package chat

import (
	"context"
	"fmt"
	"log/slog"
	"slices"
	"sort"
	"strconv"
	"strings"

	tea "github.com/charmbracelet/bubbletea/v2"
	"github.com/charmbracelet/lipgloss/v2"
	"github.com/charmbracelet/x/ansi"
	"github.com/sst/opencode-sdk-go"
	"github.com/sst/opencode/internal/app"
	"github.com/sst/opencode/internal/commands"
	"github.com/sst/opencode/internal/components/dialog"
	"github.com/sst/opencode/internal/components/diff"
	"github.com/sst/opencode/internal/components/toast"
	"github.com/sst/opencode/internal/layout"
	"github.com/sst/opencode/internal/styles"
	"github.com/sst/opencode/internal/theme"
	"github.com/sst/opencode/internal/util"
	"github.com/sst/opencode/internal/viewport"
)

type MessagesComponent interface {
	tea.Model
	tea.ViewModel
	PageUp() (tea.Model, tea.Cmd)
	PageDown() (tea.Model, tea.Cmd)
	HalfPageUp() (tea.Model, tea.Cmd)
	HalfPageDown() (tea.Model, tea.Cmd)
	ToolDetailsVisible() bool
	GotoTop() (tea.Model, tea.Cmd)
	GotoBottom() (tea.Model, tea.Cmd)
	CopyLastMessage() (tea.Model, tea.Cmd)
	UndoLastMessage() (tea.Model, tea.Cmd)
	RedoLastMessage() (tea.Model, tea.Cmd)
}

type messagesComponent struct {
	width, height   int
	app             *app.App
	header          string
	viewport        viewport.Model
	clipboard       []string
	cache           *PartCache
	loading         bool
	showToolDetails bool
	rendering       bool
	dirty           bool
	tail            bool
	partCount       int
	lineCount       int
	selection       *selection
}

type selection struct {
	startX int
	endX   int
	startY int
	endY   int
}

func (s selection) coords(offset int) *selection {
	// selecting backwards
	if s.startY > s.endY && s.endY >= 0 {
		return &selection{
			startX: max(0, s.endX-1),
			startY: s.endY - offset,
			endX:   s.startX + 1,
			endY:   s.startY - offset,
		}
	}

	// selecting backwards same line
	if s.startY == s.endY && s.startX >= s.endX {
		return &selection{
			startY: s.startY - offset,
			startX: max(0, s.endX-1),
			endY:   s.endY - offset,
			endX:   s.startX + 1,
		}
	}

	return &selection{
		startX: s.startX,
		startY: s.startY - offset,
		endX:   s.endX,
		endY:   s.endY - offset,
	}
}

type ToggleToolDetailsMsg struct{}

func (m *messagesComponent) Init() tea.Cmd {
	return tea.Batch(m.viewport.Init())
}

func (m *messagesComponent) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
	var cmds []tea.Cmd
	switch msg := msg.(type) {
	case tea.MouseClickMsg:
		slog.Info("mouse", "x", msg.X, "y", msg.Y, "offset", m.viewport.YOffset)
		y := msg.Y + m.viewport.YOffset
		if y > 0 {
			m.selection = &selection{
				startY: y,
				startX: msg.X,
				endY:   -1,
				endX:   -1,
			}

			slog.Info("mouse selection", "start", fmt.Sprintf("%d,%d", m.selection.startX, m.selection.startY), "end", fmt.Sprintf("%d,%d", m.selection.endX, m.selection.endY))
			return m, m.renderView()
		}

	case tea.MouseMotionMsg:
		if m.selection != nil {
			m.selection = &selection{
				startX: m.selection.startX,
				startY: m.selection.startY,
				endX:   msg.X + 1,
				endY:   msg.Y + m.viewport.YOffset,
			}
			return m, m.renderView()
		}

	case tea.MouseReleaseMsg:
		if m.selection != nil && len(m.clipboard) > 0 {
			content := strings.Join(m.clipboard, "\n")
			m.selection = nil
			m.clipboard = []string{}
			return m, tea.Sequence(
				m.renderView(),
				app.SetClipboard(content),
				toast.NewSuccessToast("Copied to clipboard"),
			)
		}
	case tea.WindowSizeMsg:
		effectiveWidth := msg.Width - 4
		// Clear cache on resize since width affects rendering
		if m.width != effectiveWidth {
			m.cache.Clear()
		}
		m.width = effectiveWidth
		m.height = msg.Height - 7
		m.viewport.SetWidth(m.width)
		m.loading = true
		return m, m.renderView()
	case app.SendPrompt:
		m.viewport.GotoBottom()
		m.tail = true
		return m, nil
	case dialog.ThemeSelectedMsg:
		m.cache.Clear()
		m.loading = true
		return m, m.renderView()
	case ToggleToolDetailsMsg:
		m.showToolDetails = !m.showToolDetails
		return m, m.renderView()
	case app.SessionLoadedMsg, app.SessionClearedMsg:
		m.cache.Clear()
		m.tail = true
		m.loading = true
		return m, m.renderView()
	case app.SessionUnrevertedMsg:
		if msg.Session.ID == m.app.Session.ID {
			m.cache.Clear()
			m.tail = true
			return m, m.renderView()
		}
	case app.MessageRevertedMsg:
		if msg.Session.ID == m.app.Session.ID {
			m.cache.Clear()
			m.tail = true
			return m, m.renderView()
		}

	case opencode.EventListResponseEventSessionUpdated:
		if msg.Properties.Info.ID == m.app.Session.ID {
			cmds = append(cmds, m.renderView())
		}
	case opencode.EventListResponseEventMessageUpdated:
		if msg.Properties.Info.SessionID == m.app.Session.ID {
			cmds = append(cmds, m.renderView())
		}
	case opencode.EventListResponseEventMessagePartUpdated:
		if msg.Properties.Part.SessionID == m.app.Session.ID {
			cmds = append(cmds, m.renderView())
		}
	case opencode.EventListResponseEventMessagePartRemoved:
		if msg.Properties.SessionID == m.app.Session.ID {
			// Clear the cache when a part is removed to ensure proper re-rendering
			m.cache.Clear()
			cmds = append(cmds, m.renderView())
		}
	case opencode.EventListResponseEventPermissionUpdated:
		m.tail = true
		return m, m.renderView()
	case opencode.EventListResponseEventPermissionReplied:
		m.tail = true
		return m, m.renderView()
	case renderCompleteMsg:
		m.partCount = msg.partCount
		m.lineCount = msg.lineCount
		m.rendering = false
		m.clipboard = msg.clipboard
		m.loading = false
		m.tail = m.viewport.AtBottom()
		m.viewport = msg.viewport
		m.header = msg.header
		if m.dirty {
			cmds = append(cmds, m.renderView())
		}
	}

	m.tail = m.viewport.AtBottom()

	viewport, cmd := m.viewport.Update(msg)
	m.viewport = viewport
	cmds = append(cmds, cmd)

	return m, tea.Batch(cmds...)
}

type renderCompleteMsg struct {
	viewport  viewport.Model
	clipboard []string
	header    string
	partCount int
	lineCount int
}

func (m *messagesComponent) renderView() tea.Cmd {
	if m.rendering {
		slog.Debug("pending render, skipping")
		m.dirty = true
		return func() tea.Msg {
			return nil
		}
	}
	m.dirty = false
	m.rendering = true

	viewport := m.viewport
	tail := m.tail

	return func() tea.Msg {
		header := m.renderHeader()
		measure := util.Measure("messages.renderView")
		defer measure()

		t := theme.CurrentTheme()
		blocks := make([]string, 0)
		partCount := 0
		lineCount := 0

		orphanedToolCalls := make([]opencode.ToolPart, 0)

		width := m.width // always use full width

		reverted := false
		revertedMessageCount := 0
		revertedToolCount := 0
		lastAssistantMessage := "zzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz"
		for _, msg := range slices.Backward(m.app.Messages) {
			if assistant, ok := msg.Info.(opencode.AssistantMessage); ok {
				lastAssistantMessage = assistant.ID
				break
			}
		}
		for _, message := range m.app.Messages {
			var content string
			var cached bool

			switch casted := message.Info.(type) {
			case opencode.UserMessage:
				if casted.ID == m.app.Session.Revert.MessageID {
					reverted = true
					revertedMessageCount = 1
					revertedToolCount = 0
					continue
				}
				if reverted {
					revertedMessageCount++
					continue
				}

				for partIndex, part := range message.Parts {
					switch part := part.(type) {
					case opencode.TextPart:
						if part.Synthetic {
							continue
						}
						if part.Text == "" {
							continue
						}
						remainingParts := message.Parts[partIndex+1:]
						fileParts := make([]opencode.FilePart, 0)
						for _, part := range remainingParts {
							switch part := part.(type) {
							case opencode.FilePart:
								fileParts = append(fileParts, part)
							}
						}
						flexItems := []layout.FlexItem{}
						if len(fileParts) > 0 {
							fileStyle := styles.NewStyle().Background(t.BackgroundElement()).Foreground(t.TextMuted()).Padding(0, 1)
							mediaTypeStyle := styles.NewStyle().Background(t.Secondary()).Foreground(t.BackgroundPanel()).Padding(0, 1)
							for _, filePart := range fileParts {
								mediaType := ""
								switch filePart.Mime {
								case "text/plain":
									mediaType = "txt"
								case "image/png", "image/jpeg", "image/gif", "image/webp":
									mediaType = "img"
									mediaTypeStyle = mediaTypeStyle.Background(t.Accent())
								case "application/pdf":
									mediaType = "pdf"
									mediaTypeStyle = mediaTypeStyle.Background(t.Primary())
								}
								flexItems = append(flexItems, layout.FlexItem{
									View: mediaTypeStyle.Render(mediaType) + fileStyle.Render(filePart.Filename),
								})
							}
						}
						bgColor := t.BackgroundPanel()
						files := layout.Render(
							layout.FlexOptions{
								Background: &bgColor,
								Width:      width - 6,
								Direction:  layout.Column,
							},
							flexItems...,
						)

						author := m.app.Config.Username
						if casted.ID > lastAssistantMessage {
							author += " [queued]"
						}
						key := m.cache.GenerateKey(casted.ID, part.Text, width, files, author)
						content, cached = m.cache.Get(key)
						if !cached {
							content = renderText(
								m.app,
								message.Info,
								part.Text,
								author,
								m.showToolDetails,
								width,
								files,
								fileParts,
							)
							content = lipgloss.PlaceHorizontal(
								m.width,
								lipgloss.Center,
								content,
								styles.WhitespaceStyle(t.Background()),
							)
							m.cache.Set(key, content)
						}
						if content != "" {
							partCount++
							lineCount += lipgloss.Height(content) + 1
							blocks = append(blocks, content)
						}
					}
				}

			case opencode.AssistantMessage:
				if casted.ID == m.app.Session.Revert.MessageID {
					reverted = true
					revertedMessageCount = 1
					revertedToolCount = 0
				}
				hasTextPart := false
				for partIndex, p := range message.Parts {
					switch part := p.(type) {
					case opencode.TextPart:
						if reverted {
							continue
						}
						if strings.TrimSpace(part.Text) == "" {
							continue
						}
						hasTextPart = true
						finished := part.Time.End > 0
						remainingParts := message.Parts[partIndex+1:]
						toolCallParts := make([]opencode.ToolPart, 0)

						// sometimes tool calls happen without an assistant message
						// these should be included in this assistant message as well
						if len(orphanedToolCalls) > 0 {
							toolCallParts = append(toolCallParts, orphanedToolCalls...)
							orphanedToolCalls = make([]opencode.ToolPart, 0)
						}

						remaining := true
						for _, part := range remainingParts {
							if !remaining {
								break
							}
							switch part := part.(type) {
							case opencode.TextPart:
								// we only want tool calls associated with the current text part.
								// if we hit another text part, we're done.
								remaining = false
							case opencode.ToolPart:
								toolCallParts = append(toolCallParts, part)
								if part.State.Status != opencode.ToolPartStateStatusCompleted && part.State.Status != opencode.ToolPartStateStatusError {
									// i don't think there's a case where a tool call isn't in result state
									// and the message time is 0, but just in case
									finished = false
								}
							}
						}

						if finished {
							key := m.cache.GenerateKey(casted.ID, part.Text, width, m.showToolDetails)
							content, cached = m.cache.Get(key)
							if !cached {
								content = renderText(
									m.app,
									message.Info,
									part.Text,
									casted.ModelID,
									m.showToolDetails,
									width,
									"",
									[]opencode.FilePart{},
									toolCallParts...,
								)
								content = lipgloss.PlaceHorizontal(
									m.width,
									lipgloss.Center,
									content,
									styles.WhitespaceStyle(t.Background()),
								)
								m.cache.Set(key, content)
							}
						} else {
							content = renderText(
								m.app,
								message.Info,
								part.Text,
								casted.ModelID,
								m.showToolDetails,
								width,
								"",
								[]opencode.FilePart{},
								toolCallParts...,
							)
							content = lipgloss.PlaceHorizontal(
								m.width,
								lipgloss.Center,
								content,
								styles.WhitespaceStyle(t.Background()),
							)
						}
						if content != "" {
							partCount++
							lineCount += lipgloss.Height(content) + 1
							blocks = append(blocks, content)
						}
					case opencode.ToolPart:
						if reverted {
							revertedToolCount++
							continue
						}

						permission := opencode.Permission{}
						if m.app.CurrentPermission.CallID == part.CallID {
							permission = m.app.CurrentPermission
						}

						if !m.showToolDetails && permission.ID == "" {
							if !hasTextPart {
								orphanedToolCalls = append(orphanedToolCalls, part)
							}
							continue
						}

						if part.State.Status == opencode.ToolPartStateStatusCompleted || part.State.Status == opencode.ToolPartStateStatusError {
							key := m.cache.GenerateKey(casted.ID,
								part.ID,
								m.showToolDetails,
								width,
								permission.ID,
							)
							content, cached = m.cache.Get(key)
							if !cached {
								content = renderToolDetails(
									m.app,
									part,
									permission,
									width,
								)
								content = lipgloss.PlaceHorizontal(
									m.width,
									lipgloss.Center,
									content,
									styles.WhitespaceStyle(t.Background()),
								)
								m.cache.Set(key, content)
							}
						} else {
							// if the tool call isn't finished, don't cache
							content = renderToolDetails(
								m.app,
								part,
								permission,
								width,
							)
							content = lipgloss.PlaceHorizontal(
								m.width,
								lipgloss.Center,
								content,
								styles.WhitespaceStyle(t.Background()),
							)
						}
						if content != "" {
							partCount++
							lineCount += lipgloss.Height(content) + 1
							blocks = append(blocks, content)
						}
					}
				}
			}

			error := ""
			if assistant, ok := message.Info.(opencode.AssistantMessage); ok {
				switch err := assistant.Error.AsUnion().(type) {
				case nil:
				case opencode.AssistantMessageErrorMessageOutputLengthError:
					error = "Message output length exceeded"
				case opencode.ProviderAuthError:
					error = err.Data.Message
				case opencode.MessageAbortedError:
					error = "Request was aborted"
				case opencode.UnknownError:
					error = err.Data.Message
				}
			}

			if error != "" && !reverted {
				error = styles.NewStyle().Width(width - 6).Render(error)
				error = renderContentBlock(
					m.app,
					error,
					width,
					WithBorderColor(t.Error()),
				)
				error = lipgloss.PlaceHorizontal(
					m.width,
					lipgloss.Center,
					error,
					styles.WhitespaceStyle(t.Background()),
				)
				blocks = append(blocks, error)
				lineCount += lipgloss.Height(error) + 1
			}
		}

		if revertedMessageCount > 0 || revertedToolCount > 0 {
			messagePlural := ""
			toolPlural := ""
			if revertedMessageCount != 1 {
				messagePlural = "s"
			}
			if revertedToolCount != 1 {
				toolPlural = "s"
			}
			revertedStyle := styles.NewStyle().
				Background(t.BackgroundPanel()).
				Foreground(t.TextMuted())

			content := revertedStyle.Render(fmt.Sprintf(
				"%d message%s reverted, %d tool call%s reverted",
				revertedMessageCount,
				messagePlural,
				revertedToolCount,
				toolPlural,
			))
			hintStyle := styles.NewStyle().Background(t.BackgroundPanel()).Foreground(t.Text())
			hint := hintStyle.Render(m.app.Keybind(commands.MessagesRedoCommand))
			hint += revertedStyle.Render(" (or /redo) to restore")

			content += "\n" + hint
			if m.app.Session.Revert.Diff != "" {
				t := theme.CurrentTheme()
				s := styles.NewStyle().Background(t.BackgroundPanel())
				green := s.Foreground(t.Success()).Render
				red := s.Foreground(t.Error()).Render
				content += "\n"
				stats, err := diff.ParseStats(m.app.Session.Revert.Diff)
				if err != nil {
					slog.Error("Failed to parse diff stats", "error", err)
				} else {
					var files []string
					for file := range stats {
						files = append(files, file)
					}
					sort.Strings(files)

					for _, file := range files {
						fileStats := stats[file]
						display := file
						if fileStats.Added > 0 {
							display += green(" +" + strconv.Itoa(int(fileStats.Added)))
						}
						if fileStats.Removed > 0 {
							display += red(" -" + strconv.Itoa(int(fileStats.Removed)))
						}
						content += "\n" + display
					}
				}
			}

			content = styles.NewStyle().
				Background(t.BackgroundPanel()).
				Width(width - 6).
				Render(content)
			content = renderContentBlock(
				m.app,
				content,
				width,
				WithBorderColor(t.BackgroundPanel()),
			)
			blocks = append(blocks, content)
		}

		if m.app.CurrentPermission.ID != "" &&
			m.app.CurrentPermission.SessionID != m.app.Session.ID {
			response, err := m.app.Client.Session.Message(
				context.Background(),
				m.app.CurrentPermission.SessionID,
				m.app.CurrentPermission.MessageID,
			)
			if err != nil || response == nil {
				slog.Error("Failed to get message from child session", "error", err)
			} else {
				for _, part := range response.Parts {
					if part.CallID == m.app.CurrentPermission.CallID {
						content := renderToolDetails(
							m.app,
							part.AsUnion().(opencode.ToolPart),
							m.app.CurrentPermission,
							width,
						)
						content = lipgloss.PlaceHorizontal(
							m.width,
							lipgloss.Center,
							content,
							styles.WhitespaceStyle(t.Background()),
						)
						if content != "" {
							partCount++
							lineCount += lipgloss.Height(content) + 1
							blocks = append(blocks, content)
						}
					}
				}
			}
		}

		final := []string{}
		clipboard := []string{}
		var selection *selection
		if m.selection != nil {
			selection = m.selection.coords(lipgloss.Height(header) + 1)
		}
		for _, block := range blocks {
			lines := strings.Split(block, "\n")
			for index, line := range lines {
				if selection == nil || index == 0 || index == len(lines)-1 {
					final = append(final, line)
					continue
				}
				y := len(final)
				if y >= selection.startY && y <= selection.endY {
					left := 3
					if y == selection.startY {
						left = selection.startX - 2
					}
					left = max(3, left)

					width := ansi.StringWidth(line)
					right := width - 1
					if y == selection.endY {
						right = min(selection.endX-2, right)
					}

					prefix := ansi.Cut(line, 0, left)
					middle := strings.TrimRight(ansi.Strip(ansi.Cut(line, left, right)), " ")
					suffix := ansi.Cut(line, left+ansi.StringWidth(middle), width)
					clipboard = append(clipboard, middle)
					line = prefix + styles.NewStyle().
						Background(t.Accent()).
						Foreground(t.BackgroundPanel()).
						Render(ansi.Strip(middle)) +
						suffix
				}
				final = append(final, line)
			}
			y := len(final)
			if selection != nil && y >= selection.startY && y < selection.endY {
				clipboard = append(clipboard, "")
			}
			final = append(final, "")
		}
		content := "\n" + strings.Join(final, "\n")
		viewport.SetHeight(m.height - lipgloss.Height(header))
		viewport.SetContent(content)
		if tail {
			viewport.GotoBottom()
		}

		return renderCompleteMsg{
			header:    header,
			clipboard: clipboard,
			viewport:  viewport,
			partCount: partCount,
			lineCount: lineCount,
		}
	}
}

func (m *messagesComponent) renderHeader() string {
	if m.app.Session.ID == "" {
		return ""
	}

	headerWidth := m.width

	t := theme.CurrentTheme()
	base := styles.NewStyle().Foreground(t.Text()).Background(t.Background()).Render
	muted := styles.NewStyle().Foreground(t.TextMuted()).Background(t.Background()).Render

	sessionInfo := ""
	tokens := float64(0)
	cost := float64(0)
	contextWindow := m.app.Model.Limit.Context

	for _, message := range m.app.Messages {
		if assistant, ok := message.Info.(opencode.AssistantMessage); ok {
			cost += assistant.Cost
			usage := assistant.Tokens
			if usage.Output > 0 {
				if assistant.Summary {
					tokens = usage.Output
					continue
				}
				tokens = (usage.Input +
					usage.Cache.Write +
					usage.Cache.Read +
					usage.Output +
					usage.Reasoning)
			}
		}
	}

	// Check if current model is a subscription model (cost is 0 for both input and output)
	isSubscriptionModel := m.app.Model != nil &&
		m.app.Model.Cost.Input == 0 && m.app.Model.Cost.Output == 0

	sessionInfoText := formatTokensAndCost(tokens, contextWindow, cost, isSubscriptionModel)
	sessionInfo = styles.NewStyle().
		Foreground(t.TextMuted()).
		Background(t.Background()).
		Render(sessionInfoText)

	shareEnabled := m.app.Config.Share != opencode.ConfigShareDisabled
	headerTextWidth := headerWidth
	if !shareEnabled {
		// +1 is to ensure there is always at least one space between header and session info
		headerTextWidth -= len(sessionInfoText) + 1
	}
	headerText := util.ToMarkdown(
		"# "+m.app.Session.Title,
		headerTextWidth,
		t.Background(),
	)

	var items []layout.FlexItem
	if shareEnabled {
		share := base("/share") + muted(" to create a shareable link")
		if m.app.Session.Share.URL != "" {
			share = muted(m.app.Session.Share.URL + "  /unshare")
		}
		items = []layout.FlexItem{{View: share}, {View: sessionInfo}}
	} else {
		items = []layout.FlexItem{{View: headerText}, {View: sessionInfo}}
	}

	background := t.Background()
	headerRow := layout.Render(
		layout.FlexOptions{
			Background: &background,
			Direction:  layout.Row,
			Justify:    layout.JustifySpaceBetween,
			Align:      layout.AlignStretch,
			Width:      headerWidth - 6,
		},
		items...,
	)

	headerLines := []string{headerRow}
	if shareEnabled {
		headerLines = []string{headerText, headerRow}
	}

	header := strings.Join(headerLines, "\n")
	header = styles.NewStyle().
		Background(t.Background()).
		Width(headerWidth).
		PaddingLeft(2).
		PaddingRight(2).
		BorderLeft(true).
		BorderRight(true).
		BorderBackground(t.Background()).
		BorderForeground(t.BackgroundElement()).
		BorderStyle(lipgloss.ThickBorder()).
		Render(header)
	header = lipgloss.PlaceHorizontal(
		m.width,
		lipgloss.Center,
		header,
		styles.WhitespaceStyle(t.Background()),
	)

	return "\n" + header + "\n"
}

func formatTokensAndCost(
	tokens float64,
	contextWindow float64,
	cost float64,
	isSubscriptionModel bool,
) string {
	// Format tokens in human-readable format (e.g., 110K, 1.2M)
	var formattedTokens string
	switch {
	case tokens >= 1_000_000:
		formattedTokens = fmt.Sprintf("%.1fM", float64(tokens)/1_000_000)
	case tokens >= 1_000:
		formattedTokens = fmt.Sprintf("%.1fK", float64(tokens)/1_000)
	default:
		formattedTokens = fmt.Sprintf("%d", int(tokens))
	}

	// Remove .0 suffix if present
	if strings.HasSuffix(formattedTokens, ".0K") {
		formattedTokens = strings.Replace(formattedTokens, ".0K", "K", 1)
	}
	if strings.HasSuffix(formattedTokens, ".0M") {
		formattedTokens = strings.Replace(formattedTokens, ".0M", "M", 1)
	}

	percentage := 0.0
	if contextWindow > 0 {
		percentage = (float64(tokens) / float64(contextWindow)) * 100
	}

	if isSubscriptionModel {
		return fmt.Sprintf(
			"%s/%d%%",
			formattedTokens,
			int(percentage),
		)
	}

	formattedCost := fmt.Sprintf("$%.2f", cost)
	return fmt.Sprintf(
		"%s/%d%% (%s)",
		formattedTokens,
		int(percentage),
		formattedCost,
	)
}

func (m *messagesComponent) View() string {
	t := theme.CurrentTheme()
	if m.loading {
		return lipgloss.Place(
			m.width,
			m.height,
			lipgloss.Center,
			lipgloss.Center,
			styles.NewStyle().Background(t.Background()).Render(""),
			styles.WhitespaceStyle(t.Background()),
		)
	}

	viewport := m.viewport.View()
	return styles.NewStyle().
		Background(t.Background()).
		Render(m.header + "\n" + viewport)
}

func (m *messagesComponent) PageUp() (tea.Model, tea.Cmd) {
	m.viewport.ViewUp()
	return m, nil
}

func (m *messagesComponent) PageDown() (tea.Model, tea.Cmd) {
	m.viewport.ViewDown()
	return m, nil
}

func (m *messagesComponent) HalfPageUp() (tea.Model, tea.Cmd) {
	m.viewport.HalfViewUp()
	return m, nil
}

func (m *messagesComponent) HalfPageDown() (tea.Model, tea.Cmd) {
	m.viewport.HalfViewDown()
	return m, nil
}

func (m *messagesComponent) ToolDetailsVisible() bool {
	return m.showToolDetails
}

func (m *messagesComponent) GotoTop() (tea.Model, tea.Cmd) {
	m.viewport.GotoTop()
	return m, nil
}

func (m *messagesComponent) GotoBottom() (tea.Model, tea.Cmd) {
	m.viewport.GotoBottom()
	return m, nil
}

func (m *messagesComponent) CopyLastMessage() (tea.Model, tea.Cmd) {
	if len(m.app.Messages) == 0 {
		return m, nil
	}
	lastMessage := m.app.Messages[len(m.app.Messages)-1]
	var lastTextPart *opencode.TextPart
	for _, part := range lastMessage.Parts {
		if p, ok := part.(opencode.TextPart); ok {
			lastTextPart = &p
		}
	}
	if lastTextPart == nil {
		return m, nil
	}
	var cmds []tea.Cmd
	cmds = append(cmds, app.SetClipboard(lastTextPart.Text))
	cmds = append(cmds, toast.NewSuccessToast("Message copied to clipboard"))
	return m, tea.Batch(cmds...)
}

func (m *messagesComponent) UndoLastMessage() (tea.Model, tea.Cmd) {
	after := float64(0)
	var revertedMessage app.Message
	reversedMessages := []app.Message{}
	for i := len(m.app.Messages) - 1; i >= 0; i-- {
		reversedMessages = append(reversedMessages, m.app.Messages[i])
		switch casted := m.app.Messages[i].Info.(type) {
		case opencode.UserMessage:
			if casted.ID == m.app.Session.Revert.MessageID {
				after = casted.Time.Created
			}
		case opencode.AssistantMessage:
			if casted.ID == m.app.Session.Revert.MessageID {
				after = casted.Time.Created
			}
		}
		if m.app.Session.Revert.PartID != "" {
			for _, part := range m.app.Messages[i].Parts {
				switch casted := part.(type) {
				case opencode.TextPart:
					if casted.ID == m.app.Session.Revert.PartID {
						after = casted.Time.Start
					}
				case opencode.ToolPart:
					// TODO: handle tool parts
				}
			}
		}
	}

	messageID := ""
	for _, msg := range reversedMessages {
		switch casted := msg.Info.(type) {
		case opencode.UserMessage:
			if after > 0 && casted.Time.Created >= after {
				continue
			}
			messageID = casted.ID
			revertedMessage = msg
		}
		if messageID != "" {
			break
		}
	}

	if messageID == "" {
		return m, nil
	}

	return m, func() tea.Msg {
		response, err := m.app.Client.Session.Revert(
			context.Background(),
			m.app.Session.ID,
			opencode.SessionRevertParams{
				MessageID: opencode.F(messageID),
			},
		)
		if err != nil {
			slog.Error("Failed to undo message", "error", err)
			return toast.NewErrorToast("Failed to undo message")
		}
		if response == nil {
			return toast.NewErrorToast("Failed to undo message")
		}
		return app.MessageRevertedMsg{Session: *response, Message: revertedMessage}
	}
}

func (m *messagesComponent) RedoLastMessage() (tea.Model, tea.Cmd) {
	// Check if there's a revert state to redo from
	if m.app.Session.Revert.MessageID == "" {
		return m, func() tea.Msg {
			return toast.NewErrorToast("Nothing to redo")
		}
	}

	before := float64(0)
	var revertedMessage app.Message
	for _, message := range m.app.Messages {
		switch casted := message.Info.(type) {
		case opencode.UserMessage:
			if casted.ID == m.app.Session.Revert.MessageID {
				before = casted.Time.Created
			}
		case opencode.AssistantMessage:
			if casted.ID == m.app.Session.Revert.MessageID {
				before = casted.Time.Created
			}
		}
		if m.app.Session.Revert.PartID != "" {
			for _, part := range message.Parts {
				switch casted := part.(type) {
				case opencode.TextPart:
					if casted.ID == m.app.Session.Revert.PartID {
						before = casted.Time.Start
					}
				case opencode.ToolPart:
					// TODO: handle tool parts
				}
			}
		}
	}

	messageID := ""
	for _, msg := range m.app.Messages {
		switch casted := msg.Info.(type) {
		case opencode.UserMessage:
			if casted.Time.Created <= before {
				continue
			}
			messageID = casted.ID
			revertedMessage = msg
		}
		if messageID != "" {
			break
		}
	}

	if messageID == "" {
		return m, func() tea.Msg {
			// unrevert back to original state
			response, err := m.app.Client.Session.Unrevert(
				context.Background(),
				m.app.Session.ID,
			)
			if err != nil {
				slog.Error("Failed to unrevert session", "error", err)
				return toast.NewErrorToast("Failed to redo message")
			}
			if response == nil {
				return toast.NewErrorToast("Failed to redo message")
			}
			return app.SessionUnrevertedMsg{Session: *response}
		}
	}

	return m, func() tea.Msg {
		// calling revert on a "later" message is like a redo
		response, err := m.app.Client.Session.Revert(
			context.Background(),
			m.app.Session.ID,
			opencode.SessionRevertParams{
				MessageID: opencode.F(messageID),
			},
		)
		if err != nil {
			slog.Error("Failed to redo message", "error", err)
			return toast.NewErrorToast("Failed to redo message")
		}
		if response == nil {
			return toast.NewErrorToast("Failed to redo message")
		}
		return app.MessageRevertedMsg{Session: *response, Message: revertedMessage}
	}
}

func NewMessagesComponent(app *app.App) MessagesComponent {
	vp := viewport.New()
	vp.KeyMap = viewport.KeyMap{}

	if app.State.ScrollSpeed != nil && *app.State.ScrollSpeed > 0 {
		vp.MouseWheelDelta = *app.State.ScrollSpeed
	} else {
		vp.MouseWheelDelta = 4
	}

	return &messagesComponent{
		app:             app,
		viewport:        vp,
		showToolDetails: true,
		cache:           NewPartCache(),
		tail:            true,
	}
}