.HOME)

	})

	keybinds.Register(sdl.K_q, sdl.KMOD_RCTRL, func() {
		app.Stop()
	})
}

func (app *Application) Stop() {
	app.running = false
}

func (app *Application) Quit() {
	logger.Info("User has quit the application")
	app.running = false
}