package tui

import (
	"errors"
	"fmt"
	"io"
	"os"
	"regexp"
	"strings"
	"unicode/utf8"

	"github.com/charmbracelet/bubbles/viewport"
	"github.com/charmbracelet/lipgloss"

	"proxyctl/internal/app"
	"proxyctl/internal/profile"
)

const (
	minimumWidth  = 60
	minimumHeight = 16
	wideWidth     = 100
	wideHeight    = 28
)

type themeMode uint8

const (
	themeModeAuto themeMode = iota
	themeModeDark
	themeModeLight
	themeModeNoColor
)

type modelOptions struct {
	theme  themeMode
	output io.Writer
}

// ModelOption configures terminal capabilities used by the complete TUI Model.
type ModelOption func(*modelOptions)

// WithOutput makes presentation capability detection use the same writer that
// Bubble Tea renders to. Production composition should pass tea.WithOutput's
// writer here as well.
func WithOutput(output io.Writer) ModelOption {
	return func(options *modelOptions) { options.output = output }
}

func withTheme(mode themeMode) ModelOption {
	return func(options *modelOptions) { options.theme = mode }
}

func defaultModelOptions() modelOptions {
	return modelOptions{output: os.Stdout}
}

type presentationState struct {
	snapshot  app.Snapshot
	page      page
	terminal  terminalDimensions
	dashboard dashboardPresentationState
	profile   profilePresentationState
	form      formPresentationState
	help      helpPresentationState
	operation operationPresentationState
}

type terminalDimensions struct {
	width  int
	height int
}

type dashboardPresentationState struct {
	selectedTargetID        string
	focus                   dashboardPane
	showUnavailable         bool
	detailsOffset           int
	driftResolutionTargetID string
	picker                  profilePickerState
}

type profilePresentationState struct {
	selected      int
	listOffset    int
	detailsOffset int
	deletion      *profileDeleteConfirmation
	status        string
}

type formPresentationState struct {
	state formState
}

type helpPresentationState struct {
	dialog helpDialogState
}

type operationPresentationState struct {
	confirmation       *app.Confirmation
	confirmationDialog *confirmationDialog
	status             app.OperationStatus
	currentError       *operationError
	errorExpanded      bool
	errorOffset        int
	exitDeferred       bool
	active             bool
	progress           map[string]app.TargetProgressPhase
	spinnerFrame       string
}

// terminalPresentation is the terminal-presentation Module. Application
// coordination supplies one immutable state and calls its single Render
// operation; responsive layout, theming, clipping, and final redaction stay
// inside the module.
type terminalPresentation struct {
	theme semanticTheme
}

type terminalPage struct {
	header         string
	primary        string
	context        string
	footer         string
	status         string
	statusExpanded bool
	statusOffset   int
	focusLine      int
	primaryOffset  int
	contextOffset  int
	contextAnchor  int
	anchorContext  bool
	wrapPrimary    bool
	wrapContext    bool
	dashboard      *dashboardRenderState
}

func (p terminalPresentation) Render(state presentationState) string {
	// Application snapshots, adapter diagnostics, operation updates, and form
	// input are all untrusted presentation data. Strip their controls before any
	// semanticTheme style is applied; otherwise an attacker could inject one of
	// the same allowlisted SGR sequences that the theme legitimately emits.
	state = sanitizePresentationState(state)
	width, height := state.terminal.width, state.terminal.height
	if width <= 0 {
		width = 80
	}
	if height <= 0 {
		height = 24
	}

	if width < minimumWidth || height < minimumHeight {
		content := profile.RedactText(p.minimumSizeView(width, height))
		return strings.TrimRight(viewportContent(content, width, height, 0), " \n") + "\n"
	}

	var page terminalPage
	switch state.page {
	case profilesPage:
		page = p.profilesView(state)
	case formPage:
		page = p.formView(state)
	default:
		page = p.mainView(state, width, height)
	}
	if state.help.dialog.top(state.operation.confirmation) {
		help := p.helpDialogView(state)
		// Retain the underlying page header so Help is visibly contextual and
		// modal rather than a replacement navigation destination.
		page.primary = help.primary
		page.context = ""
		page.footer = help.footer
		page.focusLine = help.focusLine
		page.primaryOffset = help.primaryOffset
		page.contextOffset = 0
		page.dashboard = nil
	}
	page.status = renderStatus(state)
	page.statusExpanded = state.operation.errorExpanded && state.operation.currentError != nil
	page.statusOffset = state.operation.errorOffset
	page = redactTerminalPage(page)
	// Untrusted values were redacted and stripped of controls before semantic
	// styling. The final pass therefore removes unexpected terminal controls
	// without reparsing clipped, composed prose as if it were a URL.
	return sanitizeStyledText(p.renderShell(page, width, height))
}

func renderStatus(state presentationState) string {
	var lines []string
	operation := state.operation
	if operation.exitDeferred {
		lines = append(lines, "Exit requested — waiting for the current mutation to finish safely")
	} else if operation.status.Summary != "" {
		lines = append(lines, operation.status.Summary)
	} else if state.profile.status != "" {
		lines = append(lines, state.profile.status)
	}
	if operation.currentError != nil {
		errorText := "Current error: " + operation.currentError.status.Summary
		if operation.errorExpanded && operation.currentError.detail != "" {
			errorText += "\n" + operation.currentError.detail
		}
		lines = append(lines, errorText)
	}
	return strings.Join(lines, "\n")
}

func redactTerminalPage(page terminalPage) terminalPage {
	page.header = protectRenderedText(page.header)
	page.primary = protectRenderedText(page.primary)
	page.context = protectRenderedText(page.context)
	page.footer = protectRenderedText(page.footer)
	page.status = protectRenderedText(page.status)
	return page
}

func protectRenderedText(value string) string {
	return sanitizeStyledText(value)
}

func sanitizeUntrustedControls(value string) string {
	return sanitizeTerminalText(value, false)
}

func sanitizeUntrustedText(value string) string {
	return sanitizeUntrustedControls(profile.RedactText(value))
}

func sanitizeUntrustedUserinfoText(value string) string {
	return sanitizeUntrustedControls(profile.RedactUserinfoText(value))
}

func sanitizePresentationState(state presentationState) presentationState {
	state.snapshot.ActiveProfile = sanitizeUntrustedText(state.snapshot.ActiveProfile)
	state.snapshot.Profiles = append([]profile.Profile(nil), state.snapshot.Profiles...)
	for i := range state.snapshot.Profiles {
		state.snapshot.Profiles[i] = sanitizePresentationProfile(state.snapshot.Profiles[i])
	}
	state.snapshot.Targets = append([]app.TargetSnapshot(nil), state.snapshot.Targets...)
	for i := range state.snapshot.Targets {
		item := &state.snapshot.Targets[i]
		item.Description.Name = sanitizeUntrustedText(item.Description.Name)
		item.Description.Summary = sanitizeUntrustedText(item.Description.Summary)
		item.Description.Scope = sanitizeUntrustedText(item.Description.Scope)
		item.Description.Permissions = sanitizeUntrustedText(item.Description.Permissions)
		item.Description.Ownership = sanitizeUntrustedText(item.Description.Ownership)
		item.Description.RestartRisk = sanitizeUntrustedText(item.Description.RestartRisk)
		item.Description.Details = sanitizeUntrustedText(item.Description.Details)
		item.AvailabilityEvidence = sanitizeUntrustedText(item.AvailabilityEvidence)
		item.Evidence = sanitizeUntrustedText(item.Evidence)
		item.DetectionErr = sanitizePresentationError(item.DetectionErr)
		item.PrimaryAction.DisabledReason = sanitizeUntrustedText(item.PrimaryAction.DisabledReason)
		item.DriftResolutionActions = append([]app.TargetAction(nil), item.DriftResolutionActions...)
		for action := range item.DriftResolutionActions {
			item.DriftResolutionActions[action].DisabledReason = sanitizeUntrustedText(item.DriftResolutionActions[action].DisabledReason)
		}
	}

	sanitizeStatus := sanitizeUntrustedText
	if state.page == formPage {
		// Profile editing treats the identity as private as well as the password.
		// Apply that stronger policy to every status/error ingress before styling.
		sanitizeStatus = sanitizeUntrustedUserinfoText
	}
	state.profile.status = sanitizeStatus(state.profile.status)
	state.operation.status.Summary = sanitizeStatus(state.operation.status.Summary)
	if state.operation.currentError != nil {
		current := *state.operation.currentError
		current.status.Summary = sanitizeStatus(current.status.Summary)
		current.detail = sanitizeStatus(current.detail)
		state.operation.currentError = &current
	}
	if state.operation.confirmation != nil {
		confirmation := sanitizePresentationConfirmation(*state.operation.confirmation)
		state.operation.confirmation = &confirmation
	}
	if state.operation.confirmationDialog != nil {
		dialog := *state.operation.confirmationDialog
		dialog.request = sanitizePresentationConfirmation(dialog.request)
		state.operation.confirmationDialog = &dialog
	}
	if state.profile.deletion != nil {
		confirmation := *state.profile.deletion
		confirmation.name = sanitizeUntrustedText(confirmation.name)
		confirmation.dialog.request = sanitizePresentationConfirmation(confirmation.dialog.request)
		state.profile.deletion = &confirmation
	}

	state.dashboard.picker.selectedName = sanitizeUntrustedText(state.dashboard.picker.selectedName)
	searchPosition := state.dashboard.picker.search.Position()
	state.dashboard.picker.search.SetValue(sanitizeUntrustedText(state.dashboard.picker.search.Value()))
	state.dashboard.picker.search.SetCursor(searchPosition)
	state.form.state = sanitizePresentationForm(state.form.state)
	return state
}

func sanitizePresentationProfile(value profile.Profile) profile.Profile {
	value.Name = sanitizeUntrustedText(value.Name)
	value.SingleURL = sanitizeUntrustedText(value.SingleURL)
	value.HTTPURL = sanitizeUntrustedText(value.HTTPURL)
	value.HTTPSURL = sanitizeUntrustedText(value.HTTPSURL)
	value.AllURL = sanitizeUntrustedText(value.AllURL)
	value.Bypass = append([]string(nil), value.Bypass...)
	for i := range value.Bypass {
		value.Bypass[i] = sanitizeUntrustedText(value.Bypass[i])
	}
	return value
}

func sanitizePresentationForm(form formState) formState {
	// Preserve credential byte/rune positions in the copied editor state so
	// textinput cursor and horizontal viewport calculations stay truthful.
	// renderedInput masks userinfo before clipping, and the final form boundary
	// redacts it again; this pass only removes terminal controls before styling.
	form.originalName = sanitizeUntrustedControls(form.originalName)
	form.profile = sanitizePresentationFormProfile(form.profile)
	form.inputs = append([]formInput(nil), form.inputs...)
	for i := range form.inputs {
		form.inputs[i].label = sanitizeUntrustedText(form.inputs[i].label)
		position := form.inputs[i].input.Position()
		form.inputs[i].input.SetValue(sanitizeUntrustedControls(form.inputs[i].input.Value()))
		form.inputs[i].input.SetCursor(position)
	}
	form.probe.address = sanitizeUntrustedText(form.probe.address)
	form.probe.feedback = sanitizeUntrustedText(form.probe.feedback)
	form.probe.sourceValue = sanitizeUntrustedText(form.probe.sourceValue)
	form.refreshValidation()
	return form
}

func sanitizePresentationFormProfile(value profile.Profile) profile.Profile {
	value.Name = sanitizeUntrustedControls(value.Name)
	value.SingleURL = sanitizeUntrustedControls(value.SingleURL)
	value.HTTPURL = sanitizeUntrustedControls(value.HTTPURL)
	value.HTTPSURL = sanitizeUntrustedControls(value.HTTPSURL)
	value.AllURL = sanitizeUntrustedControls(value.AllURL)
	value.Bypass = append([]string(nil), value.Bypass...)
	for i := range value.Bypass {
		value.Bypass[i] = sanitizeUntrustedControls(value.Bypass[i])
	}
	return value
}

func sanitizePresentationConfirmation(value app.Confirmation) app.Confirmation {
	value.Title = sanitizeUntrustedText(value.Title)
	value.Summary = sanitizeUntrustedText(value.Summary)
	value.ConfirmLabel = sanitizeUntrustedText(value.ConfirmLabel)
	value.CancelLabel = sanitizeUntrustedText(value.CancelLabel)
	value.Details = append([]string(nil), value.Details...)
	for i := range value.Details {
		value.Details[i] = sanitizeUntrustedText(value.Details[i])
	}
	return value
}

func sanitizePresentationError(err error) error {
	if err == nil {
		return nil
	}
	return errors.New(sanitizeUntrustedText(err.Error()))
}

var safeSGRPattern = regexp.MustCompile(`^(?:0|(?:(?:1;)?(?:4;)?38;5;(?:25|34|75|160|172|235|242|245|252)))$`)

// sanitizeStyledText is the final defense after semantic styling. Untrusted
// values have already passed sanitizeUntrustedText, so the only SGR retained
// here is output generated by semanticTheme.
func sanitizeStyledText(value string) string { return sanitizeTerminalText(value, true) }

func sanitizeTerminalText(value string, allowThemeSGR bool) string {
	var safe strings.Builder
	for i := 0; i < len(value); {
		if value[i] == '\x1b' {
			if i+1 < len(value) && value[i+1] == '[' {
				end := i + 2
				for end < len(value) && (value[end] < 0x40 || value[end] > 0x7e) {
					end++
				}
				if end < len(value) {
					if allowThemeSGR && value[end] == 'm' && safeSGRPattern.MatchString(value[i+2:end]) {
						safe.WriteString(value[i : end+1])
					}
					i = end + 1
					continue
				}
				i = len(value)
				continue
			}
			if i+1 < len(value) && value[i+1] == ']' {
				i = skipTerminalString(value, i+2)
				continue
			}
			i++
			continue
		}
		if value[i] == 0x9b {
			end := i + 1
			for end < len(value) && (value[end] < 0x40 || value[end] > 0x7e) {
				end++
			}
			if end < len(value) {
				i = end + 1
			} else {
				i = len(value)
			}
			continue
		}
		if value[i] == 0x9d {
			i = skipTerminalString(value, i+1)
			continue
		}
		switch value[i] {
		case '\n':
			safe.WriteByte('\n')
		case '\t':
			safe.WriteString("    ")
		default:
			if value[i] >= utf8.RuneSelf {
				r, size := utf8.DecodeRuneInString(value[i:])
				if r != utf8.RuneError || size > 1 {
					if r != '\ufeff' && !(r >= 0x80 && r <= 0x9f) && !(r >= 0x202a && r <= 0x202e) && !(r >= 0x2066 && r <= 0x2069) {
						safe.WriteString(value[i : i+size])
					}
					i += size
					continue
				}
			} else if value[i] >= 0x20 && value[i] != 0x7f {
				safe.WriteByte(value[i])
			}
		}
		i++
	}

	var visible strings.Builder
	for _, r := range safe.String() {
		if r == '\ufeff' || (r >= 0x80 && r <= 0x9f) || (r >= 0x202a && r <= 0x202e) || (r >= 0x2066 && r <= 0x2069) {
			continue
		}
		visible.WriteRune(r)
	}
	return visible.String()
}

func skipTerminalString(value string, i int) int {
	for i < len(value) {
		if value[i] == '\a' || value[i] == 0x9c {
			return i + 1
		}
		if value[i] == '\x1b' && i+1 < len(value) && value[i+1] == '\\' {
			return i + 2
		}
		i++
	}
	return i
}

func (p terminalPresentation) renderShell(page terminalPage, width, height int) string {
	header := viewportContent(page.header, width, lineCount(page.header), 0)
	footer := viewportContent(page.footer, width, lineCount(page.footer), 0)

	headerHeight := lineCount(header)
	footerHeight := lineCount(footer)
	baseSeparators := 0
	if header != "" {
		baseSeparators++
	}
	if footer != "" || page.status != "" {
		baseSeparators++
	}

	status := ""
	if page.status != "" {
		wrapped := lipgloss.NewStyle().Width(width).Render(p.theme.status.Render("Status: " + page.status))
		statusHeight := min(2, lineCount(wrapped))
		statusOffset := 0
		if page.statusExpanded {
			statusHeight = min(lineCount(wrapped), max(3, height/2))
			// The compact dashboard needs ten rows to retain both panes. Bound
			// expanded errors to the remaining terminal budget instead of
			// allowing their viewport to push the frame beyond the terminal.
			minimumBodyHeight := 1
			if page.dashboard != nil {
				minimumBodyHeight = 10
			}
			statusHeight = min(statusHeight, max(1, height-headerHeight-footerHeight-baseSeparators-minimumBodyHeight))
			statusOffset = page.statusOffset
		}
		status = viewportContent(wrapped, width, statusHeight, statusOffset)
	}

	statusHeight := lineCount(status)
	separators := baseSeparators
	bodyHeight := height - headerHeight - footerHeight - statusHeight - separators
	if bodyHeight < 1 {
		bodyHeight = 1
	}
	body := renderPageBody(page, width, bodyHeight)
	if page.dashboard != nil {
		body = p.renderDashboard(*page.dashboard, width, bodyHeight)
	}

	sections := make([]string, 0, 3)
	if header != "" {
		sections = append(sections, header)
	}
	sections = append(sections, body)
	bottom := joinNonEmpty(status, footer)
	if bottom != "" {
		sections = append(sections, bottom)
	}
	frame := strings.Join(sections, "\n\n")
	return strings.TrimRight(frame, " \n") + "\n"
}

func renderPageBody(page terminalPage, width, height int) string {
	primaryContent := page.primary
	if page.wrapPrimary {
		primaryContent = lipgloss.NewStyle().Width(width).Render(primaryContent)
	}
	if page.context == "" || height < 5 {
		return viewportContentAt(primaryContent, width, height, page.primaryOffset, page.focusLine)
	}

	context := page.context
	if page.wrapContext {
		context = lipgloss.NewStyle().Width(width).Render(context)
	}
	contextHeight := min(lineCount(context), max(3, height/2))
	primaryHeight := height - contextHeight - 1
	if primaryHeight < 1 {
		primaryHeight = 1
		contextHeight = max(1, height-primaryHeight-1)
	}
	primary := viewportContentAt(primaryContent, width, primaryHeight, page.primaryOffset, page.focusLine)
	contextFocus := -1
	if page.anchorContext {
		contextFocus = page.contextAnchor
	}
	context = viewportContentAt(context, width, contextHeight, page.contextOffset, contextFocus)
	return primary + "\n\n" + context
}

func viewportContent(content string, width, height, focusLine int) string {
	return viewportContentAt(content, width, height, 0, focusLine)
}

func viewportContentAt(content string, width, height, offset, focusLine int) string {
	if content == "" || width <= 0 || height <= 0 {
		return ""
	}
	view := viewport.New(width, height)
	view.SetContent(strings.TrimRight(content, "\n"))
	top := max(0, offset)
	if focusLine >= 0 {
		if focusLine < top {
			top = focusLine
		} else if focusLine >= top+height {
			top = focusLine - height + 1
		}
	}
	view.SetYOffset(top)
	return view.View()
}

func lineCount(content string) int {
	if content == "" {
		return 0
	}
	return strings.Count(strings.TrimRight(content, "\n"), "\n") + 1
}

func joinNonEmpty(values ...string) string {
	var present []string
	for _, value := range values {
		if value != "" {
			present = append(present, value)
		}
	}
	return strings.Join(present, "\n")
}

func (p terminalPresentation) minimumSizeView(width, height int) string {
	return fmt.Sprintf("%s\n\nMinimum size: 60×16\nCurrent size: %d×%d\nResize the terminal to continue.",
		p.theme.warning.Render("Terminal too small"), width, height)
}