package tui

import (
	"fmt"

	"git.mlow.ca/mlow/lmcli/pkg/conversation"
	"git.mlow.ca/mlow/lmcli/pkg/lmcli"
	"git.mlow.ca/mlow/lmcli/pkg/tui/model"
	"git.mlow.ca/mlow/lmcli/pkg/tui/shared"
	tuiutil "git.mlow.ca/mlow/lmcli/pkg/tui/util"
	"git.mlow.ca/mlow/lmcli/pkg/tui/views/chat"
	"git.mlow.ca/mlow/lmcli/pkg/tui/views/conversations"
	"git.mlow.ca/mlow/lmcli/pkg/tui/views/settings"
	tea "github.com/charmbracelet/bubbletea"
	"github.com/charmbracelet/lipgloss"
)

type Model struct {
	App *model.AppModel

	// window size
	width  int
	height int

	// errors to display
	// TODO: allow dismissing errors
	errs []error

	activeView shared.View
	views      map[shared.View]shared.ViewModel
}

func initialModel(ctx *lmcli.Context, opts LaunchOptions) *Model {
	app := model.NewAppModel(ctx, opts.InitialConversation)

	m := Model{
		App:        app,
		activeView: opts.InitialView,
		views: map[shared.View]shared.ViewModel{
			shared.ViewChat:          chat.Chat(app),
			shared.ViewConversations: conversations.Conversations(app),
			shared.ViewSettings:      settings.Settings(app),
		},
	}

	return &m
}

func (m *Model) Init() tea.Cmd {
	var cmds []tea.Cmd
	for _, v := range m.views {
		// Init views
		cmds = append(cmds, v.Init())
	}
	cmds = append(cmds, func() tea.Msg {
		// Initial view change
		return shared.MsgViewChange(m.activeView)
	})
	return tea.Batch(cmds...)
}

func (m *Model) handleGlobalInput(msg tea.KeyMsg) tea.Cmd {
	switch msg.String() {
	case "esc":
		if len(m.errs) > 0 {
			m.errs = m.errs[1:]
			return shared.KeyHandled(msg)
		}
	}

	view, cmd := m.views[m.activeView].Update(msg)
	m.views[m.activeView] = view
	if cmd != nil {
		return cmd
	}

	switch msg.String() {
	case "ctrl+c", "ctrl+q":
		return tea.Quit
	}
	return nil
}

func (m *Model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
	switch msg := msg.(type) {
	case tea.WindowSizeMsg:
		m.width, m.height = msg.Width, msg.Height
	case tea.KeyMsg:
		cmd := m.handleGlobalInput(msg)
		if cmd != nil {
			return m, cmd
		}
	case shared.MsgViewChange:
		currView := m.activeView
		m.activeView = shared.View(msg)
		return m, tea.Batch(tea.WindowSize(), shared.ViewEnter(currView))
	case shared.MsgError:
		m.errs = append(m.errs, msg.Err)
	}

	view, cmd := m.views[m.activeView].Update(msg)
	m.views[m.activeView] = view
	return m, cmd
}

func (m *Model) View() string {
	if m.width == 0 || m.height == 0 {
		// we're dimensionless!
		return ""
	}

	header := m.views[m.activeView].Header(m.width)
	footer := m.views[m.activeView].Footer(m.width)
	fixedUIHeight := tuiutil.Height(header) + tuiutil.Height(footer)

	errBanners := make([]string, len(m.errs))
	for idx, err := range m.errs {
		errBanners[idx] = tuiutil.ErrorBanner(err, m.width)
	}
	var errors string
	if len(errBanners) > 0 {
		errors = lipgloss.JoinVertical(lipgloss.Left, errBanners...)
	} else {
		errors = ""
	}
	fixedUIHeight += tuiutil.Height(errors)

	content := m.views[m.activeView].Content(m.width, m.height-fixedUIHeight, errors)

	sections := make([]string, 0, 4)
	if header != "" {
		sections = append(sections, header)
	}
	if content != "" {
		sections = append(sections, content)
	}
	if footer != "" {
		sections = append(sections, footer)
	}
	return lipgloss.JoinVertical(lipgloss.Left, sections...)
}

type LaunchOptions struct {
	InitialConversation *conversation.Conversation
	InitialView         shared.View
}

type LaunchOption func(*LaunchOptions)

func WithInitialConversation(conv *conversation.Conversation) LaunchOption {
	return func(opts *LaunchOptions) {
		opts.InitialConversation = conv
	}
}

func WithInitialView(view shared.View) LaunchOption {
	return func(opts *LaunchOptions) {
		opts.InitialView = view
	}
}

func Launch(ctx *lmcli.Context, options ...LaunchOption) error {
	opts := &LaunchOptions{
		InitialView: shared.ViewChat,
	}
	for _, opt := range options {
		opt(opts)
	}

	program := tea.NewProgram(initialModel(ctx, *opts), tea.WithAltScreen())
	if _, err := program.Run(); err != nil {
		return fmt.Errorf("Error running program: %v", err)
	}
	return nil
}