package banking

import (
	"fmt"
	"strings"

	tea "github.com/charmbracelet/bubbletea"
)

type messagesModel struct {
	messages []SecureMessage
	viewing  int // -1 = list, >= 0 = detail
	choice   string
}

func newMessagesModel(messages []SecureMessage) messagesModel {
	return messagesModel{messages: messages, viewing: -1}
}

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

	if m.viewing >= 0 {
		// In detail view, any key goes back to list.
		m.viewing = -1
		m.choice = ""
		return m, nil
	}

	switch keyMsg.Type {
	case tea.KeyEnter:
		if m.choice == "0" {
			m.choice = "back"
			return m, nil
		}
		for i := range m.messages {
			if m.choice == fmt.Sprintf("%d", i+1) {
				m.viewing = i
				m.messages[i].Unread = false
				return m, nil
			}
		}
		m.choice = ""
	case tea.KeyBackspace:
		if len(m.choice) > 0 {
			m.choice = m.choice[:len(m.choice)-1]
		}
	default:
		ch := keyMsg.String()
		if len(ch) == 1 && ch[0] >= '0' && ch[0] <= '9' && len(m.choice) < 2 {
			m.choice += ch
		}
	}
	return m, nil
}

func (m messagesModel) View() string {
	if m.viewing >= 0 {
		return m.viewDetail()
	}
	return m.viewList()
}

func (m messagesModel) viewList() string {
	var b strings.Builder

	b.WriteString("\n")
	b.WriteString(centerText("SECURE MESSAGES"))
	b.WriteString("\n\n")
	b.WriteString(thinDivider())
	b.WriteString("\n\n")

	b.WriteString(titleStyle.Render(fmt.Sprintf("  %-4s %-3s %-12s %-22s %s", "#", "", "DATE", "FROM", "SUBJECT")))
	b.WriteString("\n")
	b.WriteString(dimStyle.Render("  " + strings.Repeat("-", 68)))
	b.WriteString("\n")

	for i, msg := range m.messages {
		marker := "   "
		if msg.Unread {
			marker = " * "
		}
		b.WriteString(baseStyle.Render(fmt.Sprintf("  [%d]%s%-12s %-22s %s",
			i+1, marker, msg.Date, msg.From, msg.Subj)))
		b.WriteString("\n")
	}

	b.WriteString("\n")
	b.WriteString(baseStyle.Render("  [0]  RETURN TO MAIN MENU"))
	b.WriteString("\n\n")
	b.WriteString(thinDivider())
	b.WriteString("\n\n")
	b.WriteString(titleStyle.Render("  SELECT MESSAGE: "))
	b.WriteString(inputStyle.Render(m.choice))
	b.WriteString(inputStyle.Render("_"))
	b.WriteString("\n")

	return b.String()
}

func (m messagesModel) viewDetail() string {
	var b strings.Builder

	msg := m.messages[m.viewing]

	b.WriteString("\n")
	b.WriteString(centerText(fmt.Sprintf("MESSAGE #%d", m.viewing+1)))
	b.WriteString("\n\n")
	b.WriteString(thinDivider())
	b.WriteString("\n\n")
	b.WriteString(baseStyle.Render(msg.Body))
	b.WriteString("\n\n")
	b.WriteString(thinDivider())
	b.WriteString("\n\n")
	b.WriteString(dimStyle.Render("  PRESS ANY KEY TO RETURN TO MESSAGE LIST"))
	b.WriteString("\n")

	return b.String()
}