package banking

import (
	"strings"

	tea "github.com/charmbracelet/bubbletea"
)

type changePinModel struct {
	input   string
	stage   int // 0=old, 1=new, 2=confirm, 3=done
	newPin  string
	done    bool
}

func newChangePinModel() changePinModel {
	return changePinModel{}
}

func (m changePinModel) Update(msg tea.Msg) (changePinModel, tea.Cmd) {
	keyMsg, ok := msg.(tea.KeyMsg)
	if !ok {
		return m, nil
	}

	if m.stage == 3 {
		m.done = true
		return m, nil
	}

	switch keyMsg.Type {
	case tea.KeyEnter:
		switch m.stage {
		case 0:
			if m.input != "" {
				m.stage = 1
				m.input = ""
			}
		case 1:
			if len(m.input) >= 4 {
				m.newPin = m.input
				m.stage = 2
				m.input = ""
			}
		case 2:
			if m.input == m.newPin {
				m.stage = 3
			} else {
				m.input = ""
				m.newPin = ""
				m.stage = 1
			}
		}
	case tea.KeyEscape:
		m.done = true
	case tea.KeyBackspace:
		if len(m.input) > 0 {
			m.input = m.input[:len(m.input)-1]
		}
	default:
		ch := keyMsg.String()
		if len(ch) == 1 && ch[0] >= 32 && ch[0] < 127 && len(m.input) < 12 {
			m.input += ch
		}
	}
	return m, nil
}

func (m changePinModel) View() string {
	var b strings.Builder

	b.WriteString("\n")
	b.WriteString(centerText("CHANGE PIN"))
	b.WriteString("\n\n")
	b.WriteString(thinDivider())
	b.WriteString("\n\n")

	if m.stage == 3 {
		b.WriteString(titleStyle.Render("  PIN CHANGED SUCCESSFULLY"))
		b.WriteString("\n\n")
		b.WriteString(baseStyle.Render("  YOUR NEW PIN IS NOW ACTIVE."))
		b.WriteString("\n")
		b.WriteString(baseStyle.Render("  PLEASE USE YOUR NEW PIN FOR ALL FUTURE TRANSACTIONS."))
		b.WriteString("\n\n")
		b.WriteString(dimStyle.Render("  PRESS ANY KEY TO RETURN TO MAIN MENU"))
	} else {
		prompts := []string{"  CURRENT PIN:  ", "  NEW PIN:      ", "  CONFIRM PIN:  "}
		for i := 0; i < m.stage; i++ {
			b.WriteString(baseStyle.Render(prompts[i]))
			b.WriteString(baseStyle.Render(strings.Repeat("*", 4)))
			b.WriteString("\n")
		}
		if m.stage < 3 {
			b.WriteString(titleStyle.Render(prompts[m.stage]))
			masked := strings.Repeat("*", len(m.input))
			b.WriteString(inputStyle.Render(masked))
			b.WriteString(inputStyle.Render("_"))
			b.WriteString("\n")
		}
		b.WriteString("\n")
		if m.stage == 1 {
			b.WriteString(dimStyle.Render("  PIN MUST BE AT LEAST 4 CHARACTERS"))
			b.WriteString("\n")
		}
		b.WriteString("\n")
		b.WriteString(dimStyle.Render("  PRESS ESC TO RETURN TO MAIN MENU"))
	}
	b.WriteString("\n")

	return b.String()
}