package main

import (
    "github.com/veandco/go-sdl2/sdl"
    "strings"
)

var charWidth int32
var charHeight int32

var printables string

func Init() {
    tmp, _, _ := font.SizeUTF8("W")
    charWidth = int32(tmp)
    charHeight = int32(font.Height())
    printables = "abcdefghijklmnopqrstuvwxyz1234567890"
}

type keyField struct {
    charLen int
    passwd string
    onSuccess func()
    onFailure func(bool)
    enteredChar []string
    bkTimer int
}

func createKeyField(passwd string, onSuccess func(), onFailure func(bool)) *keyField {
    charLen := len(passwd)
    fld := keyField{charLen, passwd, onSuccess, onFailure, []string{}, 0}
    RegisterKeypressHandler(fld.keyListener)
    return &fld
}

func (k *keyField) Blit(renderer *sdl.Renderer) {
    if k.bkTimer / 10 % 2 == 0 {
        blockSize := charWidth + 30
        width := int32(k.charLen) * (blockSize)
        height := charHeight + 5 + 3
        leftREF := 1920 / 2 - width / 2
        topREF := 1080 - height - 80
        fieldRect := &sdl.Rect{leftREF, topREF, width, height}

        fieldSurface, _ := sdl.CreateRGBSurface(0, width, height, 32, 0x000000ff, 0x0000ff00, 0x00ff0000, 0xff000000)
        defer fieldSurface.Free()

        for i := 0; i < len(k.enteredChar); i++ {
            char, e := font.RenderUTF8Blended(k.enteredChar[i], sdl.Color{20, 20, 0, 255})
            if e == nil {
                pos := &sdl.Rect{int32(i + 1) * blockSize - blockSize / 2 - char.W / 2, 0, char.W, char.H}
                char.Blit(nil, fieldSurface, pos)
                defer char.Free()
            }
        }

        texture, _ := renderer.CreateTextureFromSurface(fieldSurface)
        defer texture.Destroy()
        renderer.Copy(texture, nil, fieldRect)

        renderer.SetDrawColor(20, 20, 0, 255)
        for i := 0; i < k.charLen; i++ {
            renderer.DrawLine(leftREF + 15 + (int32(i) * (blockSize)), topREF + height - 1, leftREF + int32(i + 1) * (blockSize) - 15, topREF + height - 1)
        }
    }
    if k.bkTimer > 0 {
        k.bkTimer--
    }
}

func (k *keyField) Blink() {
    k.bkTimer = 40
}

func (k *keyField) keyListener(scancode sdl.Scancode) {
    key := strings.ToLower(sdl.GetKeyName(sdl.GetKeyFromScancode(scancode)))
    key = strings.ToLower(key)
    if strings.Contains(printables, key) {
        if len(k.enteredChar) < k.charLen {
            k.enteredChar = append(k.enteredChar, key)
        } else {
            k.enteredChar = shiftLeft(k.enteredChar, key)
        }
    } else if scancode == sdl.SCANCODE_BACKSPACE {
        if len(k.enteredChar) > 0 {
            k.enteredChar = k.enteredChar[:len(k.enteredChar) - 1]
        }
    } else if scancode == sdl.SCANCODE_RETURN {
        if strings.Join(k.enteredChar, "") == k.passwd {
            k.onSuccess()
        } else {
            k.Blink()
        }
    }

}