package page

import (
	"fmt"
	"regexp"

	"github.com/go-gl/gl/v3.3-core/gl"
	"github.com/go-gl/mathgl/mgl32"
	"github.com/veandco/go-sdl2/sdl"
	"rhemawavetech.com/rhemawave/internal/colors"
	"rhemawavetech.com/rhemawave/internal/db"
	"rhemawavetech.com/rhemawave/internal/fontManager"
	"rhemawavetech.com/rhemawave/internal/shaderManager"
)

// emailRegex validates email format
var emailRegex = regexp.MustCompile(`^[a-zA-Z0-9._%+\-]+@[a-zA-Z0-9.\-]+\.[a-zA-Z]{2,}$`)

type EmailAddressPage struct {
	Base

	title              string
	titleTextureID     uint32
	titleTextureWidth  int32
	titleTextureHeight int32

	currentEmailDisplayTextureID     uint32
	currentEmailDisplayTextureWidth  int32
	currentEmailDisplayTextureHeight int32

	inputText              string
	inputTextTextureID     uint32
	inputTextTextureWidth  int32
	inputTextTextureHeight int32

	// Error message handling
	errorMessage       string
	errorTextureID     uint32
	errorTextureWidth  int32
	errorTextureHeight int32

	// isFirstTimeSetup tracks whether page was loaded empty (first-time setup)
	isFirstTimeSetup bool

	// Text input deduplication
	textInputSupported bool
}

// isValidEmail checks if the given string is a valid email format
func isValidEmail(email string) bool {
	return emailRegex.MatchString(email)
}

// Init performs basic page initialization and creation of static assets.
func (p *EmailAddressPage) Init(ctx *PageCtx) error {

	if err := p.Base.Init(ctx); err != nil {
		return fmt.Errorf("failed base page initialization: %w", err)
	}

	p.title = "Your Email Address"

	applicationFont := "SpaceMonoNerdFont-Regular"

	fm := fontManager.Get()
	textShader, ok := shaderManager.Get().Get("text")
	if !ok {
		return fmt.Errorf("unable to fetch text shader")
	}

	// Create title texture
	titleTextureID, titleWidth, titleHeight, err := fm.CreateStringTexture(applicationFont, p.title, textShader)
	if err != nil {
		return fmt.Errorf("failed to create title texture: %w", err)
	}
	if titleTextureID == 0 {
		return fmt.Errorf("CreateStringTexture returned a nil texture ID")
	}

	p.titleTextureID = titleTextureID
	p.titleTextureWidth = titleWidth
	p.titleTextureHeight = titleHeight

	// Load existing email address from database
	config, err := db.GetConfig(p.Context.DbPtr)
	if err != nil {
		panic(err)
	}
	emailAddress := config.EmailAddress

	if emailAddress != "" {
		p.inputText = emailAddress
		p.isFirstTimeSetup = false

		// Create current email display texture
		currentEmailText := fmt.Sprintf("Current Email: %s", emailAddress)
		currentEmailTextureID, currentEmailWidth, currentEmailHeight, err := fm.CreateStringTexture(applicationFont, currentEmailText, textShader)
		if err != nil {
			return fmt.Errorf("failed to create current email display texture: %w", err)
		}
		if currentEmailTextureID == 0 {
			return fmt.Errorf("CreateStringTexture returned a nil texture ID for current email display")
		}

		p.currentEmailDisplayTextureID = currentEmailTextureID
		p.currentEmailDisplayTextureWidth = currentEmailWidth
		p.currentEmailDisplayTextureHeight = currentEmailHeight
	} else {
		p.inputText = ""
		p.isFirstTimeSetup = true
	}

	sdl.StartTextInput()

	return nil
}

// HandleEvent processes SDL events and handles them appropriately for the EmailAddressPage.
func (p *EmailAddressPage) HandleEvent(event *sdl.Event) error {
	actualEvent := *event
	if !sdl.IsTextInputActive() {
		sdl.StartTextInput()
	}

	switch e := actualEvent.(type) {
	case *sdl.TextInputEvent:
		if !p.textInputSupported {
			// First TextInputEvent: the keyboard fallback already
			// handled this character, so just record that text input
			// is supported and skip the duplicate append.
			p.textInputSupported = true
		} else {
			p.inputText += e.GetText()
			// Clear error when user starts typing
			p.errorMessage = ""
		}
	case *sdl.KeyboardEvent:
		if e.Type == sdl.KEYDOWN {
			switch e.Keysym.Sym {
			case sdl.K_ESCAPE:
				// Block escape during first-time setup
				if p.isFirstTimeSetup {
					return nil
				}
				// Allow escape back to settings if coming from settings
				sdl.StopTextInput()
				p.Context.NavigateTo(SETTINGS)
			case sdl.K_RETURN:
				// Validate email - check empty first, then format
				if p.inputText == "" {
					p.errorMessage = "Email address cannot be empty"
					return nil
				}
				if !isValidEmail(p.inputText) {
					p.errorMessage = "Please enter a valid email address"
					return nil
				}

				sdl.StopTextInput()

				// Save email address to database
				config, err := db.GetConfig(p.Context.DbPtr)
				if err != nil {
					panic(err)
				}
				config.EmailAddress = p.inputText
				p.Context.DbPtr.Save(config)

				if p.isFirstTimeSetup {
					// First-time setup: navigate to License Key page
					p.Context.NavigateTo(LICENSE_KEY)
				} else {
					p.Context.NavigateTo(SETTINGS)
				}
			case sdl.K_BACKSPACE:
				if len(p.inputText) > 0 {
					p.inputText = p.inputText[:len(p.inputText)-1]
					// Clear error when user edits input
					p.errorMessage = ""
				}
			default:
				// Keyboard fallback: if TextInputEvent is not supported,
				// convert printable keycodes to characters directly.
				// This handles kiosk systems without an input method framework.
				if !p.textInputSupported {
					if ch := keycodeToChar(e.Keysym.Sym, e.Keysym.Mod); ch != 0 {
						p.inputText += string(ch)
						p.errorMessage = ""
					}
				}
			}
		}
	}
	return nil
}

// Update updates animations and changing textures and other changes using `dt` which represents a time delta in float32.
func (p *EmailAddressPage) Update(dt float32) error {
	// Get application font from database
	applicationFont := "SpaceMonoNerdFont-Regular"

	fm := fontManager.Get()
	sm := shaderManager.Get()
	shader, ok := sm.Get("text")
	if !ok {
		return fmt.Errorf("unable to fetch text shader")
	}

	// Update input text texture
	if len(p.inputText) > 0 {
		// Create the new inputText texture
		inputTextTextureID, inputTextTextureWidth, inputTextTextureHeight, err := fm.CreateStringTexture(
			applicationFont,
			p.inputText,
			shader,
		)
		if err != nil {
			return fmt.Errorf("unable to create new input text texture: %w", err)
		}

		// Delete old texture if it exists
		if p.inputTextTextureID != 0 {
			gl.DeleteTextures(1, &p.inputTextTextureID)
		}

		p.inputTextTextureID = inputTextTextureID
		p.inputTextTextureWidth = inputTextTextureWidth
		p.inputTextTextureHeight = inputTextTextureHeight
	}

	// Update error message texture
	if p.errorMessage != "" {
		errorTextureID, errorWidth, errorHeight, err := fm.CreateStringTexture(
			applicationFont,
			p.errorMessage,
			shader,
		)
		if err != nil {
			return fmt.Errorf("unable to create error text texture: %w", err)
		}

		// Delete old error texture if it exists
		if p.errorTextureID != 0 {
			gl.DeleteTextures(1, &p.errorTextureID)
		}

		p.errorTextureID = errorTextureID
		p.errorTextureWidth = errorWidth
		p.errorTextureHeight = errorHeight
	} else {
		// Clear error texture if no error message
		if p.errorTextureID != 0 {
			gl.DeleteTextures(1, &p.errorTextureID)
			p.errorTextureID = 0
		}
	}

	return nil
}

// Render performs page drawing logic.
func (p *EmailAddressPage) Render() error {
	config, err := db.GetConfig(p.Context.DbPtr)
	if err != nil {
		panic(err)
	}
	// Get base font size from database
	baseFontSize := config.StandardFontSize

	sm := shaderManager.Get()

	// 1. Calculate Scale
	titleFontSize := int32(64)
	titleScale := float32(titleFontSize) / float32(baseFontSize)
	currentEmailFontSize := int32(28)
	currentEmailScale := float32(currentEmailFontSize) / float32(baseFontSize)
	padding := int32(4)
	verticalMargin := int32(20)

	// 2. Define dimensions
	targetFontSize := int32(36)
	scale := float32(targetFontSize) / float32(baseFontSize)
	border := int32(3)
	boxH := targetFontSize + (padding * 2)
	boxW := int32(600) + (padding * 2)
	boxDimensions := mgl32.Vec2{float32(boxW), float32(boxH)}
	borderBoxH := boxH + (border * 2)
	borderBoxW := boxW + (border * 2)
	borderBoxDimensions := mgl32.Vec2{float32(borderBoxW), float32(borderBoxH)}
	titleH := float32(p.titleTextureHeight) * titleScale
	titleW := float32(p.titleTextureWidth) * titleScale
	titleDimensions := mgl32.Vec2{titleW, titleH}
	inputTextH := float32(p.inputTextTextureHeight) * scale
	inputTextW := float32(p.inputTextTextureWidth) * scale
	inputTextDimensions := mgl32.Vec2{inputTextW, inputTextH}

	var currentEmailDisplayH, currentEmailDisplayW float32
	var currentEmailDisplayDimensions mgl32.Vec2
	if p.currentEmailDisplayTextureID != 0 {
		currentEmailDisplayH = float32(p.currentEmailDisplayTextureHeight) * currentEmailScale
		currentEmailDisplayW = float32(p.currentEmailDisplayTextureWidth) * currentEmailScale
		currentEmailDisplayDimensions = mgl32.Vec2{currentEmailDisplayW, currentEmailDisplayH}
	}

	// Error text dimensions
	errorFontSize := int32(20)
	errorScale := float32(errorFontSize) / float32(baseFontSize)
	var errorTextH, errorTextW float32
	var errorTextDimensions mgl32.Vec2
	if p.errorTextureID != 0 {
		errorTextH = float32(p.errorTextureHeight) * errorScale
		errorTextW = float32(p.errorTextureWidth) * errorScale
		errorTextDimensions = mgl32.Vec2{errorTextW, errorTextH}
	}

	// 3. Define positions
	borderBoxY := p.Base.ScreenCenterY - (borderBoxH / 2)
	borderBoxX := p.Base.ScreenCenterX - (borderBoxW / 2)
	borderBoxPosition := mgl32.Vec2{float32(borderBoxX), float32(borderBoxY)}
	boxY := p.Base.ScreenCenterY - (boxH / 2)
	boxX := p.Base.ScreenCenterX - (boxW / 2)
	boxPosition := mgl32.Vec2{float32(boxX), float32(boxY)}
	titleY := borderBoxY + borderBoxH + verticalMargin
	titleX := p.Base.ScreenCenterX - int32(titleW/2)
	titlePosition := mgl32.Vec2{float32(titleX), float32(titleY)}
	inputTextY := boxY + padding
	inputTextX := boxX + padding
	inputTextPosition := mgl32.Vec2{float32(inputTextX), float32(inputTextY)}

	var currentEmailDisplayPosition mgl32.Vec2
	if p.currentEmailDisplayTextureID != 0 {
		currentEmailDisplayY := borderBoxY - int32(currentEmailDisplayH) - verticalMargin
		currentEmailDisplayX := p.Base.ScreenCenterX - int32(currentEmailDisplayW/2)
		currentEmailDisplayPosition = mgl32.Vec2{float32(currentEmailDisplayX), float32(currentEmailDisplayY)}
	}

	// Error text position (below current email display to avoid overlap)
	var errorTextPosition mgl32.Vec2
	if p.errorTextureID != 0 {
		var errorTextY int32
		if p.currentEmailDisplayTextureID != 0 {
			// Position below the current email display
			errorTextY = borderBoxY - int32(currentEmailDisplayH) - verticalMargin - int32(errorTextH) - (verticalMargin / 2)
		} else {
			// No current email display, position below the input box
			errorTextY = borderBoxY - int32(errorTextH) - (verticalMargin / 2)
		}
		errorTextX := p.Base.ScreenCenterX - int32(errorTextW/2)
		errorTextPosition = mgl32.Vec2{float32(errorTextX), float32(errorTextY)}
	}

	// 4. Define Colors
	white := sdl.Color{R: 255, G: 255, B: 255, A: 255}
	grey := sdl.Color{R: 120, G: 120, B: 120, A: 255}
	darkGrey := sdl.Color{R: 30, G: 30, B: 30, A: 255}

	// 5. Get Shaders
	textShader, _ := sm.Get("text")
	solidShader, _ := sm.Get("solid_color")

	// 6. Draw everything
	p.Base.RenderSolidColorQuad(solidShader, borderBoxPosition, borderBoxDimensions, grey)
	p.Base.RenderSolidColorQuad(solidShader, boxPosition, boxDimensions, darkGrey)
	p.Base.RenderTexture(textShader, p.titleTextureID, titlePosition, titleDimensions, white)

	// Draw current email display if it exists
	if p.currentEmailDisplayTextureID != 0 {
		p.Base.RenderTexture(textShader, p.currentEmailDisplayTextureID, currentEmailDisplayPosition, currentEmailDisplayDimensions, white)
	}

	if len(p.inputText) > 0 {
		p.Base.RenderTexture(textShader, p.inputTextTextureID, inputTextPosition, inputTextDimensions, white)
	}

	// Draw error message if it exists
	if p.errorTextureID != 0 {
		p.Base.RenderTexture(textShader, p.errorTextureID, errorTextPosition, errorTextDimensions, colors.ErrorRed)
	}
	return nil
}

// Destroy cleans up page-specific resources.
func (p *EmailAddressPage) Destroy() error {

	gl.DeleteTextures(1, &p.titleTextureID)

	// Delete current email display texture if it exists
	if p.currentEmailDisplayTextureID != 0 {
		gl.DeleteTextures(1, &p.currentEmailDisplayTextureID)
		p.currentEmailDisplayTextureID = 0
	}

	// Delete input text texture if it exists
	if p.inputTextTextureID != 0 {
		gl.DeleteTextures(1, &p.inputTextTextureID)
		p.inputTextTextureID = 0
	}

	// Delete error texture if it exists
	if p.errorTextureID != 0 {
		gl.DeleteTextures(1, &p.errorTextureID)
		p.errorTextureID = 0
	}

	sdl.StopTextInput()
	return p.Base.Destroy()
}