package banking

import (
	"context"
	"fmt"
	"strings"
	"time"

	tea "github.com/charmbracelet/bubbletea"

	"git.t-juice.club/torjus/oubliette/internal/shell"
)

type screen int

const (
	screenLogin screen = iota
	screenMenu
	screenAccountSummary
	screenAccountDetail
	screenTransfer
	screenHistory
	screenMessages
	screenChangePin
	screenAdmin
)

type model struct {
	sess       *shell.SessionContext
	bankName   string
	terminalID string
	region     string
	state      *bankState
	screen     screen
	quitting   bool

	login      loginModel
	menu       menuModel
	summary    accountSummaryModel
	detail     accountDetailModel
	transfer   transferModel
	history    historyModel
	messages   messagesModel
	admin      adminModel
	pinInput   string
	pinStage   int // 0=old, 1=new, 2=confirm, 3=done
	pinMessage string
}

func newModel(sess *shell.SessionContext, bankName, terminalID, region string) *model {
	state := newBankState()
	unread := 0
	for _, msg := range state.Messages {
		if msg.Unread {
			unread++
		}
	}

	return &model{
		sess:       sess,
		bankName:   bankName,
		terminalID: terminalID,
		region:     region,
		state:      state,
		screen:     screenLogin,
		login:      newLoginModel(bankName),
	}
}

func (m *model) Init() tea.Cmd {
	return nil
}

func (m *model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
	if m.quitting {
		return m, tea.Quit
	}

	if keyMsg, ok := msg.(tea.KeyMsg); ok {
		if keyMsg.Type == tea.KeyCtrlC {
			m.quitting = true
			return m, tea.Quit
		}
	}

	switch m.screen {
	case screenLogin:
		return m.updateLogin(msg)
	case screenMenu:
		return m.updateMenu(msg)
	case screenAccountSummary:
		return m.updateAccountSummary(msg)
	case screenAccountDetail:
		return m.updateAccountDetail(msg)
	case screenTransfer:
		return m.updateTransfer(msg)
	case screenHistory:
		return m.updateHistory(msg)
	case screenMessages:
		return m.updateMessages(msg)
	case screenChangePin:
		return m.updateChangePin(msg)
	case screenAdmin:
		return m.updateAdmin(msg)
	}

	return m, nil
}

func (m *model) View() string {
	var content string
	switch m.screen {
	case screenLogin:
		content = m.login.View()
	case screenMenu:
		content = m.menu.View()
	case screenAccountSummary:
		content = m.summary.View()
	case screenAccountDetail:
		content = m.detail.View()
	case screenTransfer:
		content = m.transfer.View()
	case screenHistory:
		content = m.history.View()
	case screenMessages:
		content = m.messages.View()
	case screenChangePin:
		content = m.viewChangePin()
	case screenAdmin:
		content = m.admin.View()
	}

	return screenFrame(m.bankName, m.terminalID, m.region, content)
}

// --- Screen update handlers ---

func (m *model) updateLogin(msg tea.Msg) (tea.Model, tea.Cmd) {
	var cmd tea.Cmd
	m.login, cmd = m.login.Update(msg)

	if m.login.stage == 2 {
		// Login always succeeds — this is a honeypot.
		logCmd := logAction(m.sess, fmt.Sprintf("LOGIN acct=%s", m.login.accountNum), "ACCESS GRANTED")
		m.goToMenu()
		return m, tea.Batch(cmd, logCmd)
	}
	return m, cmd
}

func (m *model) updateMenu(msg tea.Msg) (tea.Model, tea.Cmd) {
	var cmd tea.Cmd
	m.menu, cmd = m.menu.Update(msg)

	if keyMsg, ok := msg.(tea.KeyMsg); ok && keyMsg.Type == tea.KeyEnter {
		choice := strings.TrimSpace(m.menu.choice)
		switch choice {
		case "1":
			m.screen = screenAccountSummary
			m.summary = newAccountSummaryModel(m.state.Accounts)
			return m, logAction(m.sess, "MENU 1", "ACCOUNT SUMMARY")
		case "2":
			m.screen = screenAccountDetail
			m.detail = newAccountDetailModel(m.state.Accounts, m.state.Transactions)
			return m, logAction(m.sess, "MENU 2", "ACCOUNT DETAIL")
		case "3":
			m.screen = screenTransfer
			m.transfer = newTransferModel()
			return m, logAction(m.sess, "MENU 3", "WIRE TRANSFER")
		case "4":
			m.screen = screenHistory
			m.history = newHistoryModel(m.state.Accounts, m.state.Transactions)
			return m, logAction(m.sess, "MENU 4", "TRANSACTION HISTORY")
		case "5":
			m.screen = screenMessages
			m.messages = newMessagesModel(m.state.Messages)
			return m, logAction(m.sess, "MENU 5", "SECURE MESSAGES")
		case "6":
			m.screen = screenChangePin
			m.pinInput = ""
			m.pinStage = 0
			m.pinMessage = ""
			return m, logAction(m.sess, "MENU 6", "CHANGE PIN")
		case "7":
			m.quitting = true
			return m, tea.Batch(logAction(m.sess, "LOGOUT", "SESSION ENDED"), tea.Quit)
		case "99", "admin", "ADMIN":
			m.screen = screenAdmin
			m.admin = newAdminModel()
			return m, logAction(m.sess, "ADMIN ACCESS ATTEMPT", "ADMIN SCREEN SHOWN")
		}
		// Invalid choice, reset.
		m.menu.choice = ""
	}
	return m, cmd
}

func (m *model) updateAccountSummary(msg tea.Msg) (tea.Model, tea.Cmd) {
	if _, ok := msg.(tea.KeyMsg); ok {
		m.goToMenu()
	}
	return m, nil
}

func (m *model) updateAccountDetail(msg tea.Msg) (tea.Model, tea.Cmd) {
	var cmd tea.Cmd
	m.detail, cmd = m.detail.Update(msg)
	if m.detail.choice == "back" {
		m.goToMenu()
	}
	return m, cmd
}

func (m *model) updateTransfer(msg tea.Msg) (tea.Model, tea.Cmd) {
	prevStep := m.transfer.step
	var cmd tea.Cmd
	m.transfer, cmd = m.transfer.Update(msg)

	// Transfer cancelled.
	if m.transfer.confirm == "cancelled" {
		m.goToMenu()
		return m, logAction(m.sess, "WIRE TRANSFER CANCELLED", "USER CANCELLED")
	}

	// Transfer completed — log it.
	if m.transfer.step == transferStepComplete && prevStep != transferStepComplete {
		t := m.transfer.transfer
		m.state.Transfers = append(m.state.Transfers, t)
		logMsg := fmt.Sprintf("WIRE TRANSFER: routing=%s dest=%s beneficiary=%s bank=%s amount=%s memo=%s auth=%s",
			t.RoutingNumber, t.DestAccount, t.Beneficiary, t.BankName, t.Amount, t.Memo, t.AuthCode)
		return m, tea.Batch(cmd, logAction(m.sess, logMsg, "TRANSFER QUEUED"))
	}

	// Completed screen → any key goes back.
	if m.transfer.step == transferStepComplete {
		if _, ok := msg.(tea.KeyMsg); ok && prevStep == transferStepComplete {
			m.goToMenu()
		}
	}

	return m, cmd
}

func (m *model) updateHistory(msg tea.Msg) (tea.Model, tea.Cmd) {
	var cmd tea.Cmd
	m.history, cmd = m.history.Update(msg)
	if m.history.choice == "back" {
		m.goToMenu()
	}
	return m, cmd
}

func (m *model) updateMessages(msg tea.Msg) (tea.Model, tea.Cmd) {
	var cmd tea.Cmd
	m.messages, cmd = m.messages.Update(msg)
	if m.messages.choice == "back" {
		m.goToMenu()
		return m, cmd
	}
	// Log when viewing a message.
	if m.messages.viewing >= 0 {
		idx := m.messages.viewing
		return m, tea.Batch(cmd, logAction(m.sess,
			fmt.Sprintf("VIEW MESSAGE #%d", idx+1),
			m.state.Messages[idx].Subj))
	}
	return m, cmd
}

func (m *model) updateChangePin(msg tea.Msg) (tea.Model, tea.Cmd) {
	keyMsg, ok := msg.(tea.KeyMsg)
	if !ok {
		return m, nil
	}

	if m.pinStage == 3 {
		m.goToMenu()
		return m, nil
	}

	switch keyMsg.Type {
	case tea.KeyEnter:
		switch m.pinStage {
		case 0:
			if m.pinInput != "" {
				m.pinStage = 1
				m.pinInput = ""
			}
		case 1:
			if len(m.pinInput) >= 4 {
				m.pinMessage = m.pinInput
				m.pinStage = 2
				m.pinInput = ""
			}
		case 2:
			if m.pinInput == m.pinMessage {
				m.pinStage = 3
				return m, logAction(m.sess, "CHANGE PIN", "PIN CHANGED SUCCESSFULLY")
			}
			m.pinInput = ""
			m.pinMessage = ""
			m.pinStage = 1
		}
	case tea.KeyEscape:
		m.goToMenu()
		return m, nil
	case tea.KeyBackspace:
		if len(m.pinInput) > 0 {
			m.pinInput = m.pinInput[:len(m.pinInput)-1]
		}
	default:
		ch := keyMsg.String()
		if len(ch) == 1 && ch[0] >= 32 && ch[0] < 127 && len(m.pinInput) < 12 {
			m.pinInput += ch
		}
	}
	return m, nil
}

func (m *model) viewChangePin() 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.pinStage == 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.pinStage; i++ {
			b.WriteString(baseStyle.Render(prompts[i]))
			b.WriteString(baseStyle.Render(strings.Repeat("*", 4)))
			b.WriteString("\n")
		}
		if m.pinStage < 3 {
			b.WriteString(titleStyle.Render(prompts[m.pinStage]))
			masked := strings.Repeat("*", len(m.pinInput))
			b.WriteString(inputStyle.Render(masked))
			b.WriteString(inputStyle.Render("_"))
			b.WriteString("\n")
		}
		b.WriteString("\n")
		if m.pinStage == 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()
}

func (m *model) updateAdmin(msg tea.Msg) (tea.Model, tea.Cmd) {
	prevLocked := m.admin.locked
	prevAttempts := m.admin.attempts

	// Check for ESC before delegating.
	if keyMsg, ok := msg.(tea.KeyMsg); ok && keyMsg.Type == tea.KeyEscape && !m.admin.locked {
		m.goToMenu()
		return m, nil
	}

	var cmd tea.Cmd
	m.admin, cmd = m.admin.Update(msg)

	// Log failed attempts.
	if m.admin.attempts > prevAttempts {
		cmd = tea.Batch(cmd, logAction(m.sess,
			fmt.Sprintf("ADMIN PIN ATTEMPT #%d", m.admin.attempts),
			"INVALID CREDENTIALS"))
	}

	// Log lockout.
	if m.admin.locked && !prevLocked {
		cmd = tea.Batch(cmd, logAction(m.sess,
			"ADMIN LOCKOUT",
			"TERMINAL LOCKED - INCIDENT LOGGED"))
	}

	// If locked and any key pressed, go back.
	if m.admin.locked {
		if _, ok := msg.(tea.KeyMsg); ok && prevLocked {
			m.goToMenu()
		}
	}

	return m, cmd
}

func (m *model) goToMenu() {
	unread := 0
	for _, msg := range m.state.Messages {
		if msg.Unread {
			unread++
		}
	}
	m.screen = screenMenu
	m.menu = newMenuModel(m.bankName, unread)
}

// logAction returns a tea.Cmd that logs an action to the session store.
func logAction(sess *shell.SessionContext, input, output string) tea.Cmd {
	return func() tea.Msg {
		if sess.Store != nil {
			ctx, cancel := context.WithTimeout(context.Background(), 2*time.Second)
			defer cancel()
			_ = sess.Store.AppendSessionLog(ctx, sess.SessionID, input, output)
		}
		return nil
	}
}