// Package loadscreen implements a modal "Loading" screen for the game, which
// can be shown or hidden by gameplay scenes as needed.
package loadscreen

import (
	"strings"

	"git.kirsle.net/apps/doodle/pkg/balance"
	"git.kirsle.net/apps/doodle/pkg/level"
	"git.kirsle.net/apps/doodle/pkg/log"
	"git.kirsle.net/apps/doodle/pkg/shmem"
	"git.kirsle.net/apps/doodle/pkg/uix"
	"git.kirsle.net/go/render"
	"git.kirsle.net/go/ui"
)

// Configuration values.
const (
	ProgressWidth  = 300
	ProgressHeight = 34
)

// State variables for the loading screen.
var (
	visible      bool
	withProgress bool
	subtitle     string // custom subtitle text, SetSubtitle().

	// Animated title bar
	titleBase = "Loading"
	animState = 0
	animation = []string{
		".  ",
		".. ",
		"...",
		" ..",
		"  .",
		"   ",
	}
	animSpeed uint64 = 32
	titleVar  string

	// UI widgets.
	window         *ui.Frame
	canvas         *uix.Canvas
	secondary      *ui.Label // subtitle text
	progressTrough *ui.Frame
	progressBar    *ui.Frame
	progressText   *ui.Label
)

// Show the basic loading screen without a progress bar.
func Show() {
	setup()
	visible = true
	withProgress = false
	subtitle = ""
}

// ShowWithProgress initializes the loading screen with a progress bar starting at zero.
func ShowWithProgress() {
	setup()
	visible = true
	withProgress = true
	subtitle = ""
	SetProgress(0)
}

// SetSubtitle specifies secondary text beneath the Loading banner.
// The subtitle is blanked on Show() and ShowWithProgress() and must
// be specified by the caller if desired. Pass multiple values for
// multiple lines of text.
func SetSubtitle(value ...string) {
	subtitle = strings.Join(value, "\n")
}

// IsActive returns whether the loading screen is currently visible.
func IsActive() bool {
	return visible
}

// Hide the loading screen.
func Hide() {
	visible = false
}

// SetProgress sets the current progress value for loading screens having a progress bar.
func SetProgress(v float64) {
	// Resize the progress bar in the trough.
	if progressTrough != nil {
		var (
			troughSize = progressTrough.Size()
			height     = progressBar.Size().H
		)
		progressBar.Resize(render.Rect{
			W: int(float64(troughSize.W-4) * v),
			H: height,
		})
	}
}

// Common function to initialize the loading screen.
func setup() {
	if window != nil {
		return
	}

	titleVar = titleBase + animation[animState]

	// Create the parent container that will stretch full screen.
	window = ui.NewFrame("Loadscreen Window")
	window.SetBackground(render.RGBA(0, 0, 1, 40)) // makes the wallpaper darker? :/

	// "Loading" text.
	label := ui.NewLabel(ui.Label{
		TextVariable: &titleVar,
		Font:         balance.LoadScreenFont,
	})
	label.Compute(shmem.CurrentRenderEngine)
	window.Place(label, ui.Place{
		Top:    128,
		Center: true,
	})

	// Subtitle text.
	secondary = ui.NewLabel(ui.Label{
		TextVariable: &subtitle,
		Font:         balance.LoadScreenSecondaryFont,
	})
	window.Place(secondary, ui.Place{
		Top:    128 + label.Size().H + 64,
		Center: true,
	})

	// Progress bar.
	progressTrough = ui.NewFrame("Progress Trough")
	progressTrough.Configure(ui.Config{
		Width:       ProgressWidth,
		Height:      ProgressHeight,
		BorderSize:  2,
		BorderStyle: ui.BorderSunken,
		Background:  render.DarkGrey,
	})
	window.Place(progressTrough, ui.Place{
		Center: true,
		Middle: true,
	})

	progressBar = ui.NewFrame("Progress Bar")
	progressBar.Configure(ui.Config{
		Width:      0,
		Height:     ProgressHeight - 4,
		Background: render.Green,
	})
	progressTrough.Pack(progressBar, ui.Pack{
		Side: ui.W,
	})
}

// Loop is called on every game loop. If the loadscreen is not active, nothing happens.
// Otherwise the loading screen UI is drawn to screen.
func Loop(windowSize render.Rect, e render.Engine) {
	if !visible {
		return
	}

	if window != nil {
		// Initialize the wallpaper canvas?
		if canvas == nil {
			canvas = uix.NewCanvas(128, false)
			canvas.LoadLevel(&level.Level{
				Chunker:   level.NewChunker(100),
				Palette:   level.NewPalette(),
				PageType:  level.Bounded,
				Wallpaper: "blueprint.png",
			})
		}
		canvas.Resize(windowSize)
		canvas.Compute(e)
		canvas.Present(e, render.Origin)

		window.Resize(windowSize)
		window.Compute(e)
		window.Present(e, render.Origin)

		// Show/hide the progress bar.
		progressTrough.Compute(e)
		if withProgress && progressTrough.Hidden() {
			progressTrough.Show()
		} else if !withProgress && !progressTrough.Hidden() {
			progressTrough.Hide()
		}

		// Show/hide the subtitle text.
		if len(subtitle) > 0 && secondary.Hidden() {
			secondary.Show()
		} else if subtitle == "" && !secondary.Hidden() {
			secondary.Hide()
		}

		// Animate the ellipses.
		if shmem.Tick%animSpeed == 0 {
			titleVar = titleBase + animation[animState]
			animState++
			if animState >= len(animation) {
				animState = 0
			}
		}

	}
}

// PreloadAllChunkBitmaps is a helper function to eager cache all bitmap
// images of the chunks in a level drawing. It is designed to work with the
// loading screen and will set the Progress percent based on the total number
// of chunks vs. chunks remaining to pre-cache bitmaps from.
func PreloadAllChunkBitmaps(chunker *level.Chunker) {
	loadChunksTarget := len(chunker.Chunks)
	// if loadChunksTarget == 0 {
	// 	return
	// }

	for {
		remaining := chunker.PrerenderN(10)
		log.Debug("Remain: %d", remaining)

		// Set the load screen progress % based on number of chunks to render.
		if loadChunksTarget > 0 {
			percent := float64(loadChunksTarget-remaining) / float64(loadChunksTarget)
			SetProgress(percent)
		}

		if remaining == 0 {
			break
		}
	}
}