package banking

import (
	"fmt"
	"strings"

	tea "github.com/charmbracelet/bubbletea"
)

// --- Account Summary ---

type accountSummaryModel struct {
	accounts []Account
}

func newAccountSummaryModel(accounts []Account) accountSummaryModel {
	return accountSummaryModel{accounts: accounts}
}

func (m accountSummaryModel) Update(_ tea.Msg) (accountSummaryModel, tea.Cmd) {
	// Any key returns to menu.
	return m, nil
}

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

	b.WriteString("\n")
	b.WriteString(centerText("ACCOUNT SUMMARY"))
	b.WriteString("\n\n")
	b.WriteString(thinDivider())
	b.WriteString("\n\n")

	// Header.
	b.WriteString(titleStyle.Render(fmt.Sprintf("  %-12s %-18s %18s", "ACCOUNT", "TYPE", "BALANCE")))
	b.WriteString("\n")
	b.WriteString(dimStyle.Render("  " + strings.Repeat("-", 50)))
	b.WriteString("\n")

	total := int64(0)
	for _, acct := range m.accounts {
		total += acct.Balance
		b.WriteString(baseStyle.Render(fmt.Sprintf("  %-12s %-18s %18s",
			acct.Number, acct.Type, formatCurrency(acct.Balance))))
		b.WriteString("\n")
	}

	b.WriteString(dimStyle.Render("  " + strings.Repeat("-", 50)))
	b.WriteString("\n")
	b.WriteString(titleStyle.Render(fmt.Sprintf("  %-12s %-18s %18s", "", "TOTAL", formatCurrency(total))))
	b.WriteString("\n\n")
	b.WriteString(thinDivider())
	b.WriteString("\n\n")
	b.WriteString(dimStyle.Render("  PRESS ANY KEY TO RETURN TO MAIN MENU"))
	b.WriteString("\n")

	return b.String()
}

// --- Account Detail (with transactions) ---

type accountDetailModel struct {
	accounts     []Account
	transactions map[string][]Transaction
	selected     int
	page         int
	pageSize     int
	choosing     bool
	choice       string
}

func newAccountDetailModel(accounts []Account, transactions map[string][]Transaction) accountDetailModel {
	return accountDetailModel{
		accounts:     accounts,
		transactions: transactions,
		choosing:     true,
		pageSize:     10,
	}
}

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

	if m.choosing {
		switch keyMsg.Type {
		case tea.KeyEnter:
			for i := range m.accounts {
				if m.choice == fmt.Sprintf("%d", i+1) {
					m.selected = i
					m.choosing = false
					m.page = 0
					break
				}
			}
			if m.choice == "0" {
				m.choice = "back"
			}
			return m, nil
		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' {
				m.choice += ch
			}
		}
	} else {
		switch keyMsg.String() {
		case "n", "N":
			acctNum := m.accounts[m.selected].Number
			txns := m.transactions[acctNum]
			maxPage := (len(txns) - 1) / m.pageSize
			if m.page < maxPage {
				m.page++
			}
		case "p", "P":
			if m.page > 0 {
				m.page--
			}
		case "b", "B":
			m.choosing = true
			m.choice = ""
		default:
			m.choice = "back"
		}
	}
	return m, nil
}

func (m accountDetailModel) View() string {
	if m.choosing {
		return m.viewChooseAccount()
	}
	return m.viewDetail()
}

func (m accountDetailModel) viewChooseAccount() string {
	var b strings.Builder

	b.WriteString("\n")
	b.WriteString(centerText("ACCOUNT DETAIL"))
	b.WriteString("\n\n")
	b.WriteString(thinDivider())
	b.WriteString("\n\n")
	b.WriteString(titleStyle.Render("  SELECT ACCOUNT:"))
	b.WriteString("\n\n")

	for i, acct := range m.accounts {
		b.WriteString(baseStyle.Render(fmt.Sprintf("    [%d]  %s - %s  %s",
			i+1, acct.Number, acct.Type, formatCurrency(acct.Balance))))
		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("  ENTER SELECTION: "))
	b.WriteString(inputStyle.Render(m.choice))
	b.WriteString(inputStyle.Render("_"))
	b.WriteString("\n")

	return b.String()
}

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

	acct := m.accounts[m.selected]
	txns := m.transactions[acct.Number]

	b.WriteString("\n")
	b.WriteString(centerText(fmt.Sprintf("ACCOUNT DETAIL - %s", acct.Number)))
	b.WriteString("\n\n")

	b.WriteString(baseStyle.Render(fmt.Sprintf("  TYPE:    %s", acct.Type)))
	b.WriteString("\n")
	b.WriteString(baseStyle.Render(fmt.Sprintf("  BALANCE: %s", formatCurrency(acct.Balance))))
	b.WriteString("\n\n")
	b.WriteString(thinDivider())
	b.WriteString("\n\n")

	// Header.
	b.WriteString(titleStyle.Render(fmt.Sprintf("  %-12s %-34s %12s %12s", "DATE", "DESCRIPTION", "AMOUNT", "BALANCE")))
	b.WriteString("\n")
	b.WriteString(dimStyle.Render("  " + strings.Repeat("-", 72)))
	b.WriteString("\n")

	// Paginate.
	start := m.page * m.pageSize
	end := min(start+m.pageSize, len(txns))

	for _, txn := range txns[start:end] {
		b.WriteString(baseStyle.Render(fmt.Sprintf("  %-12s %-34s %12s %12s",
			txn.Date, txn.Description, formatCurrency(txn.Amount), formatCurrency(txn.Balance))))
		b.WriteString("\n")
	}

	b.WriteString("\n")
	totalPages := (len(txns) + m.pageSize - 1) / m.pageSize
	b.WriteString(dimStyle.Render(fmt.Sprintf("  PAGE %d OF %d", m.page+1, totalPages)))
	b.WriteString("\n\n")
	b.WriteString(dimStyle.Render("  [N]EXT PAGE  [P]REV PAGE  [B]ACK  ANY OTHER KEY = MAIN MENU"))
	b.WriteString("\n")

	return b.String()
}